Merge pull request #13244 from keszybz/allow-dots-in-usernames

Allow dots in usernames

src/basic/user-util.c

@@ -620,16 +620,19 @@ int take_etc_passwd_lock(const char *root) {
         return fd;
 }
 
-bool valid_user_group_name(const char *u) {
+bool valid_user_group_name_full(const char *u, bool strict) {
         const char *i;
         long sz;
 
         /* Checks if the specified name is a valid user/group name. Also see POSIX IEEE Std 1003.1-2008, 2016 Edition,
          * 3.437. We are a bit stricter here however. Specifically we deviate from POSIX rules:
          *
-         * - We don't allow any dots (this would break chown syntax which permits dots as user/group name separator)
          * - We require that names fit into the appropriate utmp field
          * - We don't allow empty user names
+         * - No dots or digits in the first character
+         *
+         * If strict==true, additionally:
+         * - We don't allow any dots (this conflicts with chown syntax which permits dots as user/group name separator)
          *
          * Note that other systems are even more restrictive, and don't permit underscores or uppercase characters.
          */
@@ -642,12 +645,25 @@ bool valid_user_group_name(const char *u) {
             u[0] != '_')
                 return false;
 
+        bool warned = false;
+
         for (i = u+1; *i; i++) {
-                if (!(*i >= 'a' && *i <= 'z') &&
-                    !(*i >= 'A' && *i <= 'Z') &&
-                    !(*i >= '0' && *i <= '9') &&
-                    !IN_SET(*i, '_', '-'))
-                        return false;
+                if (((*i >= 'a' && *i <= 'z') ||
+                     (*i >= 'A' && *i <= 'Z') ||
+                     (*i >= '0' && *i <= '9') ||
+                     IN_SET(*i, '_', '-')))
+                        continue;
+
+                if (*i == '.' && !strict) {
+                        if (!warned) {
+                                log_warning("Bad user or group name \"%s\", accepting for compatibility.", u);
+                                warned = true;
+                        }
+
+                        continue;
+                }
+
+                return false;
         }
 
         sz = sysconf(_SC_LOGIN_NAME_MAX);
@@ -662,15 +678,15 @@ bool valid_user_group_name(const char *u) {
         return true;
 }
 
-bool valid_user_group_name_or_id(const char *u) {
+bool valid_user_group_name_or_id_full(const char *u, bool strict) {
 
-        /* Similar as above, but is also fine with numeric UID/GID specifications, as long as they are in the right
-         * range, and not the invalid user ids. */
+        /* Similar as above, but is also fine with numeric UID/GID specifications, as long as they are in the
+         * right range, and not the invalid user ids. */
 
         if (isempty(u))
                 return false;
 
-        if (valid_user_group_name(u))
+        if (valid_user_group_name_full(u, strict))
                 return true;
 
         return parse_uid(u, NULL) >= 0;

src/basic/user-util.h

@@ -85,8 +85,20 @@ static inline bool userns_supported(void) {
         return access("/proc/self/uid_map", F_OK) >= 0;
 }
 
-bool valid_user_group_name(const char *u);
-bool valid_user_group_name_or_id(const char *u);
+bool valid_user_group_name_full(const char *u, bool strict);
+bool valid_user_group_name_or_id_full(const char *u, bool strict);
+static inline bool valid_user_group_name(const char *u) {
+        return valid_user_group_name_full(u, true);
+}
+static inline bool valid_user_group_name_or_id(const char *u) {
+        return valid_user_group_name_or_id_full(u, true);
+}
+static inline bool valid_user_group_name_compat(const char *u) {
+        return valid_user_group_name_full(u, false);
+}
+static inline bool valid_user_group_name_or_id_compat(const char *u) {
+        return valid_user_group_name_or_id_full(u, false);
+}
 bool valid_gecos(const char *d);
 bool valid_home(const char *p);