diff options
| author | Todd Kjos <tkjos@google.com> | 2021-10-12 09:56:12 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-11-26 11:58:33 +0100 |
| commit | 120ffcd83596fe94b6d6735d21349f118b60c936 (patch) | |
| tree | de08b6b5887b61d11c0a59fa546a8d37724d14b6 | |
| parent | 18dc3b942ce31a243fb8ca212b42cccb2711f980 (diff) | |
binder: use euid from cred instead of using task
commit 29bc22ac5e5bc63275e850f0c8fc549e3d0e306b upstream.
Save the 'struct cred' associated with a binder process
at initial open to avoid potential race conditions
when converting to an euid.
Set a transaction's sender_euid from the 'struct cred'
saved at binder_open() instead of looking up the euid
from the binder proc's 'struct task'. This ensures
the euid is associated with the security context that
of the task that opened binder.
Cc: stable@vger.kernel.org # 4.4+
Fixes: 457b9a6f09f0 ("Staging: android: add binder driver")
Signed-off-by: Todd Kjos <tkjos@google.com>
Suggested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Suggested-by: Jann Horn <jannh@google.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/android/binder.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 3bc5a7caccbf..0b27238b42c7 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -303,6 +303,7 @@ struct binder_proc { struct mm_struct *vma_vm_mm; struct task_struct *tsk; struct files_struct *files; + const struct cred *cred; struct hlist_node deferred_work_node; int deferred_work; void *buffer; @@ -1493,7 +1494,7 @@ static void binder_transaction(struct binder_proc *proc, t->from = thread; else t->from = NULL; - t->sender_euid = task_euid(proc->tsk); + t->sender_euid = proc->cred->euid; t->to_proc = target_proc; t->to_thread = target_thread; t->code = tr->code; @@ -3015,6 +3016,7 @@ static int binder_open(struct inode *nodp, struct file *filp) return -ENOMEM; get_task_struct(current->group_leader); proc->tsk = current->group_leader; + proc->cred = get_cred(filp->f_cred); INIT_LIST_HEAD(&proc->todo); init_waitqueue_head(&proc->wait); proc->default_priority = task_nice(current); @@ -3220,6 +3222,7 @@ static void binder_deferred_release(struct binder_proc *proc) } put_task_struct(proc->tsk); + put_cred(proc->cred); binder_debug(BINDER_DEBUG_OPEN_CLOSE, "%s: %d threads %d, nodes %d (ref %d), refs %d, active transactions %d, buffers %d, pages %d\n", |