8b4b9f27e5
Commit fca460f95e simplified the x32
implementation by creating a syscall bitmask, equal to 0x40000000, that
could be applied to x32 syscalls such that the masked syscall number
would be the same as a x86_64 syscall. While that patch was a nice
way to simplify the code, it went a bit too far by adding the mask to
syscall_get_nr(); returning the masked syscall numbers can cause
confusion with callers that expect syscall numbers matching the x32
ABI, e.g. unmasked syscall numbers.
This patch fixes this by simply removing the mask from syscall_get_nr()
while preserving the other changes from the original commit. While
there are several syscall_get_nr() callers in the kernel, most simply
check that the syscall number is greater than zero, in this case this
patch will have no effect. Of those remaining callers, they appear
to be few, seccomp and ftrace, and from my testing of seccomp without
this patch the original commit definitely breaks things; the seccomp
filter does not correctly filter the syscalls due to the difference in
syscall numbers in the BPF filter and the value from syscall_get_nr().
Applying this patch restores the seccomp BPF filter functionality on
x32.
I've tested this patch with the seccomp BPF filters as well as ftrace
and everything looks reasonable to me; needless to say general usage
seemed fine as well.
Signed-off-by: Paul Moore <pmoore@redhat.com>
Link: http://lkml.kernel.org/r/20130215172143.12549.10292.stgit@localhost
Cc: <stable@vger.kernel.org>
Cc: Will Drewry <wad@chromium.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
245 lines
5.1 KiB
C
245 lines
5.1 KiB
C
/*
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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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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the GNU General Public License v.2.
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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 <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/asm-offsets.h> /* For NR_syscalls */
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#include <asm/thread_info.h> /* for TS_COMPAT */
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#include <asm/unistd.h>
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extern const unsigned long sys_call_table[];
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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(task)->status & TS_COMPAT)
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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 int i, unsigned int n,
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unsigned long *args)
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{
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BUG_ON(i + n > 6);
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memcpy(args, ®s->bx + i, n * sizeof(args[0]));
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}
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static inline void syscall_set_arguments(struct task_struct *task,
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struct pt_regs *regs,
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unsigned int i, unsigned int n,
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const unsigned long *args)
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{
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BUG_ON(i + n > 6);
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memcpy(®s->bx + i, args, n * sizeof(args[0]));
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}
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static inline int syscall_get_arch(struct task_struct *task,
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struct pt_regs *regs)
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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 int i, unsigned int n,
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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(task)->status & TS_COMPAT)
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switch (i) {
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case 0:
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if (!n--) break;
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*args++ = regs->bx;
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case 1:
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if (!n--) break;
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*args++ = regs->cx;
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case 2:
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if (!n--) break;
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*args++ = regs->dx;
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case 3:
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if (!n--) break;
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*args++ = regs->si;
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case 4:
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if (!n--) break;
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*args++ = regs->di;
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case 5:
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if (!n--) break;
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*args++ = regs->bp;
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case 6:
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if (!n--) break;
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default:
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BUG();
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break;
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}
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else
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# endif
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switch (i) {
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case 0:
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if (!n--) break;
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*args++ = regs->di;
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case 1:
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if (!n--) break;
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*args++ = regs->si;
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case 2:
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if (!n--) break;
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*args++ = regs->dx;
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case 3:
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if (!n--) break;
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*args++ = regs->r10;
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case 4:
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if (!n--) break;
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*args++ = regs->r8;
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case 5:
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if (!n--) break;
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*args++ = regs->r9;
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case 6:
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if (!n--) break;
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default:
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BUG();
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break;
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}
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}
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static inline void syscall_set_arguments(struct task_struct *task,
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struct pt_regs *regs,
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unsigned int i, unsigned int n,
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const unsigned long *args)
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{
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# ifdef CONFIG_IA32_EMULATION
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if (task_thread_info(task)->status & TS_COMPAT)
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switch (i) {
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case 0:
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if (!n--) break;
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regs->bx = *args++;
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case 1:
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if (!n--) break;
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regs->cx = *args++;
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case 2:
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if (!n--) break;
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regs->dx = *args++;
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case 3:
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if (!n--) break;
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regs->si = *args++;
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case 4:
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if (!n--) break;
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regs->di = *args++;
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case 5:
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if (!n--) break;
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regs->bp = *args++;
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case 6:
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if (!n--) break;
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default:
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BUG();
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break;
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}
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else
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# endif
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switch (i) {
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case 0:
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if (!n--) break;
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regs->di = *args++;
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case 1:
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if (!n--) break;
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regs->si = *args++;
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case 2:
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if (!n--) break;
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regs->dx = *args++;
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case 3:
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if (!n--) break;
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regs->r10 = *args++;
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case 4:
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if (!n--) break;
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regs->r8 = *args++;
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case 5:
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if (!n--) break;
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regs->r9 = *args++;
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case 6:
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if (!n--) break;
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default:
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BUG();
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break;
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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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struct pt_regs *regs)
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{
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#ifdef CONFIG_IA32_EMULATION
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/*
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* TS_COMPAT is set for 32-bit syscall entry and then
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* remains set until we return to user mode.
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*
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* TIF_IA32 tasks should always have TS_COMPAT set at
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* system call time.
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*
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* x32 tasks should be considered AUDIT_ARCH_X86_64.
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*/
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if (task_thread_info(task)->status & TS_COMPAT)
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return AUDIT_ARCH_I386;
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#endif
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/* Both x32 and x86_64 are considered "64-bit". */
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return AUDIT_ARCH_X86_64;
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}
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#endif /* CONFIG_X86_32 */
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#endif /* _ASM_X86_SYSCALL_H */
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