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1553085fe9
[ Upstream commit d19d638b1e ]
Modern (fortified) memcpy() prefers to avoid writing (or reading) beyond
the end of the addressed destination (or source) struct member:
In function ‘fortify_memcpy_chk’,
inlined from ‘syscall_get_arguments’ at ./arch/x86/include/asm/syscall.h:85:2,
inlined from ‘populate_seccomp_data’ at kernel/seccomp.c:258:2,
inlined from ‘__seccomp_filter’ at kernel/seccomp.c:1231:3:
./include/linux/fortify-string.h:580:25: error: call to ‘__read_overflow2_field’ declared with attribute warning: detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Werror=attribute-warning]
580 | __read_overflow2_field(q_size_field, size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
As already done for x86_64 and compat mode, do not use memcpy() to
extract syscall arguments from struct pt_regs but rather just perform
direct assignments. Binary output differences are negligible, and actually
ends up using less stack space:
- sub $0x84,%esp
+ sub $0x6c,%esp
and less text size:
text data bss dec hex filename
10794 252 0 11046 2b26 gcc-32b/kernel/seccomp.o.stock
10714 252 0 10966 2ad6 gcc-32b/kernel/seccomp.o.after
Closes: https://lore.kernel.org/lkml/9b69fb14-df89-4677-9c82-056ea9e706f5@gmail.com/
Reported-by: Mirsad Todorovac <mtodorovac69@gmail.com>
Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Mirsad Todorovac <mtodorovac69@gmail.com>
Link: https://lore.kernel.org/all/20240708202202.work.477-kees%40kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
140 lines
3.5 KiB
C
140 lines
3.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Access to user system call parameters and results
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*
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* Copyright (C) 2008-2009 Red Hat, Inc. All rights reserved.
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*
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* See asm-generic/syscall.h for descriptions of what we must do here.
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*/
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#ifndef _ASM_X86_SYSCALL_H
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#define _ASM_X86_SYSCALL_H
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#include <uapi/linux/audit.h>
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#include <linux/sched.h>
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#include <linux/err.h>
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#include <asm/thread_info.h> /* for TS_COMPAT */
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#include <asm/unistd.h>
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/* This is used purely for kernel/trace/trace_syscalls.c */
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typedef long (*sys_call_ptr_t)(const struct pt_regs *);
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extern const sys_call_ptr_t sys_call_table[];
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/*
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* These may not exist, but still put the prototypes in so we
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* can use IS_ENABLED().
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*/
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extern long ia32_sys_call(const struct pt_regs *, unsigned int nr);
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extern long x32_sys_call(const struct pt_regs *, unsigned int nr);
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extern long x64_sys_call(const struct pt_regs *, unsigned int nr);
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/*
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* Only the low 32 bits of orig_ax are meaningful, so we return int.
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* This importantly ignores the high bits on 64-bit, so comparisons
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* sign-extend the low 32 bits.
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*/
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static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
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{
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return regs->orig_ax;
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}
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static inline void syscall_rollback(struct task_struct *task,
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struct pt_regs *regs)
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{
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regs->ax = regs->orig_ax;
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}
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static inline long syscall_get_error(struct task_struct *task,
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struct pt_regs *regs)
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{
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unsigned long error = regs->ax;
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#ifdef CONFIG_IA32_EMULATION
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/*
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* TS_COMPAT is set for 32-bit syscall entries and then
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* remains set until we return to user mode.
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*/
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if (task->thread_info.status & (TS_COMPAT|TS_I386_REGS_POKED))
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/*
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* Sign-extend the value so (int)-EFOO becomes (long)-EFOO
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* and will match correctly in comparisons.
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*/
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error = (long) (int) error;
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#endif
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return IS_ERR_VALUE(error) ? error : 0;
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}
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static inline long syscall_get_return_value(struct task_struct *task,
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struct pt_regs *regs)
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{
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return regs->ax;
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}
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static inline void syscall_set_return_value(struct task_struct *task,
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struct pt_regs *regs,
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int error, long val)
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{
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regs->ax = (long) error ?: val;
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}
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#ifdef CONFIG_X86_32
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static inline void syscall_get_arguments(struct task_struct *task,
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struct pt_regs *regs,
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unsigned long *args)
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{
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args[0] = regs->bx;
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args[1] = regs->cx;
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args[2] = regs->dx;
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args[3] = regs->si;
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args[4] = regs->di;
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args[5] = regs->bp;
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}
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static inline int syscall_get_arch(struct task_struct *task)
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{
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return AUDIT_ARCH_I386;
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}
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#else /* CONFIG_X86_64 */
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static inline void syscall_get_arguments(struct task_struct *task,
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struct pt_regs *regs,
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unsigned long *args)
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{
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# ifdef CONFIG_IA32_EMULATION
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if (task->thread_info.status & TS_COMPAT) {
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*args++ = regs->bx;
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*args++ = regs->cx;
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*args++ = regs->dx;
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*args++ = regs->si;
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*args++ = regs->di;
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*args = regs->bp;
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} else
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# endif
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{
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*args++ = regs->di;
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*args++ = regs->si;
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*args++ = regs->dx;
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*args++ = regs->r10;
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*args++ = regs->r8;
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*args = regs->r9;
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}
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}
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static inline int syscall_get_arch(struct task_struct *task)
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{
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/* x32 tasks should be considered AUDIT_ARCH_X86_64. */
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return (IS_ENABLED(CONFIG_IA32_EMULATION) &&
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task->thread_info.status & TS_COMPAT)
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? AUDIT_ARCH_I386 : AUDIT_ARCH_X86_64;
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}
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void do_syscall_64(struct pt_regs *regs, int nr);
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void do_int80_syscall_32(struct pt_regs *regs);
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long do_fast_syscall_32(struct pt_regs *regs);
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void do_int80_emulation(struct pt_regs *regs);
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#endif /* CONFIG_X86_32 */
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#endif /* _ASM_X86_SYSCALL_H */
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