Use upstream's restrictions on user- and group names again

Upstream started supporting mixed-case names some time ago.
Purely numeric names (#79682) are now forbidden again, as there is no
way of distinguishing them from user/group IDs otherwise.

Gbp-Dch: full

debian/patches/Relax-usernames-groupnames-checking.patch

@@ -1,125 +0,0 @@
-From: Shadow package maintainers <pkg-shadow-devel@lists.alioth.debian.org>
-Date: Sat, 22 Jun 2024 17:39:41 +0200
-Subject: Relax usernames/groupnames checking
-
-Allows any non-empty user/grounames that don't contain ':', ',' or '\n'
-characters and don't start with '-', '+', or '~'. This patch is more
-restrictive than original Karl's version. closes: #264879
-Also closes: #377844
-
-Comments from Karl Ramm (shadow 1:4.0.3-9, 20 Aug 2003 02:06:50 -0400):
-
-I can't come up with a good justification as to why characters other
-than ':'s and '\0's should be disallowed in group and usernames (other
-than '-' as the leading character).  Thus, the maintenance tools don't
-anymore.  closes: #79682, #166798, #171179
-
-Status wrt upstream: Debian specific. Not to be used upstream
-
-Gbp-Topic: debian
----
- lib/chkname.c      | 47 +++++++++++++++--------------------------------
- man/groupadd.8.xml |  6 ++++++
- man/useradd.8.xml  |  8 ++++++++
- 3 files changed, 29 insertions(+), 32 deletions(-)
-
-diff --git a/lib/chkname.c b/lib/chkname.c
-index 995562f..d9678c6 100644
---- a/lib/chkname.c
-+++ b/lib/chkname.c
-@@ -54,44 +54,27 @@ static bool is_valid_name (const char *name)
- 	}
- 
- 	/*
--         * User/group names must match BRE regex:
--         *    [a-zA-Z0-9_.][a-zA-Z0-9_.-]*$\?
--         *
--         * as a non-POSIX, extension, allow "$" as the last char for
--         * sake of Samba 3.x "add machine script"
--         *
--         * Also do not allow fully numeric names or just "." or "..".
--         */
--	int numeric;
--
--	if ('\0' == *name ||
--	    ('.' == *name && (('.' == name[1] && '\0' == name[2]) ||
--			      '\0' == name[1])) ||
--	    !((*name >= 'a' && *name <= 'z') ||
--	      (*name >= 'A' && *name <= 'Z') ||
--	      (*name >= '0' && *name <= '9') ||
--	      *name == '_' ||
--	      *name == '.')) {
-+	 * POSIX indicate that usernames are composed of characters from the
-+	 * portable filename character set [A-Za-z0-9._-], and that the hyphen
-+	 * should not be used as the first character of a portable user name.
-+	 *
-+	 * Allow more relaxed user/group names in Debian -- ^[^-~+:,\s][^:,\s]*$
-+	 */
-+	if (   ('\0' == *name)
-+	    || ('-'  == *name)
-+	    || ('~'  == *name)
-+	    || ('+'  == *name)) {
- 		return false;
- 	}
- 
--	numeric = isdigit(*name);
--
--	while ('\0' != *++name) {
--		if (!((*name >= 'a' && *name <= 'z') ||
--		      (*name >= 'A' && *name <= 'Z') ||
--		      (*name >= '0' && *name <= '9') ||
--		      *name == '_' ||
--		      *name == '.' ||
--		      *name == '-' ||
--		      (*name == '$' && name[1] == '\0')
--		     )) {
-+	do {
-+		if ((':' == *name) || (',' == *name) || isspace(*name)) {
- 			return false;
- 		}
--		numeric &= isdigit(*name);
--	}
-+		name++;
-+	} while ('\0' != *name);
- 
--	return !numeric;
-+	return true;
- }
- 
- 
-diff --git a/man/groupadd.8.xml b/man/groupadd.8.xml
-index 61a548f..d472bd0 100644
---- a/man/groupadd.8.xml
-+++ b/man/groupadd.8.xml
-@@ -71,6 +71,12 @@
-        Fully numeric groupnames and groupnames . or .. are
-        also disallowed.
-      </para>
-+     <para>
-+       On Debian, the only constraints are that groupnames must neither start
-+       with a dash ('-') nor plus ('+') nor tilde ('~') nor contain a
-+       colon (':'), a comma (','), or a whitespace (space:' ',
-+       end of line: '\n', tabulation: '\t', etc.).
-+     </para>
-      <para>
-        Groupnames may only be up to &GROUP_NAME_MAX_LENGTH; characters long.
-      </para>
-diff --git a/man/useradd.8.xml b/man/useradd.8.xml
-index 17987a6..c98b214 100644
---- a/man/useradd.8.xml
-+++ b/man/useradd.8.xml
-@@ -735,6 +735,14 @@
-     <para>
-       Usernames may only be up to 256 characters long.
-     </para>
-+    <para>
-+      On Debian, the only constraints are that usernames must neither start
-+      with a dash ('-') nor plus ('+') nor tilde ('~') nor contain a
-+      colon (':'), a comma (','), or a whitespace (space: ' ',
-+      end of line: '\n', tabulation: '\t', etc.). Note that using a slash
-+      ('/') may break the default algorithm for the definition of the
-+      user's home directory.
-+    </para>
-   </refsect1>
- 
-   <refsect1 id='configuration'>

debian/patches/series

@@ -5,5 +5,4 @@ Set-group-and-mode-for-g-shadow-files.patch
 Keep-using-Debian-adduser-defaults.patch
 Document-the-shadowconfig-utility.patch
 Recommend-using-adduser-and-deluser.patch
-Relax-usernames-groupnames-checking.patch
 useradd-accept-the-O-flag-for-backward-compatibility.patch