prctl: Use CAP_SYS_RESOUCE for PR_SET_MM option

CAP_SYS_ADMIN is already overloaded left and right, so to have more finegrained access control use CAP_SYS_RESOUCE here.

The CAP_SYS_RESOUCE is chosen because this prctl option allows a current process to adjust some fields of memory map descriptor which rather represent what the process owns: pointers to code, data, stack segments, command line, auxilary vector data and etc.

Suggested-by Michael Kerrisk <[email protected]>

CC Andrew Morton <[email protected]>

CC Pavel Emelyanov <[email protected]>

CC Tejun Heo <[email protected]>

CC Oleg Nesterov <[email protected]>

CC KOSAKI Motohiro <[email protected]>

CC Kees Cook <[email protected]>

Signed-off-by Cyrill Gorcunov <[email protected]>

---
 kernel/sys.c |    2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6.git/kernel/sys.c
===================================================================

CAP_SYS_ADMIN is already overloaded left and right, so to have more finegrained access control use CAP_SYS_RESOUCE here.

The CAP_SYS_RESOUCE is chosen because this prctl option allows a current process to adjust some fields of memory map descriptor which rather represent what the process owns: pointers to code, data, stack segments, command line, auxilary vector data and etc.

Suggested-by Michael Kerrisk <[email protected]>

CC Andrew Morton <[email protected]>

CC Pavel Emelyanov <[email protected]>

CC Tejun Heo <[email protected]>

CC Oleg Nesterov <[email protected]>

CC KOSAKI Motohiro <[email protected]>

CC Kees Cook <[email protected]>

Signed-off-by Cyrill Gorcunov <[email protected]>

---
 kernel/sys.c |    2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6.git/kernel/sys.c
===================================================================

kernel/sys.c +1 -1

@@ -1712,7 +1712,7 @@ static int prctl_set_mm(int opt, unsigne
        if (arg5 || (arg4 && opt != PR_SET_MM_AUXV))
                return -EINVAL;
 
-       if (!capable(CAP_SYS_ADMIN))
+       if (!capable(CAP_SYS_RESOURCE))
                return -EPERM;
 
        if (addr >= TASK_SIZE)

CAP_SYS_ADMIN is already overloaded left and right, so to have more finegrained access control use CAP_SYS_RESOUCE here.

The CAP_SYS_RESOUCE is chosen because this prctl option allows a current process to adjust some fields of memory map descriptor which rather represent what the process owns: pointers to code, data, stack segments, command line, auxilary vector data and etc.

Quoted 10 lines · Cyrill Gorcunov

CAP_SYS_ADMIN is already overloaded left and right, so to have more finegrained access control use CAP_SYS_RESOUCE here.

The CAP_SYS_RESOUCE is chosen because this prctl option allows a current process to adjust some fields of memory map descriptor which rather represent what the process owns: pointers to code, data, stack segments, command line, auxilary vector data and etc.

Nitpicking: s/CAP_SYS_RESOUCE/CAP_SYS_RESOURCE/ in both the commit summary and the commit explanation. (And if you change that you might also do a s/auxilary/auxiliary/ in the commit explanation.)