diff options
| author | Todd Kjos <tkjos@google.com> | 2021-10-12 09:56:12 -0700 |
|---|---|---|
| committer | Todd Kjos <tkjos@google.com> | 2021-11-22 10:02:27 -0800 |
| commit | dc5dc5ed761ead452c98511a1bf2918c15d7d192 (patch) | |
| tree | 136e3cac8be7814d0f0b9e84121f462219a831ed | |
| parent | 0875b76a11e991c1b5682261ed8fd82002ab7975 (diff) | |
BACKPORT: 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>
Change-Id: I91922e7f359df5901749f1b09094c3c68d45aed4
[ Fixed minor conflicts ]
Bug: 200688826
Signed-off-by: Todd Kjos <tkjos@google.com>
| -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 f763aadc379d..c3adf7a69f4a 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -553,6 +553,7 @@ struct binder_proc { struct task_struct *tsk; struct files_struct *files; struct mutex files_lock; + const struct cred *cred; struct hlist_node deferred_work_node; int deferred_work; bool is_dead; @@ -3117,7 +3118,7 @@ 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; @@ -4556,6 +4557,7 @@ static void binder_free_proc(struct binder_proc *proc) BUG_ON(!list_empty(&proc->delivered_death)); binder_alloc_deferred_release(&proc->alloc); put_task_struct(proc->tsk); + put_cred(proc->cred); binder_stats_deleted(BINDER_STAT_PROC); kfree(proc); } @@ -5027,6 +5029,7 @@ static int binder_open(struct inode *nodp, struct file *filp) atomic_set(&proc->tmp_ref, 0); get_task_struct(current->group_leader); proc->tsk = current->group_leader; + proc->cred = get_cred(filp->f_cred); mutex_init(&proc->files_lock); INIT_LIST_HEAD(&proc->todo); if (binder_supported_policy(current->policy)) { |