{"id":103053,"date":"2022-01-21T15:36:44","date_gmt":"2022-01-21T13:36:44","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/%d1%83%d1%8f%d0%b7%d0%b2%d0%b8%d0%bc%d0%be%d1%81%d1%82%d1%8c-%d0%b2-vfs-%d1%8f%d0%b4%d1%80%d0%b0-linux-%d0%bf%d0%be%d0%b7%d0%b2%d0%be%d0%bb%d1%8f%d1%8e%d1%89%d0%b0%d1%8f-%d0%bf%d0%be%d0%b2%d1%8b"},"modified":"2022-01-21T15:36:44","modified_gmt":"2022-01-21T13:36:44","slug":"%d1%83%d1%8f%d0%b7%d0%b2%d0%b8%d0%bc%d0%be%d1%81%d1%82%d1%8c-%d0%b2-vfs-%d1%8f%d0%b4%d1%80%d0%b0-linux-%d0%bf%d0%be%d0%b7%d0%b2%d0%be%d0%bb%d1%8f%d1%8e%d1%89%d0%b0%d1%8f-%d0%bf%d0%be%d0%b2%d1%8b","status":"publish","type":"post","link":"https:\/\/prohoster.info\/cs\/blog\/news\/%d1%83%d1%8f%d0%b7%d0%b2%d0%b8%d0%bc%d0%be%d1%81%d1%82%d1%8c-%d0%b2-vfs-%d1%8f%d0%b4%d1%80%d0%b0-linux-%d0%bf%d0%be%d0%b7%d0%b2%d0%be%d0%bb%d1%8f%d1%8e%d1%89%d0%b0%d1%8f-%d0%bf%d0%be%d0%b2%d1%8b","title":{"rendered":"Zranitelnost v j\u00e1d\u0159e Linuxu VFS, kter\u00e1 umo\u017e\u0148uje zv\u00fd\u0161en\u00ed vlastn\u00edch opr\u00e1vn\u011bn\u00ed.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

V API Filesystem Context poskytovan\u00e9m j\u00e1drem Linux byla zji\u0161t\u011bna zranitelnost (CVE-2022-0185), kter\u00e1 umo\u017e\u0148uje m\u00edstn\u00edmu u\u017eivateli z\u00edskat pr\u00e1va root v syst\u00e9mu. V\u00fdzkumn\u00edk, kter\u00fd probl\u00e9m odhalil, zve\u0159ejnil demonstraci exploitace, kter\u00e1 umo\u017e\u0148uje vykon\u00e1n\u00ed k\u00f3du s pr\u00e1vy root na Ubuntu 20.04 v z\u00e1kladn\u00ed konfiguraci. K\u00f3d exploitu m\u00e1 b\u00fdt zve\u0159ejn\u011bn na GitHubu b\u011bhem t\u00fddne pot\u00e9, co distribuce vydaj\u00ed aktualizaci s opravou zranitelnosti. <\/p>\n

Vulnerabilita se nach\u00e1z\u00ed ve funkci legacy_parse_param() v VFS a je zp\u016fsobena nedostate\u010dnou kontrolou maxim\u00e1ln\u00ed velikosti parametr\u016f poskytovan\u00fdch v souborov\u00fdch syst\u00e9mech, kter\u00e9 nepodporuj\u00ed API Filesystem Context. P\u0159i p\u0159ed\u00e1n\u00ed p\u0159\u00edli\u0161 velk\u00e9ho parametru m\u016f\u017ee doj\u00edt k p\u0159ete\u010den\u00ed celo\u010d\u00edseln\u00e9 prom\u011bnn\u00e9, kter\u00e1 se pou\u017e\u00edv\u00e1 k v\u00fdpo\u010dtu velikosti zapisovan\u00fdch dat \u2014 v k\u00f3du je p\u0159\u00edtomna kontrola p\u0159ete\u010den\u00ed bufferu \u201eif (len > PAGE_SIZE - 2 - size)\u201c, kter\u00e1 nefunguje, pokud je hodnota size v\u011bt\u0161\u00ed ne\u017e 4094, kv\u016fli celo\u010d\u00edseln\u00e9mu p\u0159ete\u010den\u00ed na doln\u00edm limitu (integer underflow, p\u0159i p\u0159etypov\u00e1n\u00ed 4096 - 2 - 4095 na unsigned int z\u00edsk\u00e1me 2147483648). <\/p>\n

Uveden\u00e1 chyba umo\u017e\u0148uje p\u0159i p\u0159\u00edstupu ke speci\u00e1ln\u011b form\u00e1tovan\u00e9mu obrazu F\u0421 vyvolat p\u0159ekro\u010den\u00ed bufferu a p\u0159epsat data j\u00e1dra n\u00e1sleduj\u00edc\u00ed za vyhrazenou oblast\u00ed pam\u011bti. Pro zneu\u017eit\u00ed zranitelnosti jsou vy\u017eadov\u00e1na pr\u00e1va CAP_SYS_ADMIN, tedy opr\u00e1vn\u011bn\u00ed administr\u00e1tora. Probl\u00e9m je v tom, \u017ee takov\u00e1 opr\u00e1vn\u011bn\u00ed m\u016f\u017ee nezprivilegovan\u00fd u\u017eivatel z\u00edskat v izolovan\u00e9m kontejneru, pokud je v syst\u00e9mu povolena podpora u\u017eivatelsk\u00fdch prostor\u016f (user namespaces). Nap\u0159\u00edklad u\u017eivatelsk\u00e9 prostory jsou ve v\u00fdchoz\u00edm nastaven\u00ed povoleny v Ubuntu a Fedo\u0159e, ale nejsou aktivov\u00e1ny v Debianu a RHEL (pokud se nepou\u017e\u00edvaj\u00ed platformy kontejnerov\u00e9 izolace). <\/p>\n

Probl\u00e9m se projevuje od j\u00e1dra Linux 5.1 a byl odstran\u011bn v\u010derej\u0161\u00edmi aktualizacemi 5.16.2, 5.15.16, 5.10.93, 5.4.173. Aktualizace bal\u00ed\u010dk\u016f s opravou zranitelnosti ji\u017e byly vyd\u00e1ny pro RHEL, Debian, Fedora, Ubuntu. Oprava zat\u00edm nen\u00ed dostupn\u00e1 v Arch Linux, Gentoo, SUSE a openSUSE. Jako obch\u00e1zec\u00ed ochrana pro syst\u00e9my, kter\u00e9 nepou\u017e\u00edvaj\u00ed kontejnerovou izolaci, lze nastavit hodnotu sysctl \u201euser.max_user_namespaces\u201c na 0: echo \u201euser.max_user_namespaces=0\u201c > \/etc\/sysctl.d\/userns.conf # sysctl -p \/etc\/sysctl.d\/userns.conf
\n
Zdroj: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0412 API Filesystem Context, \u043f\u0440\u0435\u0434\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u043c\u044b\u043c \u044f\u0434\u0440\u043e\u043c Linux, \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2022-0185), \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043b\u043e\u043a\u0430\u043b\u044c\u043d\u043e\u043c\u0443 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044e \u0434\u043e\u0431\u0438\u0442\u044c\u0441\u044f \u043f\u043e\u043b\u0443\u0447\u0435\u043d\u0438\u044f \u043f\u0440\u0430\u0432 root \u0432 \u0441\u0438\u0441\u0442\u0435\u043c\u0435. \u0412\u044b\u044f\u0432\u0438\u0432\u0448\u0438\u0439 \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u0443 \u0438\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u044c \u043e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043b \u0434\u0435\u043c\u043e\u043d\u0441\u0442\u0440\u0430\u0446\u0438\u044e \u0440\u0430\u0431\u043e\u0442\u044b \u044d\u043a\u0441\u043f\u043b\u043e\u0438\u0442\u0430, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0435\u0433\u043e \u0432\u044b\u043f\u043e\u043b\u043d\u0438\u0442\u044c \u043a\u043e\u0434 \u0441 \u043f\u0440\u0430\u0432\u0430\u043c\u0438 root \u0432 Ubuntu 20.04 \u0432 \u043a\u043e\u043d\u0444\u0438\u0433\u0443\u0440\u0430\u0446\u0438\u0438 \u043f\u043e \u0443\u043c\u043e\u043b\u0447\u0430\u043d\u0438\u044e. \u041a\u043e\u0434 \u044d\u043a\u0441\u043f\u043b\u043e\u0438\u0442\u0430 \u043f\u043b\u0430\u043d\u0438\u0440\u0443\u0435\u0442\u0441\u044f \u0440\u0430\u0437\u043c\u0435\u0441\u0442\u0438\u0442\u044c \u043d\u0430 GitHub \u0432 \u0442\u0435\u0447\u0435\u043d\u0438\u0435 \u043d\u0435\u0434\u0435\u043b\u0438, \u043f\u043e\u0441\u043b\u0435 \u0442\u043e\u0433\u043e \u043a\u0430\u043a \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u044b \u0432\u044b\u043f\u0443\u0441\u0442\u044f\u0442 \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0435 \u0441 […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-103053","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\n","aioseo_head_json":{"title":"\ud83e\udd47Zranitelnost v VFS j\u00e1dru Linuxu, kter\u00e1 umo\u017e\u0148uje zv\u00fd\u0161it sv\u00e9 privilegium | ProHoster","description":"V API Filesystem Context, poskytovan\u00e9m j\u00e1drem Linuxu, byla zji\u0161t\u011bna zranitelnost (CVE-2022-0185), kter\u00e1 umo\u017e\u0148uje m\u00edstn\u00edmu u\u017eivateli z\u00edskat pr\u00e1va root v 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