file capabilities: remove cap_task_kill()
authorSerge Hallyn <serge@hallyn.com>
Fri, 29 Feb 2008 15:14:57 +0000 (15:14 +0000)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 20 Mar 2008 16:46:36 +0000 (09:46 -0700)
commitaedb60a67c10a0861af179725d060765262ba0fb
tree4a4a316f9f7d1ab0bf4da2cdd5c802bfb05c947f
parent457fb605834504af294916411be128a9b21fc3f6
file capabilities: remove cap_task_kill()

The original justification for cap_task_kill() was as follows:

check_kill_permission() does appropriate uid equivalence checks.
However with file capabilities it becomes possible for an
unprivileged user to execute a file with file capabilities
resulting in a more privileged task with the same uid.

However now that cap_task_kill() always returns 0 (permission
granted) when p->uid==current->uid, the whole hook is worthless,
and only likely to create more subtle problems in the corner cases
where it might still be called but return -EPERM.  Those cases
are basically when uids are different but euid/suid is equivalent
as per the check in check_kill_permission().

One example of a still-broken application is 'at' for non-root users.

This patch removes cap_task_kill().

Signed-off-by: Serge Hallyn <serge@hallyn.com>
Acked-by: Andrew G. Morgan <morgan@kernel.org>
Earlier-version-tested-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/security.h
security/capability.c
security/commoncap.c
security/smack/smack_lsm.c