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authorEric W. Biederman <ebiederm@xmission.com>2013-03-21 18:13:15 -0700
committerEric W. Biederman <ebiederm@xmission.com>2013-03-27 07:50:06 -0700
commita636b702ed1805e988ad3d8ff8b52c060f8b341c (patch)
tree6144e89780172adc58cea3cab7d75000ae31fa04 /ipc
parent132c94e31b8bca8ea921f9f96a57d684fa4ae0a9 (diff)
downloadlinux-a636b702ed1805e988ad3d8ff8b52c060f8b341c.tar.gz
ipc: Restrict mounting the mqueue filesystem
Only allow mounting the mqueue filesystem if the caller has CAP_SYS_ADMIN rights over the ipc namespace. The principle here is if you create or have capabilities over it you can mount it, otherwise you get to live with what other people have mounted. This information is not particularly sensitive and mqueue essentially only reports which posix messages queues exist. Still when creating a restricted environment for an application to live any extra information may be of use to someone with sufficient creativity. The historical if imperfect way this information has been restricted has been not to allow mounts and restricting this to ipc namespace creators maintains the spirit of the historical restriction. Cc: stable@vger.kernel.org Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'ipc')
-rw-r--r--ipc/mqueue.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index e5c4f609f22..c4ae32ec6c6 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -330,8 +330,16 @@ static struct dentry *mqueue_mount(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *data)
{
- if (!(flags & MS_KERNMOUNT))
- data = current->nsproxy->ipc_ns;
+ if (!(flags & MS_KERNMOUNT)) {
+ struct ipc_namespace *ns = current->nsproxy->ipc_ns;
+ /* Don't allow mounting unless the caller has CAP_SYS_ADMIN
+ * over the ipc namespace.
+ */
+ if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
+ return ERR_PTR(-EPERM);
+
+ data = ns;
+ }
return mount_ns(fs_type, flags, data, mqueue_fill_super);
}