From a847899b521b0df0665e442845bcff23407d9ea0 Mon Sep 17 00:00:00 2001
From: Duncan Overbruck <mail@duncano.de>
Date: Sat, 11 Jan 2020 22:19:37 +0100
Subject: [PATCH] add new HOME_MODE login.defs(5) option

This option can be used to set a separate mode for useradd(8) and
newusers(8) to create the home directories with.
If this option is not set, the current behavior of using UMASK
or the default umask is preserved.

There are many distributions that set UMASK to 077 by default just
to create home directories not readable by others and use things like
/etc/profile, bashrc or sudo configuration files to set a less
restrictive
umask. This has always resulted in bug reports because it is hard
to follow as users tend to change files like bashrc and are not about
setting the umask to counteract the umask set in /etc/login.defs.

A recent change in sudo has also resulted in many bug reports about
this. sudo now tries to respect the umask set by pam modules and on
systems where pam does not set a umask, the login.defs UMASK value is
used.
---
 etc/login.defs             | 7 ++++++-
 lib/getdef.c               | 1 +
 man/login.defs.5.xml       | 4 ++++
 man/login.defs.d/UMASK.xml | 3 ++-
 src/newusers.c             | 6 +++---
 src/useradd.c              | 5 +++--
 6 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/etc/login.defs b/etc/login.defs
index cd2597dc..a2f8cd50 100644
--- a/etc/login.defs
+++ b/etc/login.defs
@@ -195,12 +195,17 @@ KILLCHAR	025
 # Default initial "umask" value used by login(1) on non-PAM enabled systems.
 # Default "umask" value for pam_umask(8) on PAM enabled systems.
 # UMASK is also used by useradd(8) and newusers(8) to set the mode for new
-# home directories.
+# home directories if HOME_MODE is not set.
 # 022 is the default value, but 027, or even 077, could be considered
 # for increased privacy. There is no One True Answer here: each sysadmin
 # must make up their mind.
 UMASK		022
 
+# HOME_MODE is used by useradd(8) and newusers(8) to set the mode for new
+# home directories.
+# If HOME_MODE is not set, the value of UMASK is used to create the mode.
+HOME_MODE	0700
+
 #
 # Password aging controls:
 #
diff --git a/lib/getdef.c b/lib/getdef.c
index bbb273f4..00f6abfe 100644
--- a/lib/getdef.c
+++ b/lib/getdef.c
@@ -93,6 +93,7 @@ static struct itemdef def_table[] = {
 	{"FAKE_SHELL", NULL},
 	{"GID_MAX", NULL},
 	{"GID_MIN", NULL},
+	{"HOME_MODE", NULL},
 	{"HUSHLOGIN_FILE", NULL},
 	{"KILLCHAR", NULL},
 	{"LOGIN_RETRIES", NULL},
diff --git a/man/login.defs.5.xml b/man/login.defs.5.xml
index ebf60ba3..9e95da20 100644
--- a/man/login.defs.5.xml
+++ b/man/login.defs.5.xml
@@ -50,6 +50,7 @@
 <!ENTITY FAKE_SHELL            SYSTEM "login.defs.d/FAKE_SHELL.xml">
 <!ENTITY FTMP_FILE             SYSTEM "login.defs.d/FTMP_FILE.xml">
 <!ENTITY GID_MAX               SYSTEM "login.defs.d/GID_MAX.xml">
+<!ENTITY HOME_MODE             SYSTEM "login.defs.d/HOME_MODE.xml">
 <!ENTITY HUSHLOGIN_FILE        SYSTEM "login.defs.d/HUSHLOGIN_FILE.xml">
 <!ENTITY ISSUE_FILE            SYSTEM "login.defs.d/ISSUE_FILE.xml">
 <!ENTITY KILLCHAR              SYSTEM "login.defs.d/KILLCHAR.xml">
@@ -185,6 +186,7 @@
       &FAKE_SHELL;
       &FTMP_FILE;
       &GID_MAX; <!-- documents also GID_MIN -->
+      &HOME_MODE;
       &HUSHLOGIN_FILE;
       &ISSUE_FILE;
       &KILLCHAR;
@@ -401,6 +403,7 @@
 	    ENCRYPT_METHOD
 	    GID_MAX GID_MIN
 	    MAX_MEMBERS_PER_GROUP MD5_CRYPT_ENAB
+	    HOME_MODE
 	    PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE
 	    <phrase condition="sha_crypt">SHA_CRYPT_MAX_ROUNDS
 	    SHA_CRYPT_MIN_ROUNDS</phrase>
@@ -481,6 +484,7 @@
 	  <para>
 	    CREATE_HOME
 	    GID_MAX GID_MIN
+	    HOME_MODE
 	    MAIL_DIR MAX_MEMBERS_PER_GROUP
 	    PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE
	    SUB_GID_COUNT SUB_GID_MAX SUB_GID_MIN
diff --git a/man/login.defs.d/HOME_MODE.xml b/man/login.defs.d/HOME_MODE.xml
new file mode 100644
index 00000000..21aa55f7
--- /dev/null
+++ b/man/login.defs.d/HOME_MODE.xml
@@ -0,0 +1,43 @@
+<!--
+   Copyright (c) 1991 - 1993, Julianne Frances Haugh
+   Copyright (c) 1991 - 1993, Chip Rosenthal
+   Copyright (c) 2007 - 2009, Nicolas François
+   All rights reserved.
+  
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+   1. Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+   2. Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+   3. The name of the copyright holders or contributors may not be used to
+      endorse or promote products derived from this software without
+      specific prior written permission.
+  
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+   PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT
+   HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+-->
+<varlistentry>
+  <term><option>HOME_MODE</option> (number)</term>
+  <listitem>
+    <para>
+      The mode for new home directories. If not specified,
+      the <option>UMASK</option> is used to create the mode.
+    </para>
+    <para>
+      <command>useradd</command> and <command>newusers</command> use this
+      to set the mode of the home directory they create.
+    </para>
+  </listitem>
+</varlistentry>
diff --git a/man/login.defs.d/UMASK.xml b/man/login.defs.d/UMASK.xml
index d7b71a5e..0f061dbb 100644
--- a/man/login.defs.d/UMASK.xml
+++ b/man/login.defs.d/UMASK.xml
@@ -37,7 +37,8 @@
     </para>
     <para>
       <command>useradd</command> and <command>newusers</command> use this
-      mask to set the mode of the home directory they create
+      mask to set the mode of the home directory they create if
+      <option>HOME_MODE</option> is not set.
     </para>
     <para condition="no_pam">
       It is also used by <command>login</command> to define users' initial
diff --git a/src/newusers.c b/src/newusers.c
index 99c69f78..e9fe0e27 100644
--- a/src/newusers.c
+++ b/src/newusers.c
@@ -1216,9 +1216,9 @@ int main (int argc, char **argv)
 		if (   ('\0' != fields[5][0])
 		    && (access (newpw.pw_dir, F_OK) != 0)) {
 /* FIXME: should check for directory */
-			mode_t msk = 0777 & ~getdef_num ("UMASK",
-			                                 GETDEF_DEFAULT_UMASK);
-			if (mkdir (newpw.pw_dir, msk) != 0) {
+			mode_t mode = getdef_num ("HOME_MODE",
+			                          0777 & ~getdef_num ("UMASK", GETDEF_DEFAULT_UMASK));
+			if (mkdir (newpw.pw_dir, mode) != 0) {
 				fprintf (stderr,
 				         _("%s: line %d: mkdir %s failed: %s\n"),
 				         Prog, line, newpw.pw_dir,
diff --git a/src/useradd.c b/src/useradd.c
index 4af0f7c6..8b453e3c 100644
--- a/src/useradd.c
+++ b/src/useradd.c
@@ -2152,8 +2152,9 @@ static void create_home (void)
 			fail_exit (E_HOMEDIR);
 		}
 		(void) chown (prefix_user_home, user_id, user_gid);
-		chmod (prefix_user_home,
-		       0777 & ~getdef_num ("UMASK", GETDEF_DEFAULT_UMASK));
+		mode_t mode = getdef_num ("HOME_MODE",
+		                          0777 & ~getdef_num ("UMASK", GETDEF_DEFAULT_UMASK));
+		chmod (prefix_user_home, mode);
 		home_added = true;
 #ifdef WITH_AUDIT
 		audit_logger (AUDIT_USER_MGMT, Prog,
-- 
2.25.2