LSM: new method: ->sb_add_mnt_opt()

Adding options to growing mnt_opts.  NFS kludge with passing
context= down into non-text-options mount switched to it, and
with that the last use of ->sb_parse_opts_str() is gone.

Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/nfs/super.c

@@ -2070,14 +2070,9 @@ static int nfs23_validate_mount_data(void *options,
 		if (data->context[0]){
 #ifdef CONFIG_SECURITY_SELINUX
 			int rc;
-			char *opts_str = kmalloc(sizeof(data->context) + 8, GFP_KERNEL);
-			if (!opts_str)
-				return -ENOMEM;
-			strcpy(opts_str, "context=");
 			data->context[NFS_MAX_CONTEXT_LEN] = '\0';
-			strcat(opts_str, &data->context[0]);
-			rc = security_sb_parse_opts_str(opts_str, &args->lsm_opts);
-			kfree(opts_str);
+			rc = security_add_mnt_opt("context", data->context,
+					strlen(data->context), &args->lsm_opts);
 			if (rc)
 				return rc;
 #else

include/linux/lsm_hooks.h

@@ -1479,7 +1479,8 @@ union security_list_options {
 					struct super_block *newsb,
 					unsigned long kern_flags,
 					unsigned long *set_kern_flags);
-	int (*sb_parse_opts_str)(char *options, void **mnt_opts);
+	int (*sb_add_mnt_opt)(const char *option, const char *val, int len,
+			      void **mnt_opts);
 	int (*dentry_init_security)(struct dentry *dentry, int mode,
 					const struct qstr *name, void **ctx,
 					u32 *ctxlen);
@@ -1812,7 +1813,7 @@ struct security_hook_heads {
 	struct hlist_head sb_pivotroot;
 	struct hlist_head sb_set_mnt_opts;
 	struct hlist_head sb_clone_mnt_opts;
-	struct hlist_head sb_parse_opts_str;
+	struct hlist_head sb_add_mnt_opt;
 	struct hlist_head dentry_init_security;
 	struct hlist_head dentry_create_files_as;
 #ifdef CONFIG_SECURITY_PATH

include/linux/security.h

@@ -240,7 +240,8 @@ int security_sb_clone_mnt_opts(const struct super_block *oldsb,
 				struct super_block *newsb,
 				unsigned long kern_flags,
 				unsigned long *set_kern_flags);
-int security_sb_parse_opts_str(char *options, void **mnt_opts);
+int security_add_mnt_opt(const char *option, const char *val,
+				int len, void **mnt_opts);
 int security_dentry_init_security(struct dentry *dentry, int mode,
 					const struct qstr *name, void **ctx,
 					u32 *ctxlen);
@@ -586,7 +587,8 @@ static inline int security_sb_clone_mnt_opts(const struct super_block *oldsb,
 	return 0;
 }
 
-static inline int security_sb_parse_opts_str(char *options, void **mnt_opts)
+static inline int security_add_mnt_opt(const char *option, const char *val,
+					int len, void **mnt_opts)
 {
 	return 0;
 }

security/security.c

@@ -458,11 +458,13 @@ int security_sb_clone_mnt_opts(const struct super_block *oldsb,
 }
 EXPORT_SYMBOL(security_sb_clone_mnt_opts);
 
-int security_sb_parse_opts_str(char *options, void **mnt_opts)
+int security_add_mnt_opt(const char *option, const char *val, int len,
+			 void **mnt_opts)
 {
-	return call_int_hook(sb_parse_opts_str, 0, options, mnt_opts);
+	return call_int_hook(sb_add_mnt_opt, -EINVAL,
+					option, val, len, mnt_opts);
 }
-EXPORT_SYMBOL(security_sb_parse_opts_str);
+EXPORT_SYMBOL(security_add_mnt_opt);
 
 int security_inode_alloc(struct inode *inode)
 {

security/selinux/hooks.c

@@ -1049,40 +1049,33 @@ static int selinux_add_opt(int token, const char *s, void **mnt_opts)
 	return -EINVAL;
 }
 
-static int selinux_parse_opts_str(char *options,
-				  void **mnt_opts)
+static int selinux_add_mnt_opt(const char *option, const char *val, int len,
+			       void **mnt_opts)
 {
-	char *p = options, *next;
-	int rc;
+	int token = Opt_error;
+	int rc, i;
 
-	/* Standard string-based options. */
-	for (p = options; *p; p = next) {
-		int token, len;
-		char *arg = NULL;
-
-		next = strchr(p, '|');
-		if (next) {
-			len = next++ - p;
-		} else {
-			len = strlen(p);
-			next = p + len;
-		}
-
-		if (!len)
-			continue;
-
-		token = match_opt_prefix(p, len, &arg);
-		if (arg)
-			arg = kmemdup_nul(arg, p + len - arg, GFP_KERNEL);
-		rc = selinux_add_opt(token, arg, mnt_opts);
-		if (rc) {
-			kfree(arg);
-			selinux_free_mnt_opts(*mnt_opts);
-			*mnt_opts = NULL;
-			return rc;
+	for (i = 0; i < ARRAY_SIZE(tokens); i++) {
+		if (strcmp(option, tokens[i].name) == 0) {
+			token = tokens[i].opt;
+			break;
 		}
 	}
-	return 0;
+
+	if (token == Opt_error)
+		return -EINVAL;
+
+	if (token != Opt_seclabel)
+		val = kmemdup_nul(val, len, GFP_KERNEL);
+	rc = selinux_add_opt(token, val, mnt_opts);
+	if (unlikely(rc)) {
+		kfree(val);
+		if (*mnt_opts) {
+			selinux_free_mnt_opts(*mnt_opts);
+			*mnt_opts = NULL;
+		}
+	}
+	return rc;
 }
 
 static int show_sid(struct seq_file *m, u32 sid)
@@ -6726,7 +6719,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(sb_umount, selinux_umount),
 	LSM_HOOK_INIT(sb_set_mnt_opts, selinux_set_mnt_opts),
 	LSM_HOOK_INIT(sb_clone_mnt_opts, selinux_sb_clone_mnt_opts),
-	LSM_HOOK_INIT(sb_parse_opts_str, selinux_parse_opts_str),
+	LSM_HOOK_INIT(sb_add_mnt_opt, selinux_add_mnt_opt),
 
 	LSM_HOOK_INIT(dentry_init_security, selinux_dentry_init_security),
 	LSM_HOOK_INIT(dentry_create_files_as, selinux_dentry_create_files_as),

security/smack/smack_lsm.c

@@ -4629,7 +4629,6 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(sb_eat_lsm_opts, smack_sb_eat_lsm_opts),
 	LSM_HOOK_INIT(sb_statfs, smack_sb_statfs),
 	LSM_HOOK_INIT(sb_set_mnt_opts, smack_set_mnt_opts),
-	LSM_HOOK_INIT(sb_parse_opts_str, smack_parse_opts_str),
 
 	LSM_HOOK_INIT(bprm_set_creds, smack_bprm_set_creds),