X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/066ee5ae71c8b9794436f4e203160c16d680e99b..ebb51ef0e725737ca8c1d618da6527a58660d2bf:/print-esp.c?ds=sidebyside diff --git a/print-esp.c b/print-esp.c index 6afa0631..d12b97da 100644 --- a/print-esp.c +++ b/print-esp.c @@ -21,6 +21,8 @@ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. */ +/* \summary: IPSEC Encapsulating Security Payload (ESP) printer */ + #ifdef HAVE_CONFIG_H #include "config.h" #endif @@ -143,6 +145,39 @@ EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx) } #endif +#ifdef HAVE_EVP_CIPHERINIT_EX +/* + * Initialize the cipher by calling EVP_CipherInit_ex(), because + * calling EVP_CipherInit() will reset the cipher context, clearing + * the cipher, so calling it twice, with the second call having a + * null cipher, will clear the already-set cipher. EVP_CipherInit_ex(), + * however, won't reset the cipher context, so you can use it to specify + * the IV oin a second call after a first call to EVP_CipherInit_ex() + * to set the cipher and the key. + * + * XXX - is there some reason why we need to make two calls? + */ +static int +set_cipher_parameters(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher, + const unsigned char *key, + const unsigned char *iv, int enc) +{ + return EVP_CipherInit_ex(ctx, cipher, NULL, key, iv, enc); +} +#else +/* + * Initialize the cipher by calling EVP_CipherInit(), because we don't + * have EVP_CipherInit_ex(); we rely on it not trashing the context. + */ +static int +set_cipher_parameters(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher, + const unsigned char *key, + const unsigned char *iv, int enc) +{ + return EVP_CipherInit(ctx, cipher, key, iv, enc); +} +#endif + /* * this will adjust ndo_packetp and ndo_snapend to new buffer! */ @@ -154,8 +189,10 @@ int esp_print_decrypt_buffer_by_ikev2(netdissect_options *ndo, { struct sa_list *sa; const u_char *iv; - int len; + unsigned int len; EVP_CIPHER_CTX *ctx; + unsigned int block_size, output_buffer_size; + u_char *output_buffer; /* initiator arg is any non-zero value */ if(initiator) initiator=1; @@ -186,17 +223,36 @@ int esp_print_decrypt_buffer_by_ikev2(netdissect_options *ndo, ctx = EVP_CIPHER_CTX_new(); if (ctx == NULL) return 0; - if (EVP_CipherInit(ctx, sa->evp, sa->secret, NULL, 0) < 0) + if (set_cipher_parameters(ctx, sa->evp, sa->secret, NULL, 0) < 0) (*ndo->ndo_warning)(ndo, "espkey init failed"); - EVP_CipherInit(ctx, NULL, NULL, iv, 0); - EVP_Cipher(ctx, buf, buf, len); + set_cipher_parameters(ctx, NULL, NULL, iv, 0); + /* + * Allocate a buffer for the decrypted data. + * The output buffer must be separate from the input buffer, and + * its size must be a multiple of the cipher block size. + */ + block_size = (unsigned int)EVP_CIPHER_CTX_block_size(ctx); + output_buffer_size = len + (block_size - len % block_size); + output_buffer = (u_char *)malloc(output_buffer_size); + if (output_buffer == NULL) { + (*ndo->ndo_warning)(ndo, "can't allocate memory for decryption buffer"); + EVP_CIPHER_CTX_free(ctx); + return 0; + } + EVP_Cipher(ctx, output_buffer, buf, len); EVP_CIPHER_CTX_free(ctx); + /* + * XXX - of course this is wrong, because buf is a const buffer, + * but changing this would require a more complicated fix. + */ + memcpy(buf, output_buffer, len); + free(output_buffer); + ndo->ndo_packetp = buf; ndo->ndo_snapend = end; return 1; - } USES_APPLE_RST @@ -463,8 +519,9 @@ static void esp_print_decode_onesecret(netdissect_options *ndo, char *line, secretfile = fopen(filename, FOPEN_READ_TXT); if (secretfile == NULL) { - perror(filename); - exit(3); + (*ndo->ndo_error)(ndo, "print_esp: can't open %s: %s\n", + filename, strerror(errno)); + return; } while (fgets(fileline, sizeof(fileline)-1, secretfile) != NULL) { @@ -529,8 +586,14 @@ static void esp_print_decode_onesecret(netdissect_options *ndo, char *line, USES_APPLE_DEPRECATED_API static void esp_init(netdissect_options *ndo _U_) { - + /* + * 0.9.6 doesn't appear to define OPENSSL_API_COMPAT, so + * we check whether it's undefined or it's less than the + * value for 1.1.0. + */ +#if !defined(OPENSSL_API_COMPAT) || OPENSSL_API_COMPAT < 0x10100000L OpenSSL_add_all_algorithms(); +#endif EVP_add_cipher_alias(SN_des_ede3_cbc, "3des"); } USES_APPLE_RST @@ -597,6 +660,8 @@ esp_print(netdissect_options *ndo, const u_char *ivoff; const u_char *p; EVP_CIPHER_CTX *ctx; + unsigned int block_size, output_buffer_size; + u_char *output_buffer; #endif esp = (const struct newesp *)bp; @@ -694,7 +759,9 @@ esp_print(netdissect_options *ndo, ep = bp2 + len; } + /* pointer to the IV, if there is one */ ivoff = (const u_char *)(esp + 1) + 0; + /* length of the IV, if there is one; 0, if there isn't */ ivlen = sa->ivlen; secret = sa->secret; ep = ep - sa->authlen; @@ -702,13 +769,37 @@ esp_print(netdissect_options *ndo, if (sa->evp) { ctx = EVP_CIPHER_CTX_new(); if (ctx != NULL) { - if (EVP_CipherInit(ctx, sa->evp, secret, NULL, 0) < 0) + if (set_cipher_parameters(ctx, sa->evp, secret, NULL, 0) < 0) (*ndo->ndo_warning)(ndo, "espkey init failed"); p = ivoff; - EVP_CipherInit(ctx, NULL, NULL, p, 0); - EVP_Cipher(ctx, p + ivlen, p + ivlen, ep - (p + ivlen)); + set_cipher_parameters(ctx, NULL, NULL, p, 0); + len = ep - (p + ivlen); + + /* + * Allocate a buffer for the decrypted data. + * The output buffer must be separate from the + * input buffer, and its size must be a multiple + * of the cipher block size. + */ + block_size = (unsigned int)EVP_CIPHER_CTX_block_size(ctx); + output_buffer_size = len + (block_size - len % block_size); + output_buffer = (u_char *)malloc(output_buffer_size); + if (output_buffer == NULL) { + (*ndo->ndo_warning)(ndo, "can't allocate memory for decryption buffer"); + EVP_CIPHER_CTX_free(ctx); + return -1; + } + + EVP_Cipher(ctx, output_buffer, p + ivlen, len); EVP_CIPHER_CTX_free(ctx); + /* + * XXX - of course this is wrong, because buf is a + * const buffer, but changing this would require a + * more complicated fix. + */ + memcpy(p + ivlen, output_buffer, len); + free(output_buffer); advance = ivoff - (const u_char *)esp + ivlen; } else advance = sizeof(struct newesp);