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replmd: RMD_VERSION incorrectly incremented for link conflicts

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This problem was noticed when 2 DCs added the same linked attribute at
roughly the same time. One DC would have a later timestamp than the
other, so it would re-apply the same link information. However, when it
did this, replmd_update_la_val() would incorrectly increment the
RMD_VERSION for the attribute. We then end up with one DC having a
higher RMD_VERSION than the others (and it doesn't replicate the new
RMD_VERSION out).

During replication RMD_VERSION is used to determine whether a linked
attribute is old (and should be ignored), or whether the information is
new and should be applied to the DB. This RMD_VERSION discrepancy could
potentially cause a subsequent linked attribute update to be ignored.

Normally when a local DB operation is performed, we just pass in a
version of zero and get replmd_update_la_val() to increment what's
already in the DB. However, we *never* want this to happen during
replication - we should always use the version we receive from the peer
DC.

This patch fixes the problem by separating the API into two:
- replmd_update_la_val(): we're updating a linked attribute in the DB,
  and so as part of this operation we always want to increment the
  version number (the version no longer need to be passed in because
  we can work it out from the existing DB entry).
- replmd_set_la_val(): we want to set a linked attribute to use the
  exact values we're telling it, including the version. This is what
  replication needs to use.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13038
Signed-off-by: Tim Beale <timbeale@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>

Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Tue Sep 26 09:36:48 CEST 2017 on sn-devel-144
This commit is contained in:
Tim Beale 2017-09-14 16:34:59 +12:00 committed by Andrew Bartlett
parent 5f93ac1f6f
commit 0d4c3e5e3f
2 changed files with 45 additions and 29 deletions
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5
selftest/knownfail.d/link_conflicts
View File

@ -1,9 +1,4 @@
# Currently Samba can't resolve a conflict for a single-valued link attribute
samba4.drs.link_conflicts.python\(vampire_dc\).link_conflicts.DrsReplicaLinkConflictTestCase.test_conflict_single_valued_link\(vampire_dc\)
samba4.drs.link_conflicts.python\(promoted_dc\).link_conflicts.DrsReplicaLinkConflictTestCase.test_conflict_single_valued_link\(promoted_dc\)
# There's a bug where Samba can incorrectly increment the attribute's version number
samba4.drs.link_conflicts.python\(vampire_dc\).link_conflicts.DrsReplicaLinkConflictTestCase.test_link_deletion_conflict\(vampire_dc\)
samba4.drs.link_conflicts.python\(promoted_dc\).link_conflicts.DrsReplicaLinkConflictTestCase.test_link_deletion_conflict\(promoted_dc\)
samba4.drs.link_conflicts.python\(vampire_dc\).link_conflicts.DrsReplicaLinkConflictTestCase.test_full_sync_link_conflict\(vampire_dc\)
samba4.drs.link_conflicts.python\(promoted_dc\).link_conflicts.DrsReplicaLinkConflictTestCase.test_full_sync_link_conflict\(promoted_dc\)

69
source4/dsdb/samdb/ldb_modules/repl_meta_data.c
View File

@ -2214,7 +2214,7 @@ static int replmd_build_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct ds
static int replmd_update_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct dsdb_dn *dsdb_dn,
struct dsdb_dn *old_dsdb_dn, const struct GUID *invocation_id,
uint64_t seq_num, uint64_t local_usn, NTTIME nttime,
uint32_t version, bool deleted);
bool deleted);
/*
check if any links need upgrading from w2k format
@ -2268,7 +2268,7 @@ static int replmd_check_upgrade_links(struct ldb_context *ldb,
/* it's an old one that needs upgrading */
ret = replmd_update_la_val(el->values, dns[i].v,
dns[i].dsdb_dn, dns[i].dsdb_dn,
invocation_id, 1, 1, 0, 0, false);
invocation_id, 1, 1, 0, false);
if (ret != LDB_SUCCESS) {
return ret;
}
@ -2290,14 +2290,14 @@ static int replmd_check_upgrade_links(struct ldb_context *ldb,
}
/*
update an extended DN, including all meta data fields
Sets the value for a linked attribute, including all meta data fields
see replmd_build_la_val for value names
*/
static int replmd_update_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct dsdb_dn *dsdb_dn,
struct dsdb_dn *old_dsdb_dn, const struct GUID *invocation_id,
uint64_t usn, uint64_t local_usn, NTTIME nttime,
uint32_t version, bool deleted)
static int replmd_set_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct dsdb_dn *dsdb_dn,
struct dsdb_dn *old_dsdb_dn, const struct GUID *invocation_id,
uint64_t usn, uint64_t local_usn, NTTIME nttime,
uint32_t version, bool deleted)
{
struct ldb_dn *dn = dsdb_dn->dn;
const char *tstring, *usn_string, *flags_string;
@ -2306,7 +2306,6 @@ static int replmd_update_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct d
struct ldb_val usnv, local_usnv;
struct ldb_val vers, flagsv;
const struct ldb_val *old_addtime;
uint32_t old_version;
NTSTATUS status;
int ret;
const char *dnstring;
@ -2371,11 +2370,6 @@ static int replmd_update_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct d
ret = ldb_dn_set_extended_component(dn, "RMD_LOCAL_USN", &local_usnv);
if (ret != LDB_SUCCESS) return ret;
/* increase the version by 1 */
status = dsdb_get_extended_dn_uint32(old_dsdb_dn->dn, &old_version, "RMD_VERSION");
if (NT_STATUS_IS_OK(status) && old_version >= version) {
version = old_version+1;
}
vstring = talloc_asprintf(dn, "%lu", (unsigned long)version);
vers = data_blob_string_const(vstring);
ret = ldb_dn_set_extended_component(dn, "RMD_VERSION", &vers);
@ -2390,6 +2384,33 @@ static int replmd_update_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct d
return LDB_SUCCESS;
}
/**
* Updates the value for a linked attribute, including all meta data fields
*/
static int replmd_update_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct dsdb_dn *dsdb_dn,
struct dsdb_dn *old_dsdb_dn, const struct GUID *invocation_id,
uint64_t usn, uint64_t local_usn, NTTIME nttime,
bool deleted)
{
uint32_t old_version;
uint32_t version = 0;
NTSTATUS status;
/*
* We're updating the linked attribute locally, so increase the version
* by 1 so that other DCs will see the change when it gets replicated out
*/
status = dsdb_get_extended_dn_uint32(old_dsdb_dn->dn, &old_version,
"RMD_VERSION");
if (NT_STATUS_IS_OK(status)) {
version = old_version + 1;
}
return replmd_set_la_val(mem_ctx, v, dsdb_dn, old_dsdb_dn, invocation_id,
usn, local_usn, nttime, version, deleted);
}
/*
handle adding a linked attribute
*/
@ -2520,7 +2541,7 @@ static int replmd_modify_la_add(struct ldb_module *module,
dns[i].dsdb_dn,
exact->dsdb_dn,
invocation_id, seq_num,
seq_num, now, 0, false);
seq_num, now, false);
if (ret != LDB_SUCCESS) {
talloc_free(tmp_ctx);
return ret;
@ -2727,7 +2748,7 @@ static int replmd_modify_la_delete(struct ldb_module *module,
ret = replmd_update_la_val(old_el->values, p->v,
p->dsdb_dn, p->dsdb_dn,
invocation_id, seq_num,
seq_num, now, 0, true);
seq_num, now, true);
if (ret != LDB_SUCCESS) {
talloc_free(tmp_ctx);
return ret;
@ -2824,7 +2845,7 @@ static int replmd_modify_la_delete(struct ldb_module *module,
ret = replmd_update_la_val(old_el->values, exact->v,
exact->dsdb_dn, exact->dsdb_dn,
invocation_id, seq_num, seq_num,
now, 0, true);
now, true);
if (ret != LDB_SUCCESS) {
talloc_free(tmp_ctx);
return ret;
@ -2993,7 +3014,7 @@ static int replmd_modify_la_replace(struct ldb_module *module,
old_p->dsdb_dn,
invocation_id,
seq_num, seq_num,
now, 0, true);
now, true);
if (ret != LDB_SUCCESS) {
talloc_free(tmp_ctx);
return ret;
@ -3027,7 +3048,7 @@ static int replmd_modify_la_replace(struct ldb_module *module,
old_p->dsdb_dn,
invocation_id,
seq_num, seq_num,
now, 0, false);
now, false);
if (ret != LDB_SUCCESS) {
talloc_free(tmp_ctx);
return ret;
@ -7270,12 +7291,12 @@ static int replmd_process_linked_attribute(struct ldb_module *module,
}
}
ret = replmd_update_la_val(tmp_ctx, pdn->v, dsdb_dn, pdn->dsdb_dn,
&la->meta_data.originating_invocation_id,
la->meta_data.originating_usn, seq_num,
la->meta_data.originating_change_time,
la->meta_data.version,
!active);
ret = replmd_set_la_val(tmp_ctx, pdn->v, dsdb_dn, pdn->dsdb_dn,
&la->meta_data.originating_invocation_id,
la->meta_data.originating_usn, seq_num,
la->meta_data.originating_change_time,
la->meta_data.version,
!active);
if (ret != LDB_SUCCESS) {
talloc_free(tmp_ctx);
return ret;