Commit 1c1f5718 authored Nov 10, 2021 by Todd Kjos

BACKPORT: binder: use cred instead of task for getsecid



commit 4d5b5539742d2554591751b4248b0204d20dcc9d upstream.

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.

Cc: stable@vger.kernel.org # 5.4+
Fixes: ec74136d ("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>
Reported-by: kernel test robot <lkp@intel.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>
Bug: 200688826
[ fixed minor conflict ]
Signed-off-by: Todd Kjos <tkjos@google.com>
Change-Id: I4ef69da21d7ae651895c498b3aa224f180026fa9

parent ea1a2391

drivers/android/binder.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2841,7 +2841,7 @@ static void binder_transaction(struct binder_proc *proc,
		u32 secid;
		size_t added_size;

		security_task_getsecid(proc->tsk, &secid);
		security_cred_getsecid(binder_get_cred(proc), &secid);
		ret = security_secid_to_secctx(secid, &secctx, &secctx_sz);
		if (ret) {
		return_error = BR_FAILED_REPLY;

include/linux/security.h

+5 −0

Original line number	Diff line number	Diff line
		@@ -985,6 +985,11 @@ static inline void security_transfer_creds(struct cred *new,
		{
		}

		static inline void security_cred_getsecid(const struct cred c, u32 secid)
		{
		*secid = 0;
		}

		static inline int security_kernel_act_as(struct cred *cred, u32 secid)
		{
		return 0;