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#include #include #include #include #define DEFAULT_SECRET "changeme" #define SHA1_MD_LEN 20 #define SHA1_STR_LEN 40 #define JS_SOLVER_TEMPLATE \ "" \ "" \ "" \ "" \ "%s" \ "" \ "" \ "" \ "%s" \ "" \ "" #define DEFAULT_TITLE "Verifying your browser..." typedef struct { ngx_flag_t enabled; ngx_uint_t bucket_duration; ngx_str_t secret; ngx_str_t html_path; ngx_str_t title; char *html; } ngx_http_js_challenge_loc_conf_t; static ngx_int_t ngx_http_js_challenge(ngx_conf_t *cf); static void *ngx_http_js_challenge_create_loc_conf(ngx_conf_t *cf); static char *ngx_http_js_challenge_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child); static ngx_int_t ngx_http_js_challenge_handler(ngx_http_request_t *r); unsigned char *__sha1(const unsigned char *d, size_t n, unsigned char *md); static ngx_command_t ngx_http_js_challenge_commands[] = { { ngx_string("js_challenge"), NGX_HTTP_LOC_CONF | NGX_HTTP_LIF_CONF | NGX_HTTP_SIF_CONF | NGX_HTTP_SRV_CONF | NGX_CONF_FLAG, ngx_conf_set_flag_slot, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_js_challenge_loc_conf_t, enabled), NULL }, { ngx_string("js_challenge_bucket_duration"), NGX_HTTP_LOC_CONF | NGX_HTTP_SRV_CONF | NGX_CONF_TAKE1, ngx_conf_set_num_slot, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_js_challenge_loc_conf_t, bucket_duration), NULL }, { ngx_string("js_challenge_secret"), NGX_HTTP_LOC_CONF | NGX_HTTP_SRV_CONF | NGX_CONF_TAKE1, ngx_conf_set_str_slot, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_js_challenge_loc_conf_t, secret), NULL }, { ngx_string("js_challenge_html"), NGX_HTTP_LOC_CONF | NGX_HTTP_SRV_CONF | NGX_CONF_TAKE1, ngx_conf_set_str_slot, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_js_challenge_loc_conf_t, html_path), NULL }, { ngx_string("js_challenge_title"), NGX_HTTP_LOC_CONF | NGX_HTTP_SRV_CONF | NGX_CONF_TAKE1, ngx_conf_set_str_slot, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_js_challenge_loc_conf_t, title), NULL }, ngx_null_command }; /* * Module context */ static ngx_http_module_t ngx_http_js_challenge_module_ctx = { NULL, /* preconfiguration */ ngx_http_js_challenge, /* postconfiguration */ NULL, NULL, NULL, NULL, ngx_http_js_challenge_create_loc_conf, ngx_http_js_challenge_merge_loc_conf }; ngx_module_t ngx_http_js_challenge_module = { NGX_MODULE_V1, &ngx_http_js_challenge_module_ctx, ngx_http_js_challenge_commands, NGX_HTTP_MODULE, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NGX_MODULE_V1_PADDING }; static void *ngx_http_js_challenge_create_loc_conf(ngx_conf_t *cf) { ngx_http_js_challenge_loc_conf_t *conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_js_challenge_loc_conf_t)); if (conf == NULL) { return NGX_CONF_ERROR; } conf->secret = (ngx_str_t) {0, NULL}; conf->bucket_duration = NGX_CONF_UNSET_UINT; conf->enabled = NGX_CONF_UNSET; return conf; } static char *ngx_http_js_challenge_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child) { ngx_http_js_challenge_loc_conf_t *prev = parent; ngx_http_js_challenge_loc_conf_t *conf = child; ngx_conf_merge_uint_value(conf->bucket_duration, prev->bucket_duration, 3600) ngx_conf_merge_value(conf->enabled, prev->enabled, 0) ngx_conf_merge_str_value(conf->secret, prev->secret, DEFAULT_SECRET) ngx_conf_merge_str_value(conf->html_path, prev->html_path, NULL) ngx_conf_merge_str_value(conf->title, prev->title, DEFAULT_TITLE) if (conf->bucket_duration < 1) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "bucket_duration must be equal or more than 1"); return NGX_CONF_ERROR; } if (conf->html_path.data == NULL) { conf->html = NULL; } else if (conf->enabled) { // Read file in memory char path[PATH_MAX]; memcpy(path, conf->html_path.data, conf->html_path.len); *(path + conf->html_path.len) = '\0'; struct stat info; stat(path, &info); int fd = open(path, O_RDONLY, 0); if (fd < 0) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "js_challenge_html: Could not open file '%s': %s", path, strerror(errno)); close(fd); return NGX_CONF_ERROR; } conf->html = ngx_palloc(cf->pool, info.st_size); int ret = read(fd, conf->html, info.st_size-1); *(conf->html+ret) = '\0'; close(fd); if (ret < 0) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "js_challenge_html: Could not read file '%s': %s", path, strerror(errno)); return NGX_CONF_ERROR; } } return NGX_CONF_OK; } __always_inline static void buf2hex(const unsigned char *buf, size_t buflen, char *hex_string) { static const char hexdig[] = "0123456789ABCDEF"; const unsigned char *p; size_t i; char *s = hex_string; for (i = 0, p = buf; i < buflen; i++, p++) { *s++ = hexdig[(*p >> 4) & 0x0f]; *s++ = hexdig[*p & 0x0f]; } } int serve_challenge(ngx_http_request_t *r, const char *challenge, const char *html, ngx_str_t title) { ngx_buf_t *b = ngx_pcalloc(r->pool, sizeof(ngx_buf_t)); ngx_chain_t out; char challenge_c_str[SHA1_STR_LEN + 1]; memcpy(challenge_c_str, challenge, SHA1_STR_LEN); *(challenge_c_str + SHA1_STR_LEN) = '\0'; char title_c_str[4096]; memcpy(title_c_str, title.data, title.len); *(title_c_str + title.len) = '\0'; unsigned char buf[32768]; static const ngx_str_t content_type = ngx_string("text/html;charset=utf-8"); if (html == NULL) { html = "

Set the `js_challenge_html /path/to/body.html;` directive to change this page.

"; } size_t size = snprintf((char *) buf, sizeof(buf), JS_SOLVER_TEMPLATE, title_c_str, challenge_c_str, html); out.buf = b; out.next = NULL; // TODO: is that stack buffer gonna cause problems? b->pos = buf; b->last = buf + size; b->memory = 1; b->last_buf = 1; r->headers_out.status = NGX_HTTP_SERVICE_UNAVAILABLE; r->headers_out.content_length_n = size; r->headers_out.content_type = content_type; ngx_http_send_header(r); ngx_http_output_filter(r, &out); ngx_http_finalize_request(r, 0); return NGX_DONE; } /** * @param out 40 bytes long string! */ void get_challenge_string(int32_t bucket, ngx_str_t addr, ngx_str_t secret, char *out) { char buf[4096]; unsigned char md[SHA1_MD_LEN]; char *p = (char *) &bucket; /* * Challenge= hex( SHA1( concat(bucket, addr, secret) ) ) */ memcpy(buf, p, sizeof(bucket)); memcpy((buf + sizeof(int32_t)), addr.data, addr.len); memcpy((buf + sizeof(int32_t) + addr.len), secret.data, secret.len); __sha1((unsigned char *) buf, (size_t) (sizeof(int32_t) + addr.len + secret.len), md); buf2hex(md, SHA1_MD_LEN, out); } int verify_response(ngx_str_t response, char *challenge) { /* * Response is valid if it starts by the challenge, and * its SHA1 hash contains the digits 0xB00B at the offset * of the first digit * * e.g. * challenge = "CC003677C91D53E29F7095FF90C670C69C7C46E7" * response = "CC003677C91D53E29F7095FF90C670C69C7C46E7635919" * SHA1(response) = "CCAE6E414FA62F9C2DFC2742B00B5C94A549BAE6" * ^ offset 24 */ //todo also check if the response is too large if (response.len <= SHA1_STR_LEN) { return -1; } if (strncmp(challenge, (char *) response.data, SHA1_STR_LEN) != 0) { return -1; } unsigned char md[SHA1_MD_LEN]; __sha1((unsigned char *) response.data, response.len, md); unsigned int nibble1; if (challenge[0] <= '9') { nibble1 = challenge[0] - '0'; } else { nibble1 = challenge[0] - 'A' + 10; } return md[nibble1] == 0xB0 && md[nibble1 + 1] == 0x0B ? 0 : -1; } int get_cookie(ngx_http_request_t *r, ngx_str_t *name, ngx_str_t *value) { #if defined(nginx_version) && nginx_version >= 1023000 ngx_table_elt_t *h; for (h = r->headers_in.cookie; h; h = h->next) { u_char *start = h->value.data; u_char *end = h->value.data + h->value.len; #else ngx_table_elt_t **h; h = r->headers_in.cookies.elts; ngx_uint_t i = 0; for (i = 0; i < r->headers_in.cookies.nelts; i++) { u_char *start = h[i]->value.data; u_char *end = h[i]->value.data + h[i]->value.len; #endif while (start < end) { while (start < end && *start == ' ') { start++; } if (ngx_strncmp(start, name->data, name->len) == 0) { u_char *last; for (last = start; last < end && *last != ';'; last++) {} while (*start++ != '=' && start < last) {} value->data = start; value->len = (last - start); return 0; } while (*start++ != ';' && start < end) {} } } return -1; } static ngx_int_t ngx_http_js_challenge_handler(ngx_http_request_t *r) { ngx_http_js_challenge_loc_conf_t *conf = ngx_http_get_module_loc_conf(r, ngx_http_js_challenge_module); if (!conf->enabled) { return NGX_DECLINED; } unsigned long bucket = r->start_sec - (r->start_sec % conf->bucket_duration); ngx_str_t addr = r->connection->addr_text; char challenge[SHA1_STR_LEN]; get_challenge_string(bucket, addr, conf->secret, challenge); ngx_str_t response; ngx_str_t cookie_name = ngx_string("res"); int ret = get_cookie(r, &cookie_name, &response); if (ret < 0) { ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "[ js challenge log ] sending challenge... "); return serve_challenge(r, challenge, conf->html, conf->title); } get_challenge_string(bucket, addr, conf->secret, challenge); if (verify_response(response, challenge) != 0) { ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "[ js challenge log ] wrong/expired cookie (res=%s), sending challenge...", response.data); return serve_challenge(r, challenge, conf->html, conf->title); } // Fallthrough next handler return NGX_DECLINED; } /** * post configuration */ static ngx_int_t ngx_http_js_challenge(ngx_conf_t *cf) { ngx_http_handler_pt *h; ngx_http_core_main_conf_t *main_conf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module); h = ngx_array_push(&main_conf->phases[NGX_HTTP_PRECONTENT_PHASE].handlers); if (h == NULL) { ngx_log_error(NGX_LOG_ERR, cf->log, 0, "null"); return NGX_ERROR; } *h = ngx_http_js_challenge_handler; return NGX_OK; } /** * By Steve Reid * 100% Public Domain */ void __SHA1_Transform(uint32_t state[5], const uint8_t buffer[64]); #define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits)))) #if defined (BYTE_ORDER) && defined(BIG_ENDIAN) && (BYTE_ORDER == BIG_ENDIAN) #define WORDS_BIGENDIAN 1 #endif #ifdef _BIG_ENDIAN #define WORDS_BIGENDIAN 1 #endif /* blk0() and blk() perform the initial expand. */ /* I got the idea of expanding during the round function from SSLeay */ /* FIXME: can we do this in an endian-proof way? */ #ifdef WORDS_BIGENDIAN #define blk0(i) block->l[i] #else #define blk0(i) (block->l[i] = (rol(block->l[i],24)&0xff00ff00) \ |(rol(block->l[i],8)&0x00ff00ff)) #endif #define blk(i) (block->l[i&15] = rol(block->l[(i+13)&15]^block->l[(i+8)&15] \ ^block->l[(i+2)&15]^block->l[i&15],1)) /* (R0+R1), R2, R3, R4 are the different operations used in SHA1 */ #define R0(v, w, x, y, z, i) \ z+=((w&(x^y))^y)+blk0(i)+0x5a827999+rol(v,5);w=rol(w,30); #define R1(v, w, x, y, z, i) \ z+=((w&(x^y))^y)+blk(i)+0x5a827999+rol(v,5);w=rol(w,30); #define R2(v, w, x, y, z, i) \ z+=(w^x^y)+blk(i)+0x6ed9eba1+rol(v,5);w=rol(w,30); #define R3(v, w, x, y, z, i) \ z+=(((w|x)&y)|(w&x))+blk(i)+0x8f1bbcdc+rol(v,5);w=rol(w,30); #define R4(v, w, x, y, z, i) \ z+=(w^x^y)+blk(i)+0xca62c1d6+rol(v,5);w=rol(w,30); /* Hash a single 512-bit block. This is the core of the algorithm. */ void __SHA1_Transform(uint32_t state[5], const uint8_t buffer[64]) { uint32_t a, b, c, d, e; typedef union { uint8_t c[64]; uint32_t l[16]; } CHAR64LONG16; CHAR64LONG16 *block; CHAR64LONG16 workspace; block = &workspace; memcpy(block, buffer, 64); /* Copy context->state[] to working vars */ a = state[0]; b = state[1]; c = state[2]; d = state[3]; e = state[4]; /* 4 rounds of 20 operations each. Loop unrolled. */ R0(a, b, c, d, e, 0); R0(e, a, b, c, d, 1); R0(d, e, a, b, c, 2); R0(c, d, e, a, b, 3); R0(b, c, d, e, a, 4); R0(a, b, c, d, e, 5); R0(e, a, b, c, d, 6); R0(d, e, a, b, c, 7); R0(c, d, e, a, b, 8); R0(b, c, d, e, a, 9); R0(a, b, c, d, e, 10); R0(e, a, b, c, d, 11); R0(d, e, a, b, c, 12); R0(c, d, e, a, b, 13); R0(b, c, d, e, a, 14); R0(a, b, c, d, e, 15); R1(e, a, b, c, d, 16); R1(d, e, a, b, c, 17); R1(c, d, e, a, b, 18); R1(b, c, d, e, a, 19); R2(a, b, c, d, e, 20); R2(e, a, b, c, d, 21); R2(d, e, a, b, c, 22); R2(c, d, e, a, b, 23); R2(b, c, d, e, a, 24); R2(a, b, c, d, e, 25); R2(e, a, b, c, d, 26); R2(d, e, a, b, c, 27); R2(c, d, e, a, b, 28); R2(b, c, d, e, a, 29); R2(a, b, c, d, e, 30); R2(e, a, b, c, d, 31); R2(d, e, a, b, c, 32); R2(c, d, e, a, b, 33); R2(b, c, d, e, a, 34); R2(a, b, c, d, e, 35); R2(e, a, b, c, d, 36); R2(d, e, a, b, c, 37); R2(c, d, e, a, b, 38); R2(b, c, d, e, a, 39); R3(a, b, c, d, e, 40); R3(e, a, b, c, d, 41); R3(d, e, a, b, c, 42); R3(c, d, e, a, b, 43); R3(b, c, d, e, a, 44); R3(a, b, c, d, e, 45); R3(e, a, b, c, d, 46); R3(d, e, a, b, c, 47); R3(c, d, e, a, b, 48); R3(b, c, d, e, a, 49); R3(a, b, c, d, e, 50); R3(e, a, b, c, d, 51); R3(d, e, a, b, c, 52); R3(c, d, e, a, b, 53); R3(b, c, d, e, a, 54); R3(a, b, c, d, e, 55); R3(e, a, b, c, d, 56); R3(d, e, a, b, c, 57); R3(c, d, e, a, b, 58); R3(b, c, d, e, a, 59); R4(a, b, c, d, e, 60); R4(e, a, b, c, d, 61); R4(d, e, a, b, c, 62); R4(c, d, e, a, b, 63); R4(b, c, d, e, a, 64); R4(a, b, c, d, e, 65); R4(e, a, b, c, d, 66); R4(d, e, a, b, c, 67); R4(c, d, e, a, b, 68); R4(b, c, d, e, a, 69); R4(a, b, c, d, e, 70); R4(e, a, b, c, d, 71); R4(d, e, a, b, c, 72); R4(c, d, e, a, b, 73); R4(b, c, d, e, a, 74); R4(a, b, c, d, e, 75); R4(e, a, b, c, d, 76); R4(d, e, a, b, c, 77); R4(c, d, e, a, b, 78); R4(b, c, d, e, a, 79); /* Add the working vars back into context.state[] */ state[0] += a; state[1] += b; state[2] += c; state[3] += d; state[4] += e; /* Wipe variables */ a = b = c = d = e = 0; } typedef struct { uint32_t state[5]; uint32_t count[2]; uint8_t buffer[64]; } __SHA1_CTX; void __SHA1_Update(__SHA1_CTX *context, const void *p, size_t len); void __SHA1_Final(uint8_t digest[SHA1_MD_LEN], __SHA1_CTX *context); void __SHA1_Init(__SHA1_CTX *c) { memset(c, 0, sizeof(*c)); c->state[0] = 0x67452301UL; c->state[1] = 0xefcdab89UL; c->state[2] = 0x98badcfeUL; c->state[3] = 0x10325476UL; c->state[4] = 0xc3d2e1f0UL; } /** * Run your data through this * * @param context SHA1-Context * @param p Buffer to run SHA1 on * @param len Number of bytes */ void __SHA1_Update(__SHA1_CTX *context, const void *p, size_t len) { const uint8_t *data = p; size_t i, j; j = (context->count[0] >> 3) & 63; if ((context->count[0] += (uint32_t) (len << 3)) < (len << 3)) { context->count[1]++; } context->count[1] += (uint32_t) (len >> 29); if ((j + len) > 63) { memcpy(&context->buffer[j], data, (i = 64 - j)); __SHA1_Transform(context->state, context->buffer); for (; i + 63 < len; i += 64) { __SHA1_Transform(context->state, data + i); } j = 0; } else i = 0; memcpy(&context->buffer[j], &data[i], len - i); } /** * Add padding and return the message digest * * @param digest Generated message digest * @param context SHA1-Context */ void __SHA1_Final(uint8_t digest[SHA1_MD_LEN], __SHA1_CTX *context) { uint32_t i; uint8_t finalcount[8]; for (i = 0; i < 8; i++) { finalcount[i] = (uint8_t) ((context->count[(i >= 4 ? 0 : 1)] >> ((3 - (i & 3)) * 8)) & 255); } __SHA1_Update(context, (uint8_t *) "\200", 1); while ((context->count[0] & 504) != 448) { __SHA1_Update(context, (uint8_t *) "\0", 1); } __SHA1_Update(context, finalcount, 8); /* Should cause SHA1_Transform */ for (i = 0; i < SHA1_MD_LEN; i++) { digest[i] = (uint8_t) ((context->state[i >> 2] >> ((3 - (i & 3)) * 8)) & 255); } /* Wipe variables */ i = 0; memset(context->buffer, 0, 64); memset(context->state, 0, 20); memset(context->count, 0, 8); memset(finalcount, 0, 8); /* SWR */ __SHA1_Transform(context->state, context->buffer); } unsigned char *__sha1(const unsigned char *d, size_t n, unsigned char *md) { __SHA1_CTX c; __SHA1_Init(&c); __SHA1_Update(&c, d, n); __SHA1_Final(md, &c); return md; }

Set the js_challenge_html /path/to/body.html; directive to change this page.

Set the `js_challenge_html /path/to/body.html;` directive to change this page.