userns: add argument sanity checkinguserns.2

In find_new_sub_{u,g}ids, check for min, count and max values.

In idmapping.c:get_map_ranges(), make sure that the value passed
in for ranges did not overflow.  Couldn't happen with the current
code, but this is a sanity check for any future potential mis-uses.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>

3 files changed, 26 insertions, 0 deletions

diff --git a/libmisc/find_new_sub_gids.c b/libmisc/find_new_sub_gids.c
index 68046ac8..fd44978e 100644
--- a/libmisc/find_new_sub_gids.c
+++ b/libmisc/find_new_sub_gids.c
@@ -58,6 +58,14 @@ int find_new_sub_gids (const char *owner,
 	max = getdef_ulong ("SUB_GID_MAX", 600100000UL);
 	count = getdef_ulong ("SUB_GID_COUNT", 10000);
 
+	if (min >= max || count >= max || (min + count) >= max) {
+		(void) fprintf (stderr,
+				_("%s: Invalid configuration: SUB_GID_MIN (%lu),"
+				  " SUB_GID_MAX (%lu), SUB_GID_COUNT (%lu)\n"),
+			Prog, min, max, count);
+		return -1;
+	}
+
 	/* Is there a preferred range that works? */
 	if ((*range_count != 0) &&
 	    (*range_start >= min) &&
diff --git a/libmisc/find_new_sub_uids.c b/libmisc/find_new_sub_uids.c
index f1720f91..b608c59d 100644
--- a/libmisc/find_new_sub_uids.c
+++ b/libmisc/find_new_sub_uids.c
@@ -58,6 +58,14 @@ int find_new_sub_uids (const char *owner,
 	max = getdef_ulong ("SUB_UID_MAX", 600100000UL);
 	count = getdef_ulong ("SUB_UID_COUNT", 10000);
 
+	if (min >= max || count >= max || (min + count) >= max) {
+		(void) fprintf (stderr,
+				_("%s: Invalid configuration: SUB_UID_MIN (%lu),"
+				  " SUB_UID_MAX (%lu), SUB_UID_COUNT (%lu)\n"),
+			Prog, min, max, count);
+		return -1;
+	}
+
 	/* Is there a preferred range that works? */
 	if ((*range_count != 0) &&
 	    (*range_start >= min) &&
diff --git a/libmisc/idmapping.c b/libmisc/idmapping.c
index cb9e8985..4147796b 100644
--- a/libmisc/idmapping.c
+++ b/libmisc/idmapping.c
@@ -41,6 +41,16 @@ struct map_range *get_map_ranges(int ranges, int argc, char **argv)
 	struct map_range *mappings, *mapping;
 	int idx, argidx;
 
+	if (ranges < 0 || argc < 0) {
+		fprintf(stderr, "%s: error calculating number of arguments\n", Prog);
+		return NULL;
+	}
+
+	if (ranges != ((argc - 2) + 2) / 3) {
+		fprintf(stderr, "%s: ranges: %u is wrong for argc: %d\n", Prog, ranges, argc);
+		return NULL;
+	}
+
 	if ((ranges * 3) > argc) {
 		fprintf(stderr, "ranges: %u argc: %d\n",
 			ranges, argc);