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A couple of code paths use the special area on the page passed by the function caller, expecting to find some data in it. However, feeding an incorrect page can lead to out-of-bound reads when trying to access the page special area (like a heap page that has no special area, leading PageGetSpecialPointer() to grab a pointer outside the allocated page). The functions used for hash and btree indexes have some protection already against that, while some other functions using a relation OID as argument would make sure that the access method involved is correct, but functions taking in input a raw page without knowing the relation the page is attached to would run into problems. This commit improves the set of checks used in the code paths of BRIN, btree (including one check if a leaf page is found with a non-zero level), GIN and GiST to verify that the page given in input has a special area size that fits with each access method, which is done though PageGetSpecialSize(), becore calling PageGetSpecialPointer(). The scope of the checks done is limited to work with pages that one would pass after getting a block with get_raw_page(), as it is possible to craft byteas that could bypass existing code paths. Having too many checks would also impact the usability of pageinspect, as the existing code is very useful to look at the content details in a corrupted page, so the focus is really to avoid out-of-bound reads as this is never a good thing even with functions whose execution is limited to superusers. The safest approach could be to rework the functions so as these fetch a block using a relation OID and a block number, but there are also cases where using a raw page is useful. Tests are added to cover all the code paths that needed such checks, and an error message for hash indexes is reworded to fit better with what this commit adds. Reported-By: Alexander Lakhin Author: Julien Rouhaud, Michael Paquier Discussion: https://postgr.es/m/16527-ef7606186f0610a1@postgresql.org Discussion: https://postgr.es/m/561e187b-3549-c8d5-03f5-525c14e65bd0@postgrespro.ru Backpatch-through: 10
421 lines
11 KiB
C
421 lines
11 KiB
C
/*
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* brinfuncs.c
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* Functions to investigate BRIN indexes
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*
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* Copyright (c) 2014-2019, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* contrib/pageinspect/brinfuncs.c
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*/
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#include "postgres.h"
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#include "pageinspect.h"
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#include "access/htup_details.h"
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#include "access/brin.h"
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#include "access/brin_internal.h"
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#include "access/brin_page.h"
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#include "access/brin_revmap.h"
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#include "access/brin_tuple.h"
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#include "catalog/index.h"
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#include "catalog/pg_am_d.h"
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#include "catalog/pg_type.h"
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#include "funcapi.h"
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#include "lib/stringinfo.h"
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#include "utils/array.h"
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#include "utils/builtins.h"
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#include "utils/lsyscache.h"
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#include "utils/rel.h"
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#include "miscadmin.h"
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PG_FUNCTION_INFO_V1(brin_page_type);
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PG_FUNCTION_INFO_V1(brin_page_items);
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PG_FUNCTION_INFO_V1(brin_metapage_info);
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PG_FUNCTION_INFO_V1(brin_revmap_data);
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#define IS_BRIN(r) ((r)->rd_rel->relam == BRIN_AM_OID)
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typedef struct brin_column_state
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{
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int nstored;
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FmgrInfo outputFn[FLEXIBLE_ARRAY_MEMBER];
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} brin_column_state;
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static Page verify_brin_page(bytea *raw_page, uint16 type,
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const char *strtype);
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Datum
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brin_page_type(PG_FUNCTION_ARGS)
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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Page page;
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char *type;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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(errmsg("must be superuser to use raw page functions"))));
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page = get_page_from_raw(raw_page);
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/* verify the special space has the expected size */
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if (PageGetSpecialSize(page) != MAXALIGN(sizeof(BrinSpecialSpace)))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("input page is not a valid %s page", "BRIN"),
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errdetail("Expected special size %d, got %d.",
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(int) MAXALIGN(sizeof(BrinSpecialSpace)),
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(int) PageGetSpecialSize(page))));
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switch (BrinPageType(page))
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{
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case BRIN_PAGETYPE_META:
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type = "meta";
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break;
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case BRIN_PAGETYPE_REVMAP:
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type = "revmap";
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break;
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case BRIN_PAGETYPE_REGULAR:
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type = "regular";
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break;
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default:
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type = psprintf("unknown (%02x)", BrinPageType(page));
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break;
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}
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PG_RETURN_TEXT_P(cstring_to_text(type));
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}
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/*
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* Verify that the given bytea contains a BRIN page of the indicated page
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* type, or die in the attempt. A pointer to the page is returned.
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*/
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static Page
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verify_brin_page(bytea *raw_page, uint16 type, const char *strtype)
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{
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Page page = get_page_from_raw(raw_page);
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/* verify the special space has the expected size */
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if (PageGetSpecialSize(page) != MAXALIGN(sizeof(BrinSpecialSpace)))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("input page is not a valid %s page", "BRIN"),
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errdetail("Expected special size %d, got %d.",
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(int) MAXALIGN(sizeof(BrinSpecialSpace)),
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(int) PageGetSpecialSize(page))));
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/* verify the special space says this page is what we want */
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if (BrinPageType(page) != type)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("page is not a BRIN page of type \"%s\"", strtype),
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errdetail("Expected special type %08x, got %08x.",
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type, BrinPageType(page))));
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return page;
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}
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/*
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* Extract all item values from a BRIN index page
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*
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* Usage: SELECT * FROM brin_page_items(get_raw_page('idx', 1), 'idx'::regclass);
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*/
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Datum
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brin_page_items(PG_FUNCTION_ARGS)
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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Oid indexRelid = PG_GETARG_OID(1);
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ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
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TupleDesc tupdesc;
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MemoryContext oldcontext;
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Tuplestorestate *tupstore;
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Relation indexRel;
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brin_column_state **columns;
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BrinDesc *bdesc;
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BrinMemTuple *dtup;
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Page page;
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OffsetNumber offset;
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AttrNumber attno;
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bool unusedItem;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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(errmsg("must be superuser to use raw page functions"))));
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/* check to see if caller supports us returning a tuplestore */
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if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("set-valued function called in context that cannot accept a set")));
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if (!(rsinfo->allowedModes & SFRM_Materialize) ||
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rsinfo->expectedDesc == NULL)
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("materialize mode required, but it is not allowed in this context")));
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/* Build a tuple descriptor for our result type */
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if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
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elog(ERROR, "return type must be a row type");
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/* Build tuplestore to hold the result rows */
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oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);
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tupstore = tuplestore_begin_heap(true, false, work_mem);
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rsinfo->returnMode = SFRM_Materialize;
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rsinfo->setResult = tupstore;
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rsinfo->setDesc = tupdesc;
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MemoryContextSwitchTo(oldcontext);
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indexRel = index_open(indexRelid, AccessShareLock);
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if (!IS_BRIN(indexRel))
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ereport(ERROR,
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(errcode(ERRCODE_WRONG_OBJECT_TYPE),
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errmsg("\"%s\" is not a %s index",
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RelationGetRelationName(indexRel), "BRIN")));
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bdesc = brin_build_desc(indexRel);
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/* minimally verify the page we got */
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page = verify_brin_page(raw_page, BRIN_PAGETYPE_REGULAR, "regular");
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/*
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* Initialize output functions for all indexed datatypes; simplifies
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* calling them later.
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*/
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columns = palloc(sizeof(brin_column_state *) * RelationGetDescr(indexRel)->natts);
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for (attno = 1; attno <= bdesc->bd_tupdesc->natts; attno++)
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{
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Oid output;
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bool isVarlena;
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BrinOpcInfo *opcinfo;
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int i;
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brin_column_state *column;
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opcinfo = bdesc->bd_info[attno - 1];
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column = palloc(offsetof(brin_column_state, outputFn) +
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sizeof(FmgrInfo) * opcinfo->oi_nstored);
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column->nstored = opcinfo->oi_nstored;
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for (i = 0; i < opcinfo->oi_nstored; i++)
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{
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getTypeOutputInfo(opcinfo->oi_typcache[i]->type_id, &output, &isVarlena);
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fmgr_info(output, &column->outputFn[i]);
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}
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columns[attno - 1] = column;
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}
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offset = FirstOffsetNumber;
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unusedItem = false;
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dtup = NULL;
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for (;;)
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{
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Datum values[7];
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bool nulls[7];
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/*
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* This loop is called once for every attribute of every tuple in the
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* page. At the start of a tuple, we get a NULL dtup; that's our
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* signal for obtaining and decoding the next one. If that's not the
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* case, we output the next attribute.
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*/
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if (dtup == NULL)
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{
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ItemId itemId;
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/* verify item status: if there's no data, we can't decode */
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itemId = PageGetItemId(page, offset);
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if (ItemIdIsUsed(itemId))
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{
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dtup = brin_deform_tuple(bdesc,
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(BrinTuple *) PageGetItem(page, itemId),
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NULL);
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attno = 1;
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unusedItem = false;
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}
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else
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unusedItem = true;
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}
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else
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attno++;
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MemSet(nulls, 0, sizeof(nulls));
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if (unusedItem)
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{
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values[0] = UInt16GetDatum(offset);
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nulls[1] = true;
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nulls[2] = true;
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nulls[3] = true;
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nulls[4] = true;
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nulls[5] = true;
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nulls[6] = true;
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}
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else
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{
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int att = attno - 1;
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values[0] = UInt16GetDatum(offset);
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values[1] = UInt32GetDatum(dtup->bt_blkno);
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values[2] = UInt16GetDatum(attno);
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values[3] = BoolGetDatum(dtup->bt_columns[att].bv_allnulls);
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values[4] = BoolGetDatum(dtup->bt_columns[att].bv_hasnulls);
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values[5] = BoolGetDatum(dtup->bt_placeholder);
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if (!dtup->bt_columns[att].bv_allnulls)
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{
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BrinValues *bvalues = &dtup->bt_columns[att];
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StringInfoData s;
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bool first;
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int i;
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initStringInfo(&s);
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appendStringInfoChar(&s, '{');
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first = true;
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for (i = 0; i < columns[att]->nstored; i++)
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{
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char *val;
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if (!first)
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appendStringInfoString(&s, " .. ");
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first = false;
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val = OutputFunctionCall(&columns[att]->outputFn[i],
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bvalues->bv_values[i]);
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appendStringInfoString(&s, val);
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pfree(val);
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}
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appendStringInfoChar(&s, '}');
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values[6] = CStringGetTextDatum(s.data);
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pfree(s.data);
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}
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else
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{
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nulls[6] = true;
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}
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}
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tuplestore_putvalues(tupstore, tupdesc, values, nulls);
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/*
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* If the item was unused, jump straight to the next one; otherwise,
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* the only cleanup needed here is to set our signal to go to the next
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* tuple in the following iteration, by freeing the current one.
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*/
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if (unusedItem)
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offset = OffsetNumberNext(offset);
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else if (attno >= bdesc->bd_tupdesc->natts)
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{
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pfree(dtup);
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dtup = NULL;
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offset = OffsetNumberNext(offset);
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}
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/*
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* If we're beyond the end of the page, we're done.
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*/
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if (offset > PageGetMaxOffsetNumber(page))
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break;
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}
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/* clean up and return the tuplestore */
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brin_free_desc(bdesc);
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tuplestore_donestoring(tupstore);
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index_close(indexRel, AccessShareLock);
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return (Datum) 0;
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}
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Datum
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brin_metapage_info(PG_FUNCTION_ARGS)
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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Page page;
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BrinMetaPageData *meta;
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TupleDesc tupdesc;
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Datum values[4];
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bool nulls[4];
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HeapTuple htup;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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(errmsg("must be superuser to use raw page functions"))));
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page = verify_brin_page(raw_page, BRIN_PAGETYPE_META, "metapage");
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/* Build a tuple descriptor for our result type */
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if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
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elog(ERROR, "return type must be a row type");
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tupdesc = BlessTupleDesc(tupdesc);
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/* Extract values from the metapage */
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meta = (BrinMetaPageData *) PageGetContents(page);
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MemSet(nulls, 0, sizeof(nulls));
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values[0] = CStringGetTextDatum(psprintf("0x%08X", meta->brinMagic));
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values[1] = Int32GetDatum(meta->brinVersion);
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values[2] = Int32GetDatum(meta->pagesPerRange);
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values[3] = Int64GetDatum(meta->lastRevmapPage);
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htup = heap_form_tuple(tupdesc, values, nulls);
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PG_RETURN_DATUM(HeapTupleGetDatum(htup));
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}
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/*
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* Return the TID array stored in a BRIN revmap page
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*/
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Datum
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brin_revmap_data(PG_FUNCTION_ARGS)
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{
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struct
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{
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ItemPointerData *tids;
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int idx;
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} *state;
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FuncCallContext *fctx;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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(errmsg("must be superuser to use raw page functions"))));
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if (SRF_IS_FIRSTCALL())
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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MemoryContext mctx;
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Page page;
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/* create a function context for cross-call persistence */
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fctx = SRF_FIRSTCALL_INIT();
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/* switch to memory context appropriate for multiple function calls */
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mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
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/* minimally verify the page we got */
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page = verify_brin_page(raw_page, BRIN_PAGETYPE_REVMAP, "revmap");
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state = palloc(sizeof(*state));
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state->tids = ((RevmapContents *) PageGetContents(page))->rm_tids;
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state->idx = 0;
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fctx->user_fctx = state;
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MemoryContextSwitchTo(mctx);
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}
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fctx = SRF_PERCALL_SETUP();
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state = fctx->user_fctx;
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if (state->idx < REVMAP_PAGE_MAXITEMS)
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SRF_RETURN_NEXT(fctx, PointerGetDatum(&state->tids[state->idx++]));
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SRF_RETURN_DONE(fctx);
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}
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