diff options
| author | Serge E. Hallyn <serge@hallyn.com> | 2011-03-23 16:43:19 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-03-23 19:47:04 -0700 |
| commit | 39fd33933b0209e4b6254743f2cede07c5ad4c52 (patch) | |
| tree | 394f09178324fd1e31847a6c71d81f01e6236b02 /kernel | |
| parent | bb96a6f50be27390dc959ff67d9ea0ea0cfbe177 (diff) | |
userns: allow killing tasks in your own or child userns
Changelog:
Dec 8: Fixed bug in my check_kill_permission pointed out by
Eric Biederman.
Dec 13: Apply Eric's suggestion to pass target task into kill_ok_by_cred()
for clarity
Dec 31: address comment by Eric Biederman:
don't need cred/tcred in check_kill_permission.
Jan 1: use const cred struct.
Jan 11: Per Bastian Blank's advice, clean up kill_ok_by_cred().
Feb 16: kill_ok_by_cred: fix bad parentheses
Feb 23: per akpm, let compiler inline kill_ok_by_cred
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Daniel Lezcano <daniel.lezcano@free.fr>
Acked-by: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/signal.c | 30 |
1 files changed, 22 insertions, 8 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index 31751868de88..324eff5468ad 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -636,13 +636,33 @@ static inline bool si_fromuser(const struct siginfo *info) } /* + * called with RCU read lock from check_kill_permission() + */ +static int kill_ok_by_cred(struct task_struct *t) +{ + const struct cred *cred = current_cred(); + const struct cred *tcred = __task_cred(t); + + if (cred->user->user_ns == tcred->user->user_ns && + (cred->euid == tcred->suid || + cred->euid == tcred->uid || + cred->uid == tcred->suid || + cred->uid == tcred->uid)) + return 1; + + if (ns_capable(tcred->user->user_ns, CAP_KILL)) + return 1; + + return 0; +} + +/* * Bad permissions for sending the signal * - the caller must hold the RCU read lock */ static int check_kill_permission(int sig, struct siginfo *info, struct task_struct *t) { - const struct cred *cred, *tcred; struct pid *sid; int error; @@ -656,14 +676,8 @@ static int check_kill_permission(int sig, struct siginfo *info, if (error) return error; - cred = current_cred(); - tcred = __task_cred(t); if (!same_thread_group(current, t) && - (cred->euid ^ tcred->suid) && - (cred->euid ^ tcred->uid) && - (cred->uid ^ tcred->suid) && - (cred->uid ^ tcred->uid) && - !capable(CAP_KILL)) { + !kill_ok_by_cred(t)) { switch (sig) { case SIGCONT: sid = task_session(t); |