Mercurial > hg > nginx
view src/http/modules/ngx_http_secure_link_module.c @ 7060:1adc6b0d5eaa stable-1.12
Range filter: protect from total size overflows.
The overflow can be used to circumvent the restriction on total size of
ranges introduced in c2a91088b0c0 (1.1.2). Additionally, overflow
allows producing ranges with negative start (such ranges can be created
by using a suffix, "bytes=-100"; normally this results in 200 due to
the total size check). These can result in the following errors in logs:
[crit] ... pread() ... failed (22: Invalid argument)
[alert] ... sendfile() failed (22: Invalid argument)
When using cache, it can be also used to reveal cache file header.
It is believed that there are no other negative effects, at least with
standard nginx modules.
In theory, this can also result in memory disclosure and/or segmentation
faults if multiple ranges are allowed, and the response is returned in a
single in-memory buffer. This never happens with standard nginx modules
though, as well as known 3rd party modules.
Fix is to properly protect from possible overflow when incrementing size.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Tue, 11 Jul 2017 16:06:23 +0300 |
parents | d89442dab4d1 |
children | c7d4017c8876 |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> #include <ngx_md5.h> typedef struct { ngx_http_complex_value_t *variable; ngx_http_complex_value_t *md5; ngx_str_t secret; } ngx_http_secure_link_conf_t; typedef struct { ngx_str_t expires; } ngx_http_secure_link_ctx_t; static ngx_int_t ngx_http_secure_link_old_variable(ngx_http_request_t *r, ngx_http_secure_link_conf_t *conf, ngx_http_variable_value_t *v, uintptr_t data); static ngx_int_t ngx_http_secure_link_expires_variable(ngx_http_request_t *r, ngx_http_variable_value_t *v, uintptr_t data); static void *ngx_http_secure_link_create_conf(ngx_conf_t *cf); static char *ngx_http_secure_link_merge_conf(ngx_conf_t *cf, void *parent, void *child); static ngx_int_t ngx_http_secure_link_add_variables(ngx_conf_t *cf); static ngx_command_t ngx_http_secure_link_commands[] = { { ngx_string("secure_link"), NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1, ngx_http_set_complex_value_slot, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_secure_link_conf_t, variable), NULL }, { ngx_string("secure_link_md5"), NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1, ngx_http_set_complex_value_slot, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_secure_link_conf_t, md5), NULL }, { ngx_string("secure_link_secret"), NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1, ngx_conf_set_str_slot, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_secure_link_conf_t, secret), NULL }, ngx_null_command }; static ngx_http_module_t ngx_http_secure_link_module_ctx = { ngx_http_secure_link_add_variables, /* preconfiguration */ NULL, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ ngx_http_secure_link_create_conf, /* create location configuration */ ngx_http_secure_link_merge_conf /* merge location configuration */ }; ngx_module_t ngx_http_secure_link_module = { NGX_MODULE_V1, &ngx_http_secure_link_module_ctx, /* module context */ ngx_http_secure_link_commands, /* module directives */ NGX_HTTP_MODULE, /* module type */ NULL, /* init master */ NULL, /* init module */ NULL, /* init process */ NULL, /* init thread */ NULL, /* exit thread */ NULL, /* exit process */ NULL, /* exit master */ NGX_MODULE_V1_PADDING }; static ngx_str_t ngx_http_secure_link_name = ngx_string("secure_link"); static ngx_str_t ngx_http_secure_link_expires_name = ngx_string("secure_link_expires"); static ngx_int_t ngx_http_secure_link_variable(ngx_http_request_t *r, ngx_http_variable_value_t *v, uintptr_t data) { u_char *p, *last; ngx_str_t val, hash; time_t expires; ngx_md5_t md5; ngx_http_secure_link_ctx_t *ctx; ngx_http_secure_link_conf_t *conf; u_char hash_buf[16], md5_buf[16]; conf = ngx_http_get_module_loc_conf(r, ngx_http_secure_link_module); if (conf->secret.data) { return ngx_http_secure_link_old_variable(r, conf, v, data); } if (conf->variable == NULL || conf->md5 == NULL) { goto not_found; } if (ngx_http_complex_value(r, conf->variable, &val) != NGX_OK) { return NGX_ERROR; } ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "secure link: \"%V\"", &val); last = val.data + val.len; p = ngx_strlchr(val.data, last, ','); expires = 0; if (p) { val.len = p++ - val.data; expires = ngx_atotm(p, last - p); if (expires <= 0) { goto not_found; } ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_secure_link_ctx_t)); if (ctx == NULL) { return NGX_ERROR; } ngx_http_set_ctx(r, ctx, ngx_http_secure_link_module); ctx->expires.len = last - p; ctx->expires.data = p; } if (val.len > 24) { goto not_found; } hash.len = 16; hash.data = hash_buf; if (ngx_decode_base64url(&hash, &val) != NGX_OK) { goto not_found; } if (hash.len != 16) { goto not_found; } if (ngx_http_complex_value(r, conf->md5, &val) != NGX_OK) { return NGX_ERROR; } ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "secure link md5: \"%V\"", &val); ngx_md5_init(&md5); ngx_md5_update(&md5, val.data, val.len); ngx_md5_final(md5_buf, &md5); if (ngx_memcmp(hash_buf, md5_buf, 16) != 0) { goto not_found; } v->data = (u_char *) ((expires && expires < ngx_time()) ? "0" : "1"); v->len = 1; v->valid = 1; v->no_cacheable = 0; v->not_found = 0; return NGX_OK; not_found: v->not_found = 1; return NGX_OK; } static ngx_int_t ngx_http_secure_link_old_variable(ngx_http_request_t *r, ngx_http_secure_link_conf_t *conf, ngx_http_variable_value_t *v, uintptr_t data) { u_char *p, *start, *end, *last; size_t len; ngx_int_t n; ngx_uint_t i; ngx_md5_t md5; u_char hash[16]; p = &r->unparsed_uri.data[1]; last = r->unparsed_uri.data + r->unparsed_uri.len; while (p < last) { if (*p++ == '/') { start = p; goto md5_start; } } goto not_found; md5_start: while (p < last) { if (*p++ == '/') { end = p - 1; goto url_start; } } goto not_found; url_start: len = last - p; if (end - start != 32 || len == 0) { goto not_found; } ngx_md5_init(&md5); ngx_md5_update(&md5, p, len); ngx_md5_update(&md5, conf->secret.data, conf->secret.len); ngx_md5_final(hash, &md5); for (i = 0; i < 16; i++) { n = ngx_hextoi(&start[2 * i], 2); if (n == NGX_ERROR || n != hash[i]) { goto not_found; } } v->len = len; v->valid = 1; v->no_cacheable = 0; v->not_found = 0; v->data = p; return NGX_OK; not_found: v->not_found = 1; return NGX_OK; } static ngx_int_t ngx_http_secure_link_expires_variable(ngx_http_request_t *r, ngx_http_variable_value_t *v, uintptr_t data) { ngx_http_secure_link_ctx_t *ctx; ctx = ngx_http_get_module_ctx(r, ngx_http_secure_link_module); if (ctx) { v->len = ctx->expires.len; v->valid = 1; v->no_cacheable = 0; v->not_found = 0; v->data = ctx->expires.data; } else { v->not_found = 1; } return NGX_OK; } static void * ngx_http_secure_link_create_conf(ngx_conf_t *cf) { ngx_http_secure_link_conf_t *conf; conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_secure_link_conf_t)); if (conf == NULL) { return NULL; } /* * set by ngx_pcalloc(): * * conf->variable = NULL; * conf->md5 = NULL; * conf->secret = { 0, NULL }; */ return conf; } static char * ngx_http_secure_link_merge_conf(ngx_conf_t *cf, void *parent, void *child) { ngx_http_secure_link_conf_t *prev = parent; ngx_http_secure_link_conf_t *conf = child; if (conf->secret.data) { if (conf->variable || conf->md5) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "\"secure_link_secret\" cannot be mixed with " "\"secure_link\" and \"secure_link_md5\""); return NGX_CONF_ERROR; } return NGX_CONF_OK; } if (conf->variable == NULL) { conf->variable = prev->variable; } if (conf->md5 == NULL) { conf->md5 = prev->md5; } if (conf->variable == NULL && conf->md5 == NULL) { conf->secret = prev->secret; } return NGX_CONF_OK; } static ngx_int_t ngx_http_secure_link_add_variables(ngx_conf_t *cf) { ngx_http_variable_t *var; var = ngx_http_add_variable(cf, &ngx_http_secure_link_name, 0); if (var == NULL) { return NGX_ERROR; } var->get_handler = ngx_http_secure_link_variable; var = ngx_http_add_variable(cf, &ngx_http_secure_link_expires_name, 0); if (var == NULL) { return NGX_ERROR; } var->get_handler = ngx_http_secure_link_expires_variable; return NGX_OK; }