New upstream version 4.5upstream/4.5

5 files changed, 912 insertions, 241 deletions

diff --git a/libmisc/Makefile.am b/libmisc/Makefile.am
index 76f3c052..4a620495 100644
--- a/libmisc/Makefile.am
+++ b/libmisc/Makefile.am
@@ -1,7 +1,7 @@
 
 EXTRA_DIST = .indent.pro xgetXXbyYY.c
 
-INCLUDES = -I$(top_srcdir)/lib
+AM_CPPFLAGS = -I$(top_srcdir)/lib
 
 noinst_LIBRARIES = libmisc.a
 
@@ -31,6 +31,7 @@ libmisc_a_SOURCES = \
 	getdate.y \
 	getgr_nam_gid.c \
 	getrange.c \
+	gettime.c \
 	hushed.c \
 	idmapping.h \
 	idmapping.c \
diff --git a/libmisc/find_new_gid.c b/libmisc/find_new_gid.c
index d3e51a4b..2fe6a2a9 100644
--- a/libmisc/find_new_gid.c
+++ b/libmisc/find_new_gid.c
@@ -1,6 +1,7 @@
 /*
  * Copyright (c) 1991 - 1994, Julianne Frances Haugh
  * Copyright (c) 2008 - 2011, Nicolas François
+ * Copyright (c) 2014, Red Hat, Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -39,6 +40,117 @@
 #include "getdef.h"
 
 /*
+ * get_ranges - Get the minimum and maximum ID ranges for the search
+ *
+ * This function will return the minimum and maximum ranges for IDs
+ *
+ * 0: The function completed successfully
+ * EINVAL: The provided ranges are impossible (such as maximum < minimum)
+ *
+ * preferred_min: The special-case minimum value for a specifically-
+ * requested ID, which may be lower than the standard min_id
+ */
+static int get_ranges (bool sys_group, gid_t *min_id, gid_t *max_id,
+		       gid_t *preferred_min)
+{
+	gid_t gid_def_max = 0;
+
+	if (sys_group) {
+		/* System groups */
+
+		/* A requested ID is allowed to be below the autoselect range */
+		*preferred_min = (gid_t) 1;
+
+		/* Get the minimum ID range from login.defs or default to 101 */
+		*min_id = (gid_t) getdef_ulong ("SYS_GID_MIN", 101UL);
+
+		/*
+		 * If SYS_GID_MAX is unspecified, we should assume it to be one
+		 * less than the GID_MIN (which is reserved for non-system accounts)
+		 */
+		gid_def_max = (gid_t) getdef_ulong ("GID_MIN", 1000UL) - 1;
+		*max_id = (gid_t) getdef_ulong ("SYS_GID_MAX",
+				(unsigned long) gid_def_max);
+
+		/* Check that the ranges make sense */
+		if (*max_id < *min_id) {
+			(void) fprintf (stderr,
+                            _("%s: Invalid configuration: SYS_GID_MIN (%lu), "
+                              "GID_MIN (%lu), SYS_GID_MAX (%lu)\n"),
+                            Prog, (unsigned long) *min_id,
+                            getdef_ulong ("GID_MIN", 1000UL),
+                            (unsigned long) *max_id);
+			return EINVAL;
+		}
+	} else {
+		/* Non-system groups */
+
+		/* Get the values from login.defs or use reasonable defaults */
+		*min_id = (gid_t) getdef_ulong ("GID_MIN", 1000UL);
+		*max_id = (gid_t) getdef_ulong ("GID_MAX", 60000UL);
+
+		/*
+		 * The preferred minimum should match the standard ID minimum
+		 * for non-system groups.
+		 */
+		*preferred_min = *min_id;
+
+		/* Check that the ranges make sense */
+		if (*max_id < *min_id) {
+			(void) fprintf (stderr,
+					_("%s: Invalid configuration: GID_MIN (%lu), "
+					  "GID_MAX (%lu)\n"),
+					Prog, (unsigned long) *min_id,
+					(unsigned long) *max_id);
+			return EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * check_gid - See if the requested GID is available
+ *
+ * On success, return 0
+ * If the ID is in use, return EEXIST
+ * If the ID is outside the range, return ERANGE
+ * In other cases, return errno from getgrgid()
+ */
+static int check_gid (const gid_t gid,
+		      const gid_t gid_min,
+		      const gid_t gid_max,
+		      bool *used_gids)
+{
+	/* First test that the preferred ID is in the range */
+	if (gid < gid_min || gid > gid_max) {
+		return ERANGE;
+	}
+
+	/*
+	 * Check whether we already detected this GID
+	 * using the gr_next() loop
+	 */
+	if (used_gids != NULL && used_gids[gid]) {
+		return EEXIST;
+	}
+	/* Check if the GID exists according to NSS */
+	errno = 0;
+	if (getgrgid (gid) != NULL) {
+		return EEXIST;
+	} else {
+		/* getgrgid() was NULL
+		 * we have to ignore errors as temporary
+		 * failures of remote user identity services
+		 * would completely block user/group creation
+		 */
+	}
+
+	/* If we've made it here, the GID must be available */
+	return 0;
+}
+
+/*
  * find_new_gid - Find a new unused GID.
  *
  * If successful, find_new_gid provides an unused group ID in the
@@ -49,161 +161,338 @@
  * Return 0 on success, -1 if no unused GIDs are available.
  */
 int find_new_gid (bool sys_group,
-                  gid_t *gid,
-                  /*@null@*/gid_t const *preferred_gid)
+                 gid_t *gid,
+                 /*@null@*/gid_t const *preferred_gid)
 {
-	const struct group *grp;
-	gid_t gid_min, gid_max, group_id;
 	bool *used_gids;
+	const struct group *grp;
+	gid_t gid_min, gid_max, preferred_min;
+	gid_t group_id, id;
+	gid_t lowest_found, highest_found;
+	int result;
+	int nospam = 0;
 
-	assert (gid != NULL);
+	assert(gid != NULL);
 
-	if (!sys_group) {
-		gid_min = (gid_t) getdef_ulong ("GID_MIN", 1000UL);
-		gid_max = (gid_t) getdef_ulong ("GID_MAX", 60000UL);
-		if (gid_max < gid_min) {
-			(void) fprintf (stderr,
-			                _("%s: Invalid configuration: GID_MIN (%lu), GID_MAX (%lu)\n"),
-			                Prog, (unsigned long) gid_min, (unsigned long) gid_max);
-			return -1;
-		}
-	} else {
-		gid_min = (gid_t) getdef_ulong ("SYS_GID_MIN", 101UL);
-		gid_max = (gid_t) getdef_ulong ("GID_MIN", 1000UL) - 1;
-		gid_max = (gid_t) getdef_ulong ("SYS_GID_MAX", (unsigned long) gid_max);
-		if (gid_max < gid_min) {
-			(void) fprintf (stderr,
-			                _("%s: Invalid configuration: SYS_GID_MIN (%lu), GID_MIN (%lu), SYS_GID_MAX (%lu)\n"),
-			                Prog, (unsigned long) gid_min, getdef_ulong ("GID_MIN", 1000UL), (unsigned long) gid_max);
+	/*
+	 * First, figure out what ID range is appropriate for
+	 * automatic assignment
+	 */
+	result = get_ranges (sys_group, &gid_min, &gid_max, &preferred_min);
+	if (result == EINVAL) {
+		return -1;
+	}
+
+	/* Check if the preferred GID is available */
+	if (preferred_gid) {
+		result = check_gid (*preferred_gid, preferred_min, gid_max, NULL);
+		if (result == 0) {
+			/*
+			 * Make sure the GID isn't queued for use already
+			 */
+			if (gr_locate_gid (*preferred_gid) == NULL) {
+				*gid = *preferred_gid;
+				return 0;
+			}
+			/*
+			 * gr_locate_gid() found the GID in an as-yet uncommitted
+			 * entry. We'll proceed below and auto-set a GID.
+			 */
+		} else if (result == EEXIST || result == ERANGE) {
+			/*
+			 * Continue on below. At this time, we won't
+			 * treat these two cases differently.
+			 */
+		} else {
+			/*
+			 * An unexpected error occurred. We should report
+			 * this and fail the group creation.
+			 * This differs from the automatic creation
+			 * behavior below, since if a specific GID was
+			 * requested and generated an error, the user is
+			 * more likely to want to stop and address the
+			 * issue.
+			 */
+			fprintf (stderr,
+				_("%s: Encountered error attempting to use "
+				  "preferred GID: %s\n"),
+				Prog, strerror (result));
 			return -1;
 		}
 	}
+
+	/*
+	 * Search the entire group file,
+	 * looking for the next unused value.
+	 *
+	 * We first check the local database with gr_rewind/gr_next to find
+	 * all local values that are in use.
+	 *
+	 * We then compare the next free value to all databases (local and
+	 * remote) and iterate until we find a free one. If there are free
+	 * values beyond the lowest (system groups) or highest (non-system
+	 * groups), we will prefer those and avoid potentially reclaiming a
+	 * deleted group (which can be a security issue, since it may grant
+	 * access to files belonging to that former group).
+	 *
+	 * If there are no GIDs available at the end of the search, we will
+	 * have no choice but to iterate through the range looking for gaps.
+	 *
+	 */
+
+	/* Create an array to hold all of the discovered GIDs */
 	used_gids = malloc (sizeof (bool) * (gid_max +1));
 	if (NULL == used_gids) {
 		fprintf (stderr,
-		         _("%s: failed to allocate memory: %s\n"),
-		         Prog, strerror (errno));
+			 _("%s: failed to allocate memory: %s\n"),
+			 Prog, strerror (errno));
 		return -1;
 	}
 	memset (used_gids, false, sizeof (bool) * (gid_max + 1));
 
-	if (   (NULL != preferred_gid)
-	    && (*preferred_gid >= gid_min)
-	    && (*preferred_gid <= gid_max)
-	    /* Check if the user exists according to NSS */
-	    && (getgrgid (*preferred_gid) == NULL)
-	    /* Check also the local database in case of uncommitted
-	     * changes */
-	    && (gr_locate_gid (*preferred_gid) == NULL)) {
-		*gid = *preferred_gid;
-		free (used_gids);
-		return 0;
-	}
+	/* First look for the lowest and highest value in the local database */
+	(void) gr_rewind ();
+	highest_found = gid_min;
+	lowest_found = gid_max;
+	while ((grp = gr_next ()) != NULL) {
+		/*
+		 * Does this entry have a lower GID than the lowest we've found
+		 * so far?
+		 */
+		if ((grp->gr_gid <= lowest_found) && (grp->gr_gid >= gid_min)) {
+			lowest_found = grp->gr_gid - 1;
+		}
 
+		/*
+		 * Does this entry have a higher GID than the highest we've found
+		 * so far?
+		 */
+		if ((grp->gr_gid >= highest_found) && (grp->gr_gid <= gid_max)) {
+			highest_found = grp->gr_gid + 1;
+		}
+
+		/* create index of used GIDs */
+		if (grp->gr_gid >= gid_min
+			&& grp->gr_gid <= gid_max) {
+
+			used_gids[grp->gr_gid] = true;
+		}
+	}
 
-	/*
-	 * Search the entire group file,
-	 * looking for the largest unused value.
-	 *
-	 * We check the list of groups according to NSS (setgrent/getgrent),
-	 * but we also check the local database (gr_rewind/gr_next) in case
-	 * some groups were created but the changes were not committed yet.
-	 */
 	if (sys_group) {
-		gid_t id;
-		/* setgrent / getgrent / endgrent can be very slow with
-		 * LDAP configurations (and many accounts).
-		 * Since there is a limited amount of IDs to be tested
-		 * for system accounts, we just check the existence
-		 * of IDs with getgrgid.
+		/*
+		 * For system groups, we want to start from the
+		 * top of the range and work downwards.
 		 */
-		group_id = gid_max;
-		for (id = gid_max; id >= gid_min; id--) {
-			if (getgrgid (id) != NULL) {
-				group_id = id - 1;
-				used_gids[id] = true;
-			}
+
+		/*
+		 * At the conclusion of the gr_next() search, we will either
+		 * have a presumed-free GID or we will be at GID_MIN - 1.
+		 */
+		if (lowest_found < gid_min) {
+			/*
+			 * In this case, a GID is in use at GID_MIN.
+			 *
+			 * We will reset the search to GID_MAX and proceed down
+			 * through all the GIDs (skipping those we detected with
+			 * used_gids) for a free one. It is a known issue that
+			 * this may result in reusing a previously-deleted GID,
+			 * so administrators should be instructed to use this
+			 * auto-detection with care (and prefer to assign GIDs
+			 * explicitly).
+			 */
+			lowest_found = gid_max;
 		}
 
-		(void) gr_rewind ();
-		while ((grp = gr_next ()) != NULL) {
-			if ((grp->gr_gid <= group_id) && (grp->gr_gid >= gid_min)) {
-				group_id = grp->gr_gid - 1;
-			}
-			/* create index of used GIDs */
-			if (grp->gr_gid <= gid_max) {
-				used_gids[grp->gr_gid] = true;
+		/* Search through all of the IDs in the range */
+		for (id = lowest_found; id >= gid_min; id--) {
+			result = check_gid (id, gid_min, gid_max, used_gids);
+			if (result == 0) {
+				/* This GID is available. Return it. */
+				*gid = id;
+				free (used_gids);
+				return 0;
+			} else if (result == EEXIST) {
+				/* This GID is in use, we'll continue to the next */
+			} else {
+				/*
+				 * An unexpected error occurred.
+				 *
+				 * Only report it the first time to avoid spamming
+				 * the logs
+				 *
+				 */
+				if (!nospam) {
+					fprintf (stderr,
+						_("%s: Can't get unique system GID (%s). "
+						  "Suppressing additional messages.\n"),
+						Prog, strerror (result));
+					SYSLOG ((LOG_ERR,
+						"Error checking available GIDs: %s",
+						strerror (result)));
+					nospam = 1;
+				}
+				/*
+				 * We will continue anyway. Hopefully a later GID
+				 * will work properly.
+				 */
 			}
 		}
-	} else {
-		group_id = gid_min;
-		setgrent ();
-		while ((grp = getgrent ()) != NULL) {
-			if ((grp->gr_gid >= group_id) && (grp->gr_gid <= gid_max)) {
-				group_id = grp->gr_gid + 1;
-			}
-			/* create index of used GIDs */
-			if (grp->gr_gid <= gid_max) {
-				used_gids[grp->gr_gid] = true;
+
+		/*
+		 * If we get all the way through the loop, try again from GID_MAX,
+		 * unless that was where we previously started. (NOTE: the worst-case
+		 * scenario here is that we will run through (GID_MAX - GID_MIN - 1)
+		 * cycles *again* if we fall into this case with lowest_found as
+		 * GID_MAX - 1, all groups in the range in use and maintained by
+		 * network services such as LDAP.)
+		 */
+		if (lowest_found != gid_max) {
+			for (id = gid_max; id >= gid_min; id--) {
+				result = check_gid (id, gid_min, gid_max, used_gids);
+				if (result == 0) {
+					/* This GID is available. Return it. */
+					*gid = id;
+					free (used_gids);
+					return 0;
+				} else if (result == EEXIST) {
+					/* This GID is in use, we'll continue to the next */
+				} else {
+					/*
+					 * An unexpected error occurred.
+					 *
+					 * Only report it the first time to avoid spamming
+					 * the logs
+					 *
+					 */
+					if (!nospam) {
+						fprintf (stderr,
+							_("%s: Can't get unique system GID (%s). "
+							  "Suppressing additional messages.\n"),
+							Prog, strerror (result));
+						SYSLOG ((LOG_ERR,
+							"Error checking available GIDs: %s",
+							strerror (result)));
+						nospam = 1;
+					}
+					/*
+					 * We will continue anyway. Hopefully a later GID
+					 * will work properly.
+					 */
+				}
 			}
 		}
-		endgrent ();
+	} else { /* !sys_group */
+		/*
+		 * For non-system groups, we want to start from the
+		 * bottom of the range and work upwards.
+		 */
 
-		(void) gr_rewind ();
-		while ((grp = gr_next ()) != NULL) {
-			if ((grp->gr_gid >= group_id) && (grp->gr_gid <= gid_max)) {
-				group_id = grp->gr_gid + 1;
-			}
-			/* create index of used GIDs */
-			if (grp->gr_gid <= gid_max) {
-				used_gids[grp->gr_gid] = true;
-			}
+		/*
+		 * At the conclusion of the gr_next() search, we will either
+		 * have a presumed-free GID or we will be at GID_MAX + 1.
+		 */
+		if (highest_found > gid_max) {
+			/*
+			 * In this case, a GID is in use at GID_MAX.
+			 *
+			 * We will reset the search to GID_MIN and proceed up
+			 * through all the GIDs (skipping those we detected with
+			 * used_gids) for a free one. It is a known issue that
+			 * this may result in reusing a previously-deleted GID,
+			 * so administrators should be instructed to use this
+			 * auto-detection with care (and prefer to assign GIDs
+			 * explicitly).
+			 */
+			highest_found = gid_min;
 		}
-	}
 
-	/*
-	 * If a group (resp. system group) with GID equal to GID_MAX (resp.
-	 * GID_MIN) exists, the above algorithm will give us GID_MAX+1
-	 * (resp. GID_MIN-1) even if not unique. Search for the first free
-	 * GID starting with GID_MIN (resp. GID_MAX).
-	 */
-	if (sys_group) {
-		if (group_id < gid_min) {
-			for (group_id = gid_max; group_id >= gid_min; group_id--) {
-				if (false == used_gids[group_id]) {
-					break;
-				}
-			}
-			if (group_id < gid_min) {
-				fprintf (stderr,
-				         _("%s: Can't get unique system GID (no more available GIDs)\n"),
-				         Prog);
-				SYSLOG ((LOG_WARN,
-				         "no more available GID on the system"));
+		/* Search through all of the IDs in the range */
+		for (id = highest_found; id <= gid_max; id++) {
+			result = check_gid (id, gid_min, gid_max, used_gids);
+			if (result == 0) {
+				/* This GID is available. Return it. */
+				*gid = id;
 				free (used_gids);
-				return -1;
+				return 0;
+			} else if (result == EEXIST) {
+				/* This GID is in use, we'll continue to the next */
+			} else {
+				/*
+				 * An unexpected error occurred.
+				 *
+				 * Only report it the first time to avoid spamming
+				 * the logs
+				 *
+				 */
+				if (!nospam) {
+					fprintf (stderr,
+						_("%s: Can't get unique GID (%s). "
+						  "Suppressing additional messages.\n"),
+						Prog, strerror (result));
+					SYSLOG ((LOG_ERR,
+						"Error checking available GIDs: %s",
+						strerror (result)));
+					nospam = 1;
+				}
+				/*
+				 * We will continue anyway. Hopefully a later GID
+				 * will work properly.
+				 */
 			}
 		}
-	} else {
-		if (group_id > gid_max) {
-			for (group_id = gid_min; group_id <= gid_max; group_id++) {
-				if (false == used_gids[group_id]) {
-					break;
+
+		/*
+		 * If we get all the way through the loop, try again from GID_MIN,
+		 * unless that was where we previously started. (NOTE: the worst-case
+		 * scenario here is that we will run through (GID_MAX - GID_MIN - 1)
+		 * cycles *again* if we fall into this case with highest_found as
+		 * GID_MIN + 1, all groups in the range in use and maintained by
+		 * network services such as LDAP.)
+		 */
+		if (highest_found != gid_min) {
+			for (id = gid_min; id <= gid_max; id++) {
+				result = check_gid (id, gid_min, gid_max, used_gids);
+				if (result == 0) {
+					/* This GID is available. Return it. */
+					*gid = id;
+					free (used_gids);
+					return 0;
+				} else if (result == EEXIST) {
+					/* This GID is in use, we'll continue to the next */
+				} else {
+					/*
+					 * An unexpected error occurred.
+					 *
+					 * Only report it the first time to avoid spamming
+					 * the logs
+					 *
+					 */
+					if (!nospam) {
+						fprintf (stderr,
+							_("%s: Can't get unique GID (%s). "
+							  "Suppressing additional messages.\n"),
+							Prog, strerror (result));
+						SYSLOG ((LOG_ERR,
+							"Error checking available GIDs: %s",
+							strerror (result)));
+						nospam = 1;
+					}
+					/*
+					 * We will continue anyway. Hopefully a later GID
+					 * will work properly.
+					 */
 				}
 			}
-			if (group_id > gid_max) {
-				fprintf (stderr,
-				         _("%s: Can't get unique GID (no more available GIDs)\n"),
-				         Prog);
-				SYSLOG ((LOG_WARN, "no more available GID on the system"));
-				free (used_gids);
-				return -1;
-			}
 		}
 	}
 
+	/* The code reached here and found no available IDs in the range */
+	fprintf (stderr,
+		_("%s: Can't get unique GID (no more available GIDs)\n"),
+		Prog);
+	SYSLOG ((LOG_WARN, "no more available GIDs on the system"));
 	free (used_gids);
-	*gid = group_id;
-	return 0;
+	return -1;
 }
 
diff --git a/libmisc/find_new_uid.c b/libmisc/find_new_uid.c
index aac1909c..b3143134 100644
--- a/libmisc/find_new_uid.c
+++ b/libmisc/find_new_uid.c
@@ -1,6 +1,7 @@
 /*
  * Copyright (c) 1991 - 1994, Julianne Frances Haugh
  * Copyright (c) 2008 - 2011, Nicolas François
+ * Copyright (c) 2014, Red Hat, Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -39,6 +40,117 @@
 #include "getdef.h"
 
 /*
+ * get_ranges - Get the minimum and maximum ID ranges for the search
+ *
+ * This function will return the minimum and maximum ranges for IDs
+ *
+ * 0: The function completed successfully
+ * EINVAL: The provided ranges are impossible (such as maximum < minimum)
+ *
+ * preferred_min: The special-case minimum value for a specifically-
+ * requested ID, which may be lower than the standard min_id
+ */
+static int get_ranges (bool sys_user, uid_t *min_id, uid_t *max_id,
+			uid_t *preferred_min)
+{
+	uid_t uid_def_max = 0;
+
+	if (sys_user) {
+		/* System users */
+
+		/* A requested ID is allowed to be below the autoselect range */
+		*preferred_min = (uid_t) 1;
+
+		/* Get the minimum ID range from login.defs or default to 101 */
+		*min_id = (uid_t) getdef_ulong ("SYS_UID_MIN", 101UL);
+
+		/*
+		 * If SYS_UID_MAX is unspecified, we should assume it to be one
+		 * less than the UID_MIN (which is reserved for non-system accounts)
+		 */
+		uid_def_max = (uid_t) getdef_ulong ("UID_MIN", 1000UL) - 1;
+		*max_id = (uid_t) getdef_ulong ("SYS_UID_MAX",
+				(unsigned long) uid_def_max);
+
+		/* Check that the ranges make sense */
+		if (*max_id < *min_id) {
+			(void) fprintf (stderr,
+                            _("%s: Invalid configuration: SYS_UID_MIN (%lu), "
+                              "UID_MIN (%lu), SYS_UID_MAX (%lu)\n"),
+                            Prog, (unsigned long) *min_id,
+                            getdef_ulong ("UID_MIN", 1000UL),
+                            (unsigned long) *max_id);
+			return EINVAL;
+		}
+	} else {
+		/* Non-system users */
+
+		/* Get the values from login.defs or use reasonable defaults */
+		*min_id = (uid_t) getdef_ulong ("UID_MIN", 1000UL);
+		*max_id = (uid_t) getdef_ulong ("UID_MAX", 60000UL);
+
+		/*
+		 * The preferred minimum should match the standard ID minimum
+		 * for non-system users.
+		 */
+		*preferred_min = *min_id;
+
+		/* Check that the ranges make sense */
+		if (*max_id < *min_id) {
+			(void) fprintf (stderr,
+					_("%s: Invalid configuration: UID_MIN (%lu), "
+					  "UID_MAX (%lu)\n"),
+					Prog, (unsigned long) *min_id,
+					(unsigned long) *max_id);
+			return EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * check_uid - See if the requested UID is available
+ *
+ * On success, return 0
+ * If the ID is in use, return EEXIST
+ * If the ID is outside the range, return ERANGE
+ * In other cases, return errno from getpwuid()
+ */
+static int check_uid(const uid_t uid,
+		     const uid_t uid_min,
+		     const uid_t uid_max,
+		     bool *used_uids)
+{
+	/* First test that the preferred ID is in the range */
+	if (uid < uid_min || uid > uid_max) {
+		return ERANGE;
+	}
+
+	/*
+	 * Check whether we already detected this UID
+	 * using the pw_next() loop
+	 */
+	if (used_uids != NULL && used_uids[uid]) {
+		return EEXIST;
+	}
+	/* Check if the UID exists according to NSS */
+	errno = 0;
+	if (getpwuid(uid) != NULL) {
+		return EEXIST;
+	} else {
+		/* getpwuid() was NULL
+		 * we have to ignore errors as temporary
+		 * failures of remote user identity services
+		 * would completely block user/group creation
+		 */
+	}
+
+	/* If we've made it here, the UID must be available */
+	return 0;
+}
+
+/*
  * find_new_uid - Find a new unused UID.
  *
  * If successful, find_new_uid provides an unused user ID in the
@@ -48,162 +160,339 @@
  * 
  * Return 0 on success, -1 if no unused UIDs are available.
  */
-int find_new_uid (bool sys_user,
-                  uid_t *uid,
-                  /*@null@*/uid_t const *preferred_uid)
+int find_new_uid(bool sys_user,
+                 uid_t *uid,
+                 /*@null@*/uid_t const *preferred_uid)
 {
-	const struct passwd *pwd;
-	uid_t uid_min, uid_max, user_id;
 	bool *used_uids;
+	const struct passwd *pwd;
+	uid_t uid_min, uid_max, preferred_min;
+	uid_t user_id, id;
+	uid_t lowest_found, highest_found;
+	int result;
+	int nospam = 0;
 
 	assert (uid != NULL);
 
-	if (!sys_user) {
-		uid_min = (uid_t) getdef_ulong ("UID_MIN", 1000UL);
-		uid_max = (uid_t) getdef_ulong ("UID_MAX", 60000UL);
-		if (uid_max < uid_min) {
-			(void) fprintf (stderr,
-			                _("%s: Invalid configuration: UID_MIN (%lu), UID_MAX (%lu)\n"),
-			                Prog, (unsigned long) uid_min, (unsigned long) uid_max);
-			return -1;
-		}
-	} else {
-		uid_min = (uid_t) getdef_ulong ("SYS_UID_MIN", 101UL);
-		uid_max = (uid_t) getdef_ulong ("UID_MIN", 1000UL) - 1;
-		uid_max = (uid_t) getdef_ulong ("SYS_UID_MAX", (unsigned long) uid_max);
-		if (uid_max < uid_min) {
-			(void) fprintf (stderr,
-			                _("%s: Invalid configuration: SYS_UID_MIN (%lu), UID_MIN (%lu), SYS_UID_MAX (%lu)\n"),
-			                Prog, (unsigned long) uid_min, getdef_ulong ("UID_MIN", 1000UL), (unsigned long) uid_max);
+	/*
+	 * First, figure out what ID range is appropriate for
+	 * automatic assignment
+	 */
+	result = get_ranges (sys_user, &uid_min, &uid_max, &preferred_min);
+	if (result == EINVAL) {
+		return -1;
+	}
+
+	/* Check if the preferred UID is available */
+	if (preferred_uid) {
+		result = check_uid (*preferred_uid, preferred_min, uid_max, NULL);
+		if (result == 0) {
+			/*
+			 * Make sure the UID isn't queued for use already
+			 */
+			if (pw_locate_uid (*preferred_uid) == NULL) {
+				*uid = *preferred_uid;
+				return 0;
+			}
+			/*
+			 * pw_locate_uid() found the UID in an as-yet uncommitted
+			 * entry. We'll proceed below and auto-set an UID.
+			 */
+		} else if (result == EEXIST || result == ERANGE) {
+			/*
+			 * Continue on below. At this time, we won't
+			 * treat these two cases differently.
+			 */
+		} else {
+			/*
+			 * An unexpected error occurred. We should report
+			 * this and fail the user creation.
+			 * This differs from the automatic creation
+			 * behavior below, since if a specific UID was
+			 * requested and generated an error, the user is
+			 * more likely to want to stop and address the
+			 * issue.
+			 */
+			fprintf (stderr,
+				_("%s: Encountered error attempting to use "
+				  "preferred UID: %s\n"),
+				Prog, strerror (result));
 			return -1;
 		}
 	}
+
+	/*
+	 * Search the entire passwd file,
+	 * looking for the next unused value.
+	 *
+	 * We first check the local database with pw_rewind/pw_next to find
+	 * all local values that are in use.
+	 *
+	 * We then compare the next free value to all databases (local and
+	 * remote) and iterate until we find a free one. If there are free
+	 * values beyond the lowest (system users) or highest (non-system
+	 * users), we will prefer those and avoid potentially reclaiming a
+	 * deleted user (which can be a security issue, since it may grant
+	 * access to files belonging to that former user).
+	 *
+	 * If there are no UIDs available at the end of the search, we will
+	 * have no choice but to iterate through the range looking for gaps.
+	 *
+	 */
+
+	/* Create an array to hold all of the discovered UIDs */
 	used_uids = malloc (sizeof (bool) * (uid_max +1));
 	if (NULL == used_uids) {
 		fprintf (stderr,
-		         _("%s: failed to allocate memory: %s\n"),
-		         Prog, strerror (errno));
+			 _("%s: failed to allocate memory: %s\n"),
+			 Prog, strerror (errno));
 		return -1;
 	}
 	memset (used_uids, false, sizeof (bool) * (uid_max + 1));
 
-	if (   (NULL != preferred_uid)
-	    && (*preferred_uid >= uid_min)
-	    && (*preferred_uid <= uid_max)
-	    /* Check if the user exists according to NSS */
-	    && (getpwuid (*preferred_uid) == NULL)
-	    /* Check also the local database in case of uncommitted
-	     * changes */
-	    && (pw_locate_uid (*preferred_uid) == NULL)) {
-		*uid = *preferred_uid;
-		free (used_uids);
-		return 0;
-	}
+	/* First look for the lowest and highest value in the local database */
+	(void) pw_rewind ();
+	highest_found = uid_min;
+	lowest_found = uid_max;
+	while ((pwd = pw_next ()) != NULL) {
+		/*
+		 * Does this entry have a lower UID than the lowest we've found
+		 * so far?
+		 */
+		if ((pwd->pw_uid <= lowest_found) && (pwd->pw_uid >= uid_min)) {
+			lowest_found = pwd->pw_uid - 1;
+		}
 
+		/*
+		 * Does this entry have a higher UID than the highest we've found
+		 * so far?
+		 */
+		if ((pwd->pw_uid >= highest_found) && (pwd->pw_uid <= uid_max)) {
+			highest_found = pwd->pw_uid + 1;
+		}
+
+		/* create index of used UIDs */
+		if (pwd->pw_uid >= uid_min
+			&& pwd->pw_uid <= uid_max) {
+
+			used_uids[pwd->pw_uid] = true;
+		}
+	}
 
-	/*
-	 * Search the entire password file,
-	 * looking for the largest unused value.
-	 *
-	 * We check the list of users according to NSS (setpwent/getpwent),
-	 * but we also check the local database (pw_rewind/pw_next) in case
-	 * some users were created but the changes were not committed yet.
-	 */
 	if (sys_user) {
-		uid_t id;
-		/* setpwent / getpwent / endpwent can be very slow with
-		 * LDAP configurations (and many accounts).
-		 * Since there is a limited amount of IDs to be tested
-		 * for system accounts, we just check the existence
-		 * of IDs with getpwuid.
+		/*
+		 * For system users, we want to start from the
+		 * top of the range and work downwards.
 		 */
-		user_id = uid_max;
-		for (id = uid_max; id >= uid_min; id--) {
-			if (getpwuid (id) != NULL) {
-				user_id = id - 1;
-				used_uids[id] = true;
-			}
+
+		/*
+		 * At the conclusion of the pw_next() search, we will either
+		 * have a presumed-free UID or we will be at UID_MIN - 1.
+		 */
+		if (lowest_found < uid_min) {
+			/*
+			 * In this case, an UID is in use at UID_MIN.
+			 *
+			 * We will reset the search to UID_MAX and proceed down
+			 * through all the UIDs (skipping those we detected with
+			 * used_uids) for a free one. It is a known issue that
+			 * this may result in reusing a previously-deleted UID,
+			 * so administrators should be instructed to use this
+			 * auto-detection with care (and prefer to assign UIDs
+			 * explicitly).
+			 */
+			lowest_found = uid_max;
 		}
 
-		(void) pw_rewind ();
-		while ((pwd = pw_next ()) != NULL) {
-			if ((pwd->pw_uid <= user_id) && (pwd->pw_uid >= uid_min)) {
-				user_id = pwd->pw_uid - 1;
-			}
-			/* create index of used UIDs */
-			if (pwd->pw_uid <= uid_max) {
-				used_uids[pwd->pw_uid] = true;
+		/* Search through all of the IDs in the range */
+		for (id = lowest_found; id >= uid_min; id--) {
+			result = check_uid (id, uid_min, uid_max, used_uids);
+			if (result == 0) {
+				/* This UID is available. Return it. */
+				*uid = id;
+				free (used_uids);
+				return 0;
+			} else if (result == EEXIST) {
+				/* This UID is in use, we'll continue to the next */
+			} else {
+				/*
+				 * An unexpected error occurred.
+				 *
+				 * Only report it the first time to avoid spamming
+				 * the logs
+				 *
+				 */
+				if (!nospam) {
+					fprintf (stderr,
+						_("%s: Can't get unique system UID (%s). "
+						  "Suppressing additional messages.\n"),
+						Prog, strerror (result));
+					SYSLOG ((LOG_ERR,
+						"Error checking available UIDs: %s",
+						strerror (result)));
+					nospam = 1;
+				}
+				/*
+				 * We will continue anyway. Hopefully a later UID
+				 * will work properly.
+				 */
 			}
 		}
-	} else {
-		user_id = uid_min;
-		setpwent ();
-		while ((pwd = getpwent ()) != NULL) {
-			if ((pwd->pw_uid >= user_id) && (pwd->pw_uid <= uid_max)) {
-				user_id = pwd->pw_uid + 1;
-			}
-			/* create index of used UIDs */
-			if (pwd->pw_uid <= uid_max) {
-				used_uids[pwd->pw_uid] = true;
+
+		/*
+		 * If we get all the way through the loop, try again from UID_MAX,
+		 * unless that was where we previously started. (NOTE: the worst-case
+		 * scenario here is that we will run through (UID_MAX - UID_MIN - 1)
+		 * cycles *again* if we fall into this case with lowest_found as
+		 * UID_MAX - 1, all users in the range in use and maintained by
+		 * network services such as LDAP.)
+		 */
+		if (lowest_found != uid_max) {
+			for (id = uid_max; id >= uid_min; id--) {
+				result = check_uid (id, uid_min, uid_max, used_uids);
+				if (result == 0) {
+					/* This UID is available. Return it. */
+					*uid = id;
+					free (used_uids);
+					return 0;
+				} else if (result == EEXIST) {
+					/* This UID is in use, we'll continue to the next */
+				} else {
+					/*
+					 * An unexpected error occurred.
+					 *
+					 * Only report it the first time to avoid spamming
+					 * the logs
+					 *
+					 */
+					if (!nospam) {
+						fprintf (stderr,
+							_("%s: Can't get unique system UID (%s). "
+							  "Suppressing additional messages.\n"),
+							Prog, strerror (result));
+						SYSLOG((LOG_ERR,
+							"Error checking available UIDs: %s",
+							strerror (result)));
+						nospam = 1;
+					}
+					/*
+					 * We will continue anyway. Hopefully a later UID
+					 * will work properly.
+					 */
+				}
 			}
 		}
-		endpwent ();
+	} else { /* !sys_user */
+		/*
+		 * For non-system users, we want to start from the
+		 * bottom of the range and work upwards.
+		 */
 
-		(void) pw_rewind ();
-		while ((pwd = pw_next ()) != NULL) {
-			if ((pwd->pw_uid >= user_id) && (pwd->pw_uid <= uid_max)) {
-				user_id = pwd->pw_uid + 1;
-			}
-			/* create index of used UIDs */
-			if (pwd->pw_uid <= uid_max) {
-				used_uids[pwd->pw_uid] = true;
-			}
+		/*
+		 * At the conclusion of the pw_next() search, we will either
+		 * have a presumed-free UID or we will be at UID_MAX + 1.
+		 */
+		if (highest_found > uid_max) {
+			/*
+			 * In this case, a UID is in use at UID_MAX.
+			 *
+			 * We will reset the search to UID_MIN and proceed up
+			 * through all the UIDs (skipping those we detected with
+			 * used_uids) for a free one. It is a known issue that
+			 * this may result in reusing a previously-deleted UID,
+			 * so administrators should be instructed to use this
+			 * auto-detection with care (and prefer to assign UIDs
+			 * explicitly).
+			 */
+			highest_found = uid_min;
 		}
-	}
 
-	/*
-	 * If a user (resp. system user) with UID equal to UID_MAX (resp.
-	 * UID_MIN) exists, the above algorithm will give us UID_MAX+1
-	 * (resp. UID_MIN-1) even if not unique. Search for the first free
-	 * UID starting with UID_MIN (resp. UID_MAX).
-	 */
-	if (sys_user) {
-		if (user_id < uid_min) {
-			for (user_id = uid_max; user_id >= uid_min; user_id--) {
-				if (false == used_uids[user_id]) {
-					break;
-				}
-			}
-			if (user_id < uid_min ) {
-				fprintf (stderr,
-				         _("%s: Can't get unique system UID (no more available UIDs)\n"),
-				         Prog);
-				SYSLOG ((LOG_WARN,
-				         "no more available UID on the system"));
+		/* Search through all of the IDs in the range */
+		for (id = highest_found; id <= uid_max; id++) {
+			result = check_uid (id, uid_min, uid_max, used_uids);
+			if (result == 0) {
+				/* This UID is available. Return it. */
+				*uid = id;
 				free (used_uids);
-				return -1;
+				return 0;
+			} else if (result == EEXIST) {
+				/* This UID is in use, we'll continue to the next */
+			} else {
+				/*
+				 * An unexpected error occurred.
+				 *
+				 * Only report it the first time to avoid spamming
+				 * the logs
+				 *
+				 */
+				if (!nospam) {
+					fprintf (stderr,
+						_("%s: Can't get unique UID (%s). "
+						  "Suppressing additional messages.\n"),
+						Prog, strerror (result));
+					SYSLOG ((LOG_ERR,
+						"Error checking available UIDs: %s",
+						strerror (result)));
+					nospam = 1;
+				}
+				/*
+				 * We will continue anyway. Hopefully a later UID
+				 * will work properly.
+				 */
 			}
 		}
-	} else {
-		if (user_id > uid_max) {
-			for (user_id = uid_min; user_id <= uid_max; user_id++) {
-				if (false == used_uids[user_id]) {
-					break;
+
+		/*
+		 * If we get all the way through the loop, try again from UID_MIN,
+		 * unless that was where we previously started. (NOTE: the worst-case
+		 * scenario here is that we will run through (UID_MAX - UID_MIN - 1)
+		 * cycles *again* if we fall into this case with highest_found as
+		 * UID_MIN + 1, all users in the range in use and maintained by
+		 * network services such as LDAP.)
+		 */
+		if (highest_found != uid_min) {
+			for (id = uid_min; id <= uid_max; id++) {
+				result = check_uid (id, uid_min, uid_max, used_uids);
+				if (result == 0) {
+					/* This UID is available. Return it. */
+					*uid = id;
+					free (used_uids);
+					return 0;
+				} else if (result == EEXIST) {
+					/* This UID is in use, we'll continue to the next */
+				} else {
+					/*
+					 * An unexpected error occurred.
+					 *
+					 * Only report it the first time to avoid spamming
+					 * the logs
+					 *
+					 */
+					if (!nospam) {
+						fprintf (stderr,
+							_("%s: Can't get unique UID (%s). "
+							  "Suppressing additional messages.\n"),
+							Prog, strerror (result));
+						SYSLOG ((LOG_ERR,
+							"Error checking available UIDs: %s",
+							strerror (result)));
+						nospam = 1;
+					}
+					/*
+					 * We will continue anyway. Hopefully a later UID
+					 * will work properly.
+					 */
 				}
 			}
-			if (user_id > uid_max) {
-				fprintf (stderr,
-				         _("%s: Can't get unique UID (no more available UIDs)\n"),
-				         Prog);
-				SYSLOG ((LOG_WARN, "no more available UID on the system"));
-				free (used_uids);
-				return -1;
-			}
 		}
 	}
 
+	/* The code reached here and found no available IDs in the range */
+	fprintf (stderr,
+		_("%s: Can't get unique UID (no more available UIDs)\n"),
+		Prog);
+	SYSLOG ((LOG_WARN, "no more available UIDs on the system"));
 	free (used_uids);
-	*uid = user_id;
-	return 0;
+	return -1;
 }
 
diff --git a/libmisc/gettime.c b/libmisc/gettime.c
new file mode 100644
index 00000000..53eaf516
--- /dev/null
+++ b/libmisc/gettime.c
@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2017, Chris Lamb
+ * 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.
+ */
+
+#include <config.h>
+
+#ident "$Id$"
+
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include "defines.h"
+#include "prototypes.h"
+
+/*
+ * gettime() returns the time as the number of seconds since the Epoch
+ *
+ * Like time(), gettime() returns the time as the number of seconds since the
+ * Epoch, 1970-01-01 00:00:00 +0000 (UTC), except that if the SOURCE_DATE_EPOCH
+ * environment variable is exported it will use that instead.
+ */
+/*@observer@*/time_t gettime ()
+{
+	char *endptr;
+	char *source_date_epoch;
+	time_t fallback;
+	unsigned long long epoch;
+
+	fallback = time (NULL);
+	source_date_epoch = getenv ("SOURCE_DATE_EPOCH");
+
+	if (!source_date_epoch)
+		return fallback;
+
+	errno = 0;
+	epoch = strtoull (source_date_epoch, &endptr, 10);
+	if ((errno == ERANGE && (epoch == ULLONG_MAX || epoch == 0))
+			|| (errno != 0 && epoch == 0)) {
+		fprintf (stderr,
+			 _("Environment variable $SOURCE_DATE_EPOCH: strtoull: %s\n"),
+			 strerror(errno));
+	} else if (endptr == source_date_epoch) {
+		fprintf (stderr,
+			 _("Environment variable $SOURCE_DATE_EPOCH: No digits were found: %s\n"),
+			 endptr);
+	} else if (*endptr != '\0') {
+		fprintf (stderr,
+			 _("Environment variable $SOURCE_DATE_EPOCH: Trailing garbage: %s\n"),
+			 endptr);
+	} else if (epoch > ULONG_MAX) {
+		fprintf (stderr,
+			 _("Environment variable $SOURCE_DATE_EPOCH: value must be smaller than or equal to %lu but was found to be: %llu\n"),
+			 ULONG_MAX, epoch);
+	} else if (epoch > fallback) {
+		fprintf (stderr,
+			 _("Environment variable $SOURCE_DATE_EPOCH: value must be smaller than or equal to the current time (%lu) but was found to be: %llu\n"),
+			 fallback, epoch);
+	} else {
+		/* Valid */
+		return (time_t)epoch;
+	}
+
+	return fallback;
+}
diff --git a/libmisc/user_busy.c b/libmisc/user_busy.c
index 0db32c39..b0867568 100644
--- a/libmisc/user_busy.c
+++ b/libmisc/user_busy.c
@@ -170,6 +170,9 @@ static int user_busy_processes (const char *name, uid_t uid)
 	proc = opendir ("/proc");
 	if (proc == NULL) {
 		perror ("opendir /proc");
+#ifdef ENABLE_SUBIDS
+		sub_uid_close();
+#endif
 		return 0;
 	}
 	if (stat ("/", &sbroot) != 0) {