{"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\/pl\/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":"Vulnerability in Linux kernel VFS allowing privilege escalation","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

W kontek\u015bcie API Filesystem, dostarczanym przez j\u0105dro Linux, wykryto luk\u0119 (CVE-2022-0185), kt\u00f3ra umo\u017cliwia lokalnemu u\u017cytkownikowi uzyskanie uprawnie\u0144 root w systemie. Badacz, kt\u00f3ry zidentyfikowa\u0142 problem, opublikowa\u0142 demonstracj\u0119 dzia\u0142ania exploita, kt\u00f3ry pozwala na wykonanie kodu z uprawnieniami root w Ubuntu 20.04 w konfiguracji domy\u015blnej. Kod exploita ma by\u0107 umieszczony na GitHubie w ci\u0105gu tygodnia, po wydaniu aktualizacji przez dystrybucje z poprawk\u0105 tej luki. <\/p>\n

Uwaga wyst\u0119puje w funkcji legacy_parse_param() w VFS i jest spowodowana brakiem odpowiedniej kontroli maksymalnego rozmiaru parametr\u00f3w dostarczanych przez systemy plik\u00f3w, kt\u00f3re nie obs\u0142uguj\u0105 interfejsu API Filesystem Context. Przekazuj\u0105c zbyt du\u017cy parametr, mo\u017cna spowodowa\u0107 przepe\u0142nienie zmiennej ca\u0142kowitej u\u017cywanej do obliczania rozmiaru danych do zapisania \u2014 w kodzie istnieje kontrola przekroczenia bufora \u201eif (len > PAGE_SIZE \u2014 2 \u2014 size)\u201d, kt\u00f3ra nie dzia\u0142a, gdy warto\u015b\u0107 size przekracza 4094 z powodu przepe\u0142nienia ca\u0142kowitego przez doln\u0105 granic\u0119 (integer underflow, konwertuj\u0105c 4096 \u2014 2 \u2014 4095 na unsigned int otrzymamy 2147483648). <\/p>\n

Wskazana usterka pozwala na wywo\u0142anie przepe\u0142nienia bufora przy odwo\u0142aniu si\u0119 do specjalnie przygotowanego obrazu FS i nadpisania danych j\u0105dra, kt\u00f3re znajduj\u0105 si\u0119 za przydzielonym obszarem pami\u0119ci. Aby wykorzysta\u0107 t\u0119 luk\u0119, wymagane s\u0105 uprawnienia CAP_SYS_ADMIN, tj. uprawnienia administratora. Problem polega na tym, \u017ce podobne uprawnienia u\u017cytkownik bez przywilej\u00f3w mo\u017ce uzyska\u0107 w izolowanym kontenerze, je\u015bli w systemie w\u0142\u0105czono obs\u0142ug\u0119 przestrzeni nazw identyfikator\u00f3w u\u017cytkownik\u00f3w (user namespaces). Na przyk\u0142ad, user namespaces s\u0105 domy\u015blnie w\u0142\u0105czone w Ubuntu i Fedorze, ale nieaktywne w Debianie i RHEL (chyba \u017ce wykorzystuje si\u0119 platformy izolacji kontener\u00f3w). <\/p>\n

Problem wyst\u0119puje od j\u0105dra Linux 5.1 i zosta\u0142 rozwi\u0105zany w wczorajszych aktualizacjach 5.16.2, 5.15.16, 5.10.93, 5.4.173. Aktualizacje pakiet\u00f3w usuwaj\u0105cych luk\u0119 bezpiecze\u0144stwa zosta\u0142y ju\u017c wydane dla RHEL, Debian, Fedora, Ubuntu. Poprawka jest na razie niedost\u0119pna w Arch Linux, Gentoo, SUSE i openSUSE. Jako tymczasowe rozwi\u0105zanie ochrony dla system\u00f3w, kt\u00f3re nie u\u017cywaj\u0105 izolacji kontenerowej, warto\u015b\u0107 sysctl \u201euser.max_user_namespaces\u201d mo\u017cna ustawi\u0107 na 0: echo \u201euser.max_user_namespaces=0\u201d > \/etc\/sysctl.d\/userns.conf # sysctl -p \/etc\/sysctl.d\/userns.conf
\n
\u0179r\u00f3d\u0142o: 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\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\udd47Luka w VFS j\u0105dra Linux, umo\u017cliwiaj\u0105ca podniesienie swoich uprawnie\u0144 | ProHoster","description":"W API Filesystem Context, dostarczanym przez j\u0105dro Linux, wykryto luk\u0119 (CVE-2022-0185), kt\u00f3ra pozwala lokalnemu u\u017cytkownikowi uzyska\u0107 uprawnienia root w 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