On systems without setfsuid(), use setreuid() instead.

Authors: Steve Langasek <vorlon@debian.org>

Upstream status: superseded by pam_modutil_set_euid proposal

Index: pam.debian/modules/pam_xauth/pam_xauth.c
===================================================================
--- pam.debian.orig/modules/pam_xauth/pam_xauth.c
+++ pam.debian/modules/pam_xauth/pam_xauth.c
@@ -35,7 +35,9 @@
 
 #include "config.h"
 #include <sys/types.h>
+#ifdef HAVE_SYS_FSUID_H
 #include <sys/fsuid.h>
+#endif /* HAVE_SYS_FSUID_H */
 #include <sys/wait.h>
 #include <errno.h>
 #include <fnmatch.h>
@@ -235,6 +237,9 @@
 	FILE *fp;
 	int i, save_errno;
 	uid_t euid;
+#ifndef HAVE_SYS_FSUID_H
+	uid_t uid;
+#endif
 	/* Check this user's <sense> file. */
 	pwd = pam_modutil_getpwnam(pamh, this_user);
 	if (pwd == NULL) {
@@ -251,10 +256,35 @@
 		return PAM_SESSION_ERR;
 	}
 	euid = geteuid();
+#ifdef HAVE_SYS_FSUID_H
 	setfsuid(pwd->pw_uid);
+#else
+	uid = getuid();
+	if (uid == pwd->pw_uid)
+		setreuid(euid, uid);
+	else {
+		setreuid(0, -1);
+		if (setreuid(-1, uid) == -1) {
+			setreuid(-1, 0);
+			setreuid(0, -1);
+			if (setreuid(-1, pwd->pw_uid))
+				return PAM_CRED_INSUFFICIENT;
+		}
+	}
+#endif
 	fp = fopen(path, "r");
 	save_errno = errno;
+#ifdef HAVE_SYS_FSUID_H
 	setfsuid(euid);
+#else
+	if (uid == pwd->pw_uid)
+		setreuid(uid, euid);
+	else {
+		if (setreuid(-1, 0) != -1)
+			setreuid(uid, -1);
+		setreuid(-1, euid);
+	}
+#endif
 	if (fp != NULL) {
 		char buf[LINE_MAX], *tmp;
 		/* Scan the file for a list of specs of users to "trust". */
@@ -325,6 +355,9 @@
 	int fd, i, debug = 0;
 	int retval = PAM_SUCCESS;
 	uid_t systemuser = 499, targetuser = 0, euid;
+#ifndef HAVE_SYS_FSUID_H
+	uid_t uid;
+#endif
 
 	/* Parse arguments.  We don't understand many, so no sense in breaking
 	 * this into a separate function. */
@@ -573,7 +606,22 @@
 
 		/* Generate a new file to hold the data. */
 		euid = geteuid();
+#ifdef HAVE_SYS_FSUID_H
 		setfsuid(tpwd->pw_uid);
+#else
+		uid = getuid();
+		if (uid == tpwd->pw_uid)
+			setreuid(euid, uid);
+		else {
+			setreuid(0, -1);
+			if (setreuid(-1, uid) == -1) {
+				setreuid(-1, 0);
+				setreuid(0, -1);
+				if (setreuid(-1, tpwd->pw_uid))
+					return PAM_CRED_INSUFFICIENT;
+			}
+		}
+#endif
 
 #ifdef WITH_SELINUX
 		if (is_selinux_enabled() > 0) {
@@ -603,7 +651,17 @@
 		save_errno = errno;
 #endif
 
+#ifdef HAVE_SYS_FSUID_H
 		setfsuid(euid);
+#else
+		if (uid == tpwd->pw_uid)
+			setreuid(uid, euid);
+		else {
+			if (setreuid(-1, 0) == -1)
+				setreuid(uid, -1);
+			setreuid(-1, euid);
+		}
+#endif
 		if (fd == -1) {
 			errno = save_errno;
 			pam_syslog(pamh, LOG_ERR,
@@ -614,10 +672,35 @@
 		}
 		/* Set permissions on the new file and dispose of the
 		 * descriptor. */
+#ifdef HAVE_SYS_FSUID_H
 		setfsuid(tpwd->pw_uid);
+#else
+		uid = getuid();
+		if (uid == tpwd->pw_uid)
+			setreuid(euid, uid);
+		else {
+			setreuid(0, -1);
+			if (setreuid(-1, uid) == -1) {
+				setreuid(-1, 0);
+				setreuid(0, -1);
+				if (setreuid(-1, tpwd->pw_uid))
+					return PAM_CRED_INSUFFICIENT;
+			}
+		}
+#endif
 		if (fchown(fd, tpwd->pw_uid, tpwd->pw_gid) < 0)
 		  pam_syslog (pamh, LOG_ERR, "fchown: %m");
+#ifdef HAVE_SYS_FSUID_H
 		setfsuid(euid);
+#else
+		if (uid == tpwd->pw_uid)
+			setreuid(uid, euid);
+		else {
+			if (setreuid(-1, 0) == -1)
+				setreuid(uid, -1);
+			setreuid(-1, euid);
+		}
+#endif
 		close(fd);
 
 		/* Get a copy of the filename to save as a data item for
@@ -718,6 +801,9 @@
 	struct passwd *tpwd;
 	uid_t unlinkuid, euid;
 	unlinkuid = euid = geteuid ();
+#ifndef HAVE_SYS_FSUID_H
+	uid_t uid;
+#endif
 
 	if (pam_get_user(pamh, &user, NULL) != PAM_SUCCESS)
 		pam_syslog(pamh, LOG_ERR, "error determining target user's name");
@@ -759,9 +845,34 @@
 				       (char*)cookiefile);
 			}
 			/* NFS with root_squash requires non-root user */
+#ifdef HAVE_SYS_FSUID_H
 			setfsuid (unlinkuid);
+#else
+			uid = getuid();
+			if (uid == unlinkuid)
+				setreuid(euid, uid);
+			else {
+				setreuid(0, -1);
+				if (setreuid(-1, uid) == -1) {
+					setreuid(-1, 0);
+					setreuid(0, -1);
+					if (setreuid(-1, unlinkuid))
+						return PAM_CRED_INSUFFICIENT;
+				}
+			}
+#endif
 			unlink((char*)cookiefile);
+#ifdef HAVE_SYS_FSUID_H
 			setfsuid (euid);
+#else
+			if (uid == unlinkuid)
+				setreuid(uid, euid);
+			else {
+				if (setreuid(-1, 0) == -1)
+					setreuid(uid, -1);
+				setreuid(-1, euid);
+			}
+#endif
 			*((char*)cookiefile) = '\0';
 		}
 	}
Index: pam.debian/modules/pam_env/pam_env.c
===================================================================
--- pam.debian.orig/modules/pam_env/pam_env.c
+++ pam.debian/modules/pam_env/pam_env.c
@@ -23,7 +23,9 @@
 #include <string.h>
 #include <syslog.h>
 #include <sys/stat.h>
+#ifdef HAVE_SYS_FSUID_H
 #include <sys/fsuid.h>
+#endif
 #include <sys/types.h>
 #include <unistd.h>
 
@@ -792,9 +794,37 @@
 	}
       if (stat(envpath, &statbuf) == 0) {
 	uid_t euid = geteuid();
+
+#ifdef HAVE_SYS_FSUID_H
         setfsuid (user_entry->pw_uid);
+#else
+	uid_t uid = getuid();
+	if (uid == user_entry->pw_uid)
+	  setreuid(euid, uid);
+	else {
+	  setreuid(0, -1);
+	  if (setreuid(-1, uid) == -1) {
+	    setreuid(-1, 0);
+	    setreuid(0, -1);
+	    setreuid(-1, user_entry->pw_uid);
+	    /* If this fails we didn't have root privs anyway, so we fall
+	       through; not the safest, but no different from what we do in
+	       the setfsuid() case. */
+	  }
+	}
+#endif
         retval = _parse_config_file(pamh, envpath);
+#ifdef HAVE_SYS_FSUID_H
 	setfsuid (euid);
+#else
+	if (uid == user_entry->pw_uid)
+	  setreuid(uid, euid);
+	else {
+	  if (setreuid(-1, 0) == 0)
+	    setreuid(uid, -1);
+	  setreuid(-1, euid);
+	}
+#endif
         if (retval == PAM_IGNORE)
           retval = PAM_SUCCESS;
       }
Index: pam.debian/modules/pam_mail/pam_mail.c
===================================================================
--- pam.debian.orig/modules/pam_mail/pam_mail.c
+++ pam.debian/modules/pam_mail/pam_mail.c
@@ -17,7 +17,9 @@
 #include <syslog.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#ifdef HAVE_SYS_FSUID_H
 #include <sys/fsuid.h>
+#endif
 #include <unistd.h>
 #include <dirent.h>
 #include <errno.h>
@@ -446,9 +448,37 @@
 	|| (!est && (ctrl & PAM_LOGOUT_TOO))) {
         uid_t euid = geteuid();
 
+#ifdef HAVE_SYS_FSUID_H
         setfsuid (pwd->pw_uid);
+#else
+	uid_t uid = getuid();
+
+	if (uid == pwd->pw_uid)
+	  setreuid(euid, uid);
+	else {
+	  setreuid(0, -1);
+	  if (setreuid(-1, uid) == -1) {
+	    setreuid(-1, 0);
+	    setreuid(0, -1);
+	    setreuid(-1, pwd->pw_uid);
+	    /* If this fails we didn't have root privs anyway, so we fall
+	       through; not the safest, but no different from what we do in
+	       the setfsuid() case. */
+	  }
+	}
+#endif
 	type = get_mail_status(pamh, ctrl, folder);
+#ifdef HAVE_SYS_FSUID_H
 	setfsuid (euid);
+#else
+	if (uid == pwd->pw_uid)
+	  setreuid(uid, euid);
+	else {
+	  if (setreuid(-1, 0) == 0)
+	    setreuid(uid, -1);
+	  setreuid(-1, euid);
+	}
+#endif
 
 	if (type != 0) {
 	    retval = report_mail(pamh, ctrl, type, folder);