Use the 'struct cred' saved at binder_open() to lookup the security ID via security_cred_getsecid(). This ensures that the security context that opened binder is the one used to generate the secctx.

Fixes: ec74136ded79 ("binder: create node flag to request sender's security context") Signed-off-by: Todd Kjos tkjos@google.com Suggested-by: Stephen Smalley stephen.smalley.work@gmail.com Cc: stable@vger.kernel.org # 5.4+ --- v3: added this patch to series

drivers/android/binder.c | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c index ca599ebdea4a..989afd0804ca 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2722,16 +2722,7 @@ static void binder_transaction(struct binder_proc *proc, u32 secid; size_t added_size;

- /* - * Arguably this should be the task's subjective LSM secid but - * we can't reliably access the subjective creds of a task - * other than our own so we must use the objective creds, which - * are safe to access. The downside is that if a task is - * temporarily overriding it's creds it will not be reflected - * here; however, it isn't clear that binder would handle that - * case well anyway. - */ - security_task_getsecid_obj(proc->tsk, &secid); + security_cred_getsecid(proc->cred, &secid); ret = security_secid_to_secctx(secid, &secctx, &secctx_sz); if (ret) { return_error = BR_FAILED_REPLY;