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@xxxxxxxxxx>
Suggested-by: Stephen Smalley <stephen.smalley.work@xxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # 5.4+
---
v3: added this patch to series
v4: fix build-break for !CONFIG_SECURITY
v5: set *secid=0 for !CONFIG_SECURITY version of secuirty_cred_getsecid()
drivers/android/binder.c | 11 +----------
include/linux/security.h | 5 +++++
2 files changed, 6 insertions(+), 10 deletions(-)
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index bc15325f0579..26382e982c5e 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;
diff --git a/include/linux/security.h b/include/linux/security.h
index 6344d3362df7..46a02ce34d00 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1041,6 +1041,11 @@ 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;
--
2.33.0.882.g93a45727a2-goog
