[PATCH v3] store length of ESP encryption and HMAC keys so that they can be manipulated separately for both Juniper and GP
Daniel Lenski
dlenski at gmail.com
Fri May 26 16:57:14 PDT 2017
Shame on me!!! I tested that this built and worked correctly only with
GnuTLS, not OpenSSL.
David,
Looks like you already caught and patched it yourself:
http://git.infradead.org/users/dwmw2/openconnect.git/blobdiff/b2b1dd0702239d415943cea6f821a345e0d50b63..d8b283f168c8e9574a821eef077b40984fae1026:/openssl-esp.c
A user of openconnect-gp ran into this as well. Sorry about that. :-(
-Dan
On Sun, May 14, 2017 at 9:22 PM, Daniel Lenski <dlenski at gmail.com> wrote:
> David Woodhouse wrote:
>> Daniel Lenski wrote:
>>> - unsigned char secrets[0x40];
>>> + unsigned char secrets[0x40]; /* Encryption key bytes, then HMAC key bytes */
>>
>> You're allowed to object to that horridness and split it into two
>> separate fields for the encryption and HMAC keys, instead of just
>> documenting it.
>>
>> In fact, one might argue that would be the better approach...
>
> Signed-off-by: Daniel Lenski <dlenski at gmail.com>
> ---
> esp.c | 13 ++++---------
> gnutls-esp.c | 7 ++++---
> oncp.c | 37 +++++++++++++++++++++++++++----------
> openconnect-internal.h | 11 ++++++++++-
> openssl-esp.c | 5 +++--
> 5 files changed, 48 insertions(+), 25 deletions(-)
>
> diff --git a/esp.c b/esp.c
> index 44c9407..30ec442 100644
> --- a/esp.c
> +++ b/esp.c
> @@ -32,16 +32,13 @@ int print_esp_keys(struct openconnect_info *vpninfo, const char *name, struct es
> int i;
> const char *enctype, *mactype;
> char enckey[256], mackey[256];
> - int enclen, maclen;
>
> switch(vpninfo->esp_enc) {
> case 0x02:
> enctype = "AES-128-CBC (RFC3602)";
> - enclen = 16;
> break;
> case 0x05:
> enctype = "AES-256-CBC (RFC3602)";
> - enclen = 32;
> break;
> default:
> return -EINVAL;
> @@ -49,20 +46,18 @@ int print_esp_keys(struct openconnect_info *vpninfo, const char *name, struct es
> switch(vpninfo->esp_hmac) {
> case 0x01:
> mactype = "HMAC-MD5-96 (RFC2403)";
> - maclen = 16;
> break;
> case 0x02:
> mactype = "HMAC-SHA-1-96 (RFC2404)";
> - maclen = 20;
> break;
> default:
> return -EINVAL;
> }
>
> - for (i = 0; i < enclen; i++)
> - sprintf(enckey + (2 * i), "%02x", esp->secrets[i]);
> - for (i = 0; i < maclen; i++)
> - sprintf(mackey + (2 * i), "%02x", esp->secrets[enclen + i]);
> + for (i = 0; i < vpninfo->enc_key_len; i++)
> + sprintf(enckey + (2 * i), "%02x", esp->enc_key[i]);
> + for (i = 0; i < vpninfo->hmac_key_len; i++)
> + sprintf(mackey + (2 * i), "%02x", esp->hmac_key[i]);
>
> vpn_progress(vpninfo, PRG_TRACE,
> _("Parameters for %s ESP: SPI 0x%08x\n"),
> diff --git a/gnutls-esp.c b/gnutls-esp.c
> index 1ad4e60..f3fd499 100644
> --- a/gnutls-esp.c
> +++ b/gnutls-esp.c
> @@ -48,7 +48,7 @@ static int init_esp_ciphers(struct openconnect_info *vpninfo, struct esp *esp,
> destroy_esp_ciphers(esp);
>
> enc_key.size = gnutls_cipher_get_key_size(encalg);
> - enc_key.data = esp->secrets;
> + enc_key.data = esp->enc_key;
>
> err = gnutls_cipher_init(&esp->cipher, encalg, &enc_key, NULL);
> if (err) {
> @@ -59,7 +59,7 @@ static int init_esp_ciphers(struct openconnect_info *vpninfo, struct esp *esp,
> }
>
> err = gnutls_hmac_init(&esp->hmac, macalg,
> - esp->secrets + enc_key.size,
> + esp->hmac_key,
> gnutls_hmac_get_len(macalg));
> if (err) {
> vpn_progress(vpninfo, PRG_ERR,
> @@ -111,7 +111,8 @@ int setup_esp_keys(struct openconnect_info *vpninfo)
> esp_in = &vpninfo->esp_in[vpninfo->current_esp_in];
>
> if ((ret = gnutls_rnd(GNUTLS_RND_NONCE, &esp_in->spi, sizeof(esp_in->spi))) ||
> - (ret = gnutls_rnd(GNUTLS_RND_RANDOM, &esp_in->secrets, sizeof(esp_in->secrets)))) {
> + (ret = gnutls_rnd(GNUTLS_RND_RANDOM, &esp_in->enc_key, vpninfo->enc_key_len)) ||
> + (ret = gnutls_rnd(GNUTLS_RND_RANDOM, &esp_in->hmac_key, vpninfo->hmac_key_len)) ) {
> vpn_progress(vpninfo, PRG_ERR,
> _("Failed to generate random keys for ESP: %s\n"),
> gnutls_strerror(ret));
> diff --git a/oncp.c b/oncp.c
> index 3c7cfa1..45c2f15 100644
> --- a/oncp.c
> +++ b/oncp.c
> @@ -302,11 +302,13 @@ static int process_attr(struct openconnect_info *vpninfo, int group, int attr,
>
> if (attrlen != 1)
> goto badlen;
> - if (data[0] == 0x02)
> + if (data[0] == ENC_AES_128_CBC) {
> enctype = "AES-128";
> - else if (data[0] == 0x05)
> + vpninfo->enc_key_len = 16;
> + } else if (data[0] == ENC_AES_256_CBC) {
> enctype = "AES-256";
> - else
> + vpninfo->enc_key_len = 32;
> + } else
> enctype = "unknown";
> vpn_progress(vpninfo, PRG_DEBUG, _("ESP encryption: 0x%02x (%s)\n"),
> data[0], enctype);
> @@ -319,11 +321,13 @@ static int process_attr(struct openconnect_info *vpninfo, int group, int attr,
>
> if (attrlen != 1)
> goto badlen;
> - if (data[0] == 0x01)
> + if (data[0] == HMAC_MD5) {
> mactype = "MD5";
> - else if (data[0] == 0x02)
> + vpninfo->hmac_key_len = 16;
> + } else if (data[0] == HMAC_SHA1) {
> mactype = "SHA1";
> - else
> + vpninfo->hmac_key_len = 20;
> + } else
> mactype = "unknown";
> vpn_progress(vpninfo, PRG_DEBUG, _("ESP HMAC: 0x%02x (%s)\n"),
> data[0], mactype);
> @@ -389,7 +393,8 @@ static int process_attr(struct openconnect_info *vpninfo, int group, int attr,
> case GRP_ATTR(7, 2):
> if (attrlen != 0x40)
> goto badlen;
> - memcpy(vpninfo->esp_out.secrets, data, 0x40);
> + /* data contains enc_key and hmac_key concatenated */
> + memcpy(vpninfo->esp_out.enc_key, data, 0x40);
> vpn_progress(vpninfo, PRG_DEBUG, _("%d bytes of ESP secrets\n"),
> attrlen);
> break;
> @@ -490,6 +495,7 @@ static int parse_conf_pkt(struct openconnect_info *vpninfo, unsigned char *bytes
> {
> int kmplen, kmpend, grouplen, groupend, group, attr, attrlen;
> int ofs = 0;
> + int split_enc_hmac_keys = 0;
>
> kmplen = load_be16(bytes + ofs + 18);
> kmpend = ofs + kmplen;
> @@ -533,12 +539,21 @@ static int parse_conf_pkt(struct openconnect_info *vpninfo, unsigned char *bytes
> goto eparse;
> if (process_attr(vpninfo, group, attr, bytes + ofs, attrlen))
> goto eparse;
> + if (GRP_ATTR(group, attr)==GRP_ATTR(7, 2))
> + split_enc_hmac_keys = 1;
> ofs += attrlen;
> }
> }
> +
> + /* The encryption and HMAC keys are sent concatenated together in a block of 0x40 bytes;
> + we can't split them apart until we know how long the encryption key is. */
> + if (split_enc_hmac_keys)
> + memcpy(vpninfo->esp_out.hmac_key, vpninfo->esp_out.enc_key + vpninfo->enc_key_len, vpninfo->hmac_key_len);
> +
> return 0;
> }
>
> +
> int oncp_connect(struct openconnect_info *vpninfo)
> {
> int ret, len, kmp, kmplen, group;
> @@ -786,7 +801,8 @@ int oncp_connect(struct openconnect_info *vpninfo)
> buf_append_bytes(reqbuf, esp_kmp_hdr, sizeof(esp_kmp_hdr));
> buf_append_bytes(reqbuf, &esp->spi, sizeof(esp->spi));
> buf_append_bytes(reqbuf, esp_kmp_part2, sizeof(esp_kmp_part2));
> - buf_append_bytes(reqbuf, &esp->secrets, sizeof(esp->secrets));
> + buf_append_bytes(reqbuf, &esp->enc_key, vpninfo->enc_key_len);
> + buf_append_bytes(reqbuf, &esp->hmac_key, 0x40 - vpninfo->enc_key_len);
> if (buf_error(reqbuf)) {
> vpn_progress(vpninfo, PRG_ERR,
> _("Error negotiating ESP keys\n"));
> @@ -840,8 +856,9 @@ static int oncp_receive_espkeys(struct openconnect_info *vpninfo, int len)
> p += sizeof(esp->spi);
> memcpy(p, esp_kmp_part2, sizeof(esp_kmp_part2));
> p += sizeof(esp_kmp_part2);
> - memcpy(p, esp->secrets, sizeof(esp->secrets));
> - p += sizeof(esp->secrets);
> + memcpy(p, esp->enc_key, vpninfo->enc_key_len);
> + memcpy(p+vpninfo->enc_key_len, esp->hmac_key, 0x40 - vpninfo->enc_key_len);
> + p += 0x40;
> vpninfo->cstp_pkt->len = p - vpninfo->cstp_pkt->data;
> store_le16(vpninfo->cstp_pkt->oncp.rec,
> (p - vpninfo->cstp_pkt->oncp.kmp));
> diff --git a/openconnect-internal.h b/openconnect-internal.h
> index a24a9e4..a54761f 100644
> --- a/openconnect-internal.h
> +++ b/openconnect-internal.h
> @@ -335,7 +335,8 @@ struct esp {
> uint64_t seq_backlog;
> uint64_t seq;
> uint32_t spi; /* Stored network-endian */
> - unsigned char secrets[0x40];
> + unsigned char enc_key[0x40]; /* Encryption key */
> + unsigned char hmac_key[0x40]; /* HMAC key */
> };
>
> struct openconnect_info {
> @@ -359,6 +360,8 @@ struct openconnect_info {
> int old_esp_maxseq;
> struct esp esp_in[2];
> struct esp esp_out;
> + int enc_key_len;
> + int hmac_key_len;
>
> int tncc_fd; /* For Juniper TNCC */
> const char *csd_xmltag;
> @@ -684,6 +687,12 @@ struct openconnect_info {
> #define AC_PKT_COMPRESSED 8 /* Compressed data */
> #define AC_PKT_TERM_SERVER 9 /* Server kick */
>
> +/* Encryption and HMAC algorithms (matching Juniper's binary encoding) */
> +#define ENC_AES_128_CBC 2
> +#define ENC_AES_256_CBC 5
> +#define HMAC_MD5 1
> +#define HMAC_SHA1 2
> +
> #define vpn_progress(_v, lvl, ...) do { \
> if ((_v)->verbose >= (lvl)) \
> (_v)->progress((_v)->cbdata, lvl, __VA_ARGS__); \
> diff --git a/openssl-esp.c b/openssl-esp.c
> index e20bde0..faba1ff 100644
> --- a/openssl-esp.c
> +++ b/openssl-esp.c
> @@ -99,7 +99,7 @@ static int init_esp_ciphers(struct openconnect_info *vpninfo, struct esp *esp,
> destroy_esp_ciphers(esp);
> return -ENOMEM;
> }
> - if (!HMAC_Init_ex(esp->hmac, esp->secrets + EVP_CIPHER_key_length(encalg),
> + if (!HMAC_Init_ex(esp->hmac, esp->hmac_key,
> EVP_MD_size(macalg), macalg, NULL)) {
> vpn_progress(vpninfo, PRG_ERR,
> _("Failed to initialize ESP HMAC\n"));
> @@ -151,7 +151,8 @@ int setup_esp_keys(struct openconnect_info *vpninfo)
> esp_in = &vpninfo->esp_in[vpninfo->current_esp_in];
>
> if (!RAND_bytes((void *)&esp_in->spi, sizeof(esp_in->spi)) ||
> - !RAND_bytes((void *)&esp_in->secrets, sizeof(esp_in->secrets))) {
> + !RAND_bytes((void *)&esp_in->enc_key, vpninfo->enc_key_len)) ||
> + !RAND_bytes((void *)&esp_in->hmac_key, vpninfo->hmac_key_len)) ) {
> vpn_progress(vpninfo, PRG_ERR,
> _("Failed to generate random keys for ESP:\n"));
> openconnect_report_ssl_errors(vpninfo);
> --
> 2.7.4
>
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