Prevent the -g option from preserving groups that a non-root receiver

[rsync/rsync.git] / rsync.c

diff --git a/rsync.c b/rsync.c
index 3f79f50..ceabfda 100644 (file)
--- a/rsync.c
+++ b/rsync.c
@@ -113,12 +113,46 @@ int delete_file(char *fname)
        return 0;
 }
 
+static int is_in_group(gid_t gid)
+{
+#ifdef HAVE_GETGROUPS
+       static gid_t last_in = (gid_t) -2, last_out;
+       static int ngroups = -2;
+       static gid_t *gidset;
+       int n;
+
+       if (gid == last_in)
+               return last_out;
+       if (ngroups < -1) {
+               /* treat failure (-1) as if not member of any group */
+               ngroups = getgroups(0, 0);
+               if (ngroups > 0) {
+                       gidset = (gid_t *) malloc(ngroups * sizeof(gid_t));
+                       ngroups = getgroups(ngroups, gidset);
+               }
+       }
+
+       last_in = gid;
+       last_out = 0;
+       for (n = 0; n < ngroups; n++) {
+               if (gidset[n] == gid) {
+                       last_out = 1;
+                       break;
+               }
+       }
+       return last_out;
+
+#else
+       return 0;
+#endif
+}
 
 int set_perms(char *fname,struct file_struct *file,STRUCT_STAT *st,
              int report)
 {
        int updated = 0;
        STRUCT_STAT st2;
+       int change_uid, change_gid;
        extern int am_daemon;
 
        if (dry_run) return 0;
@@ -145,22 +179,24 @@ int set_perms(char *fname,struct file_struct *file,STRUCT_STAT *st,
                }
        }
 
-       if ((am_root || !am_daemon) &&
-           ((am_root && preserve_uid && st->st_uid != file->uid) || 
-            (preserve_gid && st->st_gid != file->gid))) {
+       change_uid = am_root && preserve_uid && st->st_uid != file->uid;
+       change_gid = !am_daemon && preserve_gid && file->gid != -1 \
+                               && st->st_gid != file->gid;
+       if (change_gid && !am_root) {
+               /* enforce bsd-style group semantics: non-root can only
+                   change to groups that the user is a member of */
+               change_gid = is_in_group(file->gid);
+       }
+       if (change_uid || change_gid) {
                if (do_lchown(fname,
-                             (am_root&&preserve_uid)?file->uid:st->st_uid,
-                             preserve_gid?file->gid:st->st_gid) != 0) {
-                       if (preserve_uid && st->st_uid != file->uid)
-                               updated = 1;
-                       if (verbose>1 || preserve_uid) {
-                               rprintf(FERROR,"chown %s : %s\n",
-                                       fname,strerror(errno));
-                               return 0;
-                       }
-               } else {
-                       updated = 1;
+                             change_uid?file->uid:st->st_uid,
+                             change_gid?file->gid:st->st_gid) != 0) {
+                       /* shouldn't have attempted to change uid or gid
+                            unless have the privilege */
+                       rprintf(FERROR,"chown %s : %s\n", fname,strerror(errno));
+                       return 0;
                }
+               updated = 1;
        }
 
 #ifdef HAVE_CHMOD