[SSSD] [PATCH] SYSDB: sysdb_search_object_by_sid returns ENOENT

Lukas Slebodnik lslebodn at redhat.com
Wed Dec 10 13:30:31 UTC 2014


On (10/12/14 11:31), Pavel Reichl wrote:
>
>On 12/10/2014 10:25 AM, Lukas Slebodnik wrote:
>>On (10/12/14 10:09), Pavel Reichl wrote:
>>>On 12/10/2014 09:28 AM, Lukas Slebodnik wrote:
>>>>On (09/12/14 12:13), Pavel Reichl wrote:
>>>>>On 12/02/2014 12:50 PM, Lukas Slebodnik wrote:
>>>>>>On (29/10/14 17:17), Pavel Reichl wrote:
>>>>>>>Hello,
>>>>>>>
>>>>>>>please see attached patch.
>>>>>>>
>>>>>>>This patch is part of solution for
>>>>>>>https://fedorahosted.org/sssd/ticket/1991
>>>>>>>which aims to unify return values of sysdb calls in case no results are
>>>>>>>found.
>>>>>>>
>>>>>>a) this patch cannot be applied on current master.
>>>>>rebased
>>>>>>b) I wrote similar patch becuse sssd_be crashed in function
>>>>>>     get_object_from_cache. sysdb_search_object_by_sid didn' returned ENOENT and
>>>>>>     res->msgs was NULL (result: dereference of NULL pointer)
>>>>>>     -- it is yet another result of broken IPA <-> AD trust
>>>>>>c) Could you compare your version and mine?
>>>>>>     Feel free to include my patch to yours if it is not good enogh.
>>>>>I don't say it was not good enough but I updated my patch.
>>>>>>d) test test_sysdb_delete_by_sid seems to be unrelated to this patch.
>>>>>>    I would prefer to have it in separete patch.
>>>>>I have moved it to separate patch. This patch is just to verify that
>>>>>sysdb_delete_by_sid() was not changed by the second patch.
>>>>>>LS
>>>>>>
>>>>>Thanks, please see updated patches.
>>>>>From 53c3be375eff41dc70e17bb9e079ec98b8c2c5e7 Mon Sep 17 00:00:00 2001
>>>>>From: Pavel Reichl <preichl at redhat.com>
>>>>>Date: Tue, 9 Dec 2014 09:47:11 +0000
>>>>>Subject: [PATCH 1/2] TESTS: sysdb_delete_by_sid() test return value
>>>>>
>>>>>Check that return value of sysdb_delete_by_sid() is not changed as
>>>>>called SYSDB functions have changed the return value.
>>>>>
>>>>>Part of patches for:
>>>>>https://fedorahosted.org/sssd/ticket/1991
>>>>>---
>>>>LGTM
>>>>
>>>>>From 1cb395244d3ab3906af5b6c8b294e80055ad0a07 Mon Sep 17 00:00:00 2001
>>>>>From: Pavel Reichl <preichl at redhat.com>
>>>>>Date: Tue, 9 Dec 2014 11:01:13 +0000
>>>>>Subject: [PATCH 2/2] SYSDB: sysdb_search_object_by_sid returns ENOENT
>>>>>
>>>>>sysdb_search_object_by_sid returns ENOENT if no results are found.
>>>>>
>>>>>Part od solution for:
>>>>>https://fedorahosted.org/sssd/ticket/1991
>>>>>---
>>>>>src/db/sysdb.h                 |  2 +-
>>>>>src/db/sysdb_ops.c             | 70 ++++++------------------------------------
>>>>>src/responder/nss/nsssrv_cmd.c | 27 ++++++++--------
>>>>>src/responder/pac/pacsrv_cmd.c | 26 ++++++++++------
>>>>>src/tests/sysdb-tests.c        |  5 +--
>>>>>5 files changed, 42 insertions(+), 88 deletions(-)
>>>>>
>>>>>diff --git a/src/db/sysdb.h b/src/db/sysdb.h
>>>>>index 5bd7f90acb685bbaff5c98f433c7dce8175c33ca..9b88b4a63619456f8f3cc1961e29bbf3946ca5b8 100644
>>>>>--- a/src/db/sysdb.h
>>>>>+++ b/src/db/sysdb.h
>>>>>@@ -1033,7 +1033,7 @@ errno_t sysdb_search_object_by_sid(TALLOC_CTX *mem_ctx,
>>>>>                                    struct sss_domain_info *domain,
>>>>>                                    const char *sid_str,
>>>>>                                    const char **attrs,
>>>>>-                                   struct ldb_result **msg);
>>>>>+                                   struct ldb_result **res);
>>>>>
>>>>>errno_t sysdb_search_object_by_uuid(TALLOC_CTX *mem_ctx,
>>>>>                                     struct sss_domain_info *domain,
>>>>>diff --git a/src/db/sysdb_ops.c b/src/db/sysdb_ops.c
>>>>>index 998046a2ca1c746b2032f430e5f9c4a7151e1dbc..8d6b11c248fd7f895ff6a95c25d4372fc7f8445d 100644
>>>>>--- a/src/db/sysdb_ops.c
>>>>>+++ b/src/db/sysdb_ops.c
>>>>>@@ -2995,8 +2995,15 @@ int sysdb_delete_by_sid(struct sysdb_ctx *sysdb,
>>>>>
>>>>>     ret = sysdb_search_object_by_sid(tmp_ctx, domain, sid_str, NULL, &res);
>>>>>     if (ret != EOK) {
>>>>>-        DEBUG(SSSDBG_OP_FAILURE, "search by sid failed: %d (%s)\n",
>>>>>-              ret, strerror(ret));
>>>>>+        if (ret == ENOENT) {
>>>>>+            /* No existing entry. Just quit. */
>>>>>+            DEBUG(SSSDBG_TRACE_FUNC,
>>>>>+                  "search by sid did not return any results.\n");
>>>>>+            ret = EOK;
>>>>>+        } else {
>>>>>+            DEBUG(SSSDBG_OP_FAILURE, "search by sid failed: %d (%s)\n",
>>>>>+                  ret, strerror(ret));
>>>>>+        }
>>>>>         goto done;
>>>>I'm sorry but this isn't very readable.
>>>>I prefer flat version.
>>>>If/else if/else is easier to read and if you want to do micro optimisation
>>>>then you can use switch case.
>>>I find it better readable this way - errors are handled in single block. It's
>>>not against any code style rules I'm aware of. But I suppose if this is the
>>>only way to get the patches pushed I'll do it your preferred way...
>>The problem is that I need to spend a lot of time with "parsing this code"
>>Someone can overlook goto done in this case and introduce a bug.
>>Your solution isn't bad but it isn't straightforward.
>>
>>This is especially problem in pac responder.
>>There are 3 nested levels of if. WHY?
>>I'm sorry but I can lost easily there.
>>
>>      ret = sysdb_search_object_by_sid(cmdctx, dom, cmdctx->secid, NULL,
>>                                       &dctx->res);
>>      if (ret != EOK) {
>>         if (ret == ENOENT) {
>>             if (!dctx->check_provider) {
>>                 DEBUG(SSSDBG_OP_FAILURE, "No results for getbysid call.\n");
>>
>>                 /* set negative cache only if not result of cache check */
>>                 ret = sss_ncache_set_sid(nctx->ncache, false, cmdctx->secid);
>>                 if (ret != EOK) {
>>                     DEBUG(SSSDBG_MINOR_FAILURE,
>>                           "Cannot set negative cache for %s\n", cmdctx->secid);
>>                 }
>>             }
>>             return ENOENT;
>>         }
>>         DEBUG(SSSDBG_CRIT_FAILURE, "Failed to make request to our cache!\n");
>>         return EIO;
>>     }
>>
>>//snip
>>
>>>>>@@ -912,9 +913,14 @@ pac_store_membership(struct pac_req_ctx *pr_ctx,
>>>>>     ret = sysdb_search_object_by_sid(tmp_ctx, grp_dom, grp_sid_str,
>>>>>                                      group_attrs, &group);
>>>>>     if (ret != EOK) {
>>>>>-        DEBUG(SSSDBG_TRACE_INTERNAL, "sysdb_search_object_by_sid " \
>>>>>-                                      "for SID [%s] failed [%d][%s].\n",
>>>>>-                                      grp_sid_str, ret, strerror(ret));
>>>>>+        if (ret == ENOENT) {
>>>>>+            DEBUG(SSSDBG_OP_FAILURE, "Unexpected number of groups returned.\n");
>>>>>+            ret = EINVAL;
>>                 ^^^^^^^^^^^^^
>>             I found another interesting part.
>>Why do you override ENOENT with EINVAL. ENOENT (msg->count == 0) was not
>>special cased before your change.
>Please again see context:
>Before changing sysdb_search_object_by_sid() to return ENOENT on no result
>EOK was returned and condition '(group->count != 1)' was true in that case.
>So I just kept this behaviour. Is that clear now?
Ahh I see. I overlook != 1 I was looking for  == 0.

but still it would be better to return ENOENT. So we can distinguish between
group->count == 0 and group->count > 1. It should not happen very.

LS



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