prctl: use CAP_SYS_RESOURCE for PR_SET_MM option

CAP_SYS_ADMIN is already overloaded left and right, so to have more
fine-grained access control use CAP_SYS_RESOURCE 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
represents what the process owns: pointers to code, data, stack
segments, command line, auxiliary vector data and etc.

Suggested-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/sys.c b/kernel/sys.c
index 4070153..888d227 100644 (file)
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1706,7 +1706,7 @@ static int prctl_set_mm(int opt, unsigned long addr,
        if (arg4 | arg5)
                return -EINVAL;
 
-       if (!capable(CAP_SYS_ADMIN))
+       if (!capable(CAP_SYS_RESOURCE))
                return -EPERM;
 
        if (addr >= TASK_SIZE)