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bpf: Add namespace to BPF internal symbols

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[ Upstream commit f88886de0927a2adf4c1b4c5c1f1d31d2023ef74 ]

Add namespace to BPF internal symbols used by light skeleton
to prevent abuse and document with the code their allowed usage.

Fixes: b1d18a7574 ("bpf: Extend sys_bpf commands for bpf_syscall programs.")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20250425014542.62385-1-alexei.starovoitov@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Alexei Starovoitov 2025-04-24 18:45:42 -07:00 committed by Greg Kroah-Hartman
parent 3decda1a3c
commit 955f9ede52
3 changed files with 12 additions and 3 deletions
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8
Documentation/bpf/bpf_devel_QA.rst
View File

@ -382,6 +382,14 @@ In case of new BPF instructions, once the changes have been accepted
into the Linux kernel, please implement support into LLVM's BPF back into the Linux kernel, please implement support into LLVM's BPF back
end. See LLVM_ section below for further information. end. See LLVM_ section below for further information.
Q: What "BPF_INTERNAL" symbol namespace is for?
-----------------------------------------------
A: Symbols exported as BPF_INTERNAL can only be used by BPF infrastructure
like preload kernel modules with light skeleton. Most symbols outside
of BPF_INTERNAL are not expected to be used by code outside of BPF either.
Symbols may lack the designation because they predate the namespaces,
or due to an oversight.
Stable submission Stable submission
================= =================

1
kernel/bpf/preload/bpf_preload_kern.c
View File

@ -89,4 +89,5 @@ static void __exit fini(void)
} }
late_initcall(load); late_initcall(load);
module_exit(fini); module_exit(fini);
MODULE_IMPORT_NS("BPF_INTERNAL");
MODULE_LICENSE("GPL"); MODULE_LICENSE("GPL");

6
kernel/bpf/syscall.c
View File

@ -1457,7 +1457,7 @@ struct bpf_map *bpf_map_get(u32 ufd)
return map; return map;
} }
EXPORT_SYMBOL(bpf_map_get); EXPORT_SYMBOL_NS(bpf_map_get, BPF_INTERNAL);
struct bpf_map *bpf_map_get_with_uref(u32 ufd) struct bpf_map *bpf_map_get_with_uref(u32 ufd)
{ {
@ -3223,7 +3223,7 @@ struct bpf_link *bpf_link_get_from_fd(u32 ufd)
bpf_link_inc(link); bpf_link_inc(link);
return link; return link;
} }
EXPORT_SYMBOL(bpf_link_get_from_fd); EXPORT_SYMBOL_NS(bpf_link_get_from_fd, BPF_INTERNAL);
static void bpf_tracing_link_release(struct bpf_link *link) static void bpf_tracing_link_release(struct bpf_link *link)
{ {
@ -5853,7 +5853,7 @@ int kern_sys_bpf(int cmd, union bpf_attr *attr, unsigned int size)
return ____bpf_sys_bpf(cmd, attr, size); return ____bpf_sys_bpf(cmd, attr, size);
} }
} }
EXPORT_SYMBOL(kern_sys_bpf); EXPORT_SYMBOL_NS(kern_sys_bpf, BPF_INTERNAL);
static const struct bpf_func_proto bpf_sys_bpf_proto = { static const struct bpf_func_proto bpf_sys_bpf_proto = {
.func = bpf_sys_bpf, .func = bpf_sys_bpf,