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FAILED: patch "[PATCH] ptrace: Set PF_SUPERPRIV when checking capability" failed to apply to 4.14-stable tree

PATCH [email protected] 1 participant 1 message Nov 23, 2020

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The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From cf23705244c947151179f929774fabf71e239eee Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= <[email protected]>
Date: Fri, 30 Oct 2020 13:38:48 +0100
Subject: [PATCH] ptrace: Set PF_SUPERPRIV when checking capability
MIME-Version: 1.0
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Commit 69f594a38967 ("ptrace: do not audit capability check when outputing /proc/pid/stat") replaced the use of ns_capable() with has_ns_capability{,_noaudit}() which doesn't set PF_SUPERPRIV.

Commit 6b3ad6649a4c ("ptrace: reintroduce usage of subjective credentials in ptrace_has_cap()") replaced has_ns_capability{,_noaudit}() with security_capable(), which doesn't set PF_SUPERPRIV neither.

Since commit 98f368e9e263 ("kernel: Add noaudit variant of ns_capable()"), a new ns_capable_noaudit() helper is available. Let's use it!

As a result, the signature of ptrace_has_cap() is restored to its original one.

Cc Christian Brauner <[email protected]>
Cc Eric Paris <[email protected]>
Cc Jann Horn <[email protected]>
Cc Kees Cook <[email protected]>
Cc Oleg Nesterov <[email protected]>
Cc Serge E. Hallyn <[email protected]>
Cc Tyler Hicks <[email protected]>
Cc [email protected]
Fixes 6b3ad6649a4c ("ptrace: reintroduce usage of subjective credentials in ptrace_has_cap()")
Fixes 69f594a38967 ("ptrace: do not audit capability check when outputing /proc/pid/stat")
Signed-off-by Mickaël Salaün <[email protected]>
Reviewed-by Jann Horn <[email protected]>
Signed-off-by Kees Cook <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
kernel/ptrace.c +5 -11
index 43d6179508d6..79de1294f8eb 100644
@@ -264,17 +264,11 @@ static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
 	return ret;
 }
 
-static bool ptrace_has_cap(const struct cred *cred, struct user_namespace *ns,
-			   unsigned int mode)
+static bool ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
 {
-	int ret;
-
 	if (mode & PTRACE_MODE_NOAUDIT)
-		ret = security_capable(cred, ns, CAP_SYS_PTRACE, CAP_OPT_NOAUDIT);
-	else
-		ret = security_capable(cred, ns, CAP_SYS_PTRACE, CAP_OPT_NONE);
-
-	return ret == 0;
+		return ns_capable_noaudit(ns, CAP_SYS_PTRACE);
+	return ns_capable(ns, CAP_SYS_PTRACE);
 }
 
 /* Returns 0 on success, -errno on denial. */

@@ -326,7 +320,7 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 	    gid_eq(caller_gid, tcred->sgid) &&
 	    gid_eq(caller_gid, tcred->gid))
 		goto ok;
-	if (ptrace_has_cap(cred, tcred->user_ns, mode))
+	if (ptrace_has_cap(tcred->user_ns, mode))
 		goto ok;
 	rcu_read_unlock();
 	return -EPERM;

@@ -345,7 +339,7 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 	mm = task->mm;
 	if (mm &&
 	    ((get_dumpable(mm) != SUID_DUMP_USER) &&
-	     !ptrace_has_cap(cred, mm->user_ns, mode)))
+	     !ptrace_has_cap(mm->user_ns, mode)))
 	    return -EPERM;
 
 	return security_ptrace_access_check(task, mode);