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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)
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