Mercurial > hg > nginx-quic
view src/mail/ngx_mail_pop3_module.c @ 6359:dac6eda40475 stable-1.8
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 | ec01b1d1fff1 |
children | 73b451d304c0 |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_event.h> #include <ngx_mail.h> #include <ngx_mail_pop3_module.h> static void *ngx_mail_pop3_create_srv_conf(ngx_conf_t *cf); static char *ngx_mail_pop3_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child); static ngx_str_t ngx_mail_pop3_default_capabilities[] = { ngx_string("TOP"), ngx_string("USER"), ngx_string("UIDL"), ngx_null_string }; static ngx_conf_bitmask_t ngx_mail_pop3_auth_methods[] = { { ngx_string("plain"), NGX_MAIL_AUTH_PLAIN_ENABLED }, { ngx_string("apop"), NGX_MAIL_AUTH_APOP_ENABLED }, { ngx_string("cram-md5"), NGX_MAIL_AUTH_CRAM_MD5_ENABLED }, { ngx_null_string, 0 } }; static ngx_str_t ngx_mail_pop3_auth_plain_capability = ngx_string("+OK methods supported:" CRLF "LOGIN" CRLF "PLAIN" CRLF "." CRLF); static ngx_str_t ngx_mail_pop3_auth_cram_md5_capability = ngx_string("+OK methods supported:" CRLF "LOGIN" CRLF "PLAIN" CRLF "CRAM-MD5" CRLF "." CRLF); static ngx_mail_protocol_t ngx_mail_pop3_protocol = { ngx_string("pop3"), { 110, 995, 0, 0 }, NGX_MAIL_POP3_PROTOCOL, ngx_mail_pop3_init_session, ngx_mail_pop3_init_protocol, ngx_mail_pop3_parse_command, ngx_mail_pop3_auth_state, ngx_string("-ERR internal server error" CRLF), ngx_string("-ERR SSL certificate error" CRLF), ngx_string("-ERR No required SSL certificate" CRLF) }; static ngx_command_t ngx_mail_pop3_commands[] = { { ngx_string("pop3_capabilities"), NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_1MORE, ngx_mail_capabilities, NGX_MAIL_SRV_CONF_OFFSET, offsetof(ngx_mail_pop3_srv_conf_t, capabilities), NULL }, { ngx_string("pop3_auth"), NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_1MORE, ngx_conf_set_bitmask_slot, NGX_MAIL_SRV_CONF_OFFSET, offsetof(ngx_mail_pop3_srv_conf_t, auth_methods), &ngx_mail_pop3_auth_methods }, ngx_null_command }; static ngx_mail_module_t ngx_mail_pop3_module_ctx = { &ngx_mail_pop3_protocol, /* protocol */ NULL, /* create main configuration */ NULL, /* init main configuration */ ngx_mail_pop3_create_srv_conf, /* create server configuration */ ngx_mail_pop3_merge_srv_conf /* merge server configuration */ }; ngx_module_t ngx_mail_pop3_module = { NGX_MODULE_V1, &ngx_mail_pop3_module_ctx, /* module context */ ngx_mail_pop3_commands, /* module directives */ NGX_MAIL_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 void * ngx_mail_pop3_create_srv_conf(ngx_conf_t *cf) { ngx_mail_pop3_srv_conf_t *pscf; pscf = ngx_pcalloc(cf->pool, sizeof(ngx_mail_pop3_srv_conf_t)); if (pscf == NULL) { return NULL; } if (ngx_array_init(&pscf->capabilities, cf->pool, 4, sizeof(ngx_str_t)) != NGX_OK) { return NULL; } return pscf; } static char * ngx_mail_pop3_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child) { ngx_mail_pop3_srv_conf_t *prev = parent; ngx_mail_pop3_srv_conf_t *conf = child; u_char *p; size_t size, stls_only_size; ngx_str_t *c, *d; ngx_uint_t i; ngx_conf_merge_bitmask_value(conf->auth_methods, prev->auth_methods, (NGX_CONF_BITMASK_SET |NGX_MAIL_AUTH_PLAIN_ENABLED)); if (conf->capabilities.nelts == 0) { conf->capabilities = prev->capabilities; } if (conf->capabilities.nelts == 0) { for (d = ngx_mail_pop3_default_capabilities; d->len; d++) { c = ngx_array_push(&conf->capabilities); if (c == NULL) { return NGX_CONF_ERROR; } *c = *d; } } size = sizeof("+OK Capability list follows" CRLF) - 1 + sizeof("." CRLF) - 1; stls_only_size = size + sizeof("STLS" CRLF) - 1; c = conf->capabilities.elts; for (i = 0; i < conf->capabilities.nelts; i++) { size += c[i].len + sizeof(CRLF) - 1; if (ngx_strcasecmp(c[i].data, (u_char *) "USER") == 0) { continue; } stls_only_size += c[i].len + sizeof(CRLF) - 1; } if (conf->auth_methods & NGX_MAIL_AUTH_CRAM_MD5_ENABLED) { size += sizeof("SASL LOGIN PLAIN CRAM-MD5" CRLF) - 1; } else { size += sizeof("SASL LOGIN PLAIN" CRLF) - 1; } p = ngx_pnalloc(cf->pool, size); if (p == NULL) { return NGX_CONF_ERROR; } conf->capability.len = size; conf->capability.data = p; p = ngx_cpymem(p, "+OK Capability list follows" CRLF, sizeof("+OK Capability list follows" CRLF) - 1); for (i = 0; i < conf->capabilities.nelts; i++) { p = ngx_cpymem(p, c[i].data, c[i].len); *p++ = CR; *p++ = LF; } if (conf->auth_methods & NGX_MAIL_AUTH_CRAM_MD5_ENABLED) { p = ngx_cpymem(p, "SASL LOGIN PLAIN CRAM-MD5" CRLF, sizeof("SASL LOGIN PLAIN CRAM-MD5" CRLF) - 1); } else { p = ngx_cpymem(p, "SASL LOGIN PLAIN" CRLF, sizeof("SASL LOGIN PLAIN" CRLF) - 1); } *p++ = '.'; *p++ = CR; *p = LF; size += sizeof("STLS" CRLF) - 1; p = ngx_pnalloc(cf->pool, size); if (p == NULL) { return NGX_CONF_ERROR; } conf->starttls_capability.len = size; conf->starttls_capability.data = p; p = ngx_cpymem(p, conf->capability.data, conf->capability.len - (sizeof("." CRLF) - 1)); p = ngx_cpymem(p, "STLS" CRLF, sizeof("STLS" CRLF) - 1); *p++ = '.'; *p++ = CR; *p = LF; if (conf->auth_methods & NGX_MAIL_AUTH_CRAM_MD5_ENABLED) { conf->auth_capability = ngx_mail_pop3_auth_cram_md5_capability; } else { conf->auth_capability = ngx_mail_pop3_auth_plain_capability; } p = ngx_pnalloc(cf->pool, stls_only_size); if (p == NULL) { return NGX_CONF_ERROR; } conf->starttls_only_capability.len = stls_only_size; conf->starttls_only_capability.data = p; p = ngx_cpymem(p, "+OK Capability list follows" CRLF, sizeof("+OK Capability list follows" CRLF) - 1); for (i = 0; i < conf->capabilities.nelts; i++) { if (ngx_strcasecmp(c[i].data, (u_char *) "USER") == 0) { continue; } p = ngx_cpymem(p, c[i].data, c[i].len); *p++ = CR; *p++ = LF; } p = ngx_cpymem(p, "STLS" CRLF, sizeof("STLS" CRLF) - 1); *p++ = '.'; *p++ = CR; *p = LF; return NGX_CONF_OK; }