sysusers: allow the shell to be specified

This is necessary for some system users where the "login shell" is
set to a specific binary.

diff --git a/man/sysusers.d.xml b/man/sysusers.d.xml
index c0d8a1682a8f32c32f82a22affc3d9eb07e5b0a7..47f018f402053d4437a879a8bfaa3da6d0565e3f 100644 (file)
--- a/man/sysusers.d.xml
+++ b/man/sysusers.d.xml
@@ -57,11 +57,14 @@
   <refsect1>
     <title>Description</title>
 
-    <para><command>systemd-sysusers</command> uses the files from <filename>sysusers.d</filename> directory to create
-    system users and groups at package installation or boot time. This tool may be used to allocate system users and
-    groups only, it is not useful for creating non-system (i.e. regular, "human") users and groups, as it accesses
-    <filename>/etc/passwd</filename> and <filename>/etc/group</filename> directly, bypassing any more complex user
-    databases, for example any database involving NIS or LDAP.</para>
+    <para><command>systemd-sysusers</command> uses the files from
+    <filename>sysusers.d</filename> directory to create system users and groups and
+    to add users to groups, at package installation or boot time. This tool may be
+    used to allocate system users and groups only, it is not useful for creating
+    non-system (i.e. regular, "human") users and groups, as it accesses
+    <filename>/etc/passwd</filename> and <filename>/etc/group</filename> directly,
+    bypassing any more complex user databases, for example any database involving NIS
+    or LDAP.</para>
   </refsect1>
 
   <refsect1>
@@ -100,15 +103,16 @@
   <refsect1>
     <title>Configuration File Format</title>
 
-    <para>The file format is one line per user or group containing
-    name, ID, GECOS field description and home directory:</para>
+    <para>The file format is one line per user or group containing name, ID, GECOS
+    field description, home directory, and login shell:</para>
 
-    <programlisting>#Type  Name   ID              GECOS                 Home directory
-u      httpd  440             "HTTP User"
-u      authd  /usr/bin/authd  "Authorization user"
-g      input  -               -
-m      authd  input
-u      root   0               "Superuser"           /root</programlisting>
+    <programlisting>#Type Name     ID             GECOS                 Home directory Shell
+u     httpd    404            "HTTP User"
+u     authd    /usr/bin/authd "Authorization user"
+u     postgres -              "Postgresql Database" /var/lib/pgsql /usr/libexec/postgresdb
+g     input    -              -
+m     authd    input
+u     root     0              "Superuser"           /root          /bin/zsh</programlisting>
 
     <para>Empty lines and lines beginning with the <literal>#</literal> character are ignored, and may be used for
     commenting.</para>
@@ -122,14 +126,10 @@ u      root   0               "Superuser"           /root</programlisting>
       <variablelist>
         <varlistentry>
           <term><varname>u</varname></term>
-          <listitem><para>Create a system user and group of the
-          specified name should they not exist yet. The user's primary
-          group will be set to the group bearing the same name. The
-          user's shell will be set to
-          <filename>/sbin/nologin</filename>, the home directory to
-          the specified home directory, or <filename>/</filename> if
-          none is given. The account will be created disabled, so that
-          logins are not allowed.</para></listitem>
+          <listitem><para>Create a system user and group of the specified name should
+          they not exist yet. The user's primary group will be set to the group
+          bearing the same name. The account will be created disabled, so that logins
+          are not allowed.</para></listitem>
         </varlistentry>
 
         <varlistentry>
@@ -187,7 +187,8 @@ u      root   0               "Superuser"           /root</programlisting>
       numeric 32-bit UID or GID of the user/group. Do not use IDs 65535
       or 4294967295, as they have special placeholder meanings.
       Specify <literal>-</literal> for automatic UID/GID allocation
-      for the user or group. Alternatively, specify an absolute path
+      for the user or group (this is strongly recommended unless it is strictly
+      necessary to use a specific UID or GID). Alternatively, specify an absolute path
       in the file system. In this case, the UID/GID is read from the
       path's owner/group. This is useful to create users whose UID/GID
       match the owners of pre-existing files (such as SUID or SGID
@@ -209,37 +210,45 @@ u      root   0               "Superuser"           /root</programlisting>
     <refsect2>
       <title>GECOS</title>
 
-      <para>A short, descriptive string for users to be created,
-      enclosed in quotation marks. Note that this field may not
-      contain colons.</para>
+      <para>A short, descriptive string for users to be created, enclosed in
+      quotation marks. Note that this field may not contain colons.</para>
 
-      <para>Only applies to lines of type <varname>u</varname> and
-      should otherwise be left unset, or be set to
-      <literal>-</literal>.</para>
+      <para>Only applies to lines of type <varname>u</varname> and should otherwise
+      be left unset (or <literal>-</literal>).</para>
     </refsect2>
 
     <refsect2>
       <title>Home Directory</title>
 
-      <para>The home directory for a new system user. If omitted,
-      defaults to the root directory. It is recommended to not
-      unnecessarily specify home directories for system users, unless
-      software strictly requires one to be set.</para>
+      <para>The home directory for a new system user. If omitted, defaults to the
+      root directory.</para>
 
-      <para>Only applies to lines of type <varname>u</varname> and
-      should otherwise be left unset, or be set to
-      <literal>-</literal>.</para>
+      <para>Only applies to lines of type <varname>u</varname> and should otherwise
+      be left unset (or <literal>-</literal>). It is recommended to omit this, unless
+      software strictly requires a home directory to be set.</para>
+    </refsect2>
+
+    <refsect2>
+      <title>Shell</title>
+
+      <para>The login shell of the user. If not specified, this will be set to
+      <filename>/sbin/nologin</filename>, except if the UID of the user is 0, in
+      which case <filename>/bin/sh</filename> will be used.</para>
+
+      <para>Only applies to lines of type <varname>u</varname> and should otherwise
+      be left unset (or <literal>-</literal>). It is recommended to omit this, unless
+      a shell different <filename>/sbin/nologin</filename> must be used.</para>
     </refsect2>
   </refsect1>
 
   <refsect1>
     <title>Idempotence</title>
 
-    <para>Note that <command>systemd-sysusers</command> will do
-    nothing if the specified users or groups already exist, so
-    normally, there is no reason to override
-    <filename>sysusers.d</filename> vendor configuration, except to
-    block certain users or groups from being created.</para>
+    <para>Note that <command>systemd-sysusers</command> will do nothing if the
+    specified users or groups already exist or the users are members of specified
+    groups, so normally there is no reason to override
+    <filename>sysusers.d</filename> vendor configuration, except to block certain
+    users or groups from being created.</para>
   </refsect1>
 
   <refsect1>

diff --git a/src/basic/user-util.c b/src/basic/user-util.c
index 011b29ad023b24fa367a57633d89b46670a7f8ee..db18ee31c00160f30207e8248e554c57fcd8a9d1 100644 (file)
--- a/src/basic/user-util.c
+++ b/src/basic/user-util.c
@@ -645,6 +645,8 @@ bool valid_gecos(const char *d) {
 }
 
 bool valid_home(const char *p) {
+        /* Note that this function is also called by valid_shell(), any
+         * changes must account for that. */
 
         if (isempty(p))
                 return false;

diff --git a/src/basic/user-util.h b/src/basic/user-util.h
index 290d17a0c648419db7ae0111798017f79fdabcaa..e1259a1582648096af516cd3ac54bf9e80340ed5 100644 (file)
--- a/src/basic/user-util.h
+++ b/src/basic/user-util.h
@@ -98,6 +98,15 @@ bool valid_user_group_name_or_id(const char *u);
 bool valid_gecos(const char *d);
 bool valid_home(const char *p);
 
+static inline bool valid_shell(const char *p) {
+        /* We have the same requirements, so just piggy-back on the home check.
+         *
+         * Let's ignore /etc/shells because this is only applicable to real and
+         * not system users. It is also incompatible with the idea of empty /etc.
+         */
+        return valid_home(p);
+}
+
 int maybe_setgroups(size_t size, const gid_t *list);
 
 bool synthesize_nobody(void);

diff --git a/src/sysusers/sysusers.c b/src/sysusers/sysusers.c
index 340e0db7983338aeafc9ff60d63878eb59925d08..e2a3b9968cdff92e3edaac7fcdea4ea840896efe 100644 (file)
--- a/src/sysusers/sysusers.c
+++ b/src/sysusers/sysusers.c
@@ -59,6 +59,7 @@ typedef struct Item {
         char *gid_path;
         char *description;
         char *home;
+        char *shell;
 
         gid_t gid;
         uid_t uid;
@@ -384,6 +385,10 @@ static int rename_and_apply_smack(const char *temp_path, const char *dest_path)
         return r;
 }
 
+static const char* default_shell(uid_t uid) {
+        return uid == 0 ? "/bin/sh" : "/sbin/nologin";
+}
+
 static int write_temporary_passwd(const char *passwd_path, FILE **tmpfile, char **tmpfile_path) {
         _cleanup_fclose_ FILE *original = NULL, *passwd = NULL;
         _cleanup_(unlink_and_freep) char *passwd_tmp = NULL;
@@ -451,7 +456,7 @@ static int write_temporary_passwd(const char *passwd_path, FILE **tmpfile, char
 
                         /* Initialize the shell to nologin, with one exception:
                          * for root we patch in something special */
-                        .pw_shell = i->uid == 0 ? (char*) "/bin/sh" : (char*) "/sbin/nologin",
+                        .pw_shell = i->shell ?: (char*) default_shell(i->uid),
                 };
 
                 errno = 0;
@@ -1225,6 +1230,7 @@ static void item_free(Item *i) {
         free(i->gid_path);
         free(i->description);
         free(i->home);
+        free(i->shell);
         free(i);
 }
 
@@ -1332,6 +1338,9 @@ static bool item_equal(Item *a, Item *b) {
         if (!streq_ptr(a->home, b->home))
                 return false;
 
+        if (!streq_ptr(a->shell, b->shell))
+                return false;
+
         return true;
 }
 
@@ -1345,7 +1354,12 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
                 {}
         };
 
-        _cleanup_free_ char *action = NULL, *name = NULL, *id = NULL, *resolved_name = NULL, *resolved_id = NULL, *description = NULL, *home = NULL;
+        _cleanup_free_ char *action = NULL,
+                *name = NULL, *resolved_name = NULL,
+                *id = NULL, *resolved_id = NULL,
+                *description = NULL,
+                *home = NULL,
+                *shell, *resolved_shell = NULL;
         _cleanup_(item_freep) Item *i = NULL;
         Item *existing;
         OrderedHashmap *h;
@@ -1358,7 +1372,8 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
 
         /* Parse columns */
         p = buffer;
-        r = extract_many_words(&p, NULL, EXTRACT_QUOTES, &action, &name, &id, &description, &home, NULL);
+        r = extract_many_words(&p, NULL, EXTRACT_QUOTES,
+                               &action, &name, &id, &description, &home, &shell, NULL);
         if (r < 0) {
                 log_error("[%s:%u] Syntax error.", fname, line);
                 return r;
@@ -1434,6 +1449,24 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
                 }
         }
 
+        /* Verify shell */
+        if (isempty(shell) || streq(shell, "-"))
+                shell = mfree(shell);
+
+        if (shell) {
+                r = specifier_printf(shell, specifier_table, NULL, &resolved_shell);
+                if (r < 0) {
+                        log_error("[%s:%u] Failed to replace specifiers: %s", fname, line, shell);
+                        return r;
+                }
+
+                if (!valid_shell(resolved_shell)) {
+                        log_error("[%s:%u] '%s' is not a valid login shell field.", fname, line, resolved_shell);
+                        return -EINVAL;
+                }
+        }
+
+
         switch (action[0]) {
 
         case ADD_RANGE:
@@ -1447,13 +1480,10 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
                         return -EINVAL;
                 }
 
-                if (description) {
-                        log_error("[%s:%u] Lines of type 'r' don't take a GECOS field.", fname, line);
-                        return -EINVAL;
-                }
-
-                if (home) {
-                        log_error("[%s:%u] Lines of type 'r' don't take a home directory field.", fname, line);
+                if (description || home || shell) {
+                        log_error("[%s:%u] Lines of type '%c' don't take a %s field.",
+                                  fname, line, action[0],
+                                  description ? "GECOS" : home ? "home directory" : "login shell");
                         return -EINVAL;
                 }
 
@@ -1484,13 +1514,10 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
                         return -EINVAL;
                 }
 
-                if (description) {
-                        log_error("[%s:%u] Lines of type 'm' don't take a GECOS field.", fname, line);
-                        return -EINVAL;
-                }
-
-                if (home) {
-                        log_error("[%s:%u] Lines of type 'm' don't take a home directory field.", fname, line);
+                if (description || home || shell) {
+                        log_error("[%s:%u] Lines of type '%c' don't take a %s field.",
+                                  fname, line, action[0],
+                                  description ? "GECOS" : home ? "home directory" : "login shell");
                         return -EINVAL;
                 }
 
@@ -1574,6 +1601,9 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
                 i->home = home;
                 home = NULL;
 
+                i->shell = resolved_shell;
+                resolved_shell = NULL;
+
                 h = users;
                 break;
 
@@ -1583,13 +1613,10 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
                         return -EINVAL;
                 }
 
-                if (description) {
-                        log_error("[%s:%u] Lines of type 'g' don't take a GECOS field.", fname, line);
-                        return -EINVAL;
-                }
-
-                if (home) {
-                        log_error("[%s:%u] Lines of type 'g' don't take a home directory field.", fname, line);
+                if (description || home || shell) {
+                        log_error("[%s:%u] Lines of type '%c' don't take a %s field.",
+                                  fname, line, action[0],
+                                  description ? "GECOS" : home ? "home directory" : "login shell");
                         return -EINVAL;
                 }