linux-kernel - [PATCH 3.16 194/204] security: let security modules use PTRACE_MODE

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Date:   Thu, 28 Dec 2017 17:05:44 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Casey Schaufler" <casey@...aufler-ca.com>,
        "Kees Cook" <keescook@...omium.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Willy Tarreau" <w@....eu>, "Oleg Nesterov" <oleg@...hat.com>,
        "James Morris" <james.l.morris@...cle.com>,
        "Jann Horn" <jann@...jh.net>, "Ingo Molnar" <mingo@...hat.com>,
        "Andy Shevchenko" <andriy.shevchenko@...ux.intel.com>,
        "Al Viro" <viro@...iv.linux.org.uk>,
        "Andy Lutomirski" <luto@...nel.org>,
        "Serge E. Hallyn" <serge.hallyn@...ntu.com>
Subject: [PATCH 3.16 194/204] security: let security modules use
 PTRACE_MODE_* with bitmasks

3.16.52-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Jann Horn <jann@...jh.net>

commit 3dfb7d8cdbc7ea0c2970450e60818bb3eefbad69 upstream.

It looks like smack and yama weren't aware that the ptrace mode
can have flags ORed into it - PTRACE_MODE_NOAUDIT until now, but
only for /proc/$pid/stat, and with the PTRACE_MODE_*CREDS patch,
all modes have flags ORed into them.

Signed-off-by: Jann Horn <jann@...jh.net>
Acked-by: Kees Cook <keescook@...omium.org>
Acked-by: Casey Schaufler <casey@...aufler-ca.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: James Morris <james.l.morris@...cle.com>
Cc: "Serge E. Hallyn" <serge.hallyn@...ntu.com>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Willy Tarreau <w@....eu>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 security/smack/smack_lsm.c | 8 +++-----
 security/yama/yama_lsm.c   | 4 ++--
 2 files changed, 5 insertions(+), 7 deletions(-)

--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -163,12 +163,10 @@ static int smk_copy_rules(struct list_he
  */
 static inline unsigned int smk_ptrace_mode(unsigned int mode)
 {
-	switch (mode) {
-	case PTRACE_MODE_READ:
-		return MAY_READ;
-	case PTRACE_MODE_ATTACH:
+	if (mode & PTRACE_MODE_ATTACH)
 		return MAY_READWRITE;
-	}
+	if (mode & PTRACE_MODE_READ)
+		return MAY_READ;
 
 	return 0;
 }
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -292,7 +292,7 @@ int yama_ptrace_access_check(struct task
 		return rc;
 
 	/* require ptrace target be a child of ptracer on attach */
-	if (mode == PTRACE_MODE_ATTACH) {
+	if (mode & PTRACE_MODE_ATTACH) {
 		switch (ptrace_scope) {
 		case YAMA_SCOPE_DISABLED:
 			/* No additional restrictions. */
@@ -318,7 +318,7 @@ int yama_ptrace_access_check(struct task
 		}
 	}
 
-	if (rc) {
+	if (rc && (mode & PTRACE_MODE_NOAUDIT) == 0) {
 		printk_ratelimited(KERN_NOTICE
 			"ptrace of pid %d was attempted by: %s (pid %d)\n",
 			child->pid, current->comm, current->pid);