Commit Graph

597 Commits

Author SHA1 Message Date
Christian Göttsche
2b86e04bce selinux: use GFP_KERNEL while reading binary policy
Use GFP_KERNEL instead of GFP_ATOMIC while reading a binary policy in
sens_read() and cat_read(), similar to surrounding code.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-08-08 13:40:53 -04:00
Christian Göttsche
c50e125d05 selinux: avoid implicit conversions in services code
Use u32 as the output parameter type in security_get_classes() and
security_get_permissions(), based on the type of the symtab nprim
member.

Declare the read-only class string parameter of
security_get_permissions() const.

Avoid several implicit conversions by using the identical type for the
destination.

Use the type identical to the source for local variables.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: cleanup extra whitespace in subject]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-08-03 22:19:57 -04:00
Christian Göttsche
fd5a90ff1e selinux: avoid implicit conversions in mls code
Use u32 for ebitmap bits and sensitivity levels, char for the default
range of a class.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: description tweaks]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-08-03 22:19:57 -04:00
Christian Göttsche
c17c55c2d1 selinux: use identical iterator type in hashtab_duplicate()
Use the identical type u32 for the loop iterator.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: remove extra whitespace in subject]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-08-03 22:19:56 -04:00
Christian Göttsche
f01dd59045 selinux: move debug functions into debug configuration
avtab_hash_eval() and hashtab_stat() are only used in policydb.c when
the configuration SECURITY_SELINUX_DEBUG is enabled.

Move the function definitions under that configuration as well and
provide empty definitions in case SECURITY_SELINUX_DEBUG is disabled, to
avoid using #ifdef in the callers.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-07-28 14:09:24 -04:00
Christian Göttsche
55a0e73806 selinux: introduce SECURITY_SELINUX_DEBUG configuration
The policy database code contains several debug output statements
related to hashtable utilization.  Those are guarded by the macro
DEBUG_HASHES, which is neither documented nor set anywhere.

Introduce a new Kconfig configuration guarding this and potential
other future debugging related code.  Disable the setting by default.

Suggested-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: fixed line lengths in the help text]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-07-20 16:21:52 -04:00
Stephen Smalley
0fe53224bf selinux: update my email address
Update my email address; MAINTAINERS was updated some time ago.

Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-07-19 11:27:02 -04:00
Christian Göttsche
e5faa839c3 selinux: add missing newlines in pr_err() statements
The kernel print statements do not append an implicit newline to format
strings.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-07-19 11:12:48 -04:00
Christian Göttsche
08a12b39e2 selinux: drop avtab_search()
avtab_search() shares the same logic with avtab_search_node(), except
that it returns, if found, a pointer to the struct avtab_node member
datum instead of the node itself.  Since the member is an embedded
struct, and not a pointer, the returned value of avtab_search() and
avtab_search_node() will always in unison either be NULL or non-NULL.

Drop avtab_search() and replace its calls by avtab_search_node() to
deduplicate logic and adopt the only caller caring for the type of
the returned value accordingly.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-07-19 11:04:28 -04:00
Christian Göttsche
0e83c9c6fb selinux: fix implicit conversions in the symtab
hashtab_init() takes an u32 as size parameter type.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: subject line tweaks]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-07-18 18:29:49 -04:00
Christian Göttsche
7128578c79 selinux: use consistent type for AV rule specifier
The specifier for avtab keys is always supplied with a type of u16,
either as a macro to security_compute_sid() or the member specified of
the struct avtab_key.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-07-18 18:29:49 -04:00
Christian Göttsche
f785c54101 selinux: avoid avtab overflows
Prevent inserting more than the supported U32_MAX number of entries.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-07-18 18:29:47 -04:00
Christian Göttsche
bbea03f474 selinux: check for multiplication overflow in put_entry()
The function is always inlined and most of the time both relevant
arguments are compile time constants, allowing compilers to elide the
check.  Also the function is part of outputting the policy, which is not
performance critical.

Also convert the type of the third parameter into a size_t, since it
should always be a non-negative number of elements.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-07-18 18:29:46 -04:00
Ondrej Mosnacek
5b0eea835d selinux: introduce an initial SID for early boot processes
Currently, SELinux doesn't allow distinguishing between kernel threads
and userspace processes that are started before the policy is first
loaded - both get the label corresponding to the kernel SID. The only
way a process that persists from early boot can get a meaningful label
is by doing a voluntary dyntransition or re-executing itself.

Reusing the kernel label for userspace processes is problematic for
several reasons:
1. The kernel is considered to be a privileged domain and generally
   needs to have a wide range of permissions allowed to work correctly,
   which prevents the policy writer from effectively hardening against
   early boot processes that might remain running unintentionally after
   the policy is loaded (they represent a potential extra attack surface
   that should be mitigated).
2. Despite the kernel being treated as a privileged domain, the policy
   writer may want to impose certain special limitations on kernel
   threads that may conflict with the requirements of intentional early
   boot processes. For example, it is a good hardening practice to limit
   what executables the kernel can execute as usermode helpers and to
   confine the resulting usermode helper processes. However, a
   (legitimate) process surviving from early boot may need to execute a
   different set of executables.
3. As currently implemented, overlayfs remembers the security context of
   the process that created an overlayfs mount and uses it to bound
   subsequent operations on files using this context. If an overlayfs
   mount is created before the SELinux policy is loaded, these "mounter"
   checks are made against the kernel context, which may clash with
   restrictions on the kernel domain (see 2.).

To resolve this, introduce a new initial SID (reusing the slot of the
former "init" initial SID) that will be assigned to any userspace
process started before the policy is first loaded. This is easy to do,
as we can simply label any process that goes through the
bprm_creds_for_exec LSM hook with the new init-SID instead of
propagating the kernel SID from the parent.

To provide backwards compatibility for existing policies that are
unaware of this new semantic of the "init" initial SID, introduce a new
policy capability "userspace_initial_context" and set the "init" SID to
the same context as the "kernel" SID unless this capability is set by
the policy.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-07-10 14:23:56 -04:00
Christian Göttsche
447a568800 selinux: avoid bool as identifier name
Avoid using the identifier `bool` to improve support with future C
standards.  C23 is about to make `bool` a predefined macro (see N2654).

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-06-05 17:04:01 -04:00
Christian Göttsche
8bfbd046a3 selinux: deprecated fs ocon
The object context type `fs`, not to be confused with the well used
object context type `fscon`, was introduced in the initial git commit
1da177e4c3 ("Linux-2.6.12-rc2") but never actually used since.

The paper "A Security Policy Configuration for the Security-Enhanced
Linux" [1] mentions it under `7.2 File System Contexts` but also states:

    Currently, this configuration is unused.

The policy statement defining such object contexts is `fscon`, e.g.:

    fscon 2 3 gen_context(system_u:object_r:conA_t,s0) \
        gen_context(system_u:object_r:conB_t,s0)

It is not documented at selinuxproject.org or in the SELinux notebook
and not supported by the Reference Policy buildsystem - the statement is
not properly sorted - and thus not used in the Reference or Fedora
Policy.

Print a warning message at policy load for each such object context:

    SELinux:  void and deprecated fs ocon 02:03

This topic was initially highlighted by Nicolas Iooss [2].

[1]: https://media.defense.gov/2021/Jul/29/2002815735/-1/-1/0/SELINUX-SECURITY-POLICY-CONFIGURATION-REPORT.PDF
[2]: https://lore.kernel.org/selinux/CAJfZ7=mP2eJaq2BfO3y0VnwUJaY2cS2p=HZMN71z1pKjzaT0Eg@mail.gmail.com/

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: tweaked deprecation comment, description line wrapping]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-05-23 15:37:56 -04:00
Christian Göttsche
ed99135f76 selinux: keep context struct members in sync
Commit 53f3517ae0 ("selinux: do not leave dangling pointer behind")
reset the `str` field of the `context` struct in an OOM error branch.
In this struct the fields `str` and `len` are coupled and should be kept
in sync.  Set the length to zero according to the string be set to NULL.

Fixes: 53f3517ae0 ("selinux: do not leave dangling pointer behind")
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-05-18 13:38:39 -04:00
Paul Moore
c52df19e37 selinux: small cleanups in selinux_audit_rule_init()
A few small tweaks to selinux_audit_rule_init():

- Adjust how we use the @rc variable so we are not doing any extra
  work in the common/success case.

- Related to the above, rework the 'out' jump label so that the
  success and error paths are different, simplifying both.

- Cleanup some of the vertical whitespace while we are making the
  other changes.

Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-05-08 16:53:41 -04:00
Christian Göttsche
4158cb6000 selinux: declare read-only data arrays const
The array of mount tokens in only used in match_opt_prefix() and never
modified.

The array of symtab names is never modified and only used in the
DEBUG_HASHES configuration as output.

The array of files for the SElinux filesystem sub-directory `ss` is
similar to the other `struct tree_descr` usages only read from to
construct the containing entries.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-05-08 16:52:05 -04:00
Christian Göttsche
4595ae8c4a selinux: retain const qualifier on string literal in avtab_hash_eval()
The second parameter `tag` of avtab_hash_eval() is only used for
printing.  In policydb_index() it is called with a string literal:

    avtab_hash_eval(&p->te_avtab, "rules");

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: slight formatting tweak in description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-05-08 16:49:14 -04:00
Christian Göttsche
3d9047a064 selinux: adjust typos in comments
Found by codespell(1)

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-05-08 16:44:01 -04:00
Christian Göttsche
53f3517ae0 selinux: do not leave dangling pointer behind
In case mls_context_cpy() fails due to OOM set the free'd pointer in
context_cpy() to NULL to avoid it potentially being dereferenced or
free'd again in future.  Freeing a NULL pointer is well-defined and a
hard NULL dereference crash is at least not exploitable and should give
a workable stack trace.

Fixes: 12b29f3455 ("selinux: support deferred mapping of contexts")
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-05-08 16:37:42 -04:00
Stephen Smalley
e67b79850f selinux: stop passing selinux_state pointers and their offspring
Linus observed that the pervasive passing of selinux_state pointers
introduced by me in commit aa8e712cee ("selinux: wrap global selinux
state") adds overhead and complexity without providing any
benefit. The original idea was to pave the way for SELinux namespaces
but those have not yet been implemented and there isn't currently
a concrete plan to do so. Remove the passing of the selinux_state
pointers, reverting to direct use of the single global selinux_state,
and likewise remove passing of child pointers like the selinux_avc.
The selinux_policy pointer remains as it is needed for atomic switching
of policies.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202303101057.mZ3Gv5fK-lkp@intel.com/
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-03-14 15:22:45 -04:00
Linus Torvalds
57888f7b95 selinux/stable-6.2 PR 20221212
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Merge tag 'selinux-pr-20221212' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:
 "Two SELinux patches: one increases the sleep time on deprecated
  functionality, and one removes the indirect calls in the sidtab
  context conversion code"

* tag 'selinux-pr-20221212' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: remove the sidtab context conversion indirect calls
  selinux: increase the deprecation sleep for checkreqprot and runtime disable
2022-12-13 09:32:05 -08:00
Paul Moore
048be15649 selinux: remove the sidtab context conversion indirect calls
The sidtab conversion code has support for multiple context
conversion routines through the use of function pointers and
indirect calls.  However, the reality is that all current users rely
on the same conversion routine: convert_context().  This patch does
away with this extra complexity and replaces the indirect calls
with direct function calls; allowing us to remove a layer of
obfuscation and create cleaner, more maintainable code.

Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-11-09 11:00:49 -05:00
GONG, Ruiqi
abe3c63144 selinux: enable use of both GFP_KERNEL and GFP_ATOMIC in convert_context()
The following warning was triggered on a hardware environment:

  SELinux: Converting 162 SID table entries...
  BUG: sleeping function called from invalid context at
       __might_sleep+0x60/0x74 0x0
  in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 5943, name: tar
  CPU: 7 PID: 5943 Comm: tar Tainted: P O 5.10.0 #1
  Call trace:
   dump_backtrace+0x0/0x1c8
   show_stack+0x18/0x28
   dump_stack+0xe8/0x15c
   ___might_sleep+0x168/0x17c
   __might_sleep+0x60/0x74
   __kmalloc_track_caller+0xa0/0x7dc
   kstrdup+0x54/0xac
   convert_context+0x48/0x2e4
   sidtab_context_to_sid+0x1c4/0x36c
   security_context_to_sid_core+0x168/0x238
   security_context_to_sid_default+0x14/0x24
   inode_doinit_use_xattr+0x164/0x1e4
   inode_doinit_with_dentry+0x1c0/0x488
   selinux_d_instantiate+0x20/0x34
   security_d_instantiate+0x70/0xbc
   d_splice_alias+0x4c/0x3c0
   ext4_lookup+0x1d8/0x200 [ext4]
   __lookup_slow+0x12c/0x1e4
   walk_component+0x100/0x200
   path_lookupat+0x88/0x118
   filename_lookup+0x98/0x130
   user_path_at_empty+0x48/0x60
   vfs_statx+0x84/0x140
   vfs_fstatat+0x20/0x30
   __se_sys_newfstatat+0x30/0x74
   __arm64_sys_newfstatat+0x1c/0x2c
   el0_svc_common.constprop.0+0x100/0x184
   do_el0_svc+0x1c/0x2c
   el0_svc+0x20/0x34
   el0_sync_handler+0x80/0x17c
   el0_sync+0x13c/0x140
  SELinux: Context system_u:object_r:pssp_rsyslog_log_t:s0:c0 is
           not valid (left unmapped).

It was found that within a critical section of spin_lock_irqsave in
sidtab_context_to_sid(), convert_context() (hooked by
sidtab_convert_params.func) might cause the process to sleep via
allocating memory with GFP_KERNEL, which is problematic.

As Ondrej pointed out [1], convert_context()/sidtab_convert_params.func
has another caller sidtab_convert_tree(), which is okay with GFP_KERNEL.
Therefore, fix this problem by adding a gfp_t argument for
convert_context()/sidtab_convert_params.func and pass GFP_KERNEL/_ATOMIC
properly in individual callers.

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20221018120111.1474581-1-gongruiqi1@huawei.com/ [1]
Reported-by: Tan Ninghao <tanninghao1@huawei.com>
Fixes: ee1a84fdfe ("selinux: overhaul sidtab to fix bug and improve performance")
Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>
Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
[PM: wrap long BUG() output lines, tweak subject line]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-10-19 09:55:53 -04:00
Christian Göttsche
6354324d8a selinux: declare read-only parameters const
Declare ebitmap, mls_level and mls_context parameters const where they
are only read from.  This allows callers to supply pointers to const
as arguments and increases readability.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-08-30 17:14:36 -04:00
Xiu Jianfeng
15ec76fb29 selinux: Add boundary check in put_entry()
Just like next_entry(), boundary check is necessary to prevent memory
out-of-bound access.

Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-06-14 21:52:37 -04:00
Xiu Jianfeng
73de1befcc selinux: fix memleak in security_read_state_kernel()
In this function, it directly returns the result of __security_read_policy
without freeing the allocated memory in *data, cause memory leak issue,
so free the memory if __security_read_policy failed.

Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-06-13 19:31:53 -04:00
Linus Torvalds
efd1df1982 selinux/stable-5.19 PR 20220523
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Merge tag 'selinux-pr-20220523' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:
 "We've got twelve patches queued for v5.19, with most being fairly
  minor. The highlights are below:

   - The checkreqprot and runtime disable knobs have been deprecated for
     some time with no active users that we can find. In an effort to
     move things along we are adding a pause when the knobs are used to
     help make the deprecation more noticeable in case anyone is still
     using these hacks in the shadows.

   - We've added the anonymous inode class name to the AVC audit records
     when anonymous inodes are involved. This should make writing policy
     easier when anonymous inodes are involved.

   - More constification work. This is fairly straightforward and the
     source of most of the diffstat.

   - The usual minor cleanups: remove unnecessary assignments, assorted
     style/checkpatch fixes, kdoc fixes, macro while-loop
     encapsulations, #include tweaks, etc"

* tag 'selinux-pr-20220523' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  security: declare member holding string literal const
  selinux: log anon inode class name
  selinux: declare data arrays const
  selinux: fix indentation level of mls_ops block
  selinux: include necessary headers in headers
  selinux: avoid extra semicolon
  selinux: update parameter documentation
  selinux: resolve checkpatch errors
  selinux: don't sleep when CONFIG_SECURITY_SELINUX_CHECKREQPROT_VALUE is true
  selinux: checkreqprot is deprecated, add some ssleep() discomfort
  selinux: runtime disable is deprecated, add some ssleep() discomfort
  selinux: Remove redundant assignments
2022-05-24 13:06:32 -07:00
Ondrej Mosnacek
6254bd3db3 selinux: fix bad cleanup on error in hashtab_duplicate()
The code attempts to free the 'new' pointer using kmem_cache_free(),
which is wrong because this function isn't responsible of freeing it.
Instead, the function should free new->htable and clear the contents of
*new (to prevent double-free).

Cc: stable@vger.kernel.org
Fixes: c7c556f1e8 ("selinux: refactor changing booleans")
Reported-by: Wander Lairson Costa <wander@redhat.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-05-17 18:34:35 -04:00
Christian Göttsche
ded34574d4 selinux: declare data arrays const
The arrays for the policy capability names, the initial sid identifiers
and the class and permission names are not changed at runtime.  Declare
them const to avoid accidental modification.

Do not override the classmap and the initial sid list in the build time
script genheaders.

Check flose(3) is successful in genheaders.c, otherwise the written data
might be corrupted or incomplete.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: manual merge due to fuzz, minor style tweaks]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-05-03 15:53:49 -04:00
Christian Göttsche
a9029d9704 selinux: fix indentation level of mls_ops block
Add one level of indentation to the code block of the label mls_ops in
constraint_expr_eval(), to adjust the trailing break; to the parent
case: branch.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-05-03 14:26:53 -04:00
Christian Göttsche
1d4e8036cb selinux: avoid extra semicolon
Wrap macro into `do { } while (0)` to avoid Clang emitting warnings
about extra semicolons.
Similar to userspace commit
9d85aa60d1

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: whitespace/indenting tweaks]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-05-03 14:07:11 -04:00
Christian Göttsche
ede17552b1 selinux: resolve checkpatch errors
Reported by checkpatch:

    security/selinux/nlmsgtab.c
    ---------------------------
    ERROR: that open brace { should be on the previous line
    #29: FILE: security/selinux/nlmsgtab.c:29:
    +static const struct nlmsg_perm nlmsg_route_perms[] =
    +{

    ERROR: that open brace { should be on the previous line
    #97: FILE: security/selinux/nlmsgtab.c:97:
    +static const struct nlmsg_perm nlmsg_tcpdiag_perms[] =
    +{

    ERROR: that open brace { should be on the previous line
    #105: FILE: security/selinux/nlmsgtab.c:105:
    +static const struct nlmsg_perm nlmsg_xfrm_perms[] =
    +{

    ERROR: that open brace { should be on the previous line
    #134: FILE: security/selinux/nlmsgtab.c:134:
    +static const struct nlmsg_perm nlmsg_audit_perms[] =
    +{

    security/selinux/ss/policydb.c
    ------------------------------
    ERROR: that open brace { should be on the previous line
    #318: FILE: security/selinux/ss/policydb.c:318:
    +static int (*destroy_f[SYM_NUM]) (void *key, void *datum, void *datap) =
    +{

    ERROR: that open brace { should be on the previous line
    #674: FILE: security/selinux/ss/policydb.c:674:
    +static int (*index_f[SYM_NUM]) (void *key, void *datum, void *datap) =
    +{

    ERROR: that open brace { should be on the previous line
    #1643: FILE: security/selinux/ss/policydb.c:1643:
    +static int (*read_f[SYM_NUM]) (struct policydb *p, struct symtab *s, void *fp) =
    +{

    ERROR: that open brace { should be on the previous line
    #3246: FILE: security/selinux/ss/policydb.c:3246:
    +                               void *datap) =
    +{

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-05-03 13:59:15 -04:00
Michal Orzel
0a9876f36b selinux: Remove redundant assignments
Get rid of redundant assignments which end up in values not being
read either because they are overwritten or the function ends.

Reported by clang-tidy [deadcode.DeadStores]

Signed-off-by: Michal Orzel <michalorzel.eng@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-04-04 15:38:53 -04:00
Linus Torvalds
c269497d24 selinux/stable-5.18 PR 20220321
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Merge tag 'selinux-pr-20220321' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:
 "We've got a number of SELinux patches queued up, the highlights are:

   - Fixup the security_fs_context_parse_param() LSM hook so it executes
     all of the LSM hook implementations unless a serious error occurs.

     We also correct the SELinux hook implementation so that it returns
     zero on success.

   - In addition to a few SELinux mount option parsing fixes, we
     simplified the parsing by moving it earlier in the process.

     The logic was that it was unlikely an admin/user would use the new
     mount API and not have the policy loaded before passing the SELinux
     options.

   - Properly fixed the LSM/SELinux/SCTP hooks with the addition of the
     security_sctp_assoc_established() hook.

     This work was done in conjunction with the netdev folks and should
     complete the move of the SCTP labeling from the endpoints to the
     associations.

   - Fixed a variety of sparse warnings caused by changes in the "__rcu"
     markings of some core kernel structures.

   - Ensure we access the superblock's LSM security blob using the
     stacking-safe accessors.

   - Added the ability for the kernel to always allow FIOCLEX and
     FIONCLEX if the "ioctl_skip_cloexec" policy capability is
     specified.

   - Various constifications improvements, type casting improvements,
     additional return value checks, and dead code/parameter removal.

   - Documentation fixes"

* tag 'selinux-pr-20220321' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux: (23 commits)
  selinux: shorten the policy capability enum names
  docs: fix 'make htmldocs' warning in SCTP.rst
  selinux: allow FIOCLEX and FIONCLEX with policy capability
  selinux: use correct type for context length
  selinux: drop return statement at end of void functions
  security: implement sctp_assoc_established hook in selinux
  security: add sctp_assoc_established hook
  selinux: parse contexts for mount options early
  selinux: various sparse fixes
  selinux: try to use preparsed sid before calling parse_sid()
  selinux: Fix selinux_sb_mnt_opts_compat()
  LSM: general protection fault in legacy_parse_param
  selinux: fix a type cast problem in cred_init_security()
  selinux: drop unused macro
  selinux: simplify cred_init_security
  selinux: do not discard const qualifier in cast
  selinux: drop unused parameter of avtab_insert_node
  selinux: drop cast to same type
  selinux: enclose macro arguments in parenthesis
  selinux: declare name parameter of hash_eval const
  ...
2022-03-21 20:47:54 -07:00
Christian Göttsche
5ea33af9d4 selinux: drop return statement at end of void functions
Those return statements at the end of a void function are redundant.

Reported by clang-tidy [readability-redundant-control-flow]

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-02-18 10:42:12 -05:00
Vratislav Bendel
186edf7e36 selinux: fix double free of cond_list on error paths
On error path from cond_read_list() and duplicate_policydb_cond_list()
the cond_list_destroy() gets called a second time in caller functions,
resulting in NULL pointer deref.  Fix this by resetting the
cond_list_len to 0 in cond_list_destroy(), making subsequent calls a
noop.

Also consistently reset the cond_list pointer to NULL after freeing.

Cc: stable@vger.kernel.org
Signed-off-by: Vratislav Bendel <vbendel@redhat.com>
[PM: fix line lengths in the description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-02-02 11:02:10 -05:00
Christian Göttsche
b5e68162f8 selinux: drop unused macro
The macro _DEBUG_HASHES is nowhere used. The configuration DEBUG_HASHES
enables debugging of the SELinux hash tables, but the with an underscore
prefixed macro definition has no direct impact or any documentation.

Reported by clang [-Wunused-macros]

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-01-26 16:17:18 -05:00
Christian Göttsche
056945a96c selinux: drop unused parameter of avtab_insert_node
The parameter cur is not used in avtab_insert_node().

Reported by clang [-Wunused-parameter]

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-01-26 15:37:27 -05:00
Christian Göttsche
0b3c2b3dc9 selinux: drop cast to same type
Both the lvalue scontextp and rvalue scontext are of the type char*.
Drop the redundant explicit cast not needed since commit 9a59daa03d
("SELinux: fix sleeping allocation in security_context_to_sid"), where
the type of scontext changed from const char* to char*.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-01-26 15:25:47 -05:00
Christian Göttsche
9e2fe574c0 selinux: enclose macro arguments in parenthesis
Enclose the macro arguments in parenthesis to avoid potential evaluation
order issues.

Note the xperm and ebitmap macros are still not side-effect safe due to
double evaluation.

Reported by clang-tidy [bugprone-macro-parentheses]

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-01-26 15:13:58 -05:00
Christian Göttsche
d3b1161f29 selinux: declare name parameter of hash_eval const
String literals are passed as second argument to hash_eval(). Also the
parameter is already declared const in the DEBUG_HASHES configuration.

Reported by clang [-Wwrite-strings]:

    security/selinux/ss/policydb.c:1881:26: error: passing
      'const char [8]' to parameter of type 'char *' discards
      qualifiers
            hash_eval(&p->range_tr, rangetr);
                                    ^~~~~~~~~
    security/selinux/ss/policydb.c:707:55: note: passing argument to
      parameter 'hash_name' here
    static inline void hash_eval(struct hashtab *h, char *hash_name)
                                                          ^
    security/selinux/ss/policydb.c:2099:32: error: passing
      'const char [11]' to parameter of type 'char *' discards
      qualifiers
            hash_eval(&p->filename_trans, filenametr);
                                          ^~~~~~~~~~~~
    security/selinux/ss/policydb.c:707:55: note: passing argument to
      parameter 'hash_name' here
    static inline void hash_eval(struct hashtab *h, char *hash_name)
                                                          ^

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: line wrapping in description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-01-26 13:54:25 -05:00
Christian Göttsche
08df49054f selinux: declare path parameters of _genfs_sid const
The path parameter is only read from in security_genfs_sid(),
selinux_policy_genfs_sid() and __security_genfs_sid(). Since a string
literal is passed as argument, declare the parameter const.
Also align the parameter names in the declaration and definition.

Reported by clang [-Wwrite-strings]:

    security/selinux/hooks.c:553:60: error: passing 'const char [2]'
      to parameter of type 'char *' discards qualifiers
      [-Wincompatible-pointer-types-discards-qualifiers]
            rc = security_genfs_sid(&selinux_state, ... , /,
                                                          ^~~
    ./security/selinux/include/security.h:389:36: note: passing
      argument to parameter 'name' here
                           const char *fstype, char *name, u16 sclass,
                                                     ^

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: wrapped description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-01-25 19:59:52 -05:00
Linus Torvalds
a135ce4400 selinux/stable-5.17 PR 20220110
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Merge tag 'selinux-pr-20220110' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:
 "Nothing too significant, but five SELinux patches for v5.17 that do
  the following:

   - Harden the code through additional use of the struct_size() macro

   - Plug some memory leaks

   - Clean up the code via removal of the security_add_mnt_opt() LSM
     hook and minor tweaks to selinux_add_opt()

   - Rename security_task_getsecid_subj() to better reflect its actual
     behavior/use - now called security_current_getsecid_subj()"

* tag 'selinux-pr-20220110' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: minor tweaks to selinux_add_opt()
  selinux: fix potential memleak in selinux_add_opt()
  security,selinux: remove security_add_mnt_opt()
  selinux: Use struct_size() helper in kmalloc()
  lsm: security_task_getsecid_subj() -> security_current_getsecid_subj()
2022-01-11 13:03:06 -08:00
Xiu Jianfeng
5fe3757289 selinux: Use struct_size() helper in kmalloc()
Make use of struct_size() helper instead of an open-coded calculation.

Link: https://github.com/KSPP/linux/issues/160
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-12-05 21:58:32 -05:00
Ondrej Mosnacek
dc27f3c5d1 selinux: fix NULL-pointer dereference when hashtab allocation fails
When the hash table slot array allocation fails in hashtab_init(),
h->size is left initialized with a non-zero value, but the h->htable
pointer is NULL. This may then cause a NULL pointer dereference, since
the policydb code relies on the assumption that even after a failed
hashtab_init(), hashtab_map() and hashtab_destroy() can be safely called
on it. Yet, these detect an empty hashtab only by looking at the size.

Fix this by making sure that hashtab_init() always leaves behind a valid
empty hashtab when the allocation fails.

Cc: stable@vger.kernel.org
Fixes: 03414a49ad ("selinux: do not allocate hashtabs dynamically")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-11-19 16:11:39 -05:00
Paul Moore
e9fd729293 selinux: fix all of the W=1 build warnings
There were a number of places in the code where the function
definition did not match the associated comment block as well
at least one file where the appropriate header files were not
included (missing function declaration/prototype); this patch
fixes all of these issue such that building the SELinux code
with "W=1" is now warning free.

 % make W=1 security/selinux/

Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-10-13 16:31:51 -04:00
Ondrej Mosnacek
cbfcd13be5 selinux: fix race condition when computing ocontext SIDs
Current code contains a lot of racy patterns when converting an
ocontext's context structure to an SID. This is being done in a "lazy"
fashion, such that the SID is looked up in the SID table only when it's
first needed and then cached in the "sid" field of the ocontext
structure. However, this is done without any locking or memory barriers
and is thus unsafe.

Between commits 24ed7fdae6 ("selinux: use separate table for initial
SID lookup") and 66f8e2f03c ("selinux: sidtab reverse lookup hash
table"), this race condition lead to an actual observable bug, because a
pointer to the shared sid field was passed directly to
sidtab_context_to_sid(), which was using this location to also store an
intermediate value, which could have been read by other threads and
interpreted as an SID. In practice this caused e.g. new mounts to get a
wrong (seemingly random) filesystem context, leading to strange denials.
This bug has been spotted in the wild at least twice, see [1] and [2].

Fix the race condition by making all the racy functions use a common
helper that ensures the ocontext::sid accesses are made safely using the
appropriate SMP constructs.

Note that security_netif_sid() was populating the sid field of both
contexts stored in the ocontext, but only the first one was actually
used. The SELinux wiki's documentation on the "netifcon" policy
statement [3] suggests that using only the first context is intentional.
I kept only the handling of the first context here, as there is really
no point in doing the SID lookup for the unused one.

I wasn't able to reproduce the bug mentioned above on any kernel that
includes commit 66f8e2f03c, even though it has been reported that the
issue occurs with that commit, too, just less frequently. Thus, I wasn't
able to verify that this patch fixes the issue, but it makes sense to
avoid the race condition regardless.

[1] https://github.com/containers/container-selinux/issues/89
[2] https://lists.fedoraproject.org/archives/list/selinux@lists.fedoraproject.org/thread/6DMTAMHIOAOEMUAVTULJD45JZU7IBAFM/
[3] https://selinuxproject.org/page/NetworkStatements#netifcon

Cc: stable@vger.kernel.org
Cc: Xinjie Zheng <xinjie@google.com>
Reported-by: Sujithra Periasamy <sujithra@google.com>
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-10-11 19:18:04 -04:00
Linus Torvalds
befa491ce6 Merge tag 'selinux-pr-20210830' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux
Pull selinux update from Paul Moore:
 "We've got an unusually small SELinux pull request for v5.15 that
  consists of only one (?!) patch that is really pretty minor when you
  look at it.

  Unsurprisingly it passes all of our tests and merges cleanly on top of
  your tree right now, please merge this for v5.15"

* tag 'selinux-pr-20210830' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: return early for possible NULL audit buffers
2021-08-31 12:53:34 -07:00
Xiu Jianfeng
4c156084da selinux: correct the return value when loads initial sids
It should not return 0 when SID 0 is assigned to isids.
This patch fixes it.

Cc: stable@vger.kernel.org
Fixes: e3e0b582c3 ("selinux: remove unused initial SIDs and improve handling")
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
[PM: remove changelog from description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-08-02 09:59:50 -04:00
Austin Kim
893c47d196 selinux: return early for possible NULL audit buffers
audit_log_start() may return NULL in below cases:

  - when audit is not initialized.
  - when audit backlog limit exceeds.

After the call to audit_log_start() is made and then possible NULL audit
buffer argument is passed to audit_log_*() functions,
audit_log_*() functions return immediately in case of a NULL audit buffer
argument.

But it is optimal to return early when audit_log_start() returns NULL,
because it is not necessary for audit_log_*() functions to be called with
NULL audit buffer argument.

So add exception handling for possible NULL audit buffers where
return value can be handled from callers.

Signed-off-by: Austin Kim <austin.kim@lge.com>
[PM: tweak subject line]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-07-14 15:25:27 -04:00
Yang Li
d0a83314db selinux: Fix kernel-doc
Fix function name and add comment for parameter state in ss/services.c 
kernel-doc to remove some warnings found by running make W=1 LLVM=1.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-06-11 12:59:45 -04:00
Jiapeng Chong
fd781f459b selinux: Remove redundant assignment to rc
Variable rc is set to '-EINVAL' but this value is never read as
it is overwritten or not used later on, hence it is a redundant
assignment and can be removed.

Cleans up the following clang-analyzer warning:

security/selinux/ss/services.c:2103:3: warning: Value stored to 'rc' is
never read [clang-analyzer-deadcode.DeadStores].

security/selinux/ss/services.c:2079:2: warning: Value stored to 'rc' is
never read [clang-analyzer-deadcode.DeadStores].

security/selinux/ss/services.c:2071:2: warning: Value stored to 'rc' is
never read [clang-analyzer-deadcode.DeadStores].

security/selinux/ss/services.c:2062:2: warning: Value stored to 'rc' is
never read [clang-analyzer-deadcode.DeadStores].

security/selinux/ss/policydb.c:2592:3: warning: Value stored to 'rc' is
never read [clang-analyzer-deadcode.DeadStores].

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-05-10 21:48:11 -04:00
Ondrej Mosnacek
e1cce3a3cb selinux: constify some avtab function arguments
This makes the code a bit easier to reason about.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-05-10 21:35:02 -04:00
Ondrej Mosnacek
fba472bb38 selinux: simplify duplicate_policydb_cond_list() by using kmemdup()
We can do the allocation + copying of expr.nodes in one go using
kmemdup().

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-05-10 21:31:58 -04:00
Linus Torvalds
17ae69aba8 Add Landlock, a new LSM from Mickaël Salaün <mic@linux.microsoft.com>
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Merge tag 'landlock_v34' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull Landlock LSM from James Morris:
 "Add Landlock, a new LSM from Mickaël Salaün.

  Briefly, Landlock provides for unprivileged application sandboxing.

  From Mickaël's cover letter:
    "The goal of Landlock is to enable to restrict ambient rights (e.g.
     global filesystem access) for a set of processes. Because Landlock
     is a stackable LSM [1], it makes possible to create safe security
     sandboxes as new security layers in addition to the existing
     system-wide access-controls. This kind of sandbox is expected to
     help mitigate the security impact of bugs or unexpected/malicious
     behaviors in user-space applications. Landlock empowers any
     process, including unprivileged ones, to securely restrict
     themselves.

     Landlock is inspired by seccomp-bpf but instead of filtering
     syscalls and their raw arguments, a Landlock rule can restrict the
     use of kernel objects like file hierarchies, according to the
     kernel semantic. Landlock also takes inspiration from other OS
     sandbox mechanisms: XNU Sandbox, FreeBSD Capsicum or OpenBSD
     Pledge/Unveil.

     In this current form, Landlock misses some access-control features.
     This enables to minimize this patch series and ease review. This
     series still addresses multiple use cases, especially with the
     combined use of seccomp-bpf: applications with built-in sandboxing,
     init systems, security sandbox tools and security-oriented APIs [2]"

  The cover letter and v34 posting is here:

      https://lore.kernel.org/linux-security-module/20210422154123.13086-1-mic@digikod.net/

  See also:

      https://landlock.io/

  This code has had extensive design discussion and review over several
  years"

Link: https://lore.kernel.org/lkml/50db058a-7dde-441b-a7f9-f6837fe8b69f@schaufler-ca.com/ [1]
Link: https://lore.kernel.org/lkml/f646e1c7-33cf-333f-070c-0a40ad0468cd@digikod.net/ [2]

* tag 'landlock_v34' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  landlock: Enable user space to infer supported features
  landlock: Add user and kernel documentation
  samples/landlock: Add a sandbox manager example
  selftests/landlock: Add user space tests
  landlock: Add syscall implementations
  arch: Wire up Landlock syscalls
  fs,security: Add sb_delete hook
  landlock: Support filesystem access-control
  LSM: Infrastructure management of the superblock
  landlock: Add ptrace restrictions
  landlock: Set up the security framework and manage credentials
  landlock: Add ruleset and domain management
  landlock: Add object management
2021-05-01 18:50:44 -07:00
Linus Torvalds
f1c921fb70 selinux/stable-5.13 PR 20210426
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Merge tag 'selinux-pr-20210426' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:

 - Add support for measuring the SELinux state and policy capabilities
   using IMA.

 - A handful of SELinux/NFS patches to compare the SELinux state of one
   mount with a set of mount options. Olga goes into more detail in the
   patch descriptions, but this is important as it allows more
   flexibility when using NFS and SELinux context mounts.

 - Properly differentiate between the subjective and objective LSM
   credentials; including support for the SELinux and Smack. My clumsy
   attempt at a proper fix for AppArmor didn't quite pass muster so John
   is working on a proper AppArmor patch, in the meantime this set of
   patches shouldn't change the behavior of AppArmor in any way. This
   change explains the bulk of the diffstat beyond security/.

 - Fix a problem where we were not properly terminating the permission
   list for two SELinux object classes.

* tag 'selinux-pr-20210426' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: add proper NULL termination to the secclass_map permissions
  smack: differentiate between subjective and objective task credentials
  selinux: clarify task subjective and objective credentials
  lsm: separate security_task_getsecid() into subjective and objective variants
  nfs: account for selinux security context when deciding to share superblock
  nfs: remove unneeded null check in nfs_fill_super()
  lsm,selinux: add new hook to compare new mount to an existing mount
  selinux: fix misspellings using codespell tool
  selinux: fix misspellings using codespell tool
  selinux: measure state and policy capabilities
  selinux: Allow context mounts for unpriviliged overlayfs
2021-04-27 13:42:11 -07:00
Casey Schaufler
1aea780837 LSM: Infrastructure management of the superblock
Move management of the superblock->sb_security blob out of the
individual security modules and into the security infrastructure.
Instead of allocating the blobs from within the modules, the modules
tell the infrastructure how much space is required, and the space is
allocated there.

Cc: John Johansen <john.johansen@canonical.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210422154123.13086-6-mic@digikod.net
Signed-off-by: James Morris <jamorris@linux.microsoft.com>
2021-04-22 12:22:10 -07:00
Linus Torvalds
60144b23c9 selinux/stable-5.12 PR 20210409
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Merge tag 'selinux-pr-20210409' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux fixes from Paul Moore:
 "Three SELinux fixes.

  These fix known problems relating to (re)loading SELinux policy or
  changing the policy booleans, and pass our test suite without problem"

* tag 'selinux-pr-20210409' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: fix race between old and new sidtab
  selinux: fix cond_list corruption when changing booleans
  selinux: make nslot handling in avtab more robust
2021-04-09 11:51:06 -07:00
Ondrej Mosnacek
9ad6e9cb39 selinux: fix race between old and new sidtab
Since commit 1b8b31a2e6 ("selinux: convert policy read-write lock to
RCU"), there is a small window during policy load where the new policy
pointer has already been installed, but some threads may still be
holding the old policy pointer in their read-side RCU critical sections.
This means that there may be conflicting attempts to add a new SID entry
to both tables via sidtab_context_to_sid().

See also (and the rest of the thread):
https://lore.kernel.org/selinux/CAFqZXNvfux46_f8gnvVvRYMKoes24nwm2n3sPbMjrB8vKTW00g@mail.gmail.com/

Fix this by installing the new policy pointer under the old sidtab's
spinlock along with marking the old sidtab as "frozen". Then, if an
attempt to add new entry to a "frozen" sidtab is detected, make
sidtab_context_to_sid() return -ESTALE to indicate that a new policy
has been installed and that the caller will have to abort the policy
transaction and try again after re-taking the policy pointer (which is
guaranteed to be a newer policy). This requires adding a retry-on-ESTALE
logic to all callers of sidtab_context_to_sid(), but fortunately these
are easy to determine and aren't that many.

This seems to be the simplest solution for this problem, even if it
looks somewhat ugly. Note that other places in the kernel (e.g.
do_mknodat() in fs/namei.c) use similar stale-retry patterns, so I think
it's reasonable.

Cc: stable@vger.kernel.org
Fixes: 1b8b31a2e6 ("selinux: convert policy read-write lock to RCU")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-04-07 20:42:56 -04:00
Ondrej Mosnacek
d8f5f0ea5b selinux: fix cond_list corruption when changing booleans
Currently, duplicate_policydb_cond_list() first copies the whole
conditional avtab and then tries to link to the correct entries in
cond_dup_av_list() using avtab_search(). However, since the conditional
avtab may contain multiple entries with the same key, this approach
often fails to find the right entry, potentially leading to wrong rules
being activated/deactivated when booleans are changed.

To fix this, instead start with an empty conditional avtab and add the
individual entries one-by-one while building the new av_lists. This
approach leads to the correct result, since each entry is present in the
av_lists exactly once.

The issue can be reproduced with Fedora policy as follows:

    # sesearch -s ftpd_t -t public_content_rw_t -c dir -p create -A
    allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True
    allow ftpd_t public_content_rw_t:dir { add_name create link remove_name rename reparent rmdir setattr unlink watch watch_reads write }; [ ftpd_anon_write ]:True
    # setsebool ftpd_anon_write=off ftpd_connect_all_unreserved=off ftpd_connect_db=off ftpd_full_access=off

On fixed kernels, the sesearch output is the same after the setsebool
command:

    # sesearch -s ftpd_t -t public_content_rw_t -c dir -p create -A
    allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True
    allow ftpd_t public_content_rw_t:dir { add_name create link remove_name rename reparent rmdir setattr unlink watch watch_reads write }; [ ftpd_anon_write ]:True

While on the broken kernels, it will be different:

    # sesearch -s ftpd_t -t public_content_rw_t -c dir -p create -A
    allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True
    allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True
    allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True

While there, also simplify the computation of nslots. This changes the
nslots values for nrules 2 or 3 to just two slots instead of 4, which
makes the sequence more consistent.

Cc: stable@vger.kernel.org
Fixes: c7c556f1e8 ("selinux: refactor changing booleans")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-04-02 11:46:55 -04:00
Ondrej Mosnacek
442dc00f82 selinux: make nslot handling in avtab more robust
1. Make sure all fileds are initialized in avtab_init().
2. Slightly refactor avtab_alloc() to use the above fact.
3. Use h->nslot == 0 as a sentinel in the access functions to prevent
   dereferencing h->htable when it's not allocated.

Cc: stable@vger.kernel.org
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-04-02 11:46:37 -04:00
Linus Torvalds
8419639062 selinux/stable-5.12 PR 20210322
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Merge tag 'selinux-pr-20210322' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux fixes from Paul Moore:
 "Three SELinux patches:

   - Fix a problem where a local variable is used outside its associated
     function. Thankfully this can only be triggered by reloading the
     SELinux policy, which is a restricted operation for other obvious
     reasons.

   - Fix some incorrect, and inconsistent, audit and printk messages
     when loading the SELinux policy.

  All three patches are relatively minor and have been through our
  testing with no failures"

* tag 'selinux-pr-20210322' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinuxfs: unify policy load error reporting
  selinux: fix variable scope issue in live sidtab conversion
  selinux: don't log MAC_POLICY_LOAD record on failed policy load
2021-03-22 11:34:31 -07:00
Ondrej Mosnacek
6406887a12 selinux: fix variable scope issue in live sidtab conversion
Commit 02a52c5c8c ("selinux: move policy commit after updating
selinuxfs") moved the selinux_policy_commit() call out of
security_load_policy() into sel_write_load(), which caused a subtle yet
rather serious bug.

The problem is that security_load_policy() passes a reference to the
convert_params local variable to sidtab_convert(), which stores it in
the sidtab, where it may be accessed until the policy is swapped over
and RCU synchronized. Before 02a52c5c8c, selinux_policy_commit() was
called directly from security_load_policy(), so the convert_params
pointer remained valid all the way until the old sidtab was destroyed,
but now that's no longer the case and calls to sidtab_context_to_sid()
on the old sidtab after security_load_policy() returns may cause invalid
memory accesses.

This can be easily triggered using the stress test from commit
ee1a84fdfe ("selinux: overhaul sidtab to fix bug and improve
performance"):
```
function rand_cat() {
	echo $(( $RANDOM % 1024 ))
}

function do_work() {
	while true; do
		echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
			>/sys/fs/selinux/context 2>/dev/null || true
	done
}

do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &

while load_policy; do echo -n .; sleep 0.1; done

kill %1
kill %2
kill %3
```

Fix this by allocating the temporary sidtab convert structures
dynamically and passing them among the
selinux_policy_{load,cancel,commit} functions.

Fixes: 02a52c5c8c ("selinux: move policy commit after updating selinuxfs")
Cc: stable@vger.kernel.org
Tested-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
[PM: merge fuzz in security.h and services.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-03-18 23:23:46 -04:00
Xiong Zhenwu
63ddf1baa0 selinux: fix misspellings using codespell tool
A typo is found out by codespell tool in 16th line of hashtab.c

$ codespell ./security/selinux/ss/
./hashtab.c:16: rouding  ==> rounding

Fix a typo found by codespell.

Signed-off-by: Xiong Zhenwu <xiong.zhenwu@zte.com.cn>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-03-08 19:44:30 -05:00
Lakshmi Ramasubramanian
2554a48f44 selinux: measure state and policy capabilities
SELinux stores the configuration state and the policy capabilities
in kernel memory.  Changes to this data at runtime would have an impact
on the security guarantees provided by SELinux.  Measuring this data
through IMA subsystem provides a tamper-resistant way for
an attestation service to remotely validate it at runtime.

Measure the configuration state and policy capabilities by calling
the IMA hook ima_measure_critical_data().

To enable SELinux data measurement, the following steps are required:

 1, Add "ima_policy=critical_data" to the kernel command line arguments
    to enable measuring SELinux data at boot time.
    For example,
      BOOT_IMAGE=/boot/vmlinuz-5.11.0-rc3+ root=UUID=fd643309-a5d2-4ed3-b10d-3c579a5fab2f ro nomodeset security=selinux ima_policy=critical_data

 2, Add the following rule to /etc/ima/ima-policy
       measure func=CRITICAL_DATA label=selinux

Sample measurement of SELinux state and policy capabilities:

10 2122...65d8 ima-buf sha256:13c2...1292 selinux-state 696e...303b

Execute the following command to extract the measured data
from the IMA's runtime measurements list:

  grep "selinux-state" /sys/kernel/security/integrity/ima/ascii_runtime_measurements | tail -1 | cut -d' ' -f 6 | xxd -r -p

The output should be a list of key-value pairs. For example,
 initialized=1;enforcing=0;checkreqprot=1;network_peer_controls=1;open_perms=1;extended_socket_class=1;always_check_network=0;cgroup_seclabel=1;nnp_nosuid_transition=1;genfs_seclabel_symlinks=0;

To verify the measurement is consistent with the current SELinux state
reported on the system, compare the integer values in the following
files with those set in the IMA measurement (using the following commands):

 - cat /sys/fs/selinux/enforce
 - cat /sys/fs/selinux/checkreqprot
 - cat /sys/fs/selinux/policy_capabilities/[capability_file]

Note that the actual verification would be against an expected state
and done on a separate system (likely an attestation server) requiring
"initialized=1;enforcing=1;checkreqprot=0;"
for a secure state and then whatever policy capabilities are actually
set in the expected policy (which can be extracted from the policy
itself via seinfo, for example).

Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Suggested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Suggested-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-03-08 19:39:07 -05:00
Linus Torvalds
d643a99089 integrity-v5.12
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Merge tag 'integrity-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

Pull IMA updates from Mimi Zohar:
 "New is IMA support for measuring kernel critical data, as per usual
  based on policy. The first example measures the in memory SELinux
  policy. The second example measures the kernel version.

  In addition are four bug fixes to address memory leaks and a missing
  'static' function declaration"

* tag 'integrity-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  integrity: Make function integrity_add_key() static
  ima: Free IMA measurement buffer after kexec syscall
  ima: Free IMA measurement buffer on error
  IMA: Measure kernel version in early boot
  selinux: include a consumer of the new IMA critical data hook
  IMA: define a builtin critical data measurement policy
  IMA: extend critical data hook to limit the measurement based on a label
  IMA: limit critical data measurement based on a label
  IMA: add policy rule to measure critical data
  IMA: define a hook to measure kernel integrity critical data
  IMA: add support to measure buffer data hash
  IMA: generalize keyring specific measurement constructs
  evm: Fix memleak in init_desc
2021-02-21 17:08:06 -08:00
Lakshmi Ramasubramanian
fdd1ffe8a8 selinux: include a consumer of the new IMA critical data hook
SELinux stores the active policy in memory, so the changes to this data
at runtime would have an impact on the security guarantees provided
by SELinux.  Measuring in-memory SELinux policy through IMA subsystem
provides a secure way for the attestation service to remotely validate
the policy contents at runtime.

Measure the hash of the loaded policy by calling the IMA hook
ima_measure_critical_data().  Since the size of the loaded policy
can be large (several MB), measure the hash of the policy instead of
the entire policy to avoid bloating the IMA log entry.

To enable SELinux data measurement, the following steps are required:

1, Add "ima_policy=critical_data" to the kernel command line arguments
   to enable measuring SELinux data at boot time.
For example,
  BOOT_IMAGE=/boot/vmlinuz-5.10.0-rc1+ root=UUID=fd643309-a5d2-4ed3-b10d-3c579a5fab2f ro nomodeset security=selinux ima_policy=critical_data

2, Add the following rule to /etc/ima/ima-policy
   measure func=CRITICAL_DATA label=selinux

Sample measurement of the hash of SELinux policy:

To verify the measured data with the current SELinux policy run
the following commands and verify the output hash values match.

  sha256sum /sys/fs/selinux/policy | cut -d' ' -f 1

  grep "selinux-policy-hash" /sys/kernel/security/integrity/ima/ascii_runtime_measurements | tail -1 | cut -d' ' -f 6

Note that the actual verification of SELinux policy would require loading
the expected policy into an identical kernel on a pristine/known-safe
system and run the sha256sum /sys/kernel/selinux/policy there to get
the expected hash.

Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Suggested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2021-01-14 23:41:46 -05:00
Ondrej Mosnacek
cd2bb4cb09 selinux: mark some global variables __ro_after_init
All of these are never modified outside initcalls, so they can be
__ro_after_init.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-01-12 10:08:55 -05:00
Ondrej Mosnacek
3c797e514b selinux: drop the unnecessary aurule_callback variable
Its value is actually not changed anywhere, so it can be substituted for
a direct call to audit_update_lsm_rules().

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-01-12 09:53:57 -05:00
bauen1
44141f58e1 selinux: allow dontauditx and auditallowx rules to take effect without allowx
This allows for dontauditing very specific ioctls e.g. TCGETS without
dontauditing every ioctl or granting additional permissions.

Now either an allowx, dontauditx or auditallowx rules enables checking
for extended permissions.

Signed-off-by: Jonathan Hettwer <j2468h@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-10-27 22:21:11 -04:00
Linus Torvalds
7b540812cc selinux/stable-5.10 PR 20201012
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Merge tag 'selinux-pr-20201012' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:
 "A decent number of SELinux patches for v5.10, twenty two in total. The
  highlights are listed below, but all of the patches pass our test
  suite and merge cleanly.

   - A number of changes to how the SELinux policy is loaded and managed
     inside the kernel with the goal of improving the atomicity of a
     SELinux policy load operation.

     These changes account for the bulk of the diffstat as well as the
     patch count. A special thanks to everyone who contributed patches
     and fixes for this work.

   - Convert the SELinux policy read-write lock to RCU.

   - A tracepoint was added for audited SELinux access control events;
     this should help provide a more unified backtrace across kernel and
     userspace.

   - Allow the removal of security.selinux xattrs when a SELinux policy
     is not loaded.

   - Enable policy capabilities in SELinux policies created with the
     scripts/selinux/mdp tool.

   - Provide some "no sooner than" dates for the SELinux checkreqprot
     sysfs deprecation"

* tag 'selinux-pr-20201012' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux: (22 commits)
  selinux: provide a "no sooner than" date for the checkreqprot removal
  selinux: Add helper functions to get and set checkreqprot
  selinux: access policycaps with READ_ONCE/WRITE_ONCE
  selinux: simplify away security_policydb_len()
  selinux: move policy mutex to selinux_state, use in lockdep checks
  selinux: fix error handling bugs in security_load_policy()
  selinux: convert policy read-write lock to RCU
  selinux: delete repeated words in comments
  selinux: add basic filtering for audit trace events
  selinux: add tracepoint on audited events
  selinux: Create new booleans and class dirs out of tree
  selinux: Standardize string literal usage for selinuxfs directory names
  selinux: Refactor selinuxfs directory populating functions
  selinux: Create function for selinuxfs directory cleanup
  selinux: permit removing security.selinux xattr before policy load
  selinux: fix memdup.cocci warnings
  selinux: avoid dereferencing the policy prior to initialization
  selinux: fix allocation failure check on newpolicy->sidtab
  selinux: refactor changing booleans
  selinux: move policy commit after updating selinuxfs
  ...
2020-10-13 16:29:55 -07:00
Stephen Smalley
e8ba53d002 selinux: access policycaps with READ_ONCE/WRITE_ONCE
Use READ_ONCE/WRITE_ONCE for all accesses to the
selinux_state.policycaps booleans to prevent compiler
mischief.

Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-09-11 10:08:51 -04:00
Ondrej Mosnacek
66ccd2560a selinux: simplify away security_policydb_len()
Remove the security_policydb_len() calls from sel_open_policy() and
instead update the inode size from the size returned from
security_read_policy().

Since after this change security_policydb_len() is only called from
security_load_policy(), remove it entirely and just open-code it there.

Also, since security_load_policy() is always called with policy_mutex
held, make it dereference the policy pointer directly and drop the
unnecessary RCU locking.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-31 10:00:14 -04:00
Stephen Smalley
9ff9abc4c6 selinux: move policy mutex to selinux_state, use in lockdep checks
Move the mutex used to synchronize policy changes (reloads and setting
of booleans) from selinux_fs_info to selinux_state and use it in
lockdep checks for rcu_dereference_protected() calls in the security
server functions.  This makes the dependency on the mutex explicit
in the code rather than relying on comments.

Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-27 09:52:47 -04:00
Dan Carpenter
0256b0aa80 selinux: fix error handling bugs in security_load_policy()
There are a few bugs in the error handling for security_load_policy().

1) If the newpolicy->sidtab allocation fails then it leads to a NULL
   dereference.  Also the error code was not set to -ENOMEM on that
   path.
2) If policydb_read() failed then we call policydb_destroy() twice
   which meands we call kvfree(p->sym_val_to_name[i]) twice.
3) If policydb_load_isids() failed then we call sidtab_destroy() twice
   and that results in a double free in the sidtab_destroy_tree()
   function because entry.ptr_inner and entry.ptr_leaf are not set to
   NULL.

One thing that makes this code nice to deal with is that none of the
functions return partially allocated data.  In other words, the
policydb_read() either allocates everything successfully or it frees
all the data it allocates.  It never returns a mix of allocated and
not allocated data.

I re-wrote this to only free the successfully allocated data which
avoids the double frees.  I also re-ordered selinux_policy_free() so
it's in the reverse order of the allocation function.

Fixes: c7c556f1e8 ("selinux: refactor changing booleans")
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
[PM: partially merged by hand due to merge fuzz]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-26 10:19:08 -04:00
Stephen Smalley
1b8b31a2e6 selinux: convert policy read-write lock to RCU
Convert the policy read-write lock to RCU.  This is significantly
simplified by the earlier work to encapsulate the policy data
structures and refactor the policy load and boolean setting logic.
Move the latest_granting sequence number into the selinux_policy
structure so that it can be updated atomically with the policy.
Since removing the policy rwlock and moving latest_granting reduces
the selinux_ss structure to nothing more than a wrapper around the
selinux_policy pointer, get rid of the extra layer of indirection.

At present this change merely passes a hardcoded 1 to
rcu_dereference_check() in the cases where we know we do not need to
take rcu_read_lock(), with the preceding comment explaining why.
Alternatively we could pass fsi->mutex down from selinuxfs and
apply a lockdep check on it instead.

Based in part on earlier attempts to convert the policy rwlock
to RCU by Kaigai Kohei [1] and by Peter Enderborg [2].

[1] https://lore.kernel.org/selinux/6e2f9128-e191-ebb3-0e87-74bfccb0767f@tycho.nsa.gov/
[2] https://lore.kernel.org/selinux/20180530141104.28569-1-peter.enderborg@sony.com/

Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-25 08:34:47 -04:00
Gustavo A. R. Silva
df561f6688 treewide: Use fallthrough pseudo-keyword
Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-08-23 17:36:59 -05:00
kernel test robot
879229311b selinux: fix memdup.cocci warnings
Use kmemdup rather than duplicating its implementation

Generated by: scripts/coccinelle/api/memdup.cocci

Fixes: c7c556f1e8 ("selinux: refactor changing booleans")
CC: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: kernel test robot <lkp@intel.com>
Signed-off-by: Julia Lawall <julia.lawall@inria.fr>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-20 08:39:05 -04:00
Stephen Smalley
37ea433c66 selinux: avoid dereferencing the policy prior to initialization
Certain SELinux security server functions (e.g. security_port_sid,
called during bind) were not explicitly testing to see if SELinux
has been initialized (i.e. initial policy loaded) and handling
the no-policy-loaded case.  In the past this happened to work
because the policydb was statically allocated and could always
be accessed, but with the recent encapsulation of policy state
and conversion to dynamic allocation, we can no longer access
the policy state prior to initialization.  Add a test of
!selinux_initialized(state) to all of the exported functions that
were missing them and handle appropriately.

Fixes: 461698026f ("selinux: encapsulate policy state, refactor policy load")
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-19 21:14:41 -04:00
Colin Ian King
69ea651c40 selinux: fix allocation failure check on newpolicy->sidtab
The allocation check of newpolicy->sidtab is null checking if
newpolicy is null and not newpolicy->sidtab. Fix this.

Addresses-Coverity: ("Logically dead code")
Fixes: c7c556f1e8 ("selinux: refactor changing booleans")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-19 09:14:04 -04:00
Stephen Smalley
c7c556f1e8 selinux: refactor changing booleans
Refactor the logic for changing SELinux policy booleans in a similar
manner to the refactoring of policy load, thereby reducing the
size of the critical section when the policy write-lock is held
and making it easier to convert the policy rwlock to RCU in the
future.  Instead of directly modifying the policydb in place, modify
a copy and then swap it into place through a single pointer update.
Only fully copy the portions of the policydb that are affected by
boolean changes to avoid the full cost of a deep policydb copy.
Introduce another level of indirection for the sidtab since changing
booleans does not require updating the sidtab, unlike policy load.
While we are here, create a common helper for notifying
other kernel components and userspace of a policy change and call it
from both security_set_bools() and selinux_policy_commit().

Based on an old (2004) patch by Kaigai Kohei [1] to convert the policy
rwlock to RCU that was deferred at the time since it did not
significantly improve performance and introduced complexity. Peter
Enderborg later submitted a patch series to convert to RCU [2] that
would have made changing booleans a much more expensive operation
by requiring a full policydb_write();policydb_read(); sequence to
deep copy the entire policydb and also had concerns regarding
atomic allocations.

This change is now simplified by the earlier work to encapsulate
policy state in the selinux_policy struct and to refactor
policy load.  After this change, the last major obstacle to
converting the policy rwlock to RCU is likely the sidtab live
convert support.

[1] https://lore.kernel.org/selinux/6e2f9128-e191-ebb3-0e87-74bfccb0767f@tycho.nsa.gov/
[2] https://lore.kernel.org/selinux/20180530141104.28569-1-peter.enderborg@sony.com/

Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-17 21:00:33 -04:00
Stephen Smalley
02a52c5c8c selinux: move policy commit after updating selinuxfs
With the refactoring of the policy load logic in the security
server from the previous change, it is now possible to split out
the committing of the new policy from security_load_policy() and
perform it only after successful updating of selinuxfs.  Change
security_load_policy() to return the newly populated policy
data structures to the caller, export selinux_policy_commit()
for external callers, and introduce selinux_policy_cancel() to
provide a way to cancel the policy load in the event of an error
during updating of the selinuxfs directory tree.  Further, rework
the interfaces used by selinuxfs to get information from the policy
when creating the new directory tree to take and act upon the
new policy data structure rather than the current/active policy.
Update selinuxfs to use these updated and new interfaces.  While
we are here, stop re-creating the policy_capabilities directory
on each policy load since it does not depend on the policy, and
stop trying to create the booleans and classes directories during
the initial creation of selinuxfs since no information is available
until first policy load.

After this change, a failure while updating the booleans and class
directories will cause the entire policy load to be canceled, leaving
the original policy intact, and policy load notifications to userspace
will only happen after a successful completion of updating those
directories.  This does not (yet) provide full atomicity with respect
to the updating of the directory trees themselves.

Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-17 20:50:22 -04:00
Stephen Smalley
461698026f selinux: encapsulate policy state, refactor policy load
Encapsulate the policy state in its own structure (struct
selinux_policy) that is separately allocated but referenced from the
selinux_ss structure.  The policy state includes the SID table
(particularly the context structures), the policy database, and the
mapping between the kernel classes/permissions and the policy values.
Refactor the security server portion of the policy load logic to
cleanly separate loading of the new structures from committing the new
policy.  Unify the initial policy load and reload code paths as much
as possible, avoiding duplicated code.  Make sure we are taking the
policy read-lock prior to any dereferencing of the policy.  Move the
copying of the policy capability booleans into the state structure
outside of the policy write-lock because they are separate from the
policy and are read outside of any policy lock; possibly they should
be using at least READ_ONCE/WRITE_ONCE or smp_load_acquire/store_release.

These changes simplify the policy loading logic, reduce the size of
the critical section while holding the policy write-lock, and should
facilitate future changes to e.g. refactor the entire policy reload
logic including the selinuxfs code to make the updating of the policy
and the selinuxfs directory tree atomic and/or to convert the policy
read-write lock to RCU.

Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-17 20:48:57 -04:00
Stephen Smalley
339949be25 scripts/selinux,selinux: update mdp to enable policy capabilities
Presently mdp does not enable any SELinux policy capabilities
in the dummy policy it generates. Thus, policies derived from
it will by default lack various features commonly used in modern
policies such as open permission, extended socket classes, network
peer controls, etc.  Split the policy capability definitions out into
their own headers so that we can include them into mdp without pulling in
other kernel headers and extend mdp generate policycap statements for the
policy capabilities known to the kernel.  Policy authors may wish to
selectively remove some of these from the generated policy.

Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-08-17 20:42:00 -04:00
Linus Torvalds
49e917deeb selinux/stable-5.9 PR 20200803
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Merge tag 'selinux-pr-20200803' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:
 "Beyond the usual smattering of bug fixes, we've got three small
  improvements worth highlighting:

   - improved SELinux policy symbol table performance due to a reworking
     of the insert and search functions

   - allow reading of SELinux labels before the policy is loaded,
     allowing for some more "exotic" initramfs approaches

   - improved checking an error reporting about process
     class/permissions during SELinux policy load"

* tag 'selinux-pr-20200803' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: complete the inlining of hashtab functions
  selinux: prepare for inlining of hashtab functions
  selinux: specialize symtab insert and search functions
  selinux: Fix spelling mistakes in the comments
  selinux: fixed a checkpatch warning with the sizeof macro
  selinux: log error messages on required process class / permissions
  scripts/selinux/mdp: fix initial SID handling
  selinux: allow reading labels before policy is loaded
2020-08-04 14:18:01 -07:00
Ondrej Mosnacek
54b27f9287 selinux: complete the inlining of hashtab functions
Move (most of) the definitions of hashtab_search() and hashtab_insert()
to the header file. In combination with the previous patch, this avoids
calling the callbacks indirectly by function pointers and allows for
better optimization, leading to a drastic performance improvement of
these operations.

With this patch, I measured a speed up in the following areas (measured
on x86_64 F32 VM with 4 CPUs):
  1. Policy load (`load_policy`) - takes ~150 ms instead of ~230 ms.
  2. `chcon -R unconfined_u:object_r:user_tmp_t:s0:c381,c519 /tmp/linux-src`
     where /tmp/linux-src is an extracted linux-5.7 source tarball -
     takes ~522 ms instead of ~576 ms. This is because of many
     symtab_search() calls in string_to_context_struct() when there are
     many categories specified in the context.
  3. `stress-ng --msg 1 --msg-ops 10000000` - takes 12.41 s instead of
     13.95 s (consumes 18.6 s of kernel CPU time instead of 21.6 s).
     This is thanks to security_transition_sid() being ~43% faster after
     this patch.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-07-09 19:08:16 -04:00
Ondrej Mosnacek
24def7bb92 selinux: prepare for inlining of hashtab functions
Refactor searching and inserting into hashtabs to pave the way for
converting hashtab_search() and hashtab_insert() to inline functions in
the next patch. This will avoid indirect calls and allow the compiler to
better optimize individual callers, leading to a significant performance
improvement.

In order to avoid the indirect calls, the key hashing and comparison
callbacks need to be extracted from the hashtab struct and passed
directly to hashtab_search()/_insert() by the callers so that the
callback address is always known at compile time. The kernel's
rhashtable library (<linux/rhashtable*.h>) does the same thing.

This of course makes the hashtab functions slightly easier to misuse by
passing a wrong callback set, but unfortunately there is no better way
to implement a hash table that is both generic and efficient in C. This
patch tries to somewhat mitigate this by only calling the hashtab
functions in the same file where the corresponding callbacks are
defined (wrapping them into more specialized functions as needed).

Note that this patch doesn't bring any benefit without also moving the
definitions of hashtab_search() and -_insert() to the header file, which
is done in a follow-up patch for easier review of the hashtab.c changes
in this patch.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-07-09 19:05:36 -04:00
Ondrej Mosnacek
237389e301 selinux: specialize symtab insert and search functions
This encapsulates symtab a little better and will help with further
refactoring later.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-07-08 20:21:43 -04:00
Ethan Edwards
65d96351b1 selinux: fixed a checkpatch warning with the sizeof macro
`sizeof buf` changed to `sizeof(buf)`

Signed-off-by: Ethan Edwards <ethancarteredwards@gmail.com>
[PM: rewrote the subject line]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-06-29 19:26:17 -04:00
Stephen Smalley
7383c0f94d selinux: log error messages on required process class / permissions
In general SELinux no longer treats undefined object classes or permissions
in the policy as a fatal error, instead handling them in accordance with
handle_unknown. However, the process class and process transition and
dyntransition permissions are still required to be defined due to
dependencies on these definitions for default labeling behaviors,
role and range transitions in older policy versions that lack an explicit
class field, and role allow checking.  Log error messages in these cases
since otherwise the policy load will fail silently with no indication
to the user as to the underlying cause.  While here, fix the checking for
process transition / dyntransition so that omitting either permission is
handled as an error; both are needed in order to ensure that role allow
checking is consistently applied.

Reported-by: bauen1 <j2468h@googlemail.com>
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-06-23 20:57:01 -04:00
Linus Torvalds
817d914d17 selinux/stable-5.8 PR 20200621
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Merge tag 'selinux-pr-20200621' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull SELinux fixes from Paul Moore:
 "Three small patches to fix problems in the SELinux code, all found via
  clang.

  Two patches fix potential double-free conditions and one fixes an
  undefined return value"

* tag 'selinux-pr-20200621' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: fix undefined return of cond_evaluate_expr
  selinux: fix a double free in cond_read_node()/cond_read_list()
  selinux: fix double free
2020-06-21 15:41:24 -07:00
Tom Rix
8231b0b9c3 selinux: fix undefined return of cond_evaluate_expr
clang static analysis reports an undefined return

security/selinux/ss/conditional.c:79:2: warning: Undefined or garbage value returned to caller [core.uninitialized.UndefReturn]
        return s[0];
        ^~~~~~~~~~~

static int cond_evaluate_expr( ...
{
	u32 i;
	int s[COND_EXPR_MAXDEPTH];

	for (i = 0; i < expr->len; i++)
	  ...

	return s[0];

When expr->len is 0, the loop which sets s[0] never runs.

So return -1 if the loop never runs.

Cc: stable@vger.kernel.org
Signed-off-by: Tom Rix <trix@redhat.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-06-17 17:36:40 -04:00
Tom Rix
aa449a7965 selinux: fix a double free in cond_read_node()/cond_read_list()
Clang static analysis reports this double free error

security/selinux/ss/conditional.c:139:2: warning: Attempt to free released memory [unix.Malloc]
        kfree(node->expr.nodes);
        ^~~~~~~~~~~~~~~~~~~~~~~

When cond_read_node fails, it calls cond_node_destroy which frees the
node but does not poison the entry in the node list.  So when it
returns to its caller cond_read_list, cond_read_list deletes the
partial list.  The latest entry in the list will be deleted twice.

So instead of freeing the node in cond_read_node, let list freeing in
code_read_list handle the freeing the problem node along with all of the
earlier nodes.

Because cond_read_node no longer does any error handling, the goto's
the error case are redundant.  Instead just return the error code.

Cc: stable@vger.kernel.org
Fixes: 60abd3181d ("selinux: convert cond_list to array")
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
[PM: subject line tweaks]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-06-16 20:25:19 -04:00
Tom Rix
65de50969a selinux: fix double free
Clang's static analysis tool reports these double free memory errors.

security/selinux/ss/services.c:2987:4: warning: Attempt to free released memory [unix.Malloc]
                        kfree(bnames[i]);
                        ^~~~~~~~~~~~~~~~
security/selinux/ss/services.c:2990:2: warning: Attempt to free released memory [unix.Malloc]
        kfree(bvalues);
        ^~~~~~~~~~~~~~

So improve the security_get_bools error handling by freeing these variables
and setting their return pointers to NULL and the return len to 0

Cc: stable@vger.kernel.org
Signed-off-by: Tom Rix <trix@redhat.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-06-10 22:10:35 -04:00
Linus Torvalds
f41030a20b selinux/stable-5.8 PR 20200601
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Merge tag 'selinux-pr-20200601' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull SELinux updates from Paul Moore:
 "The highlights:

   - A number of improvements to various SELinux internal data
     structures to help improve performance. We move the role
     transitions into a hash table. In the content structure we shift
     from hashing the content string (aka SELinux label) to the
     structure itself, when it is valid. This last change not only
     offers a speedup, but it helps us simplify the code some as well.

   - Add a new SELinux policy version which allows for a more space
     efficient way of storing the filename transitions in the binary
     policy. Given the default Fedora SELinux policy with the unconfined
     module enabled, this change drops the policy size from ~7.6MB to
     ~3.3MB. The kernel policy load time dropped as well.

   - Some fixes to the error handling code in the policy parser to
     properly return error codes when things go wrong"

* tag 'selinux-pr-20200601' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: netlabel: Remove unused inline function
  selinux: do not allocate hashtabs dynamically
  selinux: fix return value on error in policydb_read()
  selinux: simplify range_write()
  selinux: fix error return code in policydb_read()
  selinux: don't produce incorrect filename_trans_count
  selinux: implement new format of filename transitions
  selinux: move context hashing under sidtab
  selinux: hash context structure directly
  selinux: store role transitions in a hash table
  selinux: drop unnecessary smp_load_acquire() call
  selinux: fix warning Comparison to bool
2020-06-02 17:16:47 -07:00
Ondrej Mosnacek
03414a49ad selinux: do not allocate hashtabs dynamically
It is simpler to allocate them statically in the corresponding
structure, avoiding unnecessary kmalloc() calls and pointer
dereferencing.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
[PM: manual merging required in policydb.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-05-01 16:34:57 -04:00
Ondrej Mosnacek
46619b44e4 selinux: fix return value on error in policydb_read()
The value of rc is still zero from the last assignment when the error
path is taken. Fix it by setting it to -ENOMEM before the
hashtab_create() call.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: e67b2ec9f6 ("selinux: store role transitions in a hash table")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-05-01 16:08:46 -04:00