[PATCH 12/13] ptrace: use cred_ids_allow_control()

[Josef Bacik]

__ptrace_may_access() picks the filesystem or the real uid and gid of the
caller by its mode and wants them to be all three of the uids and gids of
the target. Say which ids it is and use the library.

No functional change.

Assisted-by: LLM
Signed-off-by: Josef Bacik <josef at toxicpanda.com>
---
 kernel/ptrace.c | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 4e9822a87aab..2d2ffc656b41 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -305,8 +305,7 @@ static bool task_still_dumpable(struct task_struct *task, unsigned int mode)
 static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 {
 	const struct cred *cred = current_cred(), *tcred;
-	kuid_t caller_uid;
-	kgid_t caller_gid;
+	enum cred_ids caller_ids;
 
 	if (!(mode & PTRACE_MODE_FSCREDS) == !(mode & PTRACE_MODE_REALCREDS)) {
 		WARN(1, "denying ptrace access check without PTRACE_MODE_*CREDS\n");
@@ -327,8 +326,7 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 		return 0;
 	rcu_read_lock();
 	if (mode & PTRACE_MODE_FSCREDS) {
-		caller_uid = cred->fsuid;
-		caller_gid = cred->fsgid;
+		caller_ids = CRED_IDS_FS;
 	} else {
 		/*
 		 * Using the euid would make more sense here, but something
@@ -338,16 +336,10 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 		 * used a syscall that requests access to another process
 		 * (and not a filesystem syscall to procfs).
 		 */
-		caller_uid = cred->uid;
-		caller_gid = cred->gid;
+		caller_ids = CRED_IDS_REAL;
 	}
 	tcred = __task_cred(task);
-	if (uid_eq(caller_uid, tcred->euid) &&
-	    uid_eq(caller_uid, tcred->suid) &&
-	    uid_eq(caller_uid, tcred->uid)  &&
-	    gid_eq(caller_gid, tcred->egid) &&
-	    gid_eq(caller_gid, tcred->sgid) &&
-	    gid_eq(caller_gid, tcred->gid))
+	if (cred_ids_allow_control(cred, caller_ids, tcred))
 		goto ok;
 	if (ptrace_has_cap(tcred->user_ns, mode))
 		goto ok;

-- 
2.55.0