| /* $OpenBSD: cipher.c,v 1.115 2020/02/26 13:40:09 jsg Exp $ */ |
| /* |
| * Author: Tatu Ylonen <ylo@cs.hut.fi> |
| * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| * All rights reserved |
| * |
| * As far as I am concerned, the code I have written for this software |
| * can be used freely for any purpose. Any derived versions of this |
| * software must be clearly marked as such, and if the derived work is |
| * incompatible with the protocol description in the RFC file, it must be |
| * called by a name other than "ssh" or "Secure Shell". |
| * |
| * |
| * Copyright (c) 1999 Niels Provos. All rights reserved. |
| * Copyright (c) 1999, 2000 Markus Friedl. 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 ``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 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. |
| */ |
| |
| #include "includes.h" |
| |
| #include <sys/types.h> |
| |
| #include <string.h> |
| #include <stdarg.h> |
| #include <stdio.h> |
| |
| #include "cipher.h" |
| #include "misc.h" |
| #include "sshbuf.h" |
| #include "ssherr.h" |
| #include "digest.h" |
| |
| #include "openbsd-compat/openssl-compat.h" |
| |
| #ifndef WITH_OPENSSL |
| #define EVP_CIPHER_CTX void |
| #endif |
| |
| struct sshcipher_ctx { |
| int plaintext; |
| int encrypt; |
| EVP_CIPHER_CTX *evp; |
| struct chachapoly_ctx cp_ctx; /* XXX union with evp? */ |
| struct aesctr_ctx ac_ctx; /* XXX union with evp? */ |
| const struct sshcipher *cipher; |
| }; |
| |
| struct sshcipher { |
| char *name; |
| u_int block_size; |
| u_int key_len; |
| u_int iv_len; /* defaults to block_size */ |
| u_int auth_len; |
| u_int flags; |
| #define CFLAG_CBC (1<<0) |
| #define CFLAG_CHACHAPOLY (1<<1) |
| #define CFLAG_AESCTR (1<<2) |
| #define CFLAG_NONE (1<<3) |
| #define CFLAG_INTERNAL CFLAG_NONE /* Don't use "none" for packets */ |
| #ifdef WITH_OPENSSL |
| const EVP_CIPHER *(*evptype)(void); |
| #else |
| void *ignored; |
| #endif |
| }; |
| |
| static const struct sshcipher ciphers[] = { |
| #ifdef WITH_OPENSSL |
| #ifndef OPENSSL_NO_DES |
| { "3des-cbc", 8, 24, 0, 0, CFLAG_CBC, EVP_des_ede3_cbc }, |
| #endif |
| { "aes128-cbc", 16, 16, 0, 0, CFLAG_CBC, EVP_aes_128_cbc }, |
| { "aes192-cbc", 16, 24, 0, 0, CFLAG_CBC, EVP_aes_192_cbc }, |
| { "aes256-cbc", 16, 32, 0, 0, CFLAG_CBC, EVP_aes_256_cbc }, |
| { "rijndael-cbc@lysator.liu.se", |
| 16, 32, 0, 0, CFLAG_CBC, EVP_aes_256_cbc }, |
| { "aes128-ctr", 16, 16, 0, 0, 0, EVP_aes_128_ctr }, |
| { "aes192-ctr", 16, 24, 0, 0, 0, EVP_aes_192_ctr }, |
| { "aes256-ctr", 16, 32, 0, 0, 0, EVP_aes_256_ctr }, |
| # ifdef OPENSSL_HAVE_EVPGCM |
| { "aes128-gcm@openssh.com", |
| 16, 16, 12, 16, 0, EVP_aes_128_gcm }, |
| { "aes256-gcm@openssh.com", |
| 16, 32, 12, 16, 0, EVP_aes_256_gcm }, |
| # endif /* OPENSSL_HAVE_EVPGCM */ |
| #else |
| { "aes128-ctr", 16, 16, 0, 0, CFLAG_AESCTR, NULL }, |
| { "aes192-ctr", 16, 24, 0, 0, CFLAG_AESCTR, NULL }, |
| { "aes256-ctr", 16, 32, 0, 0, CFLAG_AESCTR, NULL }, |
| #endif |
| { "chacha20-poly1305@openssh.com", |
| 8, 64, 0, 16, CFLAG_CHACHAPOLY, NULL }, |
| { "none", 8, 0, 0, 0, CFLAG_NONE, NULL }, |
| |
| { NULL, 0, 0, 0, 0, 0, NULL } |
| }; |
| |
| /*--*/ |
| |
| /* Returns a comma-separated list of supported ciphers. */ |
| char * |
| cipher_alg_list(char sep, int auth_only) |
| { |
| char *tmp, *ret = NULL; |
| size_t nlen, rlen = 0; |
| const struct sshcipher *c; |
| |
| for (c = ciphers; c->name != NULL; c++) { |
| if ((c->flags & CFLAG_INTERNAL) != 0) |
| continue; |
| if (auth_only && c->auth_len == 0) |
| continue; |
| if (ret != NULL) |
| ret[rlen++] = sep; |
| nlen = strlen(c->name); |
| if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) { |
| free(ret); |
| return NULL; |
| } |
| ret = tmp; |
| memcpy(ret + rlen, c->name, nlen + 1); |
| rlen += nlen; |
| } |
| return ret; |
| } |
| |
| const char * |
| compression_alg_list(int compression) |
| { |
| #ifdef WITH_ZLIB |
| return compression ? "zlib@openssh.com,zlib,none" : |
| "none,zlib@openssh.com,zlib"; |
| #else |
| return "none"; |
| #endif |
| } |
| |
| u_int |
| cipher_blocksize(const struct sshcipher *c) |
| { |
| return (c->block_size); |
| } |
| |
| u_int |
| cipher_keylen(const struct sshcipher *c) |
| { |
| return (c->key_len); |
| } |
| |
| u_int |
| cipher_seclen(const struct sshcipher *c) |
| { |
| if (strcmp("3des-cbc", c->name) == 0) |
| return 14; |
| return cipher_keylen(c); |
| } |
| |
| u_int |
| cipher_authlen(const struct sshcipher *c) |
| { |
| return (c->auth_len); |
| } |
| |
| u_int |
| cipher_ivlen(const struct sshcipher *c) |
| { |
| /* |
| * Default is cipher block size, except for chacha20+poly1305 that |
| * needs no IV. XXX make iv_len == -1 default? |
| */ |
| return (c->iv_len != 0 || (c->flags & CFLAG_CHACHAPOLY) != 0) ? |
| c->iv_len : c->block_size; |
| } |
| |
| u_int |
| cipher_is_cbc(const struct sshcipher *c) |
| { |
| return (c->flags & CFLAG_CBC) != 0; |
| } |
| |
| u_int |
| cipher_ctx_is_plaintext(struct sshcipher_ctx *cc) |
| { |
| return cc->plaintext; |
| } |
| |
| const struct sshcipher * |
| cipher_by_name(const char *name) |
| { |
| const struct sshcipher *c; |
| for (c = ciphers; c->name != NULL; c++) |
| if (strcmp(c->name, name) == 0) |
| return c; |
| return NULL; |
| } |
| |
| #define CIPHER_SEP "," |
| int |
| ciphers_valid(const char *names) |
| { |
| const struct sshcipher *c; |
| char *cipher_list, *cp; |
| char *p; |
| |
| if (names == NULL || strcmp(names, "") == 0) |
| return 0; |
| if ((cipher_list = cp = strdup(names)) == NULL) |
| return 0; |
| for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; |
| (p = strsep(&cp, CIPHER_SEP))) { |
| c = cipher_by_name(p); |
| if (c == NULL || (c->flags & CFLAG_INTERNAL) != 0) { |
| free(cipher_list); |
| return 0; |
| } |
| } |
| free(cipher_list); |
| return 1; |
| } |
| |
| const char * |
| cipher_warning_message(const struct sshcipher_ctx *cc) |
| { |
| if (cc == NULL || cc->cipher == NULL) |
| return NULL; |
| /* XXX repurpose for CBC warning */ |
| return NULL; |
| } |
| |
| int |
| cipher_init(struct sshcipher_ctx **ccp, const struct sshcipher *cipher, |
| const u_char *key, u_int keylen, const u_char *iv, u_int ivlen, |
| int do_encrypt) |
| { |
| struct sshcipher_ctx *cc = NULL; |
| int ret = SSH_ERR_INTERNAL_ERROR; |
| #ifdef WITH_OPENSSL |
| const EVP_CIPHER *type; |
| int klen; |
| #endif |
| |
| *ccp = NULL; |
| if ((cc = calloc(sizeof(*cc), 1)) == NULL) |
| return SSH_ERR_ALLOC_FAIL; |
| |
| cc->plaintext = (cipher->flags & CFLAG_NONE) != 0; |
| cc->encrypt = do_encrypt; |
| |
| if (keylen < cipher->key_len || |
| (iv != NULL && ivlen < cipher_ivlen(cipher))) { |
| ret = SSH_ERR_INVALID_ARGUMENT; |
| goto out; |
| } |
| |
| cc->cipher = cipher; |
| if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) { |
| ret = chachapoly_init(&cc->cp_ctx, key, keylen); |
| goto out; |
| } |
| if ((cc->cipher->flags & CFLAG_NONE) != 0) { |
| ret = 0; |
| goto out; |
| } |
| #ifndef WITH_OPENSSL |
| if ((cc->cipher->flags & CFLAG_AESCTR) != 0) { |
| aesctr_keysetup(&cc->ac_ctx, key, 8 * keylen, 8 * ivlen); |
| aesctr_ivsetup(&cc->ac_ctx, iv); |
| ret = 0; |
| goto out; |
| } |
| ret = SSH_ERR_INVALID_ARGUMENT; |
| goto out; |
| #else /* WITH_OPENSSL */ |
| type = (*cipher->evptype)(); |
| if ((cc->evp = EVP_CIPHER_CTX_new()) == NULL) { |
| ret = SSH_ERR_ALLOC_FAIL; |
| goto out; |
| } |
| if (EVP_CipherInit(cc->evp, type, NULL, (u_char *)iv, |
| (do_encrypt == CIPHER_ENCRYPT)) == 0) { |
| ret = SSH_ERR_LIBCRYPTO_ERROR; |
| goto out; |
| } |
| if (cipher_authlen(cipher) && |
| !EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_SET_IV_FIXED, |
| -1, (u_char *)iv)) { |
| ret = SSH_ERR_LIBCRYPTO_ERROR; |
| goto out; |
| } |
| klen = EVP_CIPHER_CTX_key_length(cc->evp); |
| if (klen > 0 && keylen != (u_int)klen) { |
| if (EVP_CIPHER_CTX_set_key_length(cc->evp, keylen) == 0) { |
| ret = SSH_ERR_LIBCRYPTO_ERROR; |
| goto out; |
| } |
| } |
| if (EVP_CipherInit(cc->evp, NULL, (u_char *)key, NULL, -1) == 0) { |
| ret = SSH_ERR_LIBCRYPTO_ERROR; |
| goto out; |
| } |
| ret = 0; |
| #endif /* WITH_OPENSSL */ |
| out: |
| if (ret == 0) { |
| /* success */ |
| *ccp = cc; |
| } else { |
| if (cc != NULL) { |
| #ifdef WITH_OPENSSL |
| EVP_CIPHER_CTX_free(cc->evp); |
| #endif /* WITH_OPENSSL */ |
| freezero(cc, sizeof(*cc)); |
| } |
| } |
| return ret; |
| } |
| |
| /* |
| * cipher_crypt() operates as following: |
| * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'. |
| * Theses bytes are treated as additional authenticated data for |
| * authenticated encryption modes. |
| * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'. |
| * Use 'authlen' bytes at offset 'len'+'aadlen' as the authentication tag. |
| * This tag is written on encryption and verified on decryption. |
| * Both 'aadlen' and 'authlen' can be set to 0. |
| */ |
| int |
| cipher_crypt(struct sshcipher_ctx *cc, u_int seqnr, u_char *dest, |
| const u_char *src, u_int len, u_int aadlen, u_int authlen) |
| { |
| if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) { |
| return chachapoly_crypt(&cc->cp_ctx, seqnr, dest, src, |
| len, aadlen, authlen, cc->encrypt); |
| } |
| if ((cc->cipher->flags & CFLAG_NONE) != 0) { |
| memcpy(dest, src, aadlen + len); |
| return 0; |
| } |
| #ifndef WITH_OPENSSL |
| if ((cc->cipher->flags & CFLAG_AESCTR) != 0) { |
| if (aadlen) |
| memcpy(dest, src, aadlen); |
| aesctr_encrypt_bytes(&cc->ac_ctx, src + aadlen, |
| dest + aadlen, len); |
| return 0; |
| } |
| return SSH_ERR_INVALID_ARGUMENT; |
| #else |
| if (authlen) { |
| u_char lastiv[1]; |
| |
| if (authlen != cipher_authlen(cc->cipher)) |
| return SSH_ERR_INVALID_ARGUMENT; |
| /* increment IV */ |
| if (!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_IV_GEN, |
| 1, lastiv)) |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| /* set tag on decyption */ |
| if (!cc->encrypt && |
| !EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_SET_TAG, |
| authlen, (u_char *)src + aadlen + len)) |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| } |
| if (aadlen) { |
| if (authlen && |
| EVP_Cipher(cc->evp, NULL, (u_char *)src, aadlen) < 0) |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| memcpy(dest, src, aadlen); |
| } |
| if (len % cc->cipher->block_size) |
| return SSH_ERR_INVALID_ARGUMENT; |
| if (EVP_Cipher(cc->evp, dest + aadlen, (u_char *)src + aadlen, |
| len) < 0) |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| if (authlen) { |
| /* compute tag (on encrypt) or verify tag (on decrypt) */ |
| if (EVP_Cipher(cc->evp, NULL, NULL, 0) < 0) |
| return cc->encrypt ? |
| SSH_ERR_LIBCRYPTO_ERROR : SSH_ERR_MAC_INVALID; |
| if (cc->encrypt && |
| !EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_GET_TAG, |
| authlen, dest + aadlen + len)) |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| } |
| return 0; |
| #endif |
| } |
| |
| /* Extract the packet length, including any decryption necessary beforehand */ |
| int |
| cipher_get_length(struct sshcipher_ctx *cc, u_int *plenp, u_int seqnr, |
| const u_char *cp, u_int len) |
| { |
| if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) |
| return chachapoly_get_length(&cc->cp_ctx, plenp, seqnr, |
| cp, len); |
| if (len < 4) |
| return SSH_ERR_MESSAGE_INCOMPLETE; |
| *plenp = PEEK_U32(cp); |
| return 0; |
| } |
| |
| void |
| cipher_free(struct sshcipher_ctx *cc) |
| { |
| if (cc == NULL) |
| return; |
| if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) |
| explicit_bzero(&cc->cp_ctx, sizeof(cc->cp_ctx)); |
| else if ((cc->cipher->flags & CFLAG_AESCTR) != 0) |
| explicit_bzero(&cc->ac_ctx, sizeof(cc->ac_ctx)); |
| #ifdef WITH_OPENSSL |
| EVP_CIPHER_CTX_free(cc->evp); |
| cc->evp = NULL; |
| #endif |
| freezero(cc, sizeof(*cc)); |
| } |
| |
| /* |
| * Exports an IV from the sshcipher_ctx required to export the key |
| * state back from the unprivileged child to the privileged parent |
| * process. |
| */ |
| int |
| cipher_get_keyiv_len(const struct sshcipher_ctx *cc) |
| { |
| const struct sshcipher *c = cc->cipher; |
| |
| if ((c->flags & CFLAG_CHACHAPOLY) != 0) |
| return 0; |
| else if ((c->flags & CFLAG_AESCTR) != 0) |
| return sizeof(cc->ac_ctx.ctr); |
| #ifdef WITH_OPENSSL |
| return EVP_CIPHER_CTX_iv_length(cc->evp); |
| #else |
| return 0; |
| #endif |
| } |
| |
| int |
| cipher_get_keyiv(struct sshcipher_ctx *cc, u_char *iv, size_t len) |
| { |
| #ifdef WITH_OPENSSL |
| const struct sshcipher *c = cc->cipher; |
| int evplen; |
| #endif |
| |
| if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) { |
| if (len != 0) |
| return SSH_ERR_INVALID_ARGUMENT; |
| return 0; |
| } |
| if ((cc->cipher->flags & CFLAG_AESCTR) != 0) { |
| if (len != sizeof(cc->ac_ctx.ctr)) |
| return SSH_ERR_INVALID_ARGUMENT; |
| memcpy(iv, cc->ac_ctx.ctr, len); |
| return 0; |
| } |
| if ((cc->cipher->flags & CFLAG_NONE) != 0) |
| return 0; |
| |
| #ifdef WITH_OPENSSL |
| evplen = EVP_CIPHER_CTX_iv_length(cc->evp); |
| if (evplen == 0) |
| return 0; |
| else if (evplen < 0) |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| if ((size_t)evplen != len) |
| return SSH_ERR_INVALID_ARGUMENT; |
| #ifndef OPENSSL_HAVE_EVPCTR |
| if (c->evptype == evp_aes_128_ctr) |
| ssh_aes_ctr_iv(cc->evp, 0, iv, len); |
| else |
| #endif |
| if (cipher_authlen(c)) { |
| if (!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_IV_GEN, |
| len, iv)) |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| } else if (!EVP_CIPHER_CTX_get_iv(cc->evp, iv, len)) |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| #endif |
| return 0; |
| } |
| |
| int |
| cipher_set_keyiv(struct sshcipher_ctx *cc, const u_char *iv, size_t len) |
| { |
| #ifdef WITH_OPENSSL |
| const struct sshcipher *c = cc->cipher; |
| int evplen = 0; |
| #endif |
| |
| if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) |
| return 0; |
| if ((cc->cipher->flags & CFLAG_NONE) != 0) |
| return 0; |
| |
| #ifdef WITH_OPENSSL |
| evplen = EVP_CIPHER_CTX_iv_length(cc->evp); |
| if (evplen <= 0) |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| if ((size_t)evplen != len) |
| return SSH_ERR_INVALID_ARGUMENT; |
| #ifndef OPENSSL_HAVE_EVPCTR |
| /* XXX iv arg is const, but ssh_aes_ctr_iv isn't */ |
| if (c->evptype == evp_aes_128_ctr) |
| ssh_aes_ctr_iv(cc->evp, 1, (u_char *)iv, evplen); |
| else |
| #endif |
| if (cipher_authlen(c)) { |
| /* XXX iv arg is const, but EVP_CIPHER_CTX_ctrl isn't */ |
| if (!EVP_CIPHER_CTX_ctrl(cc->evp, |
| EVP_CTRL_GCM_SET_IV_FIXED, -1, (void *)iv)) |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| } else if (!EVP_CIPHER_CTX_set_iv(cc->evp, iv, evplen)) |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| #endif |
| return 0; |
| } |