mountd: Use a dynamic buffer for storing lists of gid's

Previously, in auth_unix_gid, group lists were stored in an array of
hard-coded length 100, and in the situation that the group lists for a
particular call were too large, the array was swapped with a dynamically
allocated/freed buffer.  For environments where users are commonly in
a large number of groups, this isn't an ideal approach.

Instead, use malloc/realloc to grow the list on an as-needed basis.

Signed-off-by: Sean Finney <sean.finney@sonyericsson.com>
Signed-off-by: Steve Dickson <steved@redhat.com>

diff --git a/utils/mountd/cache.c b/utils/mountd/cache.c
index 1d6e95325c489e35b6b4f05490327a84a2dd5364..ce93e3cf61b66f5b3fdfb623bcddd94a130eaf87 100644 (file)
--- a/utils/mountd/cache.c
+++ b/utils/mountd/cache.c
@@ -64,6 +64,7 @@ enum nfsd_fsid {
  */
 static int cache_export_ent(char *domain, struct exportent *exp, char *p);
 
+#define INITIAL_MANAGED_GROUPS 100
 
 char *lbuf  = NULL;
 int lbuflen = 0;
@@ -134,11 +135,21 @@ static void auth_unix_gid(FILE *f)
         */
        uid_t uid;
        struct passwd *pw;
-       gid_t glist[100], *groups = glist;
-       int ngroups = 100;
+       static gid_t *groups = NULL;
+       static int groups_len = 0;
+       gid_t *more_groups;
+       int ngroups = 0;
        int rv, i;
        char *cp;
 
+       if (groups_len == 0) {
+               groups = malloc(sizeof(gid_t) * INITIAL_MANAGED_GROUPS);
+               if (!groups)
+                       return;
+
+               groups_len = ngroups = INITIAL_MANAGED_GROUPS;
+       }
+
        if (readline(fileno(f), &lbuf, &lbuflen) != 1)
                return;
 
@@ -151,13 +162,16 @@ static void auth_unix_gid(FILE *f)
                rv = -1;
        else {
                rv = getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups);
-               if (rv == -1 && ngroups >= 100) {
-                       groups = malloc(sizeof(gid_t)*ngroups);
-                       if (!groups)
+               if (rv == -1 && ngroups >= groups_len) {
+                       more_groups = realloc(groups, sizeof(gid_t)*ngroups);
+                       if (!more_groups)
                                rv = -1;
-                       else
+                       else {
+                               groups = more_groups;
+                               groups_len = ngroups;
                                rv = getgrouplist(pw->pw_name, pw->pw_gid,
                                                  groups, &ngroups);
+                       }
                }
        }
        qword_printuint(f, uid);
@@ -169,9 +183,6 @@ static void auth_unix_gid(FILE *f)
        } else
                qword_printuint(f, 0);
        qword_eol(f);
-
-       if (groups != glist)
-               free(groups);
 }
 
 #if USE_BLKID