[PATCH] Expose additional SSL variables
Paulo Pacheco
fooinha at gmail.com
Fri Apr 24 16:17:28 UTC 2020
Hello, this looks very similar with what I've done here.
https://github.com/fooinha/nginx-ssl-ja3/blob/master/patches/nginx.1.17.1.ssl.extensions.patch <https://github.com/fooinha/nginx-ssl-ja3/blob/master/patches/nginx.1.17.1.ssl.extensions.patch>
Is this the same code?
Thanx.
> On 24 Apr 2020, at 16:17, Garret Reece <garret at trailofbits.com> wrote:
>
> # HG changeset patch
> # User Garret Reece <garret at trailofbits.com>
> # Date 1587691836 18000
> # Thu Apr 23 20:30:36 2020 -0500
> # Node ID 86d2f46807f597249fa59072b920a389f8c082ee
> # Parent 716eddd74bc2831537f5b3f7ecd16ad3e516d043
> Expose additional SSL variables.
>
> Expose the ssl extensions and elliptic curve point formats provided by client.
> This enables ja3 fingerprinting of TLS connections.
>
> diff -r 716eddd74bc2 -r 86d2f46807f5 src/event/ngx_event_openssl.c
> --- a/src/event/ngx_event_openssl.c Thu Apr 23 15:10:26 2020 +0300
> +++ b/src/event/ngx_event_openssl.c Thu Apr 23 20:30:36 2020 -0500
> @@ -1588,6 +1588,100 @@
> return NGX_OK;
> }
>
> +#if OPENSSL_VERSION_NUMBER >= 0x10101000L
> +
> +void
> +ngx_SSL_client_features(ngx_connection_t *c)
> +{
> + unsigned short *ciphers_out = NULL;
> + int *curves_out = NULL;
> + int *point_formats_out = NULL;
> + size_t len = 0;
> + SSL *s = NULL;
> +
> + if (c == NULL) {
> + return;
> + }
> + s = c->ssl->connection;
> +
> + /* Cipher suites */
> + c->ssl->ciphers = NULL;
> + c->ssl->ciphers_sz = SSL_get0_raw_cipherlist(s, &ciphers_out);
> + c->ssl->ciphers_sz /= 2;
> +
> + if (c->ssl->ciphers_sz && ciphers_out) {
> + len = c->ssl->ciphers_sz * sizeof(unsigned short);
> + c->ssl->ciphers = ngx_pnalloc(c->pool, len);
> + ngx_memcpy(c->ssl->ciphers, ciphers_out, len);
> + }
> +
> + /* Elliptic curve points */
> + c->ssl->curves_sz = SSL_get1_curves(s, NULL);
> + if (c->ssl->curves_sz) {
> + curves_out = OPENSSL_malloc(c->ssl->curves_sz * sizeof(int));
> + if (curves_out != NULL) {
> + SSL_get1_curves(s, curves_out);
> + len = c->ssl->curves_sz * sizeof(unsigned short);
> + c->ssl->curves = ngx_pnalloc(c->pool, len);
> + if (c->ssl->curves != NULL) {
> + for (size_t i = 0; i < c->ssl->curves_sz; i++) {
> + c->ssl->curves[i] = curves_out[i];
> + }
> + }
> + OPENSSL_free(curves_out);
> + }
> + }
> +
> + /* Elliptic curve point formats */
> + c->ssl->point_formats_sz = SSL_get0_ec_point_formats(s,
> + &point_formats_out);
> + if (c->ssl->point_formats_sz && point_formats_out != NULL) {
> + len = c->ssl->point_formats_sz * sizeof(unsigned char);
> + c->ssl->point_formats = ngx_pnalloc(c->pool, len);
> + if (c->ssl->point_formats != NULL) {
> + ngx_memcpy(c->ssl->point_formats, point_formats_out, len);
> + }
> + }
> +}
> +
> +int
> +ngx_SSL_early_cb_fn(SSL *s, int *al, void *arg)
> +{
> + int got_extensions;
> + int *ext_out;
> + size_t ext_len;
> + ngx_connection_t *c;
> +
> + c = arg;
> +
> + if (c == NULL) {
> + return 1;
> + }
> +
> + if (c->ssl == NULL) {
> + return 1;
> + }
> +
> + c->ssl->extensions_size = 0;
> + c->ssl->extensions = NULL;
> + got_extensions = SSL_client_hello_get1_extensions_present(s,
> + &ext_out,
> + &ext_len);
> + if (got_extensions) {
> + if (ext_out && ext_len) {
> + c->ssl->extensions =
> + ngx_palloc(c->pool, sizeof(int) * ext_len);
> + if (c->ssl->extensions != NULL) {
> + c->ssl->extensions_size = ext_len;
> + ngx_memcpy(c->ssl->extensions, ext_out, sizeof(int) * ext_len);
> + OPENSSL_free(ext_out);
> + }
> + }
> + }
> +
> + return 1;
> +}
> +#endif
>
> ngx_int_t
> ngx_ssl_handshake(ngx_connection_t *c)
> @@ -1603,6 +1697,10 @@
>
> ngx_ssl_clear_error(c->log);
>
> +#if OPENSSL_VERSION_NUMBER >= 0x10101000L
> + SSL_CTX_set_client_hello_cb(c->ssl->session_ctx, ngx_SSL_early_cb_fn, c);
> +#endif
> +
> n = SSL_do_handshake(c->ssl->connection);
>
> ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "SSL_do_handshake: %d", n);
> @@ -1623,6 +1721,10 @@
>
> c->ssl->handshaked = 1;
>
> +#if OPENSSL_VERSION_NUMBER >= 0x10101000L
> + ngx_SSL_client_features(c);
> +#endif
> +
> c->recv = ngx_ssl_recv;
> c->send = ngx_ssl_write;
> c->recv_chain = ngx_ssl_recv_chain;
> @@ -5044,6 +5146,86 @@
> return NGX_OK;
> }
>
> +#if OPENSSL_VERSION_NUMBER >= 0x10101000L
> +
> +ngx_int_t
> +ngx_ssl_get_extensions(ngx_connection_t *c, ngx_pool_t *pool, ngx_str_t *s)
> +{
> + size_t len;
> + u_char *p;
> +
> + len = 0;
> + s->len = 0;
> +
> + if (c->ssl->extensions_size && c->ssl->extensions) {
> + for (int n = c->ssl->extensions[0]; n > 9; n /= 10) {
> + len += 1;
> + }
> + len += 1;
> + for (size_t i = 1; i < c->ssl->extensions_size; ++i) {
> + len += 1; /* for the '-' separator */
> + for (int n = c->ssl->extensions[i]; n > 9; n /= 10) {
> + len += 1;
> + }
> + len += 1;
> + }
> +
> + s->data = ngx_pnalloc(pool, len+1);
> + if (s->data == NULL) {
> + return NGX_ERROR;
> + }
> + s->len = len;
> +
> + p = ngx_sprintf(s->data, "%d", c->ssl->extensions[0]);
> + for (size_t i = 1; i < c->ssl->extensions_size; ++i) {
> + p = ngx_sprintf(p, "-%d", c->ssl->extensions[i]);
> + }
> +
> + }
> + return NGX_OK;
> +}
> +
> +
> +ngx_int_t
> +ngx_ssl_get_ec_point_formats(ngx_connection_t *c, ngx_pool_t *pool,
> + ngx_str_t *s)
> +{
> + size_t len;
> + u_char *p;
> +
> + len = 0;
> + s->len = 0;
> +
> + if (c->ssl->point_formats_sz && c->ssl->point_formats) {
> + for (unsigned char n = c->ssl->point_formats[0]; n > 9; n /= 10) {
> + len += 1;
> + }
> + len += 1;
> + for (size_t i = 1; i < c->ssl->point_formats_sz; ++i) {
> + len += 1; /* for the '-' separator */
> + for (unsigned char n = c->ssl->point_formats[i]; n > 9; n /= 10) {
> + len += 1;
> + }
> + len += 1;
> + }
> +
> + s->data = ngx_pnalloc(pool, len+1);
> + if (s->data == NULL) {
> + return NGX_ERROR;
> + }
> + s->len = len;
> +
> + p = ngx_sprintf(s->data, "%d", c->ssl->point_formats[0]);
> + for (size_t i = 1; i < c->ssl->point_formats_sz; ++i) {
> + p = ngx_sprintf(p, "-%d", c->ssl->point_formats[i]);
> + }
> + }
> +
> + return NGX_OK;
> +}
> +
> +#endif
> +
>
> static time_t
> ngx_ssl_parse_time(
> diff -r 716eddd74bc2 -r 86d2f46807f5 src/event/ngx_event_openssl.h
> --- a/src/event/ngx_event_openssl.h Thu Apr 23 15:10:26 2020 +0300
> +++ b/src/event/ngx_event_openssl.h Thu Apr 23 20:30:36 2020 -0500
> @@ -99,6 +99,21 @@
> unsigned in_early:1;
> unsigned early_preread:1;
> unsigned write_blocked:1;
> +
> +#if OPENSSL_VERSION_NUMBER >= 0x10101000L
> +
> + size_t ciphers_sz;
> + unsigned short *ciphers;
> +
> + size_t extensions_size;
> + int *extensions;
> +
> + size_t curves_sz;
> + unsigned short *curves;
> +
> + size_t point_formats_sz;
> + unsigned char *point_formats;
> +#endif
> };
>
>
> @@ -263,6 +278,14 @@
> ngx_int_t ngx_ssl_get_client_v_remain(ngx_connection_t *c, ngx_pool_t *pool,
> ngx_str_t *s);
>
> +#if OPENSSL_VERSION_NUMBER >= 0x10101000L
> +
> +ngx_int_t ngx_ssl_get_extensions(ngx_connection_t *c, ngx_pool_t *pool,
> + ngx_str_t *s);
> +ngx_int_t ngx_ssl_get_ec_point_formats(ngx_connection_t *c, ngx_pool_t *pool,
> + ngx_str_t *s);
> +
> +#endif
>
> ngx_int_t ngx_ssl_handshake(ngx_connection_t *c);
> ssize_t ngx_ssl_recv(ngx_connection_t *c, u_char *buf, size_t size);
> diff -r 716eddd74bc2 -r 86d2f46807f5 src/http/modules/ngx_http_ssl_module.c
> --- a/src/http/modules/ngx_http_ssl_module.c Thu Apr 23 15:10:26 2020 +0300
> +++ b/src/http/modules/ngx_http_ssl_module.c Thu Apr 23 20:30:36 2020 -0500
> @@ -352,6 +352,17 @@
> { ngx_string("ssl_client_v_remain"), NULL, ngx_http_ssl_variable,
> (uintptr_t) ngx_ssl_get_client_v_remain, NGX_HTTP_VAR_CHANGEABLE, 0 },
>
> +#if OPENSSL_VERSION_NUMBER >= 0x10101000L
> +
> + { ngx_string("ssl_extensions"), NULL, ngx_http_ssl_variable,
> + (uintptr_t) ngx_ssl_get_extensions, NGX_HTTP_VAR_CHANGEABLE, 0 },
> +
> + { ngx_string("ssl_elliptic_curve_point_formats"), NULL,
> + ngx_http_ssl_variable, (uintptr_t) ngx_ssl_get_ec_point_formats,
> + NGX_HTTP_VAR_CHANGEABLE, 0 },
> +
> +#endif
> +
> ngx_http_null_variable
> };
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> nginx-devel at nginx.org
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