libmount: fix uid= and gid= translation

The current libmount version returns error when no able to convert
username/groupname to uid/git.

 # mount mount /dev/sda1 /mnt/test -o uid=ignore
 # mount: failed to parse mount options

This is regression, the original mount(8) has ignored possible unknown
user/group names and the option has been used unconverted (with the
original value). For example UDF kernel driver depends on this behavior
and "uid=ignore" (or "forgot") is a valid mount option.

Fixed version (unit test):

./test_mount_optstr  --fix uid=kzak,gid=forgot,aaa,bbb
optstr: uid=kzak,gid=forgot,aaa,bbb
fixed:  uid=1000,gid=forgot,aaa,bbb

Reported-By: Anthony DeRobertis <anthony@derobert.net>
Addresses: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=801527
Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 14 insertions, 11 deletions

diff --git a/libmount/src/optstr.c b/libmount/src/optstr.c
index 198890d12..9b21e63b1 100644
--- a/libmount/src/optstr.c
+++ b/libmount/src/optstr.c
@@ -959,7 +959,6 @@ static int set_uint_value(char **optstr, unsigned int num,
  */
 int mnt_optstr_fix_uid(char **optstr, char *value, size_t valsz, char **next)
 {
-	int rc = 0;
 	char *end;
 
 	if (!optstr || !*optstr || !value || !valsz)
@@ -971,10 +970,11 @@ int mnt_optstr_fix_uid(char **optstr, char *value, size_t valsz, char **next)
 
 	if (valsz == 7 && !strncmp(value, "useruid", 7) &&
 	    (*(value + 7) == ',' || !*(value + 7)))
-		rc = set_uint_value(optstr, getuid(), value, end, next);
+		return set_uint_value(optstr, getuid(), value, end, next);
 
 	else if (!isdigit(*value)) {
 		uid_t id;
+		int rc;
 		char *p = strndup(value, valsz);
 		if (!p)
 			return -ENOMEM;
@@ -982,16 +982,17 @@ int mnt_optstr_fix_uid(char **optstr, char *value, size_t valsz, char **next)
 		free(p);
 
 		if (!rc)
-			rc = set_uint_value(optstr, id, value, end, next);
+			return set_uint_value(optstr, id, value, end, next);
+	}
 
-	} else if (next) {
-		/* nothing */
+	if (next) {
+		/* no change, let's keep the original value */
 		*next = value + valsz;
 		if (**next == ',')
 			(*next)++;
 	}
 
-	return rc;
+	return 0;
 }
 
 /*
@@ -1006,7 +1007,6 @@ int mnt_optstr_fix_uid(char **optstr, char *value, size_t valsz, char **next)
  */
 int mnt_optstr_fix_gid(char **optstr, char *value, size_t valsz, char **next)
 {
-	int rc = 0;
 	char *end;
 
 	if (!optstr || !*optstr || !value || !valsz)
@@ -1018,9 +1018,10 @@ int mnt_optstr_fix_gid(char **optstr, char *value, size_t valsz, char **next)
 
 	if (valsz == 7 && !strncmp(value, "usergid", 7) &&
 	    (*(value + 7) == ',' || !*(value + 7)))
-		rc = set_uint_value(optstr, getgid(), value, end, next);
+		return set_uint_value(optstr, getgid(), value, end, next);
 
 	else if (!isdigit(*value)) {
+		int rc;
 		gid_t id;
 		char *p = strndup(value, valsz);
 		if (!p)
@@ -1029,15 +1030,17 @@ int mnt_optstr_fix_gid(char **optstr, char *value, size_t valsz, char **next)
 		free(p);
 
 		if (!rc)
-			rc = set_uint_value(optstr, id, value, end, next);
+			return set_uint_value(optstr, id, value, end, next);
+
+	}
 
-	} else if (next) {
+	if (next) {
 		/* nothing */
 		*next = value + valsz;
 		if (**next == ',')
 			(*next)++;
 	}
-	return rc;
+	return 0;
 }
 
 /*