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Remove PushOverrideSearchPath() and PopOverrideSearchPath().

Browse Source 
Since commit 681d9e4621, they have no in-tree
calls.  Any new calls would introduce security vulnerabilities like the one
fixed in that commit.

Alexander Lakhin, reviewed by Aleksander Alekseev.

Discussion: https://postgr.es/m/8ffb4650-52c4-6a81-38fc-8f99be981130@gmail.com
This commit is contained in:
Noah Misch 2023-07-31 17:04:47 -07:00
parent c9af054653
commit 7c5c4e1c03
4 changed files with 6 additions and 235 deletions
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233
src/backend/catalog/namespace.c
View File

@ -67,9 +67,7 @@
* may be included:
*
* 1. If a TEMP table namespace has been initialized in this session, it
* is implicitly searched first. (The only time this doesn't happen is
* when we are obeying an override search path spec that says not to use the
* temp namespace, or the temp namespace is included in the explicit list.)
* is implicitly searched first.
*
* 2. The system catalog namespace is always searched. If the system
* namespace is present in the explicit path then it will be searched in
@ -108,19 +106,14 @@
* namespace (if it exists), preceded by the user's personal namespace
* (if one exists).
*
* We support a stack of "override" search path settings for use within
* specific sections of backend code. namespace_search_path is ignored
* whenever the override stack is nonempty. activeSearchPath is always
* the actually active path; it points either to the search list of the
* topmost stack entry, or to baseSearchPath which is the list derived
* from namespace_search_path.
* activeSearchPath is always the actually active path; it points to
* to baseSearchPath which is the list derived from namespace_search_path.
*
* If baseSearchPathValid is false, then baseSearchPath (and other
* derived variables) need to be recomputed from namespace_search_path.
* We mark it invalid upon an assignment to namespace_search_path or receipt
* of a syscache invalidation event for pg_namespace. The recomputation
* is done during the next non-overridden lookup attempt. Note that an
* override spec is never subject to recomputation.
* is done during the next lookup attempt.
*
* Any namespaces mentioned in namespace_search_path that are not readable
* by the current user ID are simply left out of baseSearchPath; so
@ -161,17 +154,6 @@ static Oid namespaceUser = InvalidOid;
/* The above four values are valid only if baseSearchPathValid */
static bool baseSearchPathValid = true;
/* Override requests are remembered in a stack of OverrideStackEntry structs */
typedef struct
{
List *searchPath; /* the desired search path */
Oid creationNamespace; /* the desired creation namespace */
int nestLevel; /* subtransaction nesting level */
} OverrideStackEntry;
static List *overrideStack = NIL;
/*
* myTempNamespace is InvalidOid until and unless a TEMP namespace is set up
* in a particular backend session (this happens when a CREATE TEMP TABLE
@ -3392,8 +3374,7 @@ SetTempNamespaceState(Oid tempNamespaceId, Oid tempToastNamespaceId)
/*
* GetOverrideSearchPath - fetch current search path definition in form
* used by PushOverrideSearchPath.
* GetOverrideSearchPath - fetch current search path definition.
*
* The result structure is allocated in the specified memory context
* (which might or might not be equal to CurrentMemoryContext); but any
@ -3512,132 +3493,6 @@ OverrideSearchPathMatchesCurrent(OverrideSearchPath *path)
return true;
}
/*
* PushOverrideSearchPath - temporarily override the search path
*
* Do not use this function; almost any usage introduces a security
* vulnerability. It exists for the benefit of legacy code running in
* non-security-sensitive environments.
*
* We allow nested overrides, hence the push/pop terminology. The GUC
* search_path variable is ignored while an override is active.
*
* It's possible that newpath->useTemp is set but there is no longer any
* active temp namespace, if the path was saved during a transaction that
* created a temp namespace and was later rolled back. In that case we just
* ignore useTemp. A plausible alternative would be to create a new temp
* namespace, but for existing callers that's not necessary because an empty
* temp namespace wouldn't affect their results anyway.
*
* It's also worth noting that other schemas listed in newpath might not
* exist anymore either. We don't worry about this because OIDs that match
* no existing namespace will simply not produce any hits during searches.
*/
void
PushOverrideSearchPath(OverrideSearchPath *newpath)
{
OverrideStackEntry *entry;
List *oidlist;
Oid firstNS;
MemoryContext oldcxt;
/*
* Copy the list for safekeeping, and insert implicitly-searched
* namespaces as needed. This code should track recomputeNamespacePath.
*/
oldcxt = MemoryContextSwitchTo(TopMemoryContext);
oidlist = list_copy(newpath->schemas);
/*
* Remember the first member of the explicit list.
*/
if (oidlist == NIL)
firstNS = InvalidOid;
else
firstNS = linitial_oid(oidlist);
/*
* Add any implicitly-searched namespaces to the list. Note these go on
* the front, not the back; also notice that we do not check USAGE
* permissions for these.
*/
if (newpath->addCatalog)
oidlist = lcons_oid(PG_CATALOG_NAMESPACE, oidlist);
if (newpath->addTemp && OidIsValid(myTempNamespace))
oidlist = lcons_oid(myTempNamespace, oidlist);
/*
* Build the new stack entry, then insert it at the head of the list.
*/
entry = (OverrideStackEntry *) palloc(sizeof(OverrideStackEntry));
entry->searchPath = oidlist;
entry->creationNamespace = firstNS;
entry->nestLevel = GetCurrentTransactionNestLevel();
overrideStack = lcons(entry, overrideStack);
/* And make it active. */
activeSearchPath = entry->searchPath;
activeCreationNamespace = entry->creationNamespace;
activeTempCreationPending = false; /* XXX is this OK? */
/*
* We always increment activePathGeneration when pushing/popping an
* override path. In current usage, these actions always change the
* effective path state, so there's no value in checking to see if it
* didn't change.
*/
activePathGeneration++;
MemoryContextSwitchTo(oldcxt);
}
/*
* PopOverrideSearchPath - undo a previous PushOverrideSearchPath
*
* Any push during a (sub)transaction will be popped automatically at abort.
* But it's caller error if a push isn't popped in normal control flow.
*/
void
PopOverrideSearchPath(void)
{
OverrideStackEntry *entry;
/* Sanity checks. */
if (overrideStack == NIL)
elog(ERROR, "bogus PopOverrideSearchPath call");
entry = (OverrideStackEntry *) linitial(overrideStack);
if (entry->nestLevel != GetCurrentTransactionNestLevel())
elog(ERROR, "bogus PopOverrideSearchPath call");
/* Pop the stack and free storage. */
overrideStack = list_delete_first(overrideStack);
list_free(entry->searchPath);
pfree(entry);
/* Activate the next level down. */
if (overrideStack)
{
entry = (OverrideStackEntry *) linitial(overrideStack);
activeSearchPath = entry->searchPath;
activeCreationNamespace = entry->creationNamespace;
activeTempCreationPending = false; /* XXX is this OK? */
}
else
{
/* If not baseSearchPathValid, this is useless but harmless */
activeSearchPath = baseSearchPath;
activeCreationNamespace = baseCreationNamespace;
activeTempCreationPending = baseTempCreationPending;
}
/* As above, the generation always increments. */
activePathGeneration++;
}
/*
* get_collation_oid - find a collation by possibly qualified name
*
@ -3794,10 +3649,6 @@ recomputeNamespacePath(void)
bool pathChanged;
MemoryContext oldcxt;
/* Do nothing if an override search spec is active. */
if (overrideStack)
return;
/* Do nothing if path is already valid. */
if (baseSearchPathValid && namespaceUser == roleid)
return;
@ -3936,10 +3787,7 @@ recomputeNamespacePath(void)
/*
* Bump the generation only if something actually changed. (Notice that
* what we compared to was the old state of the base path variables; so
* this does not deal with the situation where we have just popped an
* override path and restored the prior state of the base path. Instead
* we rely on the override-popping logic to have bumped the generation.)
* what we compared to was the old state of the base path variables.)
*/
if (pathChanged)
activePathGeneration++;
@ -4142,29 +3990,6 @@ AtEOXact_Namespace(bool isCommit, bool parallel)
myTempNamespaceSubID = InvalidSubTransactionId;
}
/*
* Clean up if someone failed to do PopOverrideSearchPath
*/
if (overrideStack)
{
if (isCommit)
elog(WARNING, "leaked override search path");
while (overrideStack)
{
OverrideStackEntry *entry;
entry = (OverrideStackEntry *) linitial(overrideStack);
overrideStack = list_delete_first(overrideStack);
list_free(entry->searchPath);
pfree(entry);
}
/* If not baseSearchPathValid, this is useless but harmless */
activeSearchPath = baseSearchPath;
activeCreationNamespace = baseCreationNamespace;
activeTempCreationPending = baseTempCreationPending;
/* Always bump generation --- see note in recomputeNamespacePath */
activePathGeneration++;
}
}
/*
@ -4179,7 +4004,6 @@ void
AtEOSubXact_Namespace(bool isCommit, SubTransactionId mySubid,
SubTransactionId parentSubid)
{
OverrideStackEntry *entry;
if (myTempNamespaceSubID == mySubid)
{
@ -4205,51 +4029,6 @@ AtEOSubXact_Namespace(bool isCommit, SubTransactionId mySubid,
MyProc->tempNamespaceId = InvalidOid;
}
}
/*
* Clean up if someone failed to do PopOverrideSearchPath
*/
while (overrideStack)
{
entry = (OverrideStackEntry *) linitial(overrideStack);
if (entry->nestLevel < GetCurrentTransactionNestLevel())
break;
if (isCommit)
elog(WARNING, "leaked override search path");
overrideStack = list_delete_first(overrideStack);
list_free(entry->searchPath);
pfree(entry);
/* Always bump generation --- see note in recomputeNamespacePath */
activePathGeneration++;
}
/* Activate the next level down. */
if (overrideStack)
{
entry = (OverrideStackEntry *) linitial(overrideStack);
activeSearchPath = entry->searchPath;
activeCreationNamespace = entry->creationNamespace;
activeTempCreationPending = false; /* XXX is this OK? */
/*
* It's probably unnecessary to bump generation here, but this should
* not be a performance-critical case, so better to be over-cautious.
*/
activePathGeneration++;
}
else
{
/* If not baseSearchPathValid, this is useless but harmless */
activeSearchPath = baseSearchPath;
activeCreationNamespace = baseCreationNamespace;
activeTempCreationPending = baseTempCreationPending;
/*
* If we popped an override stack entry, then we already bumped the
* generation above. If we did not, then the above assignments did
* nothing and we need not bump the generation.
*/
}
}
/*

5
src/backend/commands/extension.c
View File

@ -967,11 +967,6 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
* searched anyway. (Listing pg_catalog explicitly in a non-first
* position would be bad for security.) Finally add pg_temp to ensure
* that temp objects can't take precedence over others.
*
* Note: it might look tempting to use PushOverrideSearchPath for this,
* but we cannot do that. We have to actually set the search_path GUC in
* case the extension script examines or changes it. In any case, the
* GUC_ACTION_SAVE method is just as convenient.
*/
initStringInfo(&pathbuf);
appendStringInfoString(&pathbuf, quote_identifier(schemaName));

2
src/include/catalog/namespace.h
View File

@ -167,8 +167,6 @@ extern void ResetTempTableNamespace(void);
extern OverrideSearchPath *GetOverrideSearchPath(MemoryContext context);
extern OverrideSearchPath *CopyOverrideSearchPath(OverrideSearchPath *path);
extern bool OverrideSearchPathMatchesCurrent(OverrideSearchPath *path);
extern void PushOverrideSearchPath(OverrideSearchPath *newpath);
extern void PopOverrideSearchPath(void);
extern Oid get_collation_oid(List *collname, bool missing_ok);
extern Oid get_conversion_oid(List *conname, bool missing_ok);

1
src/tools/pgindent/typedefs.list
View File

@ -1687,7 +1687,6 @@ OutputPluginCallbacks
OutputPluginOptions
OutputPluginOutputType
OverrideSearchPath
OverrideStackEntry
OverridingKind
PACE_HEADER
PACL