Mercurial > hg > nginx-quic
view src/http/modules/ngx_http_try_files_module.c @ 9075:b71e69247483 default
Variables: avoid possible buffer overrun with some "$sent_http_*".
The existing logic to evaluate multi header "$sent_http_*" variables,
such as $sent_http_cache_control, as previously introduced in 1.23.0,
doesn't take into account that one or more elements can be cleared,
yet still present in a linked list, pointed to by the next field.
Such elements don't contribute to the resulting variable length, an
attempt to append a separator for them ends up in out of bounds write.
This is not possible with standard modules, though at least one third
party module is known to override multi header values this way, so it
makes sense to harden the logic.
The fix restores a generic boundary check.
author | Sergey Kandaurov <pluknet@nginx.com> |
---|---|
date | Mon, 01 May 2023 19:16:05 +0400 |
parents | cce6936ed2f4 |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> typedef struct { ngx_array_t *lengths; ngx_array_t *values; ngx_str_t name; unsigned code:10; unsigned test_dir:1; } ngx_http_try_file_t; typedef struct { ngx_http_try_file_t *try_files; } ngx_http_try_files_loc_conf_t; static ngx_int_t ngx_http_try_files_handler(ngx_http_request_t *r); static char *ngx_http_try_files(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static void *ngx_http_try_files_create_loc_conf(ngx_conf_t *cf); static ngx_int_t ngx_http_try_files_init(ngx_conf_t *cf); static ngx_command_t ngx_http_try_files_commands[] = { { ngx_string("try_files"), NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_2MORE, ngx_http_try_files, NGX_HTTP_LOC_CONF_OFFSET, 0, NULL }, ngx_null_command }; static ngx_http_module_t ngx_http_try_files_module_ctx = { NULL, /* preconfiguration */ ngx_http_try_files_init, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ ngx_http_try_files_create_loc_conf, /* create location configuration */ NULL /* merge location configuration */ }; ngx_module_t ngx_http_try_files_module = { NGX_MODULE_V1, &ngx_http_try_files_module_ctx, /* module context */ ngx_http_try_files_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_int_t ngx_http_try_files_handler(ngx_http_request_t *r) { size_t len, root, alias, reserve, allocated; u_char *p, *name; ngx_str_t path, args; ngx_uint_t test_dir; ngx_http_try_file_t *tf; ngx_open_file_info_t of; ngx_http_script_code_pt code; ngx_http_script_engine_t e; ngx_http_core_loc_conf_t *clcf; ngx_http_script_len_code_pt lcode; ngx_http_try_files_loc_conf_t *tlcf; tlcf = ngx_http_get_module_loc_conf(r, ngx_http_try_files_module); if (tlcf->try_files == NULL) { return NGX_DECLINED; } ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "try files handler"); allocated = 0; root = 0; name = NULL; /* suppress MSVC warning */ path.data = NULL; tf = tlcf->try_files; clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module); alias = clcf->alias; for ( ;; ) { if (tf->lengths) { ngx_memzero(&e, sizeof(ngx_http_script_engine_t)); e.ip = tf->lengths->elts; e.request = r; /* 1 is for terminating '\0' as in static names */ len = 1; while (*(uintptr_t *) e.ip) { lcode = *(ngx_http_script_len_code_pt *) e.ip; len += lcode(&e); } } else { len = tf->name.len; } if (!alias) { reserve = len > r->uri.len ? len - r->uri.len : 0; } else if (alias == NGX_MAX_SIZE_T_VALUE) { reserve = len; } else { reserve = len > r->uri.len - alias ? len - (r->uri.len - alias) : 0; } if (reserve > allocated || !allocated) { /* 16 bytes are preallocation */ allocated = reserve + 16; if (ngx_http_map_uri_to_path(r, &path, &root, allocated) == NULL) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } name = path.data + root; } if (tf->values == NULL) { /* tf->name.len includes the terminating '\0' */ ngx_memcpy(name, tf->name.data, tf->name.len); path.len = (name + tf->name.len - 1) - path.data; } else { e.ip = tf->values->elts; e.pos = name; e.flushed = 1; while (*(uintptr_t *) e.ip) { code = *(ngx_http_script_code_pt *) e.ip; code((ngx_http_script_engine_t *) &e); } path.len = e.pos - path.data; *e.pos = '\0'; if (alias && alias != NGX_MAX_SIZE_T_VALUE && ngx_strncmp(name, r->uri.data, alias) == 0) { ngx_memmove(name, name + alias, len - alias); path.len -= alias; } } test_dir = tf->test_dir; tf++; ngx_log_debug3(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "trying to use %s: \"%s\" \"%s\"", test_dir ? "dir" : "file", name, path.data); if (tf->lengths == NULL && tf->name.len == 0) { if (tf->code) { return tf->code; } path.len -= root; path.data += root; if (path.data[0] == '@') { (void) ngx_http_named_location(r, &path); } else { ngx_http_split_args(r, &path, &args); (void) ngx_http_internal_redirect(r, &path, &args); } ngx_http_finalize_request(r, NGX_DONE); return NGX_DONE; } ngx_memzero(&of, sizeof(ngx_open_file_info_t)); of.read_ahead = clcf->read_ahead; of.directio = clcf->directio; of.valid = clcf->open_file_cache_valid; of.min_uses = clcf->open_file_cache_min_uses; of.test_only = 1; of.errors = clcf->open_file_cache_errors; of.events = clcf->open_file_cache_events; if (ngx_http_set_disable_symlinks(r, clcf, &path, &of) != NGX_OK) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } if (ngx_open_cached_file(clcf->open_file_cache, &path, &of, r->pool) != NGX_OK) { if (of.err == 0) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } if (of.err != NGX_ENOENT && of.err != NGX_ENOTDIR && of.err != NGX_ENAMETOOLONG) { ngx_log_error(NGX_LOG_CRIT, r->connection->log, of.err, "%s \"%s\" failed", of.failed, path.data); } continue; } if (of.is_dir != test_dir) { continue; } path.len -= root; path.data += root; if (!alias) { r->uri = path; } else if (alias == NGX_MAX_SIZE_T_VALUE) { if (!test_dir) { r->uri = path; r->add_uri_to_alias = 1; } } else { name = r->uri.data; r->uri.len = alias + path.len; r->uri.data = ngx_pnalloc(r->pool, r->uri.len); if (r->uri.data == NULL) { r->uri.len = 0; return NGX_HTTP_INTERNAL_SERVER_ERROR; } p = ngx_copy(r->uri.data, name, alias); ngx_memcpy(p, path.data, path.len); } ngx_http_set_exten(r); ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "try file uri: \"%V\"", &r->uri); return NGX_DECLINED; } /* not reached */ } static char * ngx_http_try_files(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_http_try_files_loc_conf_t *tlcf = conf; ngx_str_t *value; ngx_int_t code; ngx_uint_t i, n; ngx_http_try_file_t *tf; ngx_http_script_compile_t sc; if (tlcf->try_files) { return "is duplicate"; } tf = ngx_pcalloc(cf->pool, cf->args->nelts * sizeof(ngx_http_try_file_t)); if (tf == NULL) { return NGX_CONF_ERROR; } tlcf->try_files = tf; value = cf->args->elts; for (i = 0; i < cf->args->nelts - 1; i++) { tf[i].name = value[i + 1]; if (tf[i].name.len > 0 && tf[i].name.data[tf[i].name.len - 1] == '/' && i + 2 < cf->args->nelts) { tf[i].test_dir = 1; tf[i].name.len--; tf[i].name.data[tf[i].name.len] = '\0'; } n = ngx_http_script_variables_count(&tf[i].name); if (n) { ngx_memzero(&sc, sizeof(ngx_http_script_compile_t)); sc.cf = cf; sc.source = &tf[i].name; sc.lengths = &tf[i].lengths; sc.values = &tf[i].values; sc.variables = n; sc.complete_lengths = 1; sc.complete_values = 1; if (ngx_http_script_compile(&sc) != NGX_OK) { return NGX_CONF_ERROR; } } else { /* add trailing '\0' to length */ tf[i].name.len++; } } if (tf[i - 1].name.data[0] == '=') { code = ngx_atoi(tf[i - 1].name.data + 1, tf[i - 1].name.len - 2); if (code == NGX_ERROR || code > 999) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid code \"%*s\"", tf[i - 1].name.len - 1, tf[i - 1].name.data); return NGX_CONF_ERROR; } tf[i].code = code; } return NGX_CONF_OK; } static void * ngx_http_try_files_create_loc_conf(ngx_conf_t *cf) { ngx_http_try_files_loc_conf_t *tlcf; tlcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_try_files_loc_conf_t)); if (tlcf == NULL) { return NULL; } /* * set by ngx_pcalloc(): * * tlcf->try_files = NULL; */ return tlcf; } static ngx_int_t ngx_http_try_files_init(ngx_conf_t *cf) { ngx_http_handler_pt *h; ngx_http_core_main_conf_t *cmcf; cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module); h = ngx_array_push(&cmcf->phases[NGX_HTTP_PRECONTENT_PHASE].handlers); if (h == NULL) { return NGX_ERROR; } *h = ngx_http_try_files_handler; return NGX_OK; }