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b83dcf7928
With its current design, a careless use of pg_cryptohash_final() could would result in an out-of-bound write in memory as the size of the destination buffer to store the result digest is not known to the cryptohash internals, without the caller knowing about that. This commit adds a new argument to pg_cryptohash_final() to allow such sanity checks, and implements such defenses. The internals of SCRAM for HMAC could be tightened a bit more, but as everything is based on SCRAM_KEY_LEN with uses particular to this code there is no need to complicate its interface more than necessary, and this comes back to the refactoring of HMAC in core. Except that, this minimizes the uses of the existing DIGEST_LENGTH variables, relying instead on sizeof() for the result sizes. In ossp-uuid, this also makes the code more defensive, as it already relied on dce_uuid_t being at least the size of a MD5 digest. This is in philosophy similar tocfc40d3
for base64.c andaef8948
for hex.c. Reported-by: Ranier Vilela Author: Michael Paquier, Ranier Vilela Reviewed-by: Kyotaro Horiguchi Discussion: https://postgr.es/m/CAEudQAoqEGmcff3J4sTSV-R_16Monuz-UpJFbf_dnVH=APr02Q@mail.gmail.com
251 lines
5.1 KiB
C
251 lines
5.1 KiB
C
/*-------------------------------------------------------------------------
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*
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* cryptohash_openssl.c
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* Set of wrapper routines on top of OpenSSL to support cryptographic
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* hash functions.
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*
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* This should only be used if code is compiled with OpenSSL support.
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*
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* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* src/common/cryptohash_openssl.c
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef FRONTEND
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#include "postgres.h"
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#else
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#include "postgres_fe.h"
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#endif
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#include <openssl/evp.h>
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#include "common/cryptohash.h"
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#include "common/md5.h"
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#include "common/sha1.h"
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#include "common/sha2.h"
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#ifndef FRONTEND
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#include "utils/memutils.h"
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#include "utils/resowner.h"
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#include "utils/resowner_private.h"
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#endif
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/*
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* In the backend, use an allocation in TopMemoryContext to count for
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* resowner cleanup handling. In the frontend, use malloc to be able
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* to return a failure status back to the caller.
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*/
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#ifndef FRONTEND
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#define ALLOC(size) MemoryContextAlloc(TopMemoryContext, size)
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#define FREE(ptr) pfree(ptr)
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#else
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#define ALLOC(size) malloc(size)
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#define FREE(ptr) free(ptr)
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#endif
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/*
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* Internal pg_cryptohash_ctx structure.
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*
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* This tracks the resource owner associated to each EVP context data
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* for the backend.
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*/
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struct pg_cryptohash_ctx
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{
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pg_cryptohash_type type;
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EVP_MD_CTX *evpctx;
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#ifndef FRONTEND
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ResourceOwner resowner;
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#endif
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};
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/*
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* pg_cryptohash_create
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*
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* Allocate a hash context. Returns NULL on failure for an OOM. The
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* backend issues an error, without returning.
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*/
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pg_cryptohash_ctx *
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pg_cryptohash_create(pg_cryptohash_type type)
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{
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pg_cryptohash_ctx *ctx;
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/*
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* Make sure that the resource owner has space to remember this reference.
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* This can error out with "out of memory", so do this before any other
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* allocation to avoid leaking.
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*/
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#ifndef FRONTEND
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ResourceOwnerEnlargeCryptoHash(CurrentResourceOwner);
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#endif
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ctx = ALLOC(sizeof(pg_cryptohash_ctx));
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if (ctx == NULL)
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return NULL;
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memset(ctx, 0, sizeof(pg_cryptohash_ctx));
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ctx->type = type;
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/*
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* Initialization takes care of assigning the correct type for OpenSSL.
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*/
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ctx->evpctx = EVP_MD_CTX_create();
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if (ctx->evpctx == NULL)
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{
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explicit_bzero(ctx, sizeof(pg_cryptohash_ctx));
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FREE(ctx);
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#ifndef FRONTEND
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ereport(ERROR,
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(errcode(ERRCODE_OUT_OF_MEMORY),
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errmsg("out of memory")));
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#else
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return NULL;
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#endif
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}
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#ifndef FRONTEND
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ctx->resowner = CurrentResourceOwner;
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ResourceOwnerRememberCryptoHash(CurrentResourceOwner,
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PointerGetDatum(ctx));
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#endif
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return ctx;
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}
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/*
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* pg_cryptohash_init
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*
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* Initialize a hash context. Returns 0 on success, and -1 on failure.
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*/
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int
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pg_cryptohash_init(pg_cryptohash_ctx *ctx)
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{
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int status = 0;
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if (ctx == NULL)
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return -1;
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switch (ctx->type)
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{
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case PG_MD5:
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status = EVP_DigestInit_ex(ctx->evpctx, EVP_md5(), NULL);
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break;
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case PG_SHA1:
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status = EVP_DigestInit_ex(ctx->evpctx, EVP_sha1(), NULL);
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break;
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case PG_SHA224:
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status = EVP_DigestInit_ex(ctx->evpctx, EVP_sha224(), NULL);
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break;
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case PG_SHA256:
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status = EVP_DigestInit_ex(ctx->evpctx, EVP_sha256(), NULL);
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break;
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case PG_SHA384:
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status = EVP_DigestInit_ex(ctx->evpctx, EVP_sha384(), NULL);
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break;
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case PG_SHA512:
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status = EVP_DigestInit_ex(ctx->evpctx, EVP_sha512(), NULL);
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break;
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}
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/* OpenSSL internals return 1 on success, 0 on failure */
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if (status <= 0)
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return -1;
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return 0;
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}
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/*
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* pg_cryptohash_update
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*
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* Update a hash context. Returns 0 on success, and -1 on failure.
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*/
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int
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pg_cryptohash_update(pg_cryptohash_ctx *ctx, const uint8 *data, size_t len)
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{
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int status = 0;
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if (ctx == NULL)
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return -1;
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status = EVP_DigestUpdate(ctx->evpctx, data, len);
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/* OpenSSL internals return 1 on success, 0 on failure */
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if (status <= 0)
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return -1;
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return 0;
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}
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/*
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* pg_cryptohash_final
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*
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* Finalize a hash context. Returns 0 on success, and -1 on failure.
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*/
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int
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pg_cryptohash_final(pg_cryptohash_ctx *ctx, uint8 *dest, size_t len)
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{
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int status = 0;
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if (ctx == NULL)
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return -1;
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switch (ctx->type)
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{
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case PG_MD5:
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if (len < MD5_DIGEST_LENGTH)
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return -1;
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break;
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case PG_SHA1:
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if (len < SHA1_DIGEST_LENGTH)
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return -1;
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break;
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case PG_SHA224:
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if (len < PG_SHA224_DIGEST_LENGTH)
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return -1;
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break;
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case PG_SHA256:
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if (len < PG_SHA256_DIGEST_LENGTH)
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return -1;
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break;
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case PG_SHA384:
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if (len < PG_SHA384_DIGEST_LENGTH)
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return -1;
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break;
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case PG_SHA512:
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if (len < PG_SHA512_DIGEST_LENGTH)
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return -1;
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break;
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}
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status = EVP_DigestFinal_ex(ctx->evpctx, dest, 0);
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/* OpenSSL internals return 1 on success, 0 on failure */
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if (status <= 0)
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return -1;
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return 0;
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}
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/*
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* pg_cryptohash_free
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*
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* Free a hash context.
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*/
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void
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pg_cryptohash_free(pg_cryptohash_ctx *ctx)
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{
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if (ctx == NULL)
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return;
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EVP_MD_CTX_destroy(ctx->evpctx);
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#ifndef FRONTEND
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ResourceOwnerForgetCryptoHash(ctx->resowner,
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PointerGetDatum(ctx));
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#endif
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explicit_bzero(ctx, sizeof(pg_cryptohash_ctx));
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FREE(ctx);
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}
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