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This adds a new routine, pg_strong_random() for generating random bytes, for use in both frontend and backend. At the moment, it's only used in the backend, but the upcoming SCRAM authentication patches need strong random numbers in libpq as well. pg_strong_random() is based on, and replaces, the existing implementation in pgcrypto. It can acquire strong random numbers from a number of sources, depending on what's available: - OpenSSL RAND_bytes(), if built with OpenSSL - On Windows, the native cryptographic functions are used - /dev/urandom Unlike the current pgcrypto function, the source is chosen by configure. That makes it easier to test different implementations, and ensures that we don't accidentally fall back to a less secure implementation, if the primary source fails. All of those methods are quite reliable, it would be pretty surprising for them to fail, so we'd rather find out by failing hard. If no strong random source is available, we fall back to using erand48(), seeded from current timestamp, like PostmasterRandom() was. That isn't cryptographically secure, but allows us to still work on platforms that don't have any of the above stronger sources. Because it's not very secure, the built-in implementation is only used if explicitly requested with --disable-strong-random. This replaces the more complicated Fortuna algorithm we used to have in pgcrypto, which is unfortunate, but all modern platforms have /dev/urandom, so it doesn't seem worth the maintenance effort to keep that. pgcrypto functions that require strong random numbers will be disabled with --disable-strong-random. Original patch by Magnus Hagander, tons of further work by Michael Paquier and me. Discussion: https://www.postgresql.org/message-id/CAB7nPqRy3krN8quR9XujMVVHYtXJ0_60nqgVc6oUk8ygyVkZsA@mail.gmail.com Discussion: https://www.postgresql.org/message-id/CAB7nPqRWkNYRRPJA7-cF+LfroYV10pvjdz6GNvxk-Eee9FypKA@mail.gmail.com
469 lines
9.8 KiB
C
469 lines
9.8 KiB
C
/*
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* px.c
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* Various cryptographic stuff for PostgreSQL.
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*
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* Copyright (c) 2001 Marko Kreen
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* contrib/pgcrypto/px.c
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*/
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#include "postgres.h"
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#include "px.h"
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struct error_desc
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{
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int err;
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const char *desc;
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};
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static const struct error_desc px_err_list[] = {
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{PXE_OK, "Everything ok"},
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{PXE_ERR_GENERIC, "Some PX error (not specified)"},
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{PXE_NO_HASH, "No such hash algorithm"},
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{PXE_NO_CIPHER, "No such cipher algorithm"},
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{PXE_NOTBLOCKSIZE, "Data not a multiple of block size"},
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{PXE_BAD_OPTION, "Unknown option"},
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{PXE_BAD_FORMAT, "Badly formatted type"},
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{PXE_KEY_TOO_BIG, "Key was too big"},
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{PXE_CIPHER_INIT, "Cipher cannot be initialized ?"},
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{PXE_HASH_UNUSABLE_FOR_HMAC, "This hash algorithm is unusable for HMAC"},
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{PXE_DEV_READ_ERROR, "Error reading from random device"},
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{PXE_BUG, "pgcrypto bug"},
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{PXE_ARGUMENT_ERROR, "Illegal argument to function"},
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{PXE_UNKNOWN_SALT_ALGO, "Unknown salt algorithm"},
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{PXE_BAD_SALT_ROUNDS, "Incorrect number of rounds"},
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{PXE_MCRYPT_INTERNAL, "mcrypt internal error"},
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{PXE_NO_RANDOM, "No strong random source"},
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{PXE_DECRYPT_FAILED, "Decryption failed"},
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{PXE_PGP_CORRUPT_DATA, "Wrong key or corrupt data"},
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{PXE_PGP_CORRUPT_ARMOR, "Corrupt ascii-armor"},
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{PXE_PGP_UNSUPPORTED_COMPR, "Unsupported compression algorithm"},
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{PXE_PGP_UNSUPPORTED_CIPHER, "Unsupported cipher algorithm"},
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{PXE_PGP_UNSUPPORTED_HASH, "Unsupported digest algorithm"},
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{PXE_PGP_COMPRESSION_ERROR, "Compression error"},
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{PXE_PGP_NOT_TEXT, "Not text data"},
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{PXE_PGP_UNEXPECTED_PKT, "Unexpected packet in key data"},
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{PXE_PGP_MATH_FAILED, "Math operation failed"},
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{PXE_PGP_SHORT_ELGAMAL_KEY, "Elgamal keys must be at least 1024 bits long"},
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{PXE_PGP_UNKNOWN_PUBALGO, "Unknown public-key encryption algorithm"},
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{PXE_PGP_WRONG_KEY, "Wrong key"},
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{PXE_PGP_MULTIPLE_KEYS,
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"Several keys given - pgcrypto does not handle keyring"},
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{PXE_PGP_EXPECT_PUBLIC_KEY, "Refusing to encrypt with secret key"},
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{PXE_PGP_EXPECT_SECRET_KEY, "Cannot decrypt with public key"},
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{PXE_PGP_NOT_V4_KEYPKT, "Only V4 key packets are supported"},
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{PXE_PGP_KEYPKT_CORRUPT, "Corrupt key packet"},
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{PXE_PGP_NO_USABLE_KEY, "No encryption key found"},
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{PXE_PGP_NEED_SECRET_PSW, "Need password for secret key"},
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{PXE_PGP_BAD_S2K_MODE, "Bad S2K mode"},
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{PXE_PGP_UNSUPPORTED_PUBALGO, "Unsupported public key algorithm"},
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{PXE_PGP_MULTIPLE_SUBKEYS, "Several subkeys not supported"},
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{0, NULL},
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};
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/*
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* Call ereport(ERROR, ...), with an error code and message corresponding to
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* the PXE_* error code given as argument.
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*
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* This is similar to px_strerror(err), but for some errors, we fill in the
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* error code and detail fields more appropriately.
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*/
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void
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px_THROW_ERROR(int err)
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{
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if (err == PXE_NO_RANDOM)
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{
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#ifdef HAVE_STRONG_RANDOM
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ereport(ERROR,
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(errcode(ERRCODE_INTERNAL_ERROR),
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errmsg("could not generate a random number")));
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#else
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("pg_random_bytes() is not supported by this build"),
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errdetail("This functionality requires a source of strong random numbers"),
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errhint("You need to rebuild PostgreSQL using --enable-strong-random")));
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#endif
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}
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else
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{
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/* For other errors, use the message from the above list. */
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ereport(ERROR,
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(errcode(ERRCODE_EXTERNAL_ROUTINE_INVOCATION_EXCEPTION),
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errmsg("%s", px_strerror(err))));
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}
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}
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const char *
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px_strerror(int err)
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{
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const struct error_desc *e;
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for (e = px_err_list; e->desc; e++)
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if (e->err == err)
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return e->desc;
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return "Bad error code";
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}
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/* memset that must not be optimized away */
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void
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px_memset(void *ptr, int c, size_t len)
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{
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memset(ptr, c, len);
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}
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const char *
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px_resolve_alias(const PX_Alias *list, const char *name)
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{
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while (list->name)
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{
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if (pg_strcasecmp(list->alias, name) == 0)
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return list->name;
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list++;
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}
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return name;
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}
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static void (*debug_handler) (const char *) = NULL;
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void
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px_set_debug_handler(void (*handler) (const char *))
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{
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debug_handler = handler;
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}
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void
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px_debug(const char *fmt,...)
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{
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va_list ap;
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va_start(ap, fmt);
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if (debug_handler)
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{
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char buf[512];
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vsnprintf(buf, sizeof(buf), fmt, ap);
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debug_handler(buf);
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}
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va_end(ap);
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}
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/*
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* combo - cipher + padding (+ checksum)
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*/
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static unsigned
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combo_encrypt_len(PX_Combo *cx, unsigned dlen)
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{
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return dlen + 512;
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}
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static unsigned
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combo_decrypt_len(PX_Combo *cx, unsigned dlen)
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{
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return dlen;
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}
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static int
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combo_init(PX_Combo *cx, const uint8 *key, unsigned klen,
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const uint8 *iv, unsigned ivlen)
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{
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int err;
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unsigned ks,
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ivs;
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PX_Cipher *c = cx->cipher;
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uint8 *ivbuf = NULL;
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uint8 *keybuf;
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ks = px_cipher_key_size(c);
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ivs = px_cipher_iv_size(c);
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if (ivs > 0)
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{
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ivbuf = px_alloc(ivs);
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memset(ivbuf, 0, ivs);
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if (ivlen > ivs)
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memcpy(ivbuf, iv, ivs);
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else
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memcpy(ivbuf, iv, ivlen);
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}
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if (klen > ks)
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klen = ks;
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keybuf = px_alloc(ks);
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memset(keybuf, 0, ks);
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memcpy(keybuf, key, klen);
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err = px_cipher_init(c, keybuf, klen, ivbuf);
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if (ivbuf)
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px_free(ivbuf);
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px_free(keybuf);
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return err;
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}
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static int
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combo_encrypt(PX_Combo *cx, const uint8 *data, unsigned dlen,
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uint8 *res, unsigned *rlen)
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{
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int err = 0;
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uint8 *bbuf;
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unsigned bs,
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bpos,
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i,
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pad;
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PX_Cipher *c = cx->cipher;
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bbuf = NULL;
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bs = px_cipher_block_size(c);
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/* encrypt */
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if (bs > 1)
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{
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bbuf = px_alloc(bs * 4);
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bpos = dlen % bs;
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*rlen = dlen - bpos;
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memcpy(bbuf, data + *rlen, bpos);
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/* encrypt full-block data */
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if (*rlen)
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{
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err = px_cipher_encrypt(c, data, *rlen, res);
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if (err)
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goto out;
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}
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/* bbuf has now bpos bytes of stuff */
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if (cx->padding)
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{
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pad = bs - (bpos % bs);
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for (i = 0; i < pad; i++)
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bbuf[bpos++] = pad;
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}
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else if (bpos % bs)
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{
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/* ERROR? */
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pad = bs - (bpos % bs);
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for (i = 0; i < pad; i++)
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bbuf[bpos++] = 0;
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}
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/* encrypt the rest - pad */
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if (bpos)
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{
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err = px_cipher_encrypt(c, bbuf, bpos, res + *rlen);
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*rlen += bpos;
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}
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}
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else
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{
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/* stream cipher/mode - no pad needed */
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err = px_cipher_encrypt(c, data, dlen, res);
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if (err)
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goto out;
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*rlen = dlen;
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}
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out:
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if (bbuf)
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px_free(bbuf);
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return err;
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}
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static int
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combo_decrypt(PX_Combo *cx, const uint8 *data, unsigned dlen,
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uint8 *res, unsigned *rlen)
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{
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unsigned bs,
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i,
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pad;
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unsigned pad_ok;
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PX_Cipher *c = cx->cipher;
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/* decide whether zero-length input is allowed */
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if (dlen == 0)
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{
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/* with padding, empty ciphertext is not allowed */
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if (cx->padding)
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return PXE_DECRYPT_FAILED;
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/* without padding, report empty result */
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*rlen = 0;
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return 0;
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}
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bs = px_cipher_block_size(c);
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if (bs > 1 && (dlen % bs) != 0)
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goto block_error;
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/* decrypt */
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*rlen = dlen;
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px_cipher_decrypt(c, data, dlen, res);
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/* unpad */
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if (bs > 1 && cx->padding)
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{
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pad = res[*rlen - 1];
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pad_ok = 0;
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if (pad > 0 && pad <= bs && pad <= *rlen)
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{
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pad_ok = 1;
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for (i = *rlen - pad; i < *rlen; i++)
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if (res[i] != pad)
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{
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pad_ok = 0;
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break;
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}
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}
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if (pad_ok)
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*rlen -= pad;
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}
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return 0;
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block_error:
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return PXE_NOTBLOCKSIZE;
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}
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static void
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combo_free(PX_Combo *cx)
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{
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if (cx->cipher)
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px_cipher_free(cx->cipher);
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px_memset(cx, 0, sizeof(*cx));
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px_free(cx);
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}
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/* PARSER */
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static int
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parse_cipher_name(char *full, char **cipher, char **pad)
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{
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char *p,
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*p2,
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*q;
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*cipher = full;
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*pad = NULL;
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p = strchr(full, '/');
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if (p != NULL)
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*p++ = 0;
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while (p != NULL)
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{
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if ((q = strchr(p, '/')) != NULL)
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*q++ = 0;
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if (!*p)
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{
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p = q;
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continue;
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}
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p2 = strchr(p, ':');
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if (p2 != NULL)
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{
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*p2++ = 0;
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if (strcmp(p, "pad") == 0)
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*pad = p2;
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else
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return PXE_BAD_OPTION;
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}
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else
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return PXE_BAD_FORMAT;
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p = q;
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}
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return 0;
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}
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/* provider */
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int
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px_find_combo(const char *name, PX_Combo **res)
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{
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int err;
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char *buf,
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*s_cipher,
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*s_pad;
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PX_Combo *cx;
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cx = px_alloc(sizeof(*cx));
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memset(cx, 0, sizeof(*cx));
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buf = px_alloc(strlen(name) + 1);
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strcpy(buf, name);
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err = parse_cipher_name(buf, &s_cipher, &s_pad);
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if (err)
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{
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px_free(buf);
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px_free(cx);
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return err;
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}
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err = px_find_cipher(s_cipher, &cx->cipher);
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if (err)
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goto err1;
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if (s_pad != NULL)
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{
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if (strcmp(s_pad, "pkcs") == 0)
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cx->padding = 1;
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else if (strcmp(s_pad, "none") == 0)
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cx->padding = 0;
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else
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goto err1;
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}
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else
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cx->padding = 1;
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cx->init = combo_init;
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cx->encrypt = combo_encrypt;
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cx->decrypt = combo_decrypt;
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cx->encrypt_len = combo_encrypt_len;
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cx->decrypt_len = combo_decrypt_len;
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cx->free = combo_free;
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px_free(buf);
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*res = cx;
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return 0;
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err1:
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if (cx->cipher)
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px_cipher_free(cx->cipher);
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px_free(cx);
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px_free(buf);
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return PXE_NO_CIPHER;
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}
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