{"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\/sk\/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":"Zranite\u013enos\u0165 v VFS jadra Linuxu, ktor\u00e1 umo\u017e\u0148uje zv\u00fd\u0161i\u0165 svoje privil\u00e9gia","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

V API Filesystem Context, poskytovanom jadrom Linux, bola zisten\u00e1 zranite\u013enos\u0165 (CVE-2022-0185), ktor\u00e1 umo\u017e\u0148uje lok\u00e1lnemu u\u017e\u00edvate\u013eovi z\u00edska\u0165 pr\u00e1va root v syst\u00e9me. V\u00fdskumn\u00edk, ktor\u00fd odhalil probl\u00e9m, zverejnil demon\u0161tr\u00e1ciu fungovania exploit, ktor\u00fd umo\u017e\u0148uje vykona\u0165 k\u00f3d s pr\u00e1vami root v Ubuntu 20.04 v predvolenej konfigur\u00e1cii. K\u00f3d exploit pl\u00e1nuje zverejni\u0165 na GitHub po\u010das t\u00fd\u017ed\u0148a, po tom, \u010do distrib\u00facie vydaj\u00fa aktualiz\u00e1ciu s opravou zranite\u013enosti. <\/p>\n

Zranite\u013enos\u0165 sa vyskytuje vo funkcii legacy_parse_param() v VFS a je sp\u00f4soben\u00e1 nedostato\u010dnou kontrolou maxim\u00e1lnej ve\u013ekosti parametrov poskytovan\u00fdch v s\u00faborov\u00fdch syst\u00e9moch, ktor\u00e9 nepodporuj\u00fa API Filesystem Context. Pri odosielan\u00ed pr\u00edli\u0161 ve\u013ek\u00e9ho parametra m\u00f4\u017ee d\u00f4js\u0165 k prete\u010deniu celo\u010d\u00edselnej premennej, ktor\u00e1 sa pou\u017e\u00edva na v\u00fdpo\u010det ve\u013ekosti zapisovan\u00fdch \u00fadajov \u2014 v k\u00f3de existuje kontrola prekro\u010denia hranice bufferu \u201eif (len > PAGE_SIZE - 2 - size)\u201c, ktor\u00e1 sa nespust\u00ed, ak je hodnota size v\u00e4\u010d\u0161ia ako 4094 z d\u00f4vodu celo\u010d\u00edseln\u00e9ho prete\u010denia cez doln\u00fa hranicu (integer underflow, pri prevode 4096 - 2 - 4095 na unsigned int dostaneme 2147483648). <\/p>\n

Uveden\u00e1 chyba umo\u017e\u0148uje pri pr\u00edstupe k \u0161peci\u00e1lne form\u00e1tovan\u00e9mu obrazu FS sp\u00f4sobi\u0165 prete\u010denie bufferu a prep\u00edsa\u0165 d\u00e1ta jadra, ktor\u00e9 nasleduj\u00fa za pridelenou oblas\u0165ou pam\u00e4te. Na zneu\u017eitie zranite\u013enosti je potrebn\u00e9 ma\u0165 pr\u00e1va CAP_SYS_ADMIN, t.j. administr\u00e1torsk\u00e9 opr\u00e1vnenia. Probl\u00e9m je v tom, \u017ee podobn\u00e9 opr\u00e1vnenia m\u00f4\u017ee neprivilegovan\u00fd u\u017e\u00edvate\u013e z\u00edska\u0165 v izolovanom konte, ak je v syst\u00e9me povolen\u00e1 podpora priestorov identifika\u010dn\u00fdch \u010d\u00edsel u\u017e\u00edvate\u013eov (user namespaces). Napr\u00edklad user namespaces s\u00fa predvolene povolen\u00e9 v Ubuntu a Fedore, ale nie s\u00fa akt\u00edvne v Debiane a RHEL (ak sa nepou\u017e\u00edvaj\u00fa platformy kontajnerovej izol\u00e1cie). <\/p>\n

Probl\u00e9m sa prejavuje od jadra Linux 5.1 a bol odstr\u00e1nen\u00fd v\u010dera v aktualiz\u00e1ci\u00e1ch 5.16.2, 5.15.16, 5.10.93, 5.4.173. Aktualiz\u00e1cie bal\u00edkov na odstr\u00e1nenie zranite\u013enosti u\u017e boli vydan\u00e9 pre RHEL, Debian, Fedora, Ubuntu. Oprava zatia\u013e nie je k dispoz\u00edcii v Arch Linux, Gentoo, SUSE a openSUSE. Ako obch\u00e1dzkov\u00e1 ochrana pre syst\u00e9my, ktor\u00e9 nepou\u017e\u00edvaj\u00fa kontajnerov\u00fa izol\u00e1ciu, m\u00f4\u017eete nastavi\u0165 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\udd47Zranite\u013enos\u0165 v VFS jadra Linux, umo\u017e\u0148uj\u00faca zv\u00fd\u0161i\u0165 svoje privil\u00e9gi\u00e1 | ProHoster","description":"V API Filesystem Context, poskytovanom jadrom Linux, bola zisten\u00e1 zranite\u013enos\u0165 (CVE-2022-0185), ktor\u00e1 umo\u017e\u0148uje lok\u00e1lnemu pou\u017e\u00edvate\u013eovi z\u00edska\u0165 pr\u00e1va 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