Avoid duplicate aces

When adding arbitrary aces to an nt_ace_list we need to make sure we
are not actually adding a duplicate.
add_or_replace_ace() takes care of doing the right thing.
(cherry picked from commit 958207e321f330426536bf7e936b30fa2efffddc)

diff --git a/source/smbd/posix_acls.c b/source/smbd/posix_acls.c
index 1a90db384b7ed9f4818598e36a0ba14cddd7f006..13bf2ba89d1789b1ec56bde79ee31fba4547be1f 100644 (file)
--- a/source/smbd/posix_acls.c
+++ b/source/smbd/posix_acls.c
@@ -3,6 +3,7 @@
    SMB NT Security Descriptor / Unix permission conversion.
    Copyright (C) Jeremy Allison 1994-2000.
    Copyright (C) Andreas Gruenbacher 2002.
+   Copyright (C) Simo Sorce <idra@samba.org> 2009.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -2814,6 +2815,42 @@ static size_t merge_default_aces( SEC_ACE *nt_ace_list, size_t num_aces)
        return num_aces;
 }
 
+/*
+ * Add or Replace ACE entry.
+ * In some cases we need to add a specific ACE for compatibility reasons.
+ * When doing that we must make sure we are not actually creating a duplicate
+ * entry. So we need to search whether an ACE entry already exist and eventually
+ * replacce the access mask, or add a completely new entry if none was found.
+ *
+ * This function assumes the array has enough space to add a new entry without
+ * any reallocation of memory.
+ */
+
+static void add_or_replace_ace(SEC_ACE *nt_ace_list, size_t *num_aces,
+                               const DOM_SID *sid, enum security_ace_type type,
+                               uint32_t mask, uint8_t flags)
+{
+       int i;
+
+       /* first search for a duplicate */
+       for (i = 0; i < *num_aces; i++) {
+               if (sid_equal(&nt_ace_list[i].trustee, sid) &&
+                   (nt_ace_list[i].flags == flags)) break;
+       }
+
+       if (i < *num_aces) { /* found */
+               nt_ace_list[i].type = type;
+               nt_ace_list[i].access_mask = mask;
+               DEBUG(10, ("Replacing ACE %d with SID %s and flags %02x\n",
+                          i, sid_string_dbg(sid), flags));
+               return;
+       }
+
+       /* not found, append it */
+       init_sec_ace(&nt_ace_list[(*num_aces)++], sid, type, mask, flags);
+}
+
+
 /****************************************************************************
  Reply to query a security descriptor from an fsp. If it succeeds it allocates
  the space for the return elements and returns the size needed to return the
@@ -2977,13 +3014,10 @@ static NTSTATUS posix_get_nt_acl_common(struct connection_struct *conn,
                        /* The User must have access to a profile share - even
                         * if we can't map the SID. */
                        if (lp_profile_acls(SNUM(conn))) {
-                               SEC_ACCESS acc;
-
-                               init_sec_access(&acc,FILE_GENERIC_ALL);
-                               init_sec_ace(&nt_ace_list[num_aces++],
-                                               &global_sid_Builtin_Users,
-                                               SEC_ACE_TYPE_ACCESS_ALLOWED,
-                                               acc, 0);
+                               add_or_replace_ace(nt_ace_list, &num_aces,
+                                                  &global_sid_Builtin_Users,
+                                                  SEC_ACE_TYPE_ACCESS_ALLOWED,
+                                                  FILE_GENERIC_ALL, 0);
                        }
 
                        for (ace = dir_ace; ace != NULL; ace = ace->next) {
@@ -3007,12 +3041,13 @@ static NTSTATUS posix_get_nt_acl_common(struct connection_struct *conn,
                        /* The User must have access to a profile share - even
                         * if we can't map the SID. */
                        if (lp_profile_acls(SNUM(conn))) {
-                               SEC_ACCESS acc;
-
-                               init_sec_access(&acc,FILE_GENERIC_ALL);
-                               init_sec_ace(&nt_ace_list[num_aces++], &global_sid_Builtin_Users, SEC_ACE_TYPE_ACCESS_ALLOWED, acc,
-                                               SEC_ACE_FLAG_OBJECT_INHERIT|SEC_ACE_FLAG_CONTAINER_INHERIT|
-                                               SEC_ACE_FLAG_INHERIT_ONLY|0);
+                               add_or_replace_ace(nt_ace_list, &num_aces,
+                                               &global_sid_Builtin_Users,
+                                               SEC_ACE_TYPE_ACCESS_ALLOWED,
+                                               FILE_GENERIC_ALL,
+                                               SEC_ACE_FLAG_OBJECT_INHERIT |
+                                               SEC_ACE_FLAG_CONTAINER_INHERIT |
+                                               SEC_ACE_FLAG_INHERIT_ONLY);
                        }
 
                        /*