px.c

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/*
 * px.c
 *      Various cryptographic stuff for PostgreSQL.
 *
 * Copyright (c) 2001 Marko Kreen
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * contrib/pgcrypto/px.c
 */

#include "postgres.h"

#include "px.h"

struct error_desc
{
    int         err;
    const char *desc;
};

static const struct error_desc px_err_list[] = {
    {PXE_OK, "Everything ok"},
    {PXE_ERR_GENERIC, "Some PX error (not specified)"},
    {PXE_NO_HASH, "No such hash algorithm"},
    {PXE_NO_CIPHER, "No such cipher algorithm"},
    {PXE_NOTBLOCKSIZE, "Data not a multiple of block size"},
    {PXE_BAD_OPTION, "Unknown option"},
    {PXE_BAD_FORMAT, "Badly formatted type"},
    {PXE_KEY_TOO_BIG, "Key was too big"},
    {PXE_CIPHER_INIT, "Cipher cannot be initalized ?"},
    {PXE_HASH_UNUSABLE_FOR_HMAC, "This hash algorithm is unusable for HMAC"},
    {PXE_DEV_READ_ERROR, "Error reading from random device"},
    {PXE_OSSL_RAND_ERROR, "OpenSSL PRNG error"},
    {PXE_BUG, "pgcrypto bug"},
    {PXE_ARGUMENT_ERROR, "Illegal argument to function"},
    {PXE_UNKNOWN_SALT_ALGO, "Unknown salt algorithm"},
    {PXE_BAD_SALT_ROUNDS, "Incorrect number of rounds"},
    {PXE_MCRYPT_INTERNAL, "mcrypt internal error"},
    {PXE_NO_RANDOM, "No strong random source"},
    {PXE_DECRYPT_FAILED, "Decryption failed"},
    {PXE_PGP_CORRUPT_DATA, "Wrong key or corrupt data"},
    {PXE_PGP_CORRUPT_ARMOR, "Corrupt ascii-armor"},
    {PXE_PGP_UNSUPPORTED_COMPR, "Unsupported compression algorithm"},
    {PXE_PGP_UNSUPPORTED_CIPHER, "Unsupported cipher algorithm"},
    {PXE_PGP_UNSUPPORTED_HASH, "Unsupported digest algorithm"},
    {PXE_PGP_COMPRESSION_ERROR, "Compression error"},
    {PXE_PGP_NOT_TEXT, "Not text data"},
    {PXE_PGP_UNEXPECTED_PKT, "Unexpected packet in key data"},
    {PXE_PGP_NO_BIGNUM,
        "public-key functions disabled - "
    "pgcrypto needs OpenSSL for bignums"},
    {PXE_PGP_MATH_FAILED, "Math operation failed"},
    {PXE_PGP_SHORT_ELGAMAL_KEY, "Elgamal keys must be at least 1024 bits long"},
    {PXE_PGP_RSA_UNSUPPORTED, "pgcrypto does not support RSA keys"},
    {PXE_PGP_UNKNOWN_PUBALGO, "Unknown public-key encryption algorithm"},
    {PXE_PGP_WRONG_KEY, "Wrong key"},
    {PXE_PGP_MULTIPLE_KEYS,
    "Several keys given - pgcrypto does not handle keyring"},
    {PXE_PGP_EXPECT_PUBLIC_KEY, "Refusing to encrypt with secret key"},
    {PXE_PGP_EXPECT_SECRET_KEY, "Cannot decrypt with public key"},
    {PXE_PGP_NOT_V4_KEYPKT, "Only V4 key packets are supported"},
    {PXE_PGP_KEYPKT_CORRUPT, "Corrupt key packet"},
    {PXE_PGP_NO_USABLE_KEY, "No encryption key found"},
    {PXE_PGP_NEED_SECRET_PSW, "Need password for secret key"},
    {PXE_PGP_BAD_S2K_MODE, "Bad S2K mode"},
    {PXE_PGP_UNSUPPORTED_PUBALGO, "Unsupported public key algorithm"},
    {PXE_PGP_MULTIPLE_SUBKEYS, "Several subkeys not supported"},

    /* fake this as PXE_PGP_CORRUPT_DATA */
    {PXE_MBUF_SHORT_READ, "Corrupt data"},

    {0, NULL},
};

const char *
px_strerror(int err)
{
    const struct error_desc *e;

    for (e = px_err_list; e->desc; e++)
        if (e->err == err)
            return e->desc;
    return "Bad error code";
}


const char *
px_resolve_alias(const PX_Alias *list, const char *name)
{
    while (list->name)
    {
        if (pg_strcasecmp(list->alias, name) == 0)
            return list->name;
        list++;
    }
    return name;
}

static void (*debug_handler) (const char *) = NULL;

void
px_set_debug_handler(void (*handler) (const char *))
{
    debug_handler = handler;
}

void
px_debug(const char *fmt,...)
{
    va_list     ap;

    va_start(ap, fmt);
    if (debug_handler)
    {
        char        buf[512];

        vsnprintf(buf, sizeof(buf), fmt, ap);
        debug_handler(buf);
    }
    va_end(ap);
}

/*
 * combo - cipher + padding (+ checksum)
 */

static unsigned
combo_encrypt_len(PX_Combo *cx, unsigned dlen)
{
    return dlen + 512;
}

static unsigned
combo_decrypt_len(PX_Combo *cx, unsigned dlen)
{
    return dlen;
}

static int
combo_init(PX_Combo *cx, const uint8 *key, unsigned klen,
           const uint8 *iv, unsigned ivlen)
{
    int         err;
    unsigned    ks,
                ivs;
    PX_Cipher  *c = cx->cipher;
    uint8      *ivbuf = NULL;
    uint8      *keybuf;

    ks = px_cipher_key_size(c);

    ivs = px_cipher_iv_size(c);
    if (ivs > 0)
    {
        ivbuf = px_alloc(ivs);
        memset(ivbuf, 0, ivs);
        if (ivlen > ivs)
            memcpy(ivbuf, iv, ivs);
        else
            memcpy(ivbuf, iv, ivlen);
    }

    if (klen > ks)
        klen = ks;
    keybuf = px_alloc(ks);
    memset(keybuf, 0, ks);
    memcpy(keybuf, key, klen);

    err = px_cipher_init(c, keybuf, klen, ivbuf);

    if (ivbuf)
        px_free(ivbuf);
    px_free(keybuf);

    return err;
}

static int
combo_encrypt(PX_Combo *cx, const uint8 *data, unsigned dlen,
              uint8 *res, unsigned *rlen)
{
    int         err = 0;
    uint8      *bbuf;
    unsigned    bs,
                bpos,
                i,
                pad;

    PX_Cipher  *c = cx->cipher;

    bbuf = NULL;
    bs = px_cipher_block_size(c);

    /* encrypt */
    if (bs > 1)
    {
        bbuf = px_alloc(bs * 4);
        bpos = dlen % bs;
        *rlen = dlen - bpos;
        memcpy(bbuf, data + *rlen, bpos);

        /* encrypt full-block data */
        if (*rlen)
        {
            err = px_cipher_encrypt(c, data, *rlen, res);
            if (err)
                goto out;
        }

        /* bbuf has now bpos bytes of stuff */
        if (cx->padding)
        {
            pad = bs - (bpos % bs);
            for (i = 0; i < pad; i++)
                bbuf[bpos++] = pad;
        }
        else if (bpos % bs)
        {
            /* ERROR? */
            pad = bs - (bpos % bs);
            for (i = 0; i < pad; i++)
                bbuf[bpos++] = 0;
        }

        /* encrypt the rest - pad */
        if (bpos)
        {
            err = px_cipher_encrypt(c, bbuf, bpos, res + *rlen);
            *rlen += bpos;
        }
    }
    else
    {
        /* stream cipher/mode - no pad needed */
        err = px_cipher_encrypt(c, data, dlen, res);
        if (err)
            goto out;
        *rlen = dlen;
    }
out:
    if (bbuf)
        px_free(bbuf);

    return err;
}

static int
combo_decrypt(PX_Combo *cx, const uint8 *data, unsigned dlen,
              uint8 *res, unsigned *rlen)
{
    unsigned    bs,
                i,
                pad;
    unsigned    pad_ok;

    PX_Cipher  *c = cx->cipher;

    /* decide whether zero-length input is allowed */
    if (dlen == 0)
    {
        /* with padding, empty ciphertext is not allowed */
        if (cx->padding)
            return PXE_DECRYPT_FAILED;

        /* without padding, report empty result */
        *rlen = 0;
        return 0;
    }

    bs = px_cipher_block_size(c);
    if (bs > 1 && (dlen % bs) != 0)
        goto block_error;

    /* decrypt */
    *rlen = dlen;
    px_cipher_decrypt(c, data, dlen, res);

    /* unpad */
    if (bs > 1 && cx->padding)
    {
        pad = res[*rlen - 1];
        pad_ok = 0;
        if (pad > 0 && pad <= bs && pad <= *rlen)
        {
            pad_ok = 1;
            for (i = *rlen - pad; i < *rlen; i++)
                if (res[i] != pad)
                {
                    pad_ok = 0;
                    break;
                }
        }

        if (pad_ok)
            *rlen -= pad;
    }

    return 0;

block_error:
    return PXE_NOTBLOCKSIZE;
}

static void
combo_free(PX_Combo *cx)
{
    if (cx->cipher)
        px_cipher_free(cx->cipher);
    memset(cx, 0, sizeof(*cx));
    px_free(cx);
}

/* PARSER */

static int
parse_cipher_name(char *full, char **cipher, char **pad)
{
    char       *p,
               *p2,
               *q;

    *cipher = full;
    *pad = NULL;

    p = strchr(full, '/');
    if (p != NULL)
        *p++ = 0;
    while (p != NULL)
    {
        if ((q = strchr(p, '/')) != NULL)
            *q++ = 0;

        if (!*p)
        {
            p = q;
            continue;
        }
        p2 = strchr(p, ':');
        if (p2 != NULL)
        {
            *p2++ = 0;
            if (strcmp(p, "pad") == 0)
                *pad = p2;
            else
                return PXE_BAD_OPTION;
        }
        else
            return PXE_BAD_FORMAT;

        p = q;
    }
    return 0;
}

/* provider */

int
px_find_combo(const char *name, PX_Combo **res)
{
    int         err;
    char       *buf,
               *s_cipher,
               *s_pad;

    PX_Combo   *cx;

    cx = px_alloc(sizeof(*cx));
    memset(cx, 0, sizeof(*cx));

    buf = px_alloc(strlen(name) + 1);
    strcpy(buf, name);

    err = parse_cipher_name(buf, &s_cipher, &s_pad);
    if (err)
    {
        px_free(buf);
        px_free(cx);
        return err;
    }

    err = px_find_cipher(s_cipher, &cx->cipher);
    if (err)
        goto err1;

    if (s_pad != NULL)
    {
        if (strcmp(s_pad, "pkcs") == 0)
            cx->padding = 1;
        else if (strcmp(s_pad, "none") == 0)
            cx->padding = 0;
        else
            goto err1;
    }
    else
        cx->padding = 1;

    cx->init = combo_init;
    cx->encrypt = combo_encrypt;
    cx->decrypt = combo_decrypt;
    cx->encrypt_len = combo_encrypt_len;
    cx->decrypt_len = combo_decrypt_len;
    cx->free = combo_free;

    px_free(buf);

    *res = cx;

    return 0;

err1:
    if (cx->cipher)
        px_cipher_free(cx->cipher);
    px_free(cx);
    px_free(buf);
    return PXE_NO_CIPHER;
}