This is a note to let you know that I've just added the patch titled
binder: use cred instead of task for getsecid
to the 5.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
binder-use-cred-instead-of-task-for-getsecid.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4d5b5539742d2554591751b4248b0204d20dcc9d Mon Sep 17 00:00:00 2001
From: Todd Kjos <tkjos@xxxxxxxxxx>
Date: Tue, 12 Oct 2021 09:56:14 -0700
Subject: binder: use cred instead of task for getsecid
From: Todd Kjos <tkjos@xxxxxxxxxx>
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@xxxxxxxxxxxxxxx # 5.4+
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>
Acked-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/android/binder.c | 11 +----------
include/linux/security.h | 5 +++++
2 files changed, 6 insertions(+), 10 deletions(-)
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2722,16 +2722,7 @@ static void binder_transaction(struct bi
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;
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1041,6 +1041,11 @@ static inline void security_transfer_cre
{
}
+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;
Patches currently in stable-queue which might be from tkjos@xxxxxxxxxx are
queue-5.14/binder-use-cred-instead-of-task-for-selinux-checks.patch
queue-5.14/binder-don-t-detect-sender-target-during-buffer-cleanup.patch
queue-5.14/binder-use-cred-instead-of-task-for-getsecid.patch
queue-5.14/binder-use-euid-from-cred-instead-of-using-task.patch
