forked from Minki/linux
e9fbe68632
The documentation for syscall_get_nr() in asm-generic says: Note this returns int even on 64-bit machines. Only 32 bits of system call number can be meaningful. If the actual arch value is 64 bits, this truncates to 32 bits so 0xffffffff means -1. However our implementation was never updated to reflect this. Generally it's not important, but there is once case where it matters. For seccomp filter with SECCOMP_RET_TRACE, the tracer will set regs->gpr[0] to -1 to reject the syscall. When the task is a compat task, this means we end up with 0xffffffff in r0 because ptrace will zero extend the 32-bit value. If syscall_get_nr() returns an unsigned long, then a 64-bit kernel will see a positive value in r0 and will incorrectly allow the syscall through seccomp. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Kees Cook <keescook@chromium.org>
112 lines
2.8 KiB
C
112 lines
2.8 KiB
C
/*
|
|
* Access to user system call parameters and results
|
|
*
|
|
* Copyright (C) 2008 Red Hat, Inc. All rights reserved.
|
|
*
|
|
* This copyrighted material is made available to anyone wishing to use,
|
|
* modify, copy, or redistribute it subject to the terms and conditions
|
|
* of the GNU General Public License v.2.
|
|
*
|
|
* See asm-generic/syscall.h for descriptions of what we must do here.
|
|
*/
|
|
|
|
#ifndef _ASM_SYSCALL_H
|
|
#define _ASM_SYSCALL_H 1
|
|
|
|
#include <uapi/linux/audit.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/thread_info.h>
|
|
|
|
/* ftrace syscalls requires exporting the sys_call_table */
|
|
#ifdef CONFIG_FTRACE_SYSCALLS
|
|
extern const unsigned long sys_call_table[];
|
|
#endif /* CONFIG_FTRACE_SYSCALLS */
|
|
|
|
static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
|
|
{
|
|
/*
|
|
* Note that we are returning an int here. That means 0xffffffff, ie.
|
|
* 32-bit negative 1, will be interpreted as -1 on a 64-bit kernel.
|
|
* This is important for seccomp so that compat tasks can set r0 = -1
|
|
* to reject the syscall.
|
|
*/
|
|
return TRAP(regs) == 0xc00 ? regs->gpr[0] : -1;
|
|
}
|
|
|
|
static inline void syscall_rollback(struct task_struct *task,
|
|
struct pt_regs *regs)
|
|
{
|
|
regs->gpr[3] = regs->orig_gpr3;
|
|
}
|
|
|
|
static inline long syscall_get_return_value(struct task_struct *task,
|
|
struct pt_regs *regs)
|
|
{
|
|
return regs->gpr[3];
|
|
}
|
|
|
|
static inline void syscall_set_return_value(struct task_struct *task,
|
|
struct pt_regs *regs,
|
|
int error, long val)
|
|
{
|
|
/*
|
|
* In the general case it's not obvious that we must deal with CCR
|
|
* here, as the syscall exit path will also do that for us. However
|
|
* there are some places, eg. the signal code, which check ccr to
|
|
* decide if the value in r3 is actually an error.
|
|
*/
|
|
if (error) {
|
|
regs->ccr |= 0x10000000L;
|
|
regs->gpr[3] = error;
|
|
} else {
|
|
regs->ccr &= ~0x10000000L;
|
|
regs->gpr[3] = val;
|
|
}
|
|
}
|
|
|
|
static inline void syscall_get_arguments(struct task_struct *task,
|
|
struct pt_regs *regs,
|
|
unsigned int i, unsigned int n,
|
|
unsigned long *args)
|
|
{
|
|
unsigned long val, mask = -1UL;
|
|
|
|
BUG_ON(i + n > 6);
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
if (test_tsk_thread_flag(task, TIF_32BIT))
|
|
mask = 0xffffffff;
|
|
#endif
|
|
while (n--) {
|
|
if (n == 0 && i == 0)
|
|
val = regs->orig_gpr3;
|
|
else
|
|
val = regs->gpr[3 + i + n];
|
|
|
|
args[n] = val & mask;
|
|
}
|
|
}
|
|
|
|
static inline void syscall_set_arguments(struct task_struct *task,
|
|
struct pt_regs *regs,
|
|
unsigned int i, unsigned int n,
|
|
const unsigned long *args)
|
|
{
|
|
BUG_ON(i + n > 6);
|
|
memcpy(®s->gpr[3 + i], args, n * sizeof(args[0]));
|
|
|
|
/* Also copy the first argument into orig_gpr3 */
|
|
if (i == 0 && n > 0)
|
|
regs->orig_gpr3 = args[0];
|
|
}
|
|
|
|
static inline int syscall_get_arch(void)
|
|
{
|
|
int arch = is_32bit_task() ? AUDIT_ARCH_PPC : AUDIT_ARCH_PPC64;
|
|
#ifdef __LITTLE_ENDIAN__
|
|
arch |= __AUDIT_ARCH_LE;
|
|
#endif
|
|
return arch;
|
|
}
|
|
#endif /* _ASM_SYSCALL_H */
|