Mercurial > hg > nginx
view src/http/modules/ngx_http_slice_filter_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 | 3ff293cfdab8 |
children | e3723f2a11b7 |
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/* * Copyright (C) Roman Arutyunyan * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> typedef struct { size_t size; } ngx_http_slice_loc_conf_t; typedef struct { off_t start; off_t end; ngx_str_t range; ngx_str_t etag; unsigned last:1; unsigned active:1; ngx_http_request_t *sr; } ngx_http_slice_ctx_t; typedef struct { off_t start; off_t end; off_t complete_length; } ngx_http_slice_content_range_t; static ngx_int_t ngx_http_slice_header_filter(ngx_http_request_t *r); static ngx_int_t ngx_http_slice_body_filter(ngx_http_request_t *r, ngx_chain_t *in); static ngx_int_t ngx_http_slice_parse_content_range(ngx_http_request_t *r, ngx_http_slice_content_range_t *cr); static ngx_int_t ngx_http_slice_range_variable(ngx_http_request_t *r, ngx_http_variable_value_t *v, uintptr_t data); static off_t ngx_http_slice_get_start(ngx_http_request_t *r); static void *ngx_http_slice_create_loc_conf(ngx_conf_t *cf); static char *ngx_http_slice_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child); static ngx_int_t ngx_http_slice_add_variables(ngx_conf_t *cf); static ngx_int_t ngx_http_slice_init(ngx_conf_t *cf); static ngx_command_t ngx_http_slice_filter_commands[] = { { ngx_string("slice"), NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1, ngx_conf_set_size_slot, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_slice_loc_conf_t, size), NULL }, ngx_null_command }; static ngx_http_module_t ngx_http_slice_filter_module_ctx = { ngx_http_slice_add_variables, /* preconfiguration */ ngx_http_slice_init, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ ngx_http_slice_create_loc_conf, /* create location configuration */ ngx_http_slice_merge_loc_conf /* merge location configuration */ }; ngx_module_t ngx_http_slice_filter_module = { NGX_MODULE_V1, &ngx_http_slice_filter_module_ctx, /* module context */ ngx_http_slice_filter_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_slice_range_name = ngx_string("slice_range"); static ngx_http_output_header_filter_pt ngx_http_next_header_filter; static ngx_http_output_body_filter_pt ngx_http_next_body_filter; static ngx_int_t ngx_http_slice_header_filter(ngx_http_request_t *r) { off_t end; ngx_int_t rc; ngx_table_elt_t *h; ngx_http_slice_ctx_t *ctx; ngx_http_slice_loc_conf_t *slcf; ngx_http_slice_content_range_t cr; ctx = ngx_http_get_module_ctx(r, ngx_http_slice_filter_module); if (ctx == NULL) { return ngx_http_next_header_filter(r); } if (r->headers_out.status != NGX_HTTP_PARTIAL_CONTENT) { if (r == r->main) { ngx_http_set_ctx(r, NULL, ngx_http_slice_filter_module); return ngx_http_next_header_filter(r); } ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "unexpected status code %ui in slice response", r->headers_out.status); return NGX_ERROR; } h = r->headers_out.etag; if (ctx->etag.len) { if (h == NULL || h->value.len != ctx->etag.len || ngx_strncmp(h->value.data, ctx->etag.data, ctx->etag.len) != 0) { ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "etag mismatch in slice response"); return NGX_ERROR; } } if (h) { ctx->etag = h->value; } if (ngx_http_slice_parse_content_range(r, &cr) != NGX_OK) { ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "invalid range in slice response"); return NGX_ERROR; } if (cr.complete_length == -1) { ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "no complete length in slice response"); return NGX_ERROR; } ngx_log_debug3(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "http slice response range: %O-%O/%O", cr.start, cr.end, cr.complete_length); slcf = ngx_http_get_module_loc_conf(r, ngx_http_slice_filter_module); end = ngx_min(cr.start + (off_t) slcf->size, cr.complete_length); if (cr.start != ctx->start || cr.end != end) { ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "unexpected range in slice response: %O-%O", cr.start, cr.end); return NGX_ERROR; } ctx->start = end; ctx->active = 1; r->headers_out.status = NGX_HTTP_OK; r->headers_out.status_line.len = 0; r->headers_out.content_length_n = cr.complete_length; r->headers_out.content_offset = cr.start; r->headers_out.content_range->hash = 0; r->headers_out.content_range = NULL; r->allow_ranges = 1; r->subrequest_ranges = 1; r->single_range = 1; rc = ngx_http_next_header_filter(r); if (r != r->main) { return rc; } if (r->headers_out.status == NGX_HTTP_PARTIAL_CONTENT) { if (ctx->start + (off_t) slcf->size <= r->headers_out.content_offset) { ctx->start = slcf->size * (r->headers_out.content_offset / slcf->size); } ctx->end = r->headers_out.content_offset + r->headers_out.content_length_n; } else { ctx->end = cr.complete_length; } return rc; } static ngx_int_t ngx_http_slice_body_filter(ngx_http_request_t *r, ngx_chain_t *in) { ngx_int_t rc; ngx_chain_t *cl; ngx_http_slice_ctx_t *ctx; ngx_http_slice_loc_conf_t *slcf; ctx = ngx_http_get_module_ctx(r, ngx_http_slice_filter_module); if (ctx == NULL || r != r->main) { return ngx_http_next_body_filter(r, in); } for (cl = in; cl; cl = cl->next) { if (cl->buf->last_buf) { cl->buf->last_buf = 0; cl->buf->last_in_chain = 1; cl->buf->sync = 1; ctx->last = 1; } } rc = ngx_http_next_body_filter(r, in); if (rc == NGX_ERROR || !ctx->last) { return rc; } if (ctx->sr && !ctx->sr->done) { return rc; } if (!ctx->active) { ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "missing slice response"); return NGX_ERROR; } if (ctx->start >= ctx->end) { ngx_http_set_ctx(r, NULL, ngx_http_slice_filter_module); ngx_http_send_special(r, NGX_HTTP_LAST); return rc; } if (r->buffered) { return rc; } if (ngx_http_subrequest(r, &r->uri, &r->args, &ctx->sr, NULL, NGX_HTTP_SUBREQUEST_CLONE) != NGX_OK) { return NGX_ERROR; } ngx_http_set_ctx(ctx->sr, ctx, ngx_http_slice_filter_module); slcf = ngx_http_get_module_loc_conf(r, ngx_http_slice_filter_module); ctx->range.len = ngx_sprintf(ctx->range.data, "bytes=%O-%O", ctx->start, ctx->start + (off_t) slcf->size - 1) - ctx->range.data; ctx->active = 0; ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "http slice subrequest: \"%V\"", &ctx->range); return rc; } static ngx_int_t ngx_http_slice_parse_content_range(ngx_http_request_t *r, ngx_http_slice_content_range_t *cr) { off_t start, end, complete_length, cutoff, cutlim; u_char *p; ngx_table_elt_t *h; h = r->headers_out.content_range; if (h == NULL || h->value.len < 7 || ngx_strncmp(h->value.data, "bytes ", 6) != 0) { return NGX_ERROR; } p = h->value.data + 6; cutoff = NGX_MAX_OFF_T_VALUE / 10; cutlim = NGX_MAX_OFF_T_VALUE % 10; start = 0; end = 0; complete_length = 0; while (*p == ' ') { p++; } if (*p < '0' || *p > '9') { return NGX_ERROR; } while (*p >= '0' && *p <= '9') { if (start >= cutoff && (start > cutoff || *p - '0' > cutlim)) { return NGX_ERROR; } start = start * 10 + *p++ - '0'; } while (*p == ' ') { p++; } if (*p++ != '-') { return NGX_ERROR; } while (*p == ' ') { p++; } if (*p < '0' || *p > '9') { return NGX_ERROR; } while (*p >= '0' && *p <= '9') { if (end >= cutoff && (end > cutoff || *p - '0' > cutlim)) { return NGX_ERROR; } end = end * 10 + *p++ - '0'; } end++; while (*p == ' ') { p++; } if (*p++ != '/') { return NGX_ERROR; } while (*p == ' ') { p++; } if (*p != '*') { if (*p < '0' || *p > '9') { return NGX_ERROR; } while (*p >= '0' && *p <= '9') { if (complete_length >= cutoff && (complete_length > cutoff || *p - '0' > cutlim)) { return NGX_ERROR; } complete_length = complete_length * 10 + *p++ - '0'; } } else { complete_length = -1; p++; } while (*p == ' ') { p++; } if (*p != '\0') { return NGX_ERROR; } cr->start = start; cr->end = end; cr->complete_length = complete_length; return NGX_OK; } static ngx_int_t ngx_http_slice_range_variable(ngx_http_request_t *r, ngx_http_variable_value_t *v, uintptr_t data) { u_char *p; ngx_http_slice_ctx_t *ctx; ngx_http_slice_loc_conf_t *slcf; ctx = ngx_http_get_module_ctx(r, ngx_http_slice_filter_module); if (ctx == NULL) { if (r != r->main || r->headers_out.status) { v->not_found = 1; return NGX_OK; } slcf = ngx_http_get_module_loc_conf(r, ngx_http_slice_filter_module); if (slcf->size == 0) { v->not_found = 1; return NGX_OK; } ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_slice_ctx_t)); if (ctx == NULL) { return NGX_ERROR; } ngx_http_set_ctx(r, ctx, ngx_http_slice_filter_module); p = ngx_pnalloc(r->pool, sizeof("bytes=-") - 1 + 2 * NGX_OFF_T_LEN); if (p == NULL) { return NGX_ERROR; } ctx->start = slcf->size * (ngx_http_slice_get_start(r) / slcf->size); ctx->range.data = p; ctx->range.len = ngx_sprintf(p, "bytes=%O-%O", ctx->start, ctx->start + (off_t) slcf->size - 1) - p; } v->data = ctx->range.data; v->valid = 1; v->not_found = 0; v->no_cacheable = 1; v->len = ctx->range.len; return NGX_OK; } static off_t ngx_http_slice_get_start(ngx_http_request_t *r) { off_t start, cutoff, cutlim; u_char *p; ngx_table_elt_t *h; if (r->headers_in.if_range) { return 0; } h = r->headers_in.range; if (h == NULL || h->value.len < 7 || ngx_strncasecmp(h->value.data, (u_char *) "bytes=", 6) != 0) { return 0; } p = h->value.data + 6; if (ngx_strchr(p, ',')) { return 0; } while (*p == ' ') { p++; } if (*p == '-') { return 0; } cutoff = NGX_MAX_OFF_T_VALUE / 10; cutlim = NGX_MAX_OFF_T_VALUE % 10; start = 0; while (*p >= '0' && *p <= '9') { if (start >= cutoff && (start > cutoff || *p - '0' > cutlim)) { return 0; } start = start * 10 + *p++ - '0'; } return start; } static void * ngx_http_slice_create_loc_conf(ngx_conf_t *cf) { ngx_http_slice_loc_conf_t *slcf; slcf = ngx_palloc(cf->pool, sizeof(ngx_http_slice_loc_conf_t)); if (slcf == NULL) { return NULL; } slcf->size = NGX_CONF_UNSET_SIZE; return slcf; } static char * ngx_http_slice_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child) { ngx_http_slice_loc_conf_t *prev = parent; ngx_http_slice_loc_conf_t *conf = child; ngx_conf_merge_size_value(conf->size, prev->size, 0); return NGX_CONF_OK; } static ngx_int_t ngx_http_slice_add_variables(ngx_conf_t *cf) { ngx_http_variable_t *var; var = ngx_http_add_variable(cf, &ngx_http_slice_range_name, 0); if (var == NULL) { return NGX_ERROR; } var->get_handler = ngx_http_slice_range_variable; return NGX_OK; } static ngx_int_t ngx_http_slice_init(ngx_conf_t *cf) { ngx_http_next_header_filter = ngx_http_top_header_filter; ngx_http_top_header_filter = ngx_http_slice_header_filter; ngx_http_next_body_filter = ngx_http_top_body_filter; ngx_http_top_body_filter = ngx_http_slice_body_filter; return NGX_OK; }