[PATCH 6.18.y 1/3] cred: add kernel_cred() helper

[Sasha Levin <sashal@kernel.org>]

From: Christian Brauner <brauner@kernel.org>

[ Upstream commit 4c7ceeb62d3330b6fb2b549ae833a92c0f481f3e ]

Access kernel creds based off of init_task. This will let us avoid any
direct access to init_cred.

Link: https://patch.msgid.link/20251103-work-creds-init_cred-v1-2-cb3ec8711a6a@kernel.org
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Stable-dep-of: 981ccd97f715 ("dm: avoid leaking the caller's thread keyring via the table device file")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/cred.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/include/linux/cred.h b/include/linux/cred.h
index 89ae50ad2acea9..8ab3718184adf8 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -20,6 +20,8 @@
 struct cred;
 struct inode;
 
+extern struct task_struct init_task;
+
 /*
  * COW Supplementary groups list
  */
@@ -156,6 +158,11 @@ extern struct cred *prepare_exec_creds(void);
 extern int commit_creds(struct cred *);
 extern void abort_creds(struct cred *);
 extern struct cred *prepare_kernel_cred(struct task_struct *);
+static inline const struct cred *kernel_cred(void)
+{
+	/* shut up sparse */
+	return rcu_dereference_raw(init_task.cred);
+}
 extern int set_security_override(struct cred *, u32);
 extern int set_security_override_from_ctx(struct cred *, const char *);
 extern int set_create_files_as(struct cred *, struct inode *);
-- 
2.53.0