view src/core/ngx_file.h @ 6351:497d0cff8ace

Resolver: fixed use-after-free memory accesses with CNAME. When several requests were waiting for a response, then after getting a CNAME response only the last request's context had the name updated. Contexts of other requests had the wrong name. This name was used by ngx_resolve_name_done() to find the node to remove the request context from. When the name was wrong, the request could not be properly cancelled, its context was freed but stayed linked to the node's waiting list. This happened e.g. when the first request was aborted or timed out before the resolving completed. When it completed, this triggered a use-after-free memory access by calling ctx->handler of already freed request context. The bug manifests itself by "could not cancel <name> resolving" alerts in error_log. When a request was responded with a CNAME, the request context kept the pointer to the original node's rn->u.cname. If the original node expired before the resolving timed out or completed with an error, this would trigger a use-after-free memory access via ctx->name in ctx->handler(). The fix is to keep ctx->name unmodified. The name from context is no longer used by ngx_resolve_name_done(). Instead, we now keep the pointer to resolver node to which this request is linked. Keeping the original name intact also improves logging.
author Roman Arutyunyan <arut@nginx.com>
date Tue, 26 Jan 2016 16:46:59 +0300
parents 1fdba317ee6d
children 9fd738b85fad
line wrap: on
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/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_FILE_H_INCLUDED_
#define _NGX_FILE_H_INCLUDED_


#include <ngx_config.h>
#include <ngx_core.h>


struct ngx_file_s {
    ngx_fd_t                   fd;
    ngx_str_t                  name;
    ngx_file_info_t            info;

    off_t                      offset;
    off_t                      sys_offset;

    ngx_log_t                 *log;

#if (NGX_THREADS)
    ngx_int_t                (*thread_handler)(ngx_thread_task_t *task,
                                               ngx_file_t *file);
    void                      *thread_ctx;
#endif

#if (NGX_HAVE_FILE_AIO)
    ngx_event_aio_t           *aio;
#endif

    unsigned                   valid_info:1;
    unsigned                   directio:1;
};


#define NGX_MAX_PATH_LEVEL  3


typedef time_t (*ngx_path_manager_pt) (void *data);
typedef void (*ngx_path_loader_pt) (void *data);


typedef struct {
    ngx_str_t                  name;
    size_t                     len;
    size_t                     level[3];

    ngx_path_manager_pt        manager;
    ngx_path_loader_pt         loader;
    void                      *data;

    u_char                    *conf_file;
    ngx_uint_t                 line;
} ngx_path_t;


typedef struct {
    ngx_str_t                  name;
    size_t                     level[3];
} ngx_path_init_t;


typedef struct {
    ngx_file_t                 file;
    off_t                      offset;
    ngx_path_t                *path;
    ngx_pool_t                *pool;
    char                      *warn;

    ngx_uint_t                 access;

    unsigned                   log_level:8;
    unsigned                   persistent:1;
    unsigned                   clean:1;
} ngx_temp_file_t;


typedef struct {
    ngx_uint_t                 access;
    ngx_uint_t                 path_access;
    time_t                     time;
    ngx_fd_t                   fd;

    unsigned                   create_path:1;
    unsigned                   delete_file:1;

    ngx_log_t                 *log;
} ngx_ext_rename_file_t;


typedef struct {
    off_t                      size;
    size_t                     buf_size;

    ngx_uint_t                 access;
    time_t                     time;

    ngx_log_t                 *log;
} ngx_copy_file_t;


typedef struct ngx_tree_ctx_s  ngx_tree_ctx_t;

typedef ngx_int_t (*ngx_tree_init_handler_pt) (void *ctx, void *prev);
typedef ngx_int_t (*ngx_tree_handler_pt) (ngx_tree_ctx_t *ctx, ngx_str_t *name);

struct ngx_tree_ctx_s {
    off_t                      size;
    off_t                      fs_size;
    ngx_uint_t                 access;
    time_t                     mtime;

    ngx_tree_init_handler_pt   init_handler;
    ngx_tree_handler_pt        file_handler;
    ngx_tree_handler_pt        pre_tree_handler;
    ngx_tree_handler_pt        post_tree_handler;
    ngx_tree_handler_pt        spec_handler;

    void                      *data;
    size_t                     alloc;

    ngx_log_t                 *log;
};


ngx_int_t ngx_get_full_name(ngx_pool_t *pool, ngx_str_t *prefix,
    ngx_str_t *name);

ssize_t ngx_write_chain_to_temp_file(ngx_temp_file_t *tf, ngx_chain_t *chain);
ngx_int_t ngx_create_temp_file(ngx_file_t *file, ngx_path_t *path,
    ngx_pool_t *pool, ngx_uint_t persistent, ngx_uint_t clean,
    ngx_uint_t access);
void ngx_create_hashed_filename(ngx_path_t *path, u_char *file, size_t len);
ngx_int_t ngx_create_path(ngx_file_t *file, ngx_path_t *path);
ngx_err_t ngx_create_full_path(u_char *dir, ngx_uint_t access);
ngx_int_t ngx_add_path(ngx_conf_t *cf, ngx_path_t **slot);
ngx_int_t ngx_create_paths(ngx_cycle_t *cycle, ngx_uid_t user);
ngx_int_t ngx_ext_rename_file(ngx_str_t *src, ngx_str_t *to,
    ngx_ext_rename_file_t *ext);
ngx_int_t ngx_copy_file(u_char *from, u_char *to, ngx_copy_file_t *cf);
ngx_int_t ngx_walk_tree(ngx_tree_ctx_t *ctx, ngx_str_t *tree);

ngx_atomic_uint_t ngx_next_temp_number(ngx_uint_t collision);

char *ngx_conf_set_path_slot(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
char *ngx_conf_merge_path_value(ngx_conf_t *cf, ngx_path_t **path,
    ngx_path_t *prev, ngx_path_init_t *init);
char *ngx_conf_set_access_slot(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);


extern ngx_atomic_t      *ngx_temp_number;
extern ngx_atomic_int_t   ngx_random_number;


#endif /* _NGX_FILE_H_INCLUDED_ */