[SSSD] [sssd][patch] SYSDB: sysdb_getnetgr returns ENOENT

Lukas Slebodnik lslebodn at redhat.com
Wed Jun 25 13:45:01 UTC 2014


On (24/06/14 17:28), Pavel Reichl wrote:
>On Tue, 2014-06-24 at 16:18 +0200, Lukas Slebodnik wrote:
>> On (24/06/14 13:33), Pavel Reichl wrote:
>> >On Mon, 2014-06-23 at 13:50 +0200, Jakub Hrozek wrote:
>> >> On Thu, Jun 19, 2014 at 05:53:37PM +0200, Pavel Reichl wrote:
>> >> > From 6e2af6d696fd0e731467c50dbb715756a4bcb0a3 Mon Sep 17 00:00:00 2001
>> >> > From: Pavel Reichl <preichl at redhat.com>
>> >> > Date: Tue, 27 May 2014 19:11:20 +0100
>> >> > Subject: [PATCH 1/4] SYSDB: sss_ldb_search - wrapper around ldb_search
>> >> > 
>> >> > Make sure that if no results were found ENOENT is returned rather than just
>> >> > empty list of results.
>> >> > 
>> >> > Resolves:
>> >> > https://fedorahosted.org/sssd/ticket/1991
>> >> > ---
>> >> >  src/db/sysdb.h     |  5 +++++
>> >> >  src/db/sysdb_ops.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
>> >> >  2 files changed, 52 insertions(+)
>> >> > 
>> >> > diff --git a/src/db/sysdb.h b/src/db/sysdb.h
>> >> > index dd14190bfa156c6b2842e2af81d7b58efa3ea06f..634df049421586959531d8d1a365a2d50d15d1a6 100644
>> >> > --- a/src/db/sysdb.h
>> >> > +++ b/src/db/sysdb.h
>> >> > @@ -480,6 +480,11 @@ int sysdb_get_netgroup_attr(TALLOC_CTX *mem_ctx,
>> >> >                              const char **attributes,
>> >> >                              struct ldb_result **res);
>> >> >  
>> >> > +errno_t sss_ldb_search(struct ldb_context *ldb, TALLOC_CTX *mem_ctx,
>> >> > +                       struct ldb_result **_result, struct ldb_dn *base,
>> >> > +                       enum ldb_scope scope, const char * const *attrs,
>> >> > +                       const char *exp_fmt, ...);
>> >> 
>> >> You need to use SSS_ATTRIBUTE_PRINTF here.
>> >
>> >OK, but it didn't like "" being passed as fmt causing:
>> >-Werror=format-zero-length. 
>> >
>> >To avoid this warning, NULL is passed instead of "". sss_ldb_search now
>> >handles explicitly case when fmt is NULL because no filter processing is
>> >required then.
>> >
>> And null caused warning in static analysers :-)
>> 
>> Error: PW.NON_CONST_PRINTF_FORMAT_STRING:
>> sssd-1.11.92/src/db/sysdb_ops.c:109: non_const_printf_format_string: format string is not a string literal, potential security vulnerability if user controlled
>> sssd-1.11.92/src/db/sysdb_ops.c:109: caretline:
>> 
>> I prefer to avoid compiler warnings. It will be better to use NULL.
>
>(lret = ldb_search(ldb, mem_ctx, _result, base, scope, attrs, NULL);)
>
>It's a common practice in SSSD anyway.
>
>> 
>> 
>> 
>> >From: Pavel Reichl <preichl at redhat.com>
>> >Date: Tue, 27 May 2014 19:11:20 +0100
>> >Subject: [PATCH 1/5] SYSDB: sss_ldb_search - wrapper around ldb_search
>> >
>> >Make sure that if no results were found ENOENT is returned rather than just
>> >empty list of results.
>> >
>> >Resolves:
>> >https://fedorahosted.org/sssd/ticket/1991
>> >---
>> > src/db/sysdb.h     |  5 +++++
>> > src/db/sysdb_ops.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
>> > 2 files changed, 55 insertions(+)
>> >
>> >diff --git a/src/db/sysdb.h b/src/db/sysdb.h
>> >index 911430eefcbf520ca04f123a3b6f1882dc25876b..17cd5110c9bdafd8d7b18e621188523ed41e5c8a 100644
>> >--- a/src/db/sysdb.h
>> >+++ b/src/db/sysdb.h
>> >@@ -481,6 +481,11 @@ int sysdb_get_netgroup_attr(TALLOC_CTX *mem_ctx,
>> >                             const char **attributes,
>> >                             struct ldb_result **res);
>> > 
>> >+errno_t sss_ldb_search(struct ldb_context *ldb, TALLOC_CTX *mem_ctx,
>> >+                       struct ldb_result **_result, struct ldb_dn *base,
>> >+                       enum ldb_scope scope, const char * const *attrs,
>> >+                       const char *exp_fmt, ...) SSS_ATTRIBUTE_PRINTF(7, 8);
>> >+
>> > /* functions that modify the databse
>> >  * they have to be called within a transaction
>> >  * See sysdb_transaction_send()/_recv() */
>> >diff --git a/src/db/sysdb_ops.c b/src/db/sysdb_ops.c
>> >index 4d31cb6a0e83370a2c49a666f9474d93baf430b0..25fccc5fdacd85416268e02632826fd87174e7f7 100644
>> >--- a/src/db/sysdb_ops.c
>> >+++ b/src/db/sysdb_ops.c
>> >@@ -74,6 +74,56 @@ static uint32_t get_attr_as_uint32(struct ldb_message *msg, const char *attr)
>> >     return l;
>> > }
>> > 
>> >+
>> >+/* Wrapper around ldb_search to ensure that if zero results are found then
>> >+ * ENOENT is returned
>> >+ */
>> >+errno_t sss_ldb_search(struct ldb_context *ldb, TALLOC_CTX *mem_ctx,
>> >+                       struct ldb_result **_result, struct ldb_dn *base,
>> >+                       enum ldb_scope scope, const char * const *attrs,
>> >+                       const char *exp_fmt, ...)
>> >+{
>> >+    char *s;
>> >+    int lret;
>> >+    va_list ap;
>> >+    errno_t ret;
>> >+    TALLOC_CTX *tmp_ctx = NULL;
>> >+
>> >+    if (exp_fmt != NULL) {
>> >+        tmp_ctx = talloc_new(NULL);
>> >+        if (tmp_ctx == NULL) {
>> >+            ret = ENOMEM;
>> >+            goto done;
>> >+        }
>> >+
>> >+        va_start(ap, exp_fmt);
>> >+        s = talloc_vasprintf(tmp_ctx, exp_fmt, ap);
>> >+        if (s == NULL) {
>> >+            DEBUG(SSSDBG_MINOR_FAILURE, "Failed to process filter.\n");
>> >+            ret = ENOMEM;
>> >+            goto done;
>> va_end is not called in this case.
>> It will be better to move va_end before if condition.
>Yep, I missed that sorry. Fixed in attached patch set.
>
Thank you.

>> 
>> >+        }
>> >+        va_end(ap);
>> >+        lret = ldb_search(ldb, mem_ctx, _result, base, scope, attrs, "%s", s);
>> >+    } else {
>> >+        lret = ldb_search(ldb, mem_ctx, _result, base, scope, attrs, NULL);
>> >+    }
>> >+
>> >+    ret = sysdb_error_to_errno(lret);
>> >+    if (ret != EOK) {
>> >+        goto done;
>> >+    }
>> >+
>> >+    if ((*_result)->count == 0) {
>> >+        ret = ENOENT;
>> >+        goto done;
>> >+    }
>> >+
>> >+done:
>> >+    talloc_free(tmp_ctx);
>> >+    return ret;
>> >+}
>> >+
>> > /*
>> >  * The wrapper around ldb_modify that uses LDB_CONTROL_PERMISSIVE_MODIFY_OID
>> >  * so that on adds entries that already exist are skipped and similarly
>> >-- 
>> >1.8.4.2
>> >
>> 
>> >From 7954ad8ee3310d7e7bc9ac12c3b764786c052a4d Mon Sep 17 00:00:00 2001
>> >From: Pavel Reichl <preichl at redhat.com>
>> >Date: Wed, 26 Feb 2014 16:52:26 +0000
>> >Subject: [PATCH 3/5] SYSDB: sysdb_getnetgr returns ENOENT
>> >
>> >Replace call of ldb_search by sss_ldb_search to make sure that ENOENT is
>> >returned if no results were found.
>> >
>> >Resolves:
>> >https://fedorahosted.org/sssd/ticket/1991
>> >---
>> > src/db/sysdb_search.c | 20 ++++++++------------
>> > 1 file changed, 8 insertions(+), 12 deletions(-)
>> >
>> >diff --git a/src/db/sysdb_search.c b/src/db/sysdb_search.c
>> >index 60ad61368d92d12bca3833bc08b0673c581ab882..608277ab34c3280659cb2cf04ea57721bd9790f5 100644
>> >--- a/src/db/sysdb_search.c
>> >+++ b/src/db/sysdb_search.c
>> >@@ -786,7 +786,6 @@ errno_t sysdb_getnetgr(TALLOC_CTX *mem_ctx,
>> >     char *sanitized_netgroup;
>> >     char *lc_sanitized_netgroup;
>> >     char *netgroup_dn;
>> >-    int lret;
>> >     errno_t ret;
>> > 
>> >     tmp_ctx = talloc_new(NULL);
>> >@@ -816,18 +815,15 @@ errno_t sysdb_getnetgr(TALLOC_CTX *mem_ctx,
>> >         goto done;
>> >     }
>> > 
>> >-    lret = ldb_search(domain->sysdb->ldb, tmp_ctx, &result, base_dn,
>> >-                     LDB_SCOPE_SUBTREE, attrs,
>> >-                     SYSDB_NETGR_TRIPLES_FILTER, lc_sanitized_netgroup,
>> >-                     sanitized_netgroup, sanitized_netgroup,
>> >-                     netgroup_dn);
>> >-    ret = sysdb_error_to_errno(lret);
>> >-    if (ret != EOK) {
>> >-        goto done;
>> >-    }
>> >+    ret = sss_ldb_search(domain->sysdb->ldb, tmp_ctx, &result, base_dn,
>> >+                         LDB_SCOPE_SUBTREE, attrs,
>> >+                         SYSDB_NETGR_TRIPLES_FILTER, lc_sanitized_netgroup,
>> >+                         sanitized_netgroup, sanitized_netgroup,
>> >+                         netgroup_dn);
>> > 
>> >-    *res = talloc_steal(mem_ctx, result);
>> >-    ret = EOK;
>> >+    if (ret == EOK || ret == ENOENT) {
>> >+        *res = talloc_steal(mem_ctx, result);
>> There is a warning from coverity
>> Error: UNINIT (CWE-457):
>> sssd-1.11.92/src/db/sysdb_search.c:785: var_decl: Declaring variable "result" without initializer.
>> sssd-1.11.92/src/db/sysdb_search.c:825: uninit_use_in_call: Using uninitialized value "result" when calling "_talloc_steal_loc".
>> 
>> I think it is false positive.
>So do I. But I wonder if initiating result to NULL would make coverity
>to be quiet. (done in attached patch).
>
Yes. it is.
I hope we did not hide any real problem and it was false positive.

>>
>> >+    }
>> > 
>> > done:
>> >     talloc_zfree(tmp_ctx);
>> >-- 
>> >1.8.4.2
>> >
>> 
>> >From 94a3501fa6d0f238c889e2e05858c0a42579815d Mon Sep 17 00:00:00 2001
>> >From: Pavel Reichl <preichl at redhat.com>
>> >Date: Thu, 19 Jun 2014 16:18:12 +0100
>> >Subject: [PATCH 4/5] TESTS: sysdb_getnetgr - return ENOENT
>> >
>> >Resolves:
>> >https://fedorahosted.org/sssd/ticket/1991
>> >---
>> BTW 3rd and 4th patch are small.
>> 
>> I am used to sending a fix and an unit test in single patch. Small benefit is
>> that we don't forgot to backport a test. I don't have strong preferences.
>> I just want to start discussion what should be prefered way
>>     a) to send a fix and an unit test in two patches
>>     b) to send a fix and an unit test in single patch
>> (of course there can be exceptions :-)
>I don't have strong preferences either as I'm not paid per commit so far.
>
>I agree with your statement about 'forgetting to back-port'. On the
>other hand I believe that patch should do just one thing and one thing
>only. Either to fix the bug or introduce a test.
>
>Direct advantage of separate patches is possibility to run test before
>applying patch with bug fix and then to see if it really fixes the
>issue.
>
We can leave these patches as are continue with discussion in different part of
this thread.

>
>
>> >From 44c4d576c840c01bade8f7f7aa6c980793d79505 Mon Sep 17 00:00:00 2001
>> >From: Pavel Reichl <preichl at redhat.com>
>> >Date: Tue, 24 Jun 2014 09:47:09 +0100
>> >Subject: [PATCH 5/5] NSS: lookup_netgr_step don't access result on ENOENT
>> >
>> >Don't access result if return value is not EOK.
>> >---
>> > src/responder/nss/nsssrv_netgroup.c | 45 +++++++++++++++++++------------------
>> > 1 file changed, 23 insertions(+), 22 deletions(-)
>> >
>> >diff --git a/src/responder/nss/nsssrv_netgroup.c b/src/responder/nss/nsssrv_netgroup.c
>> >index 1c9b72ae30c6ef1115d1ed972a12dc554db04bbe..d60f72a743157066dffca86493dfebf40bb451f6 100644
>> >--- a/src/responder/nss/nsssrv_netgroup.c
>> >+++ b/src/responder/nss/nsssrv_netgroup.c
>> >@@ -514,30 +514,31 @@ static errno_t lookup_netgr_step(struct setent_step_ctx *step_ctx)
>> > 
>> >         /* Look up the netgroup in the cache */
>> >         ret = sysdb_getnetgr(step_ctx->dctx, dom, name, &step_ctx->dctx->res);
>> >-        if (ret == ENOENT) {
>> >-            /* This netgroup was not found in this domain */
>> >-            if (!step_ctx->dctx->check_provider) {
>> >-                if (step_ctx->check_next) {
>> >-                    dom = get_next_domain(dom, false);
>> >-                    continue;
>> >+        if (ret == EOK) {
>> >+            if (step_ctx->dctx->res->count > 1) {
>> >+                DEBUG(SSSDBG_FATAL_FAILURE,
>> >+                      "getnetgr call returned more than one result !?!\n");
>> >+                ret = EMSGSIZE;
>> >+                goto done;
>> >+            }
>> >+        } else {
>> >+            if (ret == ENOENT) {
>> >+                /* This netgroup was not found in this domain */
>> >+                if (!step_ctx->dctx->check_provider) {
>> >+                    if (step_ctx->check_next) {
>> >+                        dom = get_next_domain(dom, false);
>> >+                        continue;
>> >+                    } else {
>> >+                        break;
>> >+                    }
>> >                 }
>> >-                else break;
>> >+                ret = EOK;
>>                   warning: Value stored to 'ret' is never read
>> I think conditionc could be more flatten
>> if (ret == EOK) {
>> ...
>> } else if (ret == ENOENT) {
>> ...
>> } else {
>> ...
>> }
>OK.
>
It loks better now.

>From 78eb31fd7be6ef8b2485f7058a31557a0a1758b6 Mon Sep 17 00:00:00 2001
>From: Pavel Reichl <preichl at redhat.com>
>Date: Tue, 27 May 2014 19:11:20 +0100
>Subject: [PATCH 1/5] SYSDB: sss_ldb_search - wrapper around ldb_search
>
>Make sure that if no results were found ENOENT is returned rather than just
>empty list of results.
>
>Resolves:
>https://fedorahosted.org/sssd/ticket/1991
>---
ACK

>From e1b6545759bef0c6e97831c969a331c3fff54c1d Mon Sep 17 00:00:00 2001
>From: Pavel Reichl <preichl at redhat.com>
>Date: Thu, 19 Jun 2014 15:38:59 +0100
>Subject: [PATCH 2/5] TESTS: add tests for sss_ldb_search
>
>Resolves:
>https://fedorahosted.org/sssd/ticket/1991
>---
ACK

>From 11fcecadf767a3ecb24492d314274860d8fefba2 Mon Sep 17 00:00:00 2001
>From: Pavel Reichl <preichl at redhat.com>
>Date: Wed, 26 Feb 2014 16:52:26 +0000
>Subject: [PATCH 3/5] SYSDB: sysdb_getnetgr returns ENOENT
>
>Replace call of ldb_search by sss_ldb_search to make sure that ENOENT is
>returned if no results were found.
>
>Resolves:
>https://fedorahosted.org/sssd/ticket/1991
>---
ACK

>-    lret = ldb_search(domain->sysdb->ldb, tmp_ctx, &result, base_dn,
>-                     LDB_SCOPE_SUBTREE, attrs,
>-                     SYSDB_NETGR_TRIPLES_FILTER, lc_sanitized_netgroup,
>-                     sanitized_netgroup, sanitized_netgroup,
>-                     netgroup_dn);
>-    ret = sysdb_error_to_errno(lret);
>-    if (ret != EOK) {
>-        goto done;
>-    }
>+    ret = sss_ldb_search(domain->sysdb->ldb, tmp_ctx, &result, base_dn,
>+                         LDB_SCOPE_SUBTREE, attrs,
>+                         SYSDB_NETGR_TRIPLES_FILTER, lc_sanitized_netgroup,
>+                         sanitized_netgroup, sanitized_netgroup,
>+                         netgroup_dn);
> 
>-    *res = talloc_steal(mem_ctx, result);
>-    ret = EOK;
>+    if (ret == EOK || ret == ENOENT) {
>+        *res = talloc_steal(mem_ctx, result);
Please file a ticket. It should be blocked by #1991.
We should not use result in case of ret != 0. ENOENT should not be exception.

>From 79bf514e4d528d4c41d82c4e0398db4244350262 Mon Sep 17 00:00:00 2001
>From: Pavel Reichl <preichl at redhat.com>
>Date: Thu, 19 Jun 2014 16:18:12 +0100
>Subject: [PATCH 4/5] TESTS: sysdb_getnetgr - return ENOENT
>
>Resolves:
>https://fedorahosted.org/sssd/ticket/1991
>---
ACK

>From eb08103aae3f81e11e60bd9843627043c6427a60 Mon Sep 17 00:00:00 2001
>From: Pavel Reichl <preichl at redhat.com>
>Date: Tue, 24 Jun 2014 09:47:09 +0100
>Subject: [PATCH 5/5] NSS: lookup_netgr_step don't access result on ENOENT
>
>Don't access result if return value is not EOK.
>---
ACK

LS



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