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[PATCH 4/9] allow killing tasks in your own or child userns [message #41749 is a reply to message #41743]

Thu, 17 February 2011 15:03

serge
Messages: 72
Registered: January 2007

Member

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

Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
---
kernel/signal.c | 30 ++++++++++++++++++++++--------
1 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index 4e3cff1..ffe4bdf 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 inline 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);
--
1.7.0.4

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[Message index]

		userns: targeted capabilities v5 By: serge on Thu, 17 February 2011 15:02
		[PATCH 2/9] security: Make capabilities relative to the user namespace. By: serge on Thu, 17 February 2011 15:03
		Re: [PATCH 2/9] security: Make capabilities relative to the user namespace. By: ebiederm on Fri, 18 February 2011 03:46
		Re: [PATCH 2/9] security: Make capabilities relative to the user namespace. By: Daniel Lezcano on Fri, 18 February 2011 23:44
		Re: [PATCH 2/9] security: Make capabilities relative to the user namespace. By: akpm on Fri, 18 February 2011 23:59
		Re: [PATCH 2/9] security: Make capabilities relative to the user namespace. By: David Howells on Wed, 23 February 2011 12:01
		Re: [PATCH 2/9] security: Make capabilities relative to the user namespace. By: serge on Wed, 23 February 2011 13:43
		Re: [PATCH 2/9] security: Make capabilities relative to the user namespace. By: David Howells on Wed, 23 February 2011 11:40
		Re: [PATCH 2/9] security: Make capabilities relative to the user namespace. By: David Howells on Wed, 23 February 2011 16:59
		[PATCH 9/9] userns: check user namespace for task->file uid equivalence checks By: serge on Thu, 17 February 2011 15:04
		Re: [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks By: ebiederm on Fri, 18 February 2011 01:29
		Re: [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks By: akpm on Fri, 18 February 2011 23:59
		Re: [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks By: serge on Thu, 24 February 2011 03:24
		Re: [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks By: akpm on Thu, 24 February 2011 05:08
		Re: [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks By: Daniel Lezcano on Sat, 19 February 2011 19:22
		[PATCH 7/9] add a user namespace owner of ipc ns By: serge on Thu, 17 February 2011 15:03
		Re: [PATCH 7/9] add a user namespace owner of ipc ns By: ebiederm on Fri, 18 February 2011 03:19
		Re: [PATCH 7/9] add a user namespace owner of ipc ns By: akpm on Fri, 18 February 2011 23:59
		Re: [PATCH 7/9] add a user namespace owner of ipc ns By: Daniel Lezcano on Sat, 19 February 2011 17:57
		[PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: serge on Thu, 17 February 2011 15:02
		Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: ebiederm on Fri, 18 February 2011 03:31
		Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: Daniel Lezcano on Fri, 18 February 2011 16:57
		Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: akpm on Fri, 18 February 2011 23:59
		Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: David Howells on Wed, 23 February 2011 17:16
		Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: ebiederm on Wed, 23 February 2011 21:21
		Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: David Howells on Wed, 23 February 2011 23:19
		Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace By: ebiederm on Wed, 23 February 2011 23:54
		[PATCH 3/9] allow sethostname in a container By: serge on Thu, 17 February 2011 15:03
		Re: [PATCH 3/9] allow sethostname in a container By: ebiederm on Fri, 18 February 2011 03:05
		Re: [PATCH 3/9] allow sethostname in a container By: Daniel Lezcano on Fri, 18 February 2011 23:46
		[PATCH 4/9] allow killing tasks in your own or child userns By: serge on Thu, 17 February 2011 15:03
		Re: [PATCH 4/9] allow killing tasks in your own or child userns By: ebiederm on Fri, 18 February 2011 03:00
		Re: [PATCH 4/9] allow killing tasks in your own or child userns By: akpm on Fri, 18 February 2011 23:59
		Re: [PATCH 4/9] allow killing tasks in your own or child userns By: serge on Thu, 24 February 2011 00:48
		Re: [PATCH 4/9] allow killing tasks in your own or child userns By: akpm on Thu, 24 February 2011 00:54
		Re: [PATCH 4/9] allow killing tasks in your own or child userns By: Daniel Lezcano on Sat, 19 February 2011 10:55
		[PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c By: serge on Thu, 17 February 2011 15:03
		Re: [PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c By: ebiederm on Fri, 18 February 2011 01:57
		Re: [PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c By: akpm on Fri, 18 February 2011 23:59
		Re: [PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c By: akpm on Sat, 19 February 2011 00:01
		Re: [PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c By: Daniel Lezcano on Sat, 19 February 2011 17:52
		[PATCH 5/9] Allow ptrace from non-init user namespaces By: serge on Thu, 17 February 2011 15:03
		Re: [PATCH 5/9] Allow ptrace from non-init user namespaces By: ebiederm on Fri, 18 February 2011 02:59
		Re: [PATCH 5/9] Allow ptrace from non-init user namespaces By: serge on Fri, 18 February 2011 04:36
		[PATCH] userns: ptrace: incorporate feedback from Eric By: serge on Thu, 24 February 2011 00:49
		Re: [PATCH] userns: ptrace: incorporate feedback from Eric By: akpm on Thu, 24 February 2011 00:56
		Re: [PATCH] userns: ptrace: incorporate feedback from Eric By: serge on Thu, 24 February 2011 03:15
		Re: [PATCH 5/9] Allow ptrace from non-init user namespaces By: akpm on Fri, 18 February 2011 23:59
		Re: [PATCH 5/9] Allow ptrace from non-init user namespaces By: serge on Thu, 24 February 2011 00:43
		Re: [PATCH 5/9] Allow ptrace from non-init user namespaces By: Daniel Lezcano on Sat, 19 February 2011 17:49
		Re: [PATCH 5/9] Allow ptrace from non-init user namespaces By: David Howells on Wed, 23 February 2011 17:05
		Re: [PATCH 5/9] Allow ptrace from non-init user namespaces By: David Howells on Wed, 23 February 2011 17:11
		[PATCH 8/9] user namespaces: convert several capable() calls By: serge on Thu, 17 February 2011 15:03
		Re: [PATCH 8/9] user namespaces: convert several capable() calls By: ebiederm on Fri, 18 February 2011 01:51
		Re: [PATCH 8/9] user namespaces: convert several capable() calls By: Daniel Lezcano on Sat, 19 February 2011 19:07
		Re: userns: targeted capabilities v5 By: akpm on Fri, 18 February 2011 00:21
		Re: userns: targeted capabilities v5 By: ebiederm on Fri, 18 February 2011 03:53
		Re: userns: targeted capabilities v5 By: serge on Fri, 18 February 2011 04:28
		User namespaces and keys By: David Howells on Wed, 23 February 2011 12:05
		Re: User namespaces and keys By: serge on Wed, 23 February 2011 13:58
		Re: User namespaces and keys By: ebiederm on Wed, 23 February 2011 14:46
		Re: User namespaces and keys By: David Howells on Wed, 23 February 2011 15:06
		Re: User namespaces and keys By: ebiederm on Wed, 23 February 2011 15:45
		Re: User namespaces and keys By: Serge E. Hallyn on Wed, 23 February 2011 15:53
		Re: User namespaces and keys By: Casey Schaufler on Wed, 23 February 2011 19:24
		Re: User namespaces and keys By: ebiederm on Wed, 23 February 2011 20:55
		Re: User namespaces and keys By: Casey Schaufler on Wed, 23 February 2011 21:37
		Re: User namespaces and keys By: ebiederm on Thu, 24 February 2011 06:56

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