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BACKPORT: binder: use cred instead of task for getsecid

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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: ec74136ded ("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>
Bug: 200688826
(cherry picked from commit 4d5b553974)
[ refactored to avoid changing KMI: struct binder_proc ]
Change-Id: Ie023be3190caf20ca3901560455e9f027c9426cd
This commit is contained in:
Todd Kjos 2021-10-12 09:56:14 -07:00
commit 11db2de0af
2 changed files with 6 additions and 1 deletions
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2
drivers/android/binder.c
View file

@ -2865,7 +2865,7 @@ static void binder_transaction(struct binder_proc *proc,
size_t added_size;
int max_retries = 100;
security_task_getsecid(proc->tsk, &secid);
security_cred_getsecid(binder_get_cred(proc), &secid);
retry_alloc:
ret = security_secid_to_secctx(secid, &secctx, &secctx_sz);
if (ret == -ENOMEM && max_retries-- > 0) {

5
include/linux/security.h
View file

@ -1011,6 +1011,11 @@ 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;