linux-kernel - [PATCH 3.10 115/268] apparmor: internal paths should be treated as disconnected

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Date:   Mon, 19 Jun 2017 20:30:14 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     John Johansen <john.johansen@...onical.com>,
        Jiri Slaby <jslaby@...e.cz>, Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 115/268] apparmor: internal paths should be treated as disconnected

From: John Johansen <john.johansen@...onical.com>

commit bd35db8b8ca6e27fc17a9057ef78e1ddfc0de351 upstream.

Internal mounts are not mounted anywhere and as such should be treated
as disconnected paths.

Signed-off-by: John Johansen <john.johansen@...onical.com>
Acked-by: Seth Arnold <seth.arnold@...onical.com>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Signed-off-by: Willy Tarreau <w@....eu>
---
 security/apparmor/path.c | 64 +++++++++++++++++++++++++++---------------------
 1 file changed, 36 insertions(+), 28 deletions(-)

diff --git a/security/apparmor/path.c b/security/apparmor/path.c
index ebc7780..07bf2ac 100644
--- a/security/apparmor/path.c
+++ b/security/apparmor/path.c
@@ -25,7 +25,6 @@
 #include "include/path.h"
 #include "include/policy.h"
 
-
 /* modified from dcache.c */
 static int prepend(char **buffer, int buflen, const char *str, int namelen)
 {
@@ -39,6 +38,38 @@ static int prepend(char **buffer, int buflen, const char *str, int namelen)
 
 #define CHROOT_NSCONNECT (PATH_CHROOT_REL | PATH_CHROOT_NSCONNECT)
 
+/* If the path is not connected to the expected root,
+ * check if it is a sysctl and handle specially else remove any
+ * leading / that __d_path may have returned.
+ * Unless
+ *     specifically directed to connect the path,
+ * OR
+ *     if in a chroot and doing chroot relative paths and the path
+ *     resolves to the namespace root (would be connected outside
+ *     of chroot) and specifically directed to connect paths to
+ *     namespace root.
+ */
+static int disconnect(const struct path *path, char *buf, char **name,
+		      int flags)
+{
+	int error = 0;
+
+	if (!(flags & PATH_CONNECT_PATH) &&
+	    !(((flags & CHROOT_NSCONNECT) == CHROOT_NSCONNECT) &&
+	      our_mnt(path->mnt))) {
+		/* disconnected path, don't return pathname starting
+		 * with '/'
+		 */
+		error = -EACCES;
+		if (**name == '/')
+			*name = *name + 1;
+	} else if (**name != '/')
+		/* CONNECT_PATH with missing root */
+		error = prepend(name, *name - buf, "/", 1);
+
+	return error;
+}
+
 /**
  * d_namespace_path - lookup a name associated with a given path
  * @path: path to lookup  (NOT NULL)
@@ -74,7 +105,8 @@ static int d_namespace_path(struct path *path, char *buf, int buflen,
 			 * control instead of hard coded /proc
 			 */
 			return prepend(name, *name - buf, "/proc", 5);
-		}
+		} else
+			return disconnect(path, buf, name, flags);
 		return 0;
 	}
 
@@ -120,32 +152,8 @@ static int d_namespace_path(struct path *path, char *buf, int buflen,
 			goto out;
 	}
 
-	/* If the path is not connected to the expected root,
-	 * check if it is a sysctl and handle specially else remove any
-	 * leading / that __d_path may have returned.
-	 * Unless
-	 *     specifically directed to connect the path,
-	 * OR
-	 *     if in a chroot and doing chroot relative paths and the path
-	 *     resolves to the namespace root (would be connected outside
-	 *     of chroot) and specifically directed to connect paths to
-	 *     namespace root.
-	 */
-	if (!connected) {
-		if (!(flags & PATH_CONNECT_PATH) &&
-			   !(((flags & CHROOT_NSCONNECT) == CHROOT_NSCONNECT) &&
-			     our_mnt(path->mnt))) {
-			/* disconnected path, don't return pathname starting
-			 * with '/'
-			 */
-			error = -EACCES;
-			if (*res == '/')
-				*name = res + 1;
-		} else if (*res != '/')
-			/* CONNECT_PATH with missing root */
-			error = prepend(name, *name - buf, "/", 1);
-
-	}
+	if (!connected)
+		error = disconnect(path, buf, name, flags);
 
 out:
 	return error;
-- 
2.8.0.rc2.1.gbe9624a