LSM: lift parsing LSM options into the caller of ->sb_kern_mount()

This paves the way for retaining the LSM options from a common filesystem
mount context during a mount parameter parsing phase to be instituted prior
to actual mount/reconfiguration actions.
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/super.c

@@ -1246,17 +1246,26 @@ mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
 {
 	struct dentry *root;
 	struct super_block *sb;
-	char *secdata = NULL;
 	int error = -ENOMEM;
+	struct security_mnt_opts opts;
+
+	security_init_mnt_opts(&opts);
 
 	if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
-		secdata = alloc_secdata();
+		char *secdata = alloc_secdata();
 		if (!secdata)
-			goto out;
+			return ERR_PTR(-ENOMEM);
 
 		error = security_sb_copy_data(data, secdata);
+		if (error) {
+			free_secdata(secdata);
+			return ERR_PTR(error);
+		}
+
+		error = security_sb_parse_opts_str(secdata, &opts);
+		free_secdata(secdata);
 		if (error)
-			goto out_free_secdata;
+			return ERR_PTR(error);
 	}
 
 	root = type->mount(type, flags, name, data);
@@ -1277,7 +1286,7 @@ mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
 	smp_wmb();
 	sb->s_flags |= SB_BORN;
 
-	error = security_sb_kern_mount(sb, flags, secdata);
+	error = security_sb_kern_mount(sb, flags, &opts);
 	if (error)
 		goto out_sb;
 
@@ -1291,14 +1300,13 @@ mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
 		"negative value (%lld)\n", type->name, sb->s_maxbytes);
 
 	up_write(&sb->s_umount);
-	free_secdata(secdata);
+	security_free_mnt_opts(&opts);
 	return root;
 out_sb:
 	dput(root);
 	deactivate_locked_super(sb);
 out_free_secdata:
-	free_secdata(secdata);
-out:
+	security_free_mnt_opts(&opts);
 	return ERR_PTR(error);
 }
 

include/linux/lsm_hooks.h

@@ -1463,7 +1463,8 @@ union security_list_options {
 	void (*sb_free_security)(struct super_block *sb);
 	int (*sb_copy_data)(char *orig, char *copy);
 	int (*sb_remount)(struct super_block *sb, void *data);
-	int (*sb_kern_mount)(struct super_block *sb, int flags, void *data);
+	int (*sb_kern_mount)(struct super_block *sb, int flags,
+			     struct security_mnt_opts *opts);
 	int (*sb_show_options)(struct seq_file *m, struct super_block *sb);
 	int (*sb_statfs)(struct dentry *dentry);
 	int (*sb_mount)(const char *dev_name, const struct path *path,

include/linux/security.h

@@ -250,7 +250,8 @@ int security_sb_alloc(struct super_block *sb);
 void security_sb_free(struct super_block *sb);
 int security_sb_copy_data(char *orig, char *copy);
 int security_sb_remount(struct super_block *sb, void *data);
-int security_sb_kern_mount(struct super_block *sb, int flags, void *data);
+int security_sb_kern_mount(struct super_block *sb, int flags,
+			   struct security_mnt_opts *opts);
 int security_sb_show_options(struct seq_file *m, struct super_block *sb);
 int security_sb_statfs(struct dentry *dentry);
 int security_sb_mount(const char *dev_name, const struct path *path,
@@ -565,7 +566,8 @@ static inline int security_sb_remount(struct super_block *sb, void *data)
 	return 0;
 }
 
-static inline int security_sb_kern_mount(struct super_block *sb, int flags, void *data)
+static inline int security_sb_kern_mount(struct super_block *sb, int flags,
+					 struct security_mnt_opts *opts)
 {
 	return 0;
 }

security/security.c

@@ -395,9 +395,10 @@ int security_sb_remount(struct super_block *sb, void *data)
 	return call_int_hook(sb_remount, 0, sb, data);
 }
 
-int security_sb_kern_mount(struct super_block *sb, int flags, void *data)
+int security_sb_kern_mount(struct super_block *sb, int flags,
+			   struct security_mnt_opts *opts)
 {
-	return call_int_hook(sb_kern_mount, 0, sb, flags, data);
+	return call_int_hook(sb_kern_mount, 0, sb, flags, opts);
 }
 
 int security_sb_show_options(struct seq_file *m, struct super_block *sb)

security/selinux/hooks.c

@@ -2897,30 +2897,12 @@ static int selinux_sb_remount(struct super_block *sb, void *data)
 	goto out_free_opts;
 }
 
-static int selinux_sb_kern_mount(struct super_block *sb, int flags, void *data)
+static int selinux_sb_kern_mount(struct super_block *sb, int flags,
+				 struct security_mnt_opts *opts)
 {
-	char *options = data;
 	const struct cred *cred = current_cred();
 	struct common_audit_data ad;
-	int rc = 0;
-	struct security_mnt_opts opts;
-
-	security_init_mnt_opts(&opts);
-
-	if (!data)
-		goto out;
-
-	BUG_ON(sb->s_type->fs_flags & FS_BINARY_MOUNTDATA);
-
-	rc = selinux_parse_opts_str(options, &opts);
-	if (rc)
-		goto out_err;
-
-out:
-	rc = selinux_set_mnt_opts(sb, &opts, 0, NULL);
-
-out_err:
-	security_free_mnt_opts(&opts);
+	int rc = selinux_set_mnt_opts(sb, opts, 0, NULL);
 	if (rc)
 		return rc;
 

security/smack/smack_lsm.c

@@ -859,27 +859,10 @@ static int smack_set_mnt_opts(struct super_block *sb,
  *
  * Returns 0 on success, an error code on failure
  */
-static int smack_sb_kern_mount(struct super_block *sb, int flags, void *data)
+static int smack_sb_kern_mount(struct super_block *sb, int flags,
+			       struct security_mnt_opts *opts)
 {
-	int rc = 0;
-	char *options = data;
-	struct security_mnt_opts opts;
-
-	security_init_mnt_opts(&opts);
-
-	if (!options)
-		goto out;
-
-	rc = smack_parse_opts_str(options, &opts);
-	if (rc)
-		goto out_err;
-
-out:
-	rc = smack_set_mnt_opts(sb, &opts, 0, NULL);
-
-out_err:
-	security_free_mnt_opts(&opts);
-	return rc;
+	return smack_set_mnt_opts(sb, opts, 0, NULL);
 }
 
 /**