Kernel/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-01-13 16:50:05 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

powerpc/kernel: Switch to using MAX_ERRNO

Browse Source 
Currently on powerpc we have our own #define for the highest (negative)
errno value, called _LAST_ERRNO. This is defined to be 516, for reasons
which are not clear.

The generic code, and x86, use MAX_ERRNO, which is defined to be 4095.

In particular seccomp uses MAX_ERRNO to restrict the value that a
seccomp filter can return.

Currently with the mismatch between _LAST_ERRNO and MAX_ERRNO, a seccomp
tracer wanting to return 600, expecting it to be seen as an error, would
instead find on powerpc that userspace sees a successful syscall with a
return value of 600.

To avoid this inconsistency, switch powerpc to use MAX_ERRNO.

We are somewhat confident that generic syscalls that can return a
non-error value above negative MAX_ERRNO have already been updated to
use force_successful_syscall_return().

I have also checked all the powerpc specific syscalls, and believe that
none of them expect to return a non-error value between -MAX_ERRNO and
-516. So this change should be safe ...

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Michael Ellerman 2015-07-23 20:21:01 +10:00
parent f0322f7f1e
commit c3525940cc
3 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/powerpc/include/uapi/asm/errno.h
View File

@ -6,6 +6,4 @@
#undef EDEADLOCK #undef EDEADLOCK
#define EDEADLOCK 58 /* File locking deadlock error */ #define EDEADLOCK 58 /* File locking deadlock error */
#define _LAST_ERRNO 516
#endif /* _ASM_POWERPC_ERRNO_H */ #endif /* _ASM_POWERPC_ERRNO_H */

3
arch/powerpc/kernel/entry_32.S
View File

@ -20,6 +20,7 @@
*/ */
#include <linux/errno.h> #include <linux/errno.h>
#include <linux/err.h>
#include <linux/sys.h> #include <linux/sys.h>
#include <linux/threads.h> #include <linux/threads.h>
#include <asm/reg.h> #include <asm/reg.h>
@ -354,7 +355,7 @@ ret_from_syscall:
SYNC SYNC
MTMSRD(r10) MTMSRD(r10)
lwz r9,TI_FLAGS(r12) lwz r9,TI_FLAGS(r12)
li r8,-_LAST_ERRNO li r8,-MAX_ERRNO
andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK) andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK)
bne- syscall_exit_work bne- syscall_exit_work
cmplw 0,r3,r8 cmplw 0,r3,r8

5
arch/powerpc/kernel/entry_64.S
View File

@ -19,6 +19,7 @@
*/ */
#include <linux/errno.h> #include <linux/errno.h>
#include <linux/err.h>
#include <asm/unistd.h> #include <asm/unistd.h>
#include <asm/processor.h> #include <asm/processor.h>
#include <asm/page.h> #include <asm/page.h>
@ -207,7 +208,7 @@ system_call: /* label this so stack traces look sane */
#endif /* CONFIG_PPC_BOOK3E */ #endif /* CONFIG_PPC_BOOK3E */
ld r9,TI_FLAGS(r12) ld r9,TI_FLAGS(r12)
li r11,-_LAST_ERRNO li r11,-MAX_ERRNO
andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK) andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK)
bne- syscall_exit_work bne- syscall_exit_work
cmpld r3,r11 cmpld r3,r11
@ -277,7 +278,7 @@ syscall_exit_work:
beq+ 0f beq+ 0f
REST_NVGPRS(r1) REST_NVGPRS(r1)
b 2f b 2f
0: cmpld r3,r11 /* r10 is -LAST_ERRNO */ 0: cmpld r3,r11 /* r11 is -MAX_ERRNO */
blt+ 1f blt+ 1f
andi. r0,r9,_TIF_NOERROR andi. r0,r9,_TIF_NOERROR
bne- 1f bne- 1f