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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'>
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