#endif
#include "netdissect.h"
-#include "strtoaddr.h"
#include "extract.h"
+#ifdef HAVE_LIBCRYPTO
+#include "strtoaddr.h"
#include "ascii_strcasecmp.h"
+#endif
#include "ip.h"
#include "ip6.h"
#ifdef HAVE_LIBCRYPTO
union inaddr_u {
- struct in_addr in4;
- struct in6_addr in6;
+ nd_ipv4 in4;
+ nd_ipv6 in6;
};
struct sa_list {
struct sa_list *next;
u_char spii[8]; /* for IKEv2 */
u_char spir[8];
const EVP_CIPHER *evp;
- int ivlen;
+ u_int ivlen;
int authlen;
u_char authsecret[256];
int authsecret_len;
}
#endif
-#ifdef HAVE_EVP_CIPHERINIT_EX
+#ifdef HAVE_EVP_DECRYPTINIT_EX
/*
- * Initialize the cipher by calling EVP_CipherInit_ex(), because
- * calling EVP_CipherInit() will reset the cipher context, clearing
+ * Initialize the cipher by calling EVP_DecryptInit_ex(), because
+ * calling EVP_DecryptInit() 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(),
+ * null cipher, will clear the already-set cipher. EVP_DecryptInit_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()
+ * the IV in a second call after a first call to EVP_DecryptInit_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)
+ const unsigned char *iv)
{
- return EVP_CipherInit_ex(ctx, cipher, NULL, key, iv, enc);
+ return EVP_DecryptInit_ex(ctx, cipher, NULL, key, iv);
}
#else
/*
- * Initialize the cipher by calling EVP_CipherInit(), because we don't
- * have EVP_CipherInit_ex(); we rely on it not trashing the context.
+ * Initialize the cipher by calling EVP_DecryptInit(), because we don't
+ * have EVP_DecryptInit_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)
+ const unsigned char *iv)
{
- return EVP_CipherInit(ctx, cipher, key, iv, enc);
+ return EVP_DecryptInit(ctx, cipher, key, iv);
}
#endif
+static u_char *
+do_decrypt(netdissect_options *ndo, const char *caller, struct sa_list *sa,
+ const u_char *iv, const u_char *ct, unsigned int ctlen)
+{
+ EVP_CIPHER_CTX *ctx;
+ unsigned int block_size;
+ unsigned int ptlen;
+ u_char *pt;
+ int len;
+
+ ctx = EVP_CIPHER_CTX_new();
+ if (ctx == NULL) {
+ /*
+ * Failed to initialize the cipher context.
+ * From a look at the OpenSSL code, this appears to
+ * mean "couldn't allocate memory for the cipher context";
+ * note that we're not passing any parameters, so there's
+ * not much else it can mean.
+ */
+ (*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC,
+ "%s: can't allocate memory for cipher context", caller);
+ return NULL;
+ }
+
+ if (set_cipher_parameters(ctx, sa->evp, sa->secret, NULL) < 0) {
+ EVP_CIPHER_CTX_free(ctx);
+ (*ndo->ndo_warning)(ndo, "%s: espkey init failed", caller);
+ return NULL;
+ }
+ if (set_cipher_parameters(ctx, NULL, NULL, iv) < 0) {
+ EVP_CIPHER_CTX_free(ctx);
+ (*ndo->ndo_warning)(ndo, "%s: IV init failed", caller);
+ return NULL;
+ }
+
+ /*
+ * At least as I read RFC 5996 section 3.14 and RFC 4303 section 2.4,
+ * if the cipher has a block size of which the ciphertext's size must
+ * be a multiple, the payload must be padded to make that happen, so
+ * the ciphertext length must be a multiple of the block size. Fail
+ * if that's not the case.
+ */
+ block_size = (unsigned int)EVP_CIPHER_CTX_block_size(ctx);
+ if ((ctlen % block_size) != 0) {
+ EVP_CIPHER_CTX_free(ctx);
+ (*ndo->ndo_warning)(ndo,
+ "%s: ciphertext size %u is not a multiple of the cipher block size %u",
+ caller, ctlen, block_size);
+ return NULL;
+ }
+
+ /*
+ * Attempt to allocate a buffer for the decrypted data, because
+ * we can't decrypt on top of the input buffer.
+ */
+ ptlen = ctlen;
+ pt = (u_char *)malloc(ptlen);
+ if (pt == NULL) {
+ EVP_CIPHER_CTX_free(ctx);
+ (*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC,
+ "%s: can't allocate memory for decryption buffer", caller);
+ return NULL;
+ }
+
+ /*
+ * The size of the ciphertext handed to us is a multiple of the
+ * cipher block size, so we don't need to worry about padding.
+ */
+ if (!EVP_CIPHER_CTX_set_padding(ctx, 0)) {
+ free(pt);
+ EVP_CIPHER_CTX_free(ctx);
+ (*ndo->ndo_warning)(ndo,
+ "%s: EVP_CIPHER_CTX_set_padding failed", caller);
+ return NULL;
+ }
+ if (!EVP_DecryptUpdate(ctx, pt, &len, ct, ctlen)) {
+ free(pt);
+ EVP_CIPHER_CTX_free(ctx);
+ (*ndo->ndo_warning)(ndo, "%s: EVP_DecryptUpdate failed",
+ caller);
+ return NULL;
+ }
+ EVP_CIPHER_CTX_free(ctx);
+ return pt;
+}
+
/*
- * this will adjust ndo_packetp and ndo_snapend to new buffer!
+ * This will allocate a new buffer containing the decrypted data.
+ * It returns 1 on success and 0 on failure.
+ *
+ * It will push the new buffer and the values of ndo->ndo_packetp and
+ * ndo->ndo_snapend onto the buffer stack, and change ndo->ndo_packetp
+ * and ndo->ndo_snapend to refer to the new buffer.
+ *
+ * Our caller must pop the buffer off the stack when it's finished
+ * dissecting anything in it and before it does any dissection of
+ * anything in the old buffer. That will free the new buffer.
*/
USES_APPLE_DEPRECATED_API
-int esp_print_decrypt_buffer_by_ikev2(netdissect_options *ndo,
+int esp_decrypt_buffer_by_ikev2_print(netdissect_options *ndo,
int initiator,
const u_char spii[8],
const u_char spir[8],
{
struct sa_list *sa;
const u_char *iv;
- unsigned int len;
- EVP_CIPHER_CTX *ctx;
- unsigned int block_size, buffer_size;
- u_char *input_buffer, *output_buffer;
+ const u_char *ct;
+ unsigned int ctlen;
+ u_char *pt;
/* initiator arg is any non-zero value */
if(initiator) initiator=1;
*/
end = end - sa->authlen;
iv = buf;
- buf = buf + sa->ivlen;
- len = end-buf;
+ ct = iv + sa->ivlen;
+ ctlen = end-ct;
- if(end <= buf) return 0;
+ if(end <= ct) return 0;
- ctx = EVP_CIPHER_CTX_new();
- if (ctx == NULL)
+ pt = do_decrypt(ndo, "esp_decrypt_buffer_by_ikev2_print", sa, iv,
+ ct, ctlen);
+ if (pt == NULL)
return 0;
- if (set_cipher_parameters(ctx, sa->evp, sa->secret, NULL, 0) < 0)
- (*ndo->ndo_warning)(ndo, "espkey init failed");
- set_cipher_parameters(ctx, NULL, NULL, iv, 0);
- /*
- * Allocate buffers for the encrypted and decrypted data.
- * Both buffers' sizes must be a multiple of the cipher block
- * size, and the output buffer must be separate from the input
- * buffer.
- */
- block_size = (unsigned int)EVP_CIPHER_CTX_block_size(ctx);
- buffer_size = len + (block_size - len % block_size);
/*
- * Attempt to allocate the input buffer.
+ * Switch to the output buffer for dissection, and save it
+ * on the buffer stack so it can be freed; our caller must
+ * pop it when done.
*/
- input_buffer = (u_char *)malloc(buffer_size);
- if (input_buffer == NULL) {
- EVP_CIPHER_CTX_free(ctx);
- (*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC,
- "can't allocate memory for encrypted data buffer");
- }
- /*
- * Copy the input data to the encrypted data buffer, and pad it
- * with zeroes.
- */
- memcpy(input_buffer, buf, len);
- memset(input_buffer + len, 0, buffer_size - len);
-
- /*
- * Attempt to allocate the output buffer.
- */
- output_buffer = (u_char *)malloc(buffer_size);
- if (output_buffer == NULL) {
- free(input_buffer);
- EVP_CIPHER_CTX_free(ctx);
- (*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC,
- "can't allocate memory for decryption buffer");
+ if (!nd_push_buffer(ndo, pt, pt, pt + ctlen)) {
+ free(pt);
+ return 0;
}
- EVP_Cipher(ctx, output_buffer, input_buffer, 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(input_buffer);
- free(output_buffer);
-
- ndo->ndo_packetp = buf;
- ndo->ndo_snapend = end;
return 1;
}
sa->evp = evp;
sa->authlen = authlen;
+ /* This returns an int, but it should never be negative */
sa->ivlen = EVP_CIPHER_iv_length(evp);
colon++;
}
*colon = '\0';
- if(ascii_strcasecmp(colon,"sha1") == 0 ||
- ascii_strcasecmp(colon,"md5") == 0) {
+ if(ascii_strcasecmp(decode,"sha1") == 0 ||
+ ascii_strcasecmp(decode,"md5") == 0) {
sa->authlen = 12;
}
return 1;
if (decode) {
/* skip any blank spaces */
- while (isspace((unsigned char)*decode))
+ while (*decode == ' ' || *decode == '\t' || *decode == '\r' || *decode == '\n')
decode++;
if(!espprint_decode_encalgo(ndo, decode, &sa1)) {
}
USES_APPLE_RST
-void esp_print_decodesecret(netdissect_options *ndo)
+void esp_decodesecret_print(netdissect_options *ndo)
{
char *line;
char *p;
#endif
+#ifdef HAVE_LIBCRYPTO
+#define USED_IF_LIBCRYPTO
+#else
+#define USED_IF_LIBCRYPTO _U_
+#endif
+
#ifdef HAVE_LIBCRYPTO
USES_APPLE_DEPRECATED_API
#endif
-int
+void
esp_print(netdissect_options *ndo,
- const u_char *bp, const int length, const u_char *bp2
-#ifndef HAVE_LIBCRYPTO
- _U_
-#endif
- ,
- u_int *nhdr
-#ifndef HAVE_LIBCRYPTO
- _U_
-#endif
- ,
- u_int *padlen
-#ifndef HAVE_LIBCRYPTO
- _U_
-#endif
- )
+ const u_char *bp, u_int length,
+ const u_char *bp2 USED_IF_LIBCRYPTO,
+ u_int ver USED_IF_LIBCRYPTO,
+ int fragmented USED_IF_LIBCRYPTO,
+ u_int ttl_hl USED_IF_LIBCRYPTO)
{
const struct newesp *esp;
const u_char *ep;
const struct ip *ip;
struct sa_list *sa = NULL;
const struct ip6_hdr *ip6 = NULL;
- int advance;
- int len;
- u_char *secret;
- int ivlen = 0;
- const u_char *ivoff;
- const u_char *p;
- EVP_CIPHER_CTX *ctx;
- unsigned int block_size, buffer_size;
- u_char *input_buffer, *output_buffer;
+ const u_char *iv;
+ u_int ivlen;
+ u_int payloadlen;
+ const u_char *ct;
+ u_char *pt;
+ u_int padlen;
+ u_int nh;
#endif
ndo->ndo_protocol = "esp";
esp = (const struct newesp *)bp;
-#ifdef HAVE_LIBCRYPTO
- secret = NULL;
- advance = 0;
-#endif
-
-#if 0
- /* keep secret out of a register */
- p = (u_char *)&secret;
-#endif
-
/* 'ep' points to the end of available data. */
ep = ndo->ndo_snapend;
if ((const u_char *)(esp + 1) >= ep) {
nd_print_trunc(ndo);
- goto fail;
+ return;
}
ND_PRINT("ESP(spi=0x%08x", GET_BE_U_4(esp->esp_spi));
ND_PRINT(",seq=0x%x)", GET_BE_U_4(esp->esp_seq));
ND_PRINT(", length %u", length);
-#ifndef HAVE_LIBCRYPTO
- goto fail;
-#else
+#ifdef HAVE_LIBCRYPTO
/* initiailize SAs */
if (ndo->ndo_sa_list_head == NULL) {
if (!ndo->ndo_espsecret)
- goto fail;
+ return;
- esp_print_decodesecret(ndo);
+ esp_decodesecret_print(ndo);
}
if (ndo->ndo_sa_list_head == NULL)
- goto fail;
+ return;
ip = (const struct ip *)bp2;
- switch (IP_V(ip)) {
+ switch (ver) {
case 6:
ip6 = (const struct ip6_hdr *)bp2;
/* we do not attempt to decrypt jumbograms */
if (!GET_BE_U_2(ip6->ip6_plen))
- goto fail;
+ return;
+ /* XXX - check whether it's fragmented? */
/* if we can't get nexthdr, we do not need to decrypt it */
- len = sizeof(struct ip6_hdr) + GET_BE_U_2(ip6->ip6_plen);
/* see if we can find the SA, and if so, decode it */
for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
break;
case 4:
/* nexthdr & padding are in the last fragment */
- if (GET_BE_U_2(ip->ip_off) & IP_MF)
- goto fail;
- len = GET_BE_U_2(ip->ip_len);
+ if (fragmented)
+ return;
/* see if we can find the SA, and if so, decode it */
for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
}
break;
default:
- goto fail;
+ return;
}
/* if we didn't find the specific one, then look for
/* if not found fail */
if (sa == NULL)
- goto fail;
-
- /* if we can't get nexthdr, we do not need to decrypt it */
- if (ep - bp2 < len)
- goto fail;
- if (ep - bp2 > len) {
- /* FCS included at end of frame (NetBSD 1.6 or later) */
- ep = bp2 + len;
- }
+ return;
/* pointer to the IV, if there is one */
- ivoff = (const u_char *)(esp + 1) + 0;
+ iv = (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;
+
+ /*
+ * Get a pointer to the ciphertext.
+ *
+ * p points to the beginning of the payload, i.e. to the
+ * initialization vector, so if we skip past the initialization
+ * vector, it points to the beginning of the ciphertext.
+ */
+ ct = iv + ivlen;
+
+ /*
+ * Make sure the authentication data/integrity check value length
+ * isn't bigger than the total amount of data available after
+ * the ESP header and initialization vector is removed and,
+ * if not, slice the authentication data/ICV off.
+ */
+ if (ep - ct < sa->authlen) {
+ nd_print_trunc(ndo);
+ return;
+ }
ep = ep - sa->authlen;
- if (sa->evp) {
- ctx = EVP_CIPHER_CTX_new();
- if (ctx != NULL) {
- if (set_cipher_parameters(ctx, sa->evp, secret, NULL, 0) < 0)
- (*ndo->ndo_warning)(ndo, "espkey init failed");
-
- p = ivoff;
- set_cipher_parameters(ctx, NULL, NULL, p, 0);
- len = ep - (p + ivlen);
-
- /*
- * Allocate buffers for the encrypted and decrypted
- * data. Both buffers' sizes must be a multiple of
- * the cipher block size, and the output buffer must
- * be separate from the input buffer.
- */
- block_size = (unsigned int)EVP_CIPHER_CTX_block_size(ctx);
- buffer_size = len + (block_size - len % block_size);
-
- /*
- * Attempt to allocate the input buffer.
- */
- input_buffer = (u_char *)malloc(buffer_size);
- if (input_buffer == NULL) {
- EVP_CIPHER_CTX_free(ctx);
- (*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC,
- "esp_print: can't allocate memory for encrypted data buffer");
- }
- /*
- * Copy the input data to the encrypted data buffer,
- * and pad it with zeroes.
- */
- memcpy(input_buffer, p + ivlen, len);
- memset(input_buffer + len, 0, buffer_size - len);
-
- /*
- * Attempt to allocate the output buffer.
- */
- output_buffer = (u_char *)malloc(buffer_size);
- if (output_buffer == NULL) {
- free(input_buffer);
- EVP_CIPHER_CTX_free(ctx);
- (*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC,
- "esp_print: can't allocate memory for decryption buffer");
- }
+ /*
+ * Calculate the length of the ciphertext. ep points to
+ * the beginning of the authentication data/integrity check
+ * value, i.e. right past the end of the ciphertext;
+ */
+ payloadlen = ep - ct;
- EVP_Cipher(ctx, output_buffer, input_buffer, len);
- free(input_buffer);
- 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);
- } else
- advance = sizeof(struct newesp);
+ if (sa->evp == NULL)
+ return;
- /* sanity check for pad length */
- if (ep - bp < GET_U_1(ep - 2))
- goto fail;
+ /*
+ * If the next header value is past the end of the available
+ * data, we won't be able to fetch it once we've decrypted
+ * the ciphertext, so there's no point in decrypting the data.
+ *
+ * Report it as truncation.
+ */
+ if (!ND_TTEST_1(ep - 1)) {
+ nd_print_trunc(ndo);
+ return;
+ }
- if (padlen)
- *padlen = GET_U_1(ep - 2) + 2;
+ pt = do_decrypt(ndo, "esp_print", sa, iv, ct, payloadlen);
+ if (pt == NULL)
+ return;
- if (nhdr)
- *nhdr = GET_U_1(ep - 1);
+ /*
+ * Switch to the output buffer for dissection, and
+ * save it on the buffer stack so it can be freed.
+ */
+ ep = pt + payloadlen;
+ if (!nd_push_buffer(ndo, pt, pt, ep)) {
+ free(pt);
+ (*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC,
+ "esp_print: can't push buffer on buffer stack");
+ }
+
+ /*
+ * Sanity check for pad length; if it, plus 2 for the pad
+ * length and next header fields, is bigger than the ciphertext
+ * length (which is also the plaintext length), it's too big.
+ *
+ * XXX - the check can fail if the packet is corrupt *or* if
+ * it was not decrypted with the correct key, so that the
+ * "plaintext" is not what was being sent.
+ */
+ padlen = GET_U_1(ep - 2);
+ if (padlen + 2 > payloadlen) {
+ nd_print_trunc(ndo);
+ return;
+ }
+
+ /* Get the next header */
+ nh = GET_U_1(ep - 1);
ND_PRINT(": ");
- return advance;
-#endif
-fail:
- return -1;
+ /* Now dissect the plaintext. */
+ ip_demux_print(ndo, pt, payloadlen - (padlen + 2), ver, fragmented,
+ ttl_hl, nh, bp2);
+
+ /* Pop the buffer, freeing it. */
+ nd_pop_packet_info(ndo);
+#endif
}
#ifdef HAVE_LIBCRYPTO
USES_APPLE_RST
projects / tcpdump / blobdiff