cryptohash_openssl.c

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/*-------------------------------------------------------------------------
 *
 * cryptohash_openssl.c
 *    Set of wrapper routines on top of OpenSSL to support cryptographic
 *    hash functions.
 *
 * This should only be used if code is compiled with OpenSSL support.
 *
 * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *        src/common/cryptohash_openssl.c
 *
 *-------------------------------------------------------------------------
 */
 
#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif
 
#include <openssl/err.h>
#include <openssl/evp.h>
 
#include "common/cryptohash.h"
#include "common/md5.h"
#include "common/sha1.h"
#include "common/sha2.h"
#ifndef FRONTEND
#include "utils/memutils.h"
#include "utils/resowner.h"
#endif
 
/*
 * In the backend, use an allocation in TopMemoryContext to count for
 * resowner cleanup handling.  In the frontend, use malloc to be able
 * to return a failure status back to the caller.
 */
#ifndef FRONTEND
#define ALLOC(size) MemoryContextAlloc(TopMemoryContext, size)
#define FREE(ptr) pfree(ptr)
#else
#define ALLOC(size) malloc(size)
#define FREE(ptr) free(ptr)
#endif
 
/* Set of error states */
typedef enum pg_cryptohash_errno
{
    PG_CRYPTOHASH_ERROR_NONE = 0,
    PG_CRYPTOHASH_ERROR_DEST_LEN,
    PG_CRYPTOHASH_ERROR_OPENSSL,
} pg_cryptohash_errno;
 
/*
 * Internal pg_cryptohash_ctx structure.
 *
 * This tracks the resource owner associated to each EVP context data
 * for the backend.
 */
struct pg_cryptohash_ctx
{
    pg_cryptohash_type type;
    pg_cryptohash_errno error;
    const char *errreason;
 
    EVP_MD_CTX *evpctx;
 
#ifndef FRONTEND
    ResourceOwner resowner;
#endif
};
 
/* ResourceOwner callbacks to hold cryptohash contexts */
#ifndef FRONTEND
static void ResOwnerReleaseCryptoHash(Datum res);
 
static const ResourceOwnerDesc cryptohash_resowner_desc =
{
    .name = "OpenSSL cryptohash context",
    .release_phase = RESOURCE_RELEASE_BEFORE_LOCKS,
    .release_priority = RELEASE_PRIO_CRYPTOHASH_CONTEXTS,
    .ReleaseResource = ResOwnerReleaseCryptoHash,
    .DebugPrint = NULL          /* the default message is fine */
};
 
/* Convenience wrappers over ResourceOwnerRemember/Forget */
static inline void
ResourceOwnerRememberCryptoHash(ResourceOwner owner, pg_cryptohash_ctx *ctx)
{
    ResourceOwnerRemember(owner, PointerGetDatum(ctx), &cryptohash_resowner_desc);
}
static inline void
ResourceOwnerForgetCryptoHash(ResourceOwner owner, pg_cryptohash_ctx *ctx)
{
    ResourceOwnerForget(owner, PointerGetDatum(ctx), &cryptohash_resowner_desc);
}
#endif
 
static const char *
SSLerrmessage(unsigned long ecode)
{
    if (ecode == 0)
        return NULL;
 
    /*
     * This may return NULL, but we would fall back to a default error path if
     * that were the case.
     */
    return ERR_reason_error_string(ecode);
}
 
/*
 * pg_cryptohash_create
 *
 * Allocate a hash context.  Returns NULL on failure for an OOM.  The
 * backend issues an error, without returning.
 */
pg_cryptohash_ctx *
pg_cryptohash_create(pg_cryptohash_type type)
{
    pg_cryptohash_ctx *ctx;
 
    /*
     * Make sure that the resource owner has space to remember this reference.
     * This can error out with "out of memory", so do this before any other
     * allocation to avoid leaking.
     */
#ifndef FRONTEND
    ResourceOwnerEnlarge(CurrentResourceOwner);
#endif
 
    ctx = ALLOC(sizeof(pg_cryptohash_ctx));
    if (ctx == NULL)
        return NULL;
    memset(ctx, 0, sizeof(pg_cryptohash_ctx));
    ctx->type = type;
    ctx->error = PG_CRYPTOHASH_ERROR_NONE;
    ctx->errreason = NULL;
 
    /*
     * Initialization takes care of assigning the correct type for OpenSSL.
     * Also ensure that there aren't any unconsumed errors in the queue from
     * previous runs.
     */
    ERR_clear_error();
    ctx->evpctx = EVP_MD_CTX_create();
 
    if (ctx->evpctx == NULL)
    {
        explicit_bzero(ctx, sizeof(pg_cryptohash_ctx));
        FREE(ctx);
#ifndef FRONTEND
        ereport(ERROR,
                (errcode(ERRCODE_OUT_OF_MEMORY),
                 errmsg("out of memory")));
#else
        return NULL;
#endif
    }
 
#ifndef FRONTEND
    ctx->resowner = CurrentResourceOwner;
    ResourceOwnerRememberCryptoHash(CurrentResourceOwner, ctx);
#endif
 
    return ctx;
}
 
/*
 * pg_cryptohash_init
 *
 * Initialize a hash context.  Returns 0 on success, and -1 on failure.
 */
int
pg_cryptohash_init(pg_cryptohash_ctx *ctx)
{
    int         status = 0;
 
    if (ctx == NULL)
        return -1;
 
    switch (ctx->type)
    {
        case PG_MD5:
            status = EVP_DigestInit_ex(ctx->evpctx, EVP_md5(), NULL);
            break;
        case PG_SHA1:
            status = EVP_DigestInit_ex(ctx->evpctx, EVP_sha1(), NULL);
            break;
        case PG_SHA224:
            status = EVP_DigestInit_ex(ctx->evpctx, EVP_sha224(), NULL);
            break;
        case PG_SHA256:
            status = EVP_DigestInit_ex(ctx->evpctx, EVP_sha256(), NULL);
            break;
        case PG_SHA384:
            status = EVP_DigestInit_ex(ctx->evpctx, EVP_sha384(), NULL);
            break;
        case PG_SHA512:
            status = EVP_DigestInit_ex(ctx->evpctx, EVP_sha512(), NULL);
            break;
    }
 
    /* OpenSSL internals return 1 on success, 0 on failure */
    if (status <= 0)
    {
        ctx->errreason = SSLerrmessage(ERR_get_error());
        ctx->error = PG_CRYPTOHASH_ERROR_OPENSSL;
 
        /*
         * The OpenSSL error queue should normally be empty since we've
         * consumed an error, but cipher initialization can in FIPS-enabled
         * OpenSSL builds generate two errors so clear the queue here as well.
         */
        ERR_clear_error();
        return -1;
    }
    return 0;
}
 
/*
 * pg_cryptohash_update
 *
 * Update a hash context.  Returns 0 on success, and -1 on failure.
 */
int
pg_cryptohash_update(pg_cryptohash_ctx *ctx, const uint8 *data, size_t len)
{
    int         status = 0;
 
    if (ctx == NULL)
        return -1;
 
    status = EVP_DigestUpdate(ctx->evpctx, data, len);
 
    /* OpenSSL internals return 1 on success, 0 on failure */
    if (status <= 0)
    {
        ctx->errreason = SSLerrmessage(ERR_get_error());
        ctx->error = PG_CRYPTOHASH_ERROR_OPENSSL;
        return -1;
    }
    return 0;
}
 
/*
 * pg_cryptohash_final
 *
 * Finalize a hash context.  Returns 0 on success, and -1 on failure.
 */
int
pg_cryptohash_final(pg_cryptohash_ctx *ctx, uint8 *dest, size_t len)
{
    int         status = 0;
 
    if (ctx == NULL)
        return -1;
 
    switch (ctx->type)
    {
        case PG_MD5:
            if (len < MD5_DIGEST_LENGTH)
            {
                ctx->error = PG_CRYPTOHASH_ERROR_DEST_LEN;
                return -1;
            }
            break;
        case PG_SHA1:
            if (len < SHA1_DIGEST_LENGTH)
            {
                ctx->error = PG_CRYPTOHASH_ERROR_DEST_LEN;
                return -1;
            }
            break;
        case PG_SHA224:
            if (len < PG_SHA224_DIGEST_LENGTH)
            {
                ctx->error = PG_CRYPTOHASH_ERROR_DEST_LEN;
                return -1;
            }
            break;
        case PG_SHA256:
            if (len < PG_SHA256_DIGEST_LENGTH)
            {
                ctx->error = PG_CRYPTOHASH_ERROR_DEST_LEN;
                return -1;
            }
            break;
        case PG_SHA384:
            if (len < PG_SHA384_DIGEST_LENGTH)
            {
                ctx->error = PG_CRYPTOHASH_ERROR_DEST_LEN;
                return -1;
            }
            break;
        case PG_SHA512:
            if (len < PG_SHA512_DIGEST_LENGTH)
            {
                ctx->error = PG_CRYPTOHASH_ERROR_DEST_LEN;
                return -1;
            }
            break;
    }
 
    status = EVP_DigestFinal_ex(ctx->evpctx, dest, 0);
 
    /* OpenSSL internals return 1 on success, 0 on failure */
    if (status <= 0)
    {
        ctx->errreason = SSLerrmessage(ERR_get_error());
        ctx->error = PG_CRYPTOHASH_ERROR_OPENSSL;
        return -1;
    }
    return 0;
}
 
/*
 * pg_cryptohash_free
 *
 * Free a hash context.
 */
void
pg_cryptohash_free(pg_cryptohash_ctx *ctx)
{
    if (ctx == NULL)
        return;
 
    EVP_MD_CTX_destroy(ctx->evpctx);
 
#ifndef FRONTEND
    if (ctx->resowner)
        ResourceOwnerForgetCryptoHash(ctx->resowner, ctx);
#endif
 
    explicit_bzero(ctx, sizeof(pg_cryptohash_ctx));
    FREE(ctx);
}
 
/*
 * pg_cryptohash_error
 *
 * Returns a static string providing details about an error that
 * happened during a computation.
 */
const char *
pg_cryptohash_error(pg_cryptohash_ctx *ctx)
{
    /*
     * This implementation would never fail because of an out-of-memory error,
     * except when creating the context.
     */
    if (ctx == NULL)
        return _("out of memory");
 
    /*
     * If a reason is provided, rely on it, else fallback to any error code
     * set.
     */
    if (ctx->errreason)
        return ctx->errreason;
 
    switch (ctx->error)
    {
        case PG_CRYPTOHASH_ERROR_NONE:
            return _("success");
        case PG_CRYPTOHASH_ERROR_DEST_LEN:
            return _("destination buffer too small");
        case PG_CRYPTOHASH_ERROR_OPENSSL:
            return _("OpenSSL failure");
    }
 
    Assert(false);              /* cannot be reached */
    return _("success");
}
 
/* ResourceOwner callbacks */
 
#ifndef FRONTEND
static void
ResOwnerReleaseCryptoHash(Datum res)
{
    pg_cryptohash_ctx *ctx = (pg_cryptohash_ctx *) DatumGetPointer(res);
 
    ctx->resowner = NULL;
    pg_cryptohash_free(ctx);
}
#endif