apparmor: allow profiles to provide info to disconnected paths

Signed-off-by: John Johansen <john.johansen@canonical.com>

security/apparmor/domain.c

@@ -366,7 +366,7 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 
 	/* buffer freed below, name is pointer into buffer */
 	error = aa_path_name(&bprm->file->f_path, profile->path_flags, &buffer,
-			     &name, &info);
+			     &name, &info, profile->disconnected);
 	if (error) {
 		if (unconfined(profile) ||
 		    (profile->flags & PFLAG_IX_ON_NAME_ERROR))

security/apparmor/file.c

@@ -285,7 +285,8 @@ int aa_path_perm(const char *op, struct aa_profile *profile,
 	int error;
 
 	flags |= profile->path_flags | (S_ISDIR(cond->mode) ? PATH_IS_DIR : 0);
-	error = aa_path_name(path, flags, &buffer, &name, &info);
+	error = aa_path_name(path, flags, &buffer, &name, &info,
+			     profile->disconnected);
 	if (error) {
 		if (error == -ENOENT && is_deleted(path->dentry)) {
 			/* Access to open files that are deleted are
@@ -366,13 +367,13 @@ int aa_path_link(struct aa_profile *profile, struct dentry *old_dentry,
 
 	/* buffer freed below, lname is pointer in buffer */
 	error = aa_path_name(&link, profile->path_flags, &buffer, &lname,
-			     &info);
+			     &info, profile->disconnected);
 	if (error)
 		goto audit;
 
 	/* buffer2 freed below, tname is pointer in buffer2 */
 	error = aa_path_name(&target, profile->path_flags, &buffer2, &tname,
-			     &info);
+			     &info, profile->disconnected);
 	if (error)
 		goto audit;
 

security/apparmor/include/path.h

@@ -27,7 +27,8 @@ enum path_flags {
 };
 
 int aa_path_name(const struct path *path, int flags, char **buffer,
-		 const char **name, const char **info);
+		 const char **name, const char **info,
+		 const char *disconnected);
 
 #define MAX_PATH_BUFFERS 2
 

security/apparmor/include/policy.h

@@ -128,6 +128,7 @@ struct aa_data {
  * @mode: the enforcement mode of the profile
  * @flags: flags controlling profile behavior
  * @path_flags: flags controlling path generation behavior
+ * @disconnected: what to prepend if attach_disconnected is specified
  * @size: the memory consumed by this profiles rules
  * @policy: general match rules governing policy
  * @file: The set of rules governing basic file access and domain transitions
@@ -169,6 +170,7 @@ struct aa_profile {
 	long mode;
 	long flags;
 	u32 path_flags;
+	const char *disconnected;
 	int size;
 
 	struct aa_policydb policy;

security/apparmor/path.c

@@ -50,7 +50,7 @@ static int prepend(char **buffer, int buflen, const char *str, int namelen)
  *     namespace root.
  */
 static int disconnect(const struct path *path, char *buf, char **name,
-		      int flags)
+		      int flags, const char *disconnected)
 {
 	int error = 0;
 
@@ -63,9 +63,14 @@ static int disconnect(const struct path *path, char *buf, char **name,
 		error = -EACCES;
 		if (**name == '/')
 			*name = *name + 1;
-	} else if (**name != '/')
-		/* CONNECT_PATH with missing root */
-		error = prepend(name, *name - buf, "/", 1);
+	} else {
+		if (**name != '/')
+			/* CONNECT_PATH with missing root */
+			error = prepend(name, *name - buf, "/", 1);
+		if (!error && disconnected)
+			error = prepend(name, *name - buf, disconnected,
+					strlen(disconnected));
+	}
 
 	return error;
 }
@@ -77,6 +82,7 @@ static int disconnect(const struct path *path, char *buf, char **name,
  * @buflen: length of @buf
  * @name: Returns - pointer for start of path name with in @buf (NOT NULL)
  * @flags: flags controlling path lookup
+ * @disconnected: string to prefix to disconnected paths
  *
  * Handle path name lookup.
  *
@@ -85,7 +91,7 @@ static int disconnect(const struct path *path, char *buf, char **name,
  *          to a position in @buf
  */
 static int d_namespace_path(const struct path *path, char *buf, int buflen,
-			    char **name, int flags)
+			    char **name, int flags, const char *disconnected)
 {
 	char *res;
 	int error = 0;
@@ -106,8 +112,8 @@ static int d_namespace_path(const struct path *path, char *buf, int buflen,
 			 */
 			return prepend(name, *name - buf, "/proc", 5);
 		} else
-			return disconnect(path, buf, name, flags);
-		return 0;
+			return disconnect(path, buf, name, flags,
+					  disconnected);
 	}
 
 	/* resolve paths relative to chroot?*/
@@ -153,7 +159,7 @@ static int d_namespace_path(const struct path *path, char *buf, int buflen,
 	}
 
 	if (!connected)
-		error = disconnect(path, buf, name, flags);
+		error = disconnect(path, buf, name, flags, disconnected);
 
 out:
 	return error;
@@ -170,10 +176,12 @@ out:
  * Returns: %0 else error on failure
  */
 static int get_name_to_buffer(const struct path *path, int flags, char *buffer,
-			      int size, char **name, const char **info)
+			      int size, char **name, const char **info,
+			      const char *disconnected)
 {
 	int adjust = (flags & PATH_IS_DIR) ? 1 : 0;
-	int error = d_namespace_path(path, buffer, size - adjust, name, flags);
+	int error = d_namespace_path(path, buffer, size - adjust, name, flags,
+				     disconnected);
 
 	if (!error && (flags & PATH_IS_DIR) && (*name)[1] != '\0')
 		/*
@@ -203,6 +211,7 @@ static int get_name_to_buffer(const struct path *path, int flags, char *buffer,
  * @buffer: buffer that aa_get_name() allocated  (NOT NULL)
  * @name: Returns - the generated path name if !error (NOT NULL)
  * @info: Returns - information on why the path lookup failed (MAYBE NULL)
+ * @disconnected: string to prepend to disconnected paths
  *
  * @name is a pointer to the beginning of the pathname (which usually differs
  * from the beginning of the buffer), or NULL.  If there is an error @name
@@ -216,7 +225,7 @@ static int get_name_to_buffer(const struct path *path, int flags, char *buffer,
  * Returns: %0 else error code if could retrieve name
  */
 int aa_path_name(const struct path *path, int flags, char **buffer,
-		 const char **name, const char **info)
+		 const char **name, const char **info, const char *disconnected)
 {
 	char *buf, *str = NULL;
 	int size = 256;
@@ -230,7 +239,8 @@ int aa_path_name(const struct path *path, int flags, char **buffer,
 		if (!buf)
 			return -ENOMEM;
 
-		error = get_name_to_buffer(path, flags, buf, size, &str, info);
+		error = get_name_to_buffer(path, flags, buf, size, &str, info,
+					   disconnected);
 		if (error != -ENAMETOOLONG)
 			break;
 

security/apparmor/policy_unpack.c

@@ -569,6 +569,9 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name)
 		profile->xmatch_len = tmp;
 	}
 
+	/* disconnected attachment string is optional */
+	(void) unpack_str(e, &profile->disconnected, "disconnected");
+
 	/* per profile debug flags (complain, audit) */
 	if (!unpack_nameX(e, AA_STRUCT, "flags"))
 		goto fail;