gnu: linux-pam: Allow compilation on GNU/Hurd.

* gnu/packages/patches/linux-pam-no-setfsuid.patch: New file.
* gnu/packages/linux.scm (linux-pam)[source]: Use it.
(linux-pam-1.2)[source]: Likewise.
* gnu/local.mk (dist_patch_DATA): Add it.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu/local.mk

@@ -5,6 +5,7 @@
 # Copyright © 2013, 2014, 2015, 2016 Mark H Weaver <mhw@netris.org>
 # Copyright © 2016 Chris Marusich <cmmarusich@gmail.com>
 # Copyright © 2016 Kei Kebreau <kei@openmailbox.org>
+# Copyright © 2016 Rene Saavedra <rennes@openmailbox.org>
 #
 # This file is part of GNU Guix.
 #
@@ -651,6 +652,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/libwmf-CVE-2015-4695.patch		\
   %D%/packages/patches/libwmf-CVE-2015-4696.patch		\
   %D%/packages/patches/libxslt-generated-ids.patch		\
+  %D%/packages/patches/linux-pam-no-setfsuid.patch		\
   %D%/packages/patches/lirc-localstatedir.patch			\
   %D%/packages/patches/lm-sensors-hwmon-attrs.patch		\
   %D%/packages/patches/lua-CVE-2014-5461.patch                      \

gnu/packages/linux.scm

@@ -15,6 +15,7 @@
 ;;; Copyright © 2016 Ricardo Wurmus <rekado@elephly.net>
 ;;; Copyright © 2016 David Craven <david@craven.ch>
 ;;; Copyright © 2016 John Darrington <jmd@gnu.org>
+;;; Copyright © 2016 Rene Saavedra <rennes@openmailbox.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -414,7 +415,9 @@ It has been modified to remove all non-free binary blobs.")
             "Linux-PAM-" version ".tar.bz2"))
       (sha256
        (base32
-        "1fyi04d5nsh8ivd0rn2y0z83ylgc0licz7kifbb6xxi2ylgfs6i4"))))
+        "1fyi04d5nsh8ivd0rn2y0z83ylgc0licz7kifbb6xxi2ylgfs6i4"))
+      (patches (search-patches "linux-pam-no-setfsuid.patch"))))
+
     (build-system gnu-build-system)
     (native-inputs
      `(("flex" ,flex)
@@ -455,8 +458,8 @@ at login.  Local and dynamic reconfiguration are its key features.")
             "Linux-PAM-" version ".tar.bz2"))
       (sha256
        (base32
-        "1n9lnf9gjs72kbj1g354v1xhi2j27aqaah15vykh7cnkq08i4arl"))))))
+        "1n9lnf9gjs72kbj1g354v1xhi2j27aqaah15vykh7cnkq08i4arl"))
-
+      (patches (search-patches "linux-pam-no-setfsuid.patch"))))))
 
 
 ;;;

gnu/packages/patches/linux-pam-no-setfsuid.patch

@@ -0,0 +1,75 @@
+On systems without 'setfsuid', use 'setreuid' instead.
+
+The patch originates from the Debian project for GNU/Hurd.
+Authors: Steve Langasek <vorlon@debian.org>
+Upstream status: A ticket was opened to request apply the patch,
+ticket: 'https://fedorahosted.org/linux-pam/ticket/64'.
+
+--- Linux-PAM-1.2.1/libpam/pam_modutil_priv.c	2015-03-24 06:02:32.000000000 -0600
++++ pam_modutil_priv-mod.c	2016-09-20 13:36:53.150663205 -0500
+@@ -14,7 +14,9 @@
+ #include <syslog.h>
+ #include <pwd.h>
+ #include <grp.h>
++#ifdef HAVE_SYS_FSUID_H
+ #include <sys/fsuid.h>
++#endif /* HAVE_SYS_FSUID_H */
+ 
+ /*
+  * Two setfsuid() calls in a row are necessary to check
+@@ -22,17 +24,55 @@
+  */
+ static int change_uid(uid_t uid, uid_t *save)
+ {
++#ifdef HAVE_SYS_FSUID_H
+ 	uid_t tmp = setfsuid(uid);
+ 	if (save)
+ 		*save = tmp;
+ 	return (uid_t) setfsuid(uid) == uid ? 0 : -1;
++#else
++	uid_t euid = geteuid();
++	uid_t ruid = getuid();
++	if (save)
++		*save = ruid;
++	if (ruid == uid && uid != 0)
++		if (setreuid(euid, uid))
++			return -1;
++	else {
++		setreuid(0, -1);
++		if (setreuid(-1, uid)) {
++			setreuid(-1, 0);
++			setreuid(0, -1);
++			if (setreuid(-1, uid))
++				return -1;
++		}
++	}
++#endif
+ }
+ static int change_gid(gid_t gid, gid_t *save)
+ {
++#ifdef HAVE_SYS_FSUID_H
+ 	gid_t tmp = setfsgid(gid);
+ 	if (save)
+ 		*save = tmp;
+ 	return (gid_t) setfsgid(gid) == gid ? 0 : -1;
++#else
++	gid_t egid = getegid();
++	gid_t rgid = getgid();
++	if (save)
++		*save = rgid;
++	if (rgid == gid)
++		if (setregid(egid, gid))
++			return -1;
++	else {
++		setregid(0, -1);
++		if (setregid(-1, gid)) {
++			setregid(-1, 0);
++			setregid(0, -1);
++			if (setregid(-1, gid))
++				return -1;
++		}
++	}
++#endif
+ }
+ 
+ static int cleanup(struct pam_modutil_privs *p)