{"id":100548,"date":"2021-06-20T10:22:54","date_gmt":"2021-06-20T08:22:55","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimost-v-yadre-linux-zatragivayushhaya-setevoj-protokol-can-bcm"},"modified":"2021-06-20T10:22:54","modified_gmt":"2021-06-20T08:22:55","slug":"uyazvimost-v-yadre-linux-zatragivayushhaya-setevoj-protokol-can-bcm","status":"publish","type":"post","link":"https:\/\/prohoster.info\/et\/blog\/news\/uyazvimost-v-yadre-linux-zatragivayushhaya-setevoj-protokol-can-bcm","title":{"rendered":"Viga Linuxi tuumas, mis m\u00f5jutab CAN BCM v\u00f5rgu protokolli.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Linuxi tuumas leiti haavatavus (CVE-2021-3609), mis v\u00f5imaldab kohalikul kasutajal oma \u00f5igusi s\u00fcsteemis t\u00f5sta. Probleem on tingitud v\u00f5istlusolukorrast CAN BCM protokolli rakenduses ja see avaldub Linuxi tuumade versioonides 2.6.25 kuni 5.13-rc6. Probleem on jaotustes endiselt parandamata (RHEL, Fedora, Debian, Ubuntu, SUSE, Arch). <\/p>\n

Haavatavuse avastanud teadlane suutis valmistada ette eksploiti root-\u00f5iguste saamiseks Linuxi tuumadega s\u00fcsteemides, mille versioon on 5.4 ja uuem, sealhulgas on n\u00e4idatud v\u00f5imalust edukaks r\u00fcnnakuks Ubuntu 20.04.02 LTS. Ei saa v\u00e4listada eksploidi \u00fcmbertegemise v\u00f5imalust ka vanemate tuumade jaoks (tuumas 5.4 on CAN BCM kood (net\/can\/bcm.c) muudetud hrtimer_tasklet'ilt HRTIMER_MODE_SOFT'ile). <\/p>\n

CAN BCM protokoll v\u00f5imaldab registreerida oma teate t\u00f6\u00f6tleja, mis saab teateid CAN (controller area network) bussist, ja siduda selle konkreetse v\u00f5rgu soketiga. Sissetuleva s\u00f5numi saabudes kutsutakse funktsioon bcm_rx_handler(). R\u00fcndaja v\u00f5ib kasutada v\u00f5istlusolukorda ja saavutada v\u00f5rgu soketi sulgemise samal ajal bcm_rx_handler() t\u00e4itmisega. Soketi sulgemisel kutsutakse esile funktsioon bcm_release(), kus vabastatakse m\u00e4lu, mis on eraldatud bcm_op ja bcm_sock struktuuride jaoks, mida kasutatakse endiselt aktiivses bcm_rx_handler() t\u00f6\u00f6tlejas. Tekib olukord, mis viib juba vabastatud m\u00e4luploki juurde (use-after-free). <\/p>\n

R\u00fcnnak seisneb kahe CAN BCM soketi avamises ja nende sidumises vcan liidesega. Esimeses soketis tehakse sendmsg() kutsumine RX_SETUP lipuga, et seadistada sissetulevate CAN s\u00f5numite t\u00f6\u00f6tlejat, ja teises soketis tehakse sendmsg() kutsumine, et saata s\u00f5num esimesse soketisse. P\u00e4rast s\u00f5numi saamist kutsub bcm_rx_handler() v\u00e4lja, samas kui r\u00fcndaja valib \u00f5ige hetke ja sulgeb esimese soketi, mis viib bcm_release() k\u00e4ivitamiseni ja bcm_op ja bcm_sock struktuuride vabastamiseni, kuigi bcm_rx_handler() t\u00f6\u00f6 ei ole veel l\u00f5ppenud. <\/p>\n

\u0427\u0435\u0440\u0435\u0437 \u043c\u0430\u043d\u0438\u043f\u0443\u043b\u044f\u0446\u0438\u0438 \u0441 \u0441\u043e\u0434\u0435\u0440\u0436\u0438\u043c\u044b\u043c bcm_sock \u0430\u0442\u0430\u043a\u0443\u044e\u0449\u0438\u0439 \u043c\u043e\u0436\u0435\u0442 \u043f\u0435\u0440\u0435\u043e\u043f\u0440\u0435\u0434\u0435\u043b\u0438\u0442\u044c \u0443\u043a\u0430\u0437\u0430\u0442\u0435\u043b\u044c \u043d\u0430 \u0444\u0443\u043d\u043a\u0446\u0438\u044e sk->sk_data_ready(sk), \u043f\u0435\u0440\u0435\u043d\u0430\u043f\u0440\u0430\u0432\u0438\u0442\u044c \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u0435 \u0438 \u043f\u0440\u0438 \u043f\u043e\u043c\u043e\u0449\u0438 \u043f\u0440\u0438\u0451\u043c\u043e\u0432 \u0432\u043e\u0437\u0432\u0440\u0430\u0442\u043d\u043e-\u043e\u0440\u0438\u0435\u043d\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u0433\u043e \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u044f (ROP — Return-Oriented Programming) \u043e\u0440\u0433\u0430\u043d\u0438\u0437\u043e\u0432\u0430\u0442\u044c \u043f\u0435\u0440\u0435\u0437\u0430\u043f\u0438\u0441\u044c \u043f\u0430\u0440\u0430\u043c\u0435\u0442\u0440\u0430 modprobe_path \u0438 \u0434\u043e\u0431\u0438\u0442\u044c\u0441\u044f \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044f \u0441\u0432\u043e\u0435\u0433\u043e \u043a\u043e\u0434\u0430 \u0441 \u043f\u0440\u0430\u0432\u0430\u043c\u0438 root. \u041f\u0440\u0438 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0438 \u0442\u0435\u0445\u043d\u0438\u043a\u0438 ROP \u0430\u0442\u0430\u043a\u0443\u044e\u0449\u0438\u0439 \u043d\u0435 \u043f\u044b\u0442\u0430\u0435\u0442\u0441\u044f \u0440\u0430\u0437\u043c\u0435\u0441\u0442\u0438\u0442\u044c \u0441\u0432\u043e\u0439 \u043a\u043e\u0434 \u0432 \u043f\u0430\u043c\u044f\u0442\u0438, \u0430 \u043e\u043f\u0435\u0440\u0438\u0440\u0443\u0435\u0442 \u0443\u0436\u0435 \u0438\u043c\u0435\u044e\u0449\u0438\u043c\u0438\u0441\u044f \u0432 \u0437\u0430\u0433\u0440\u0443\u0436\u0435\u043d\u043d\u044b\u0445 \u0431\u0438\u0431\u043b\u0438\u043e\u0442\u0435\u043a\u0430\u0445 \u043a\u0443\u0441\u043a\u0430\u043c\u0438 \u043c\u0430\u0448\u0438\u043d\u043d\u044b\u0445 \u0438\u043d\u0441\u0442\u0440\u0443\u043a\u0446\u0438\u0439, \u0437\u0430\u0432\u0435\u0440\u0448\u0430\u044e\u0449\u0438\u0445\u0441\u044f \u0438\u043d\u0441\u0442\u0440\u0443\u043a\u0446\u0438\u0435\u0439 \u0432\u043e\u0437\u0432\u0440\u0430\u0442\u0430 \u0443\u043f\u0440\u0430\u0432\u043b\u0435\u043d\u0438\u044f (\u043a\u0430\u043a \u043f\u0440\u0430\u0432\u0438\u043b\u043e, \u044d\u0442\u043e \u043e\u043a\u043e\u043d\u0447\u0430\u043d\u0438\u044f \u0431\u0438\u0431\u043b\u0438\u043e\u0442\u0435\u0447\u043d\u044b\u0445 \u0444\u0443\u043d\u043a\u0446\u0438\u0439). \u0420\u0430\u0431\u043e\u0442\u0430 \u044d\u043a\u0441\u043f\u043b\u043e\u0438\u0442\u0430 \u0441\u0432\u043e\u0434\u0438\u0442\u0441\u044f \u043a \u043f\u043e\u0441\u0442\u0440\u043e\u0435\u043d\u0438\u044e \u0446\u0435\u043f\u043e\u0447\u043a\u0438 \u0432\u044b\u0437\u043e\u0432\u043e\u0432 \u043f\u043e\u0434\u043e\u0431\u043d\u044b\u0445 \u0431\u043b\u043e\u043a\u043e\u0432 («\u0433\u0430\u0434\u0436\u0435\u0442\u043e\u0432») \u0434\u043b\u044f \u043f\u043e\u043b\u0443\u0447\u0435\u043d\u0438\u044f \u043d\u0443\u0436\u043d\u043e\u0439 \u0444\u0443\u043d\u043a\u0446\u0438\u043e\u043d\u0430\u043b\u044c\u043d\u043e\u0441\u0442\u0438.

\"Viga<\/center> <\/p>\n

R\u00fcnnaku jaoks on vajalik juurdep\u00e4\u00e4s CAN sokkide loomisele ja seadistatud vcan v\u00f5rguliides. R\u00fcnnakuks vajalikud \u00f5igused v\u00f5ivad olla saadud mitteprivilegiseeritud kasutajale konteinerites, mis on loodud s\u00fcsteemides, kus on aktiveeritud kasutaja identifikaatori nimespaced (user namespaces) tugi. N\u00e4iteks on Ubuntu ja Fedora vaikimisi l\u00fclitatud kasutaja nimespaced, kuid Debianis ja RHEL-is pole see aktiveeritud.
\n
Allikas: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0412 \u044f\u0434\u0440\u0435 Linux \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0430 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c (CVE-2021-3609), \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 \u043f\u043e\u0434\u043d\u044f\u0442\u044c \u0441\u0432\u043e\u0438 \u043f\u0440\u0438\u0432\u0438\u043b\u0435\u0433\u0438\u0438 \u0432 \u0441\u0438\u0441\u0442\u0435\u043c\u0435. \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u0432\u044b\u0437\u0432\u0430\u043d\u0430 \u0441\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0435\u043c \u0433\u043e\u043d\u043a\u0438 \u0432 \u0440\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u0438 \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b\u0430 CAN BCM \u0438 \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u0432 \u0432\u044b\u043f\u0443\u0441\u043a\u0430\u0445 \u044f\u0434\u0440\u0430 Linux \u0441 2.6.25 \u043f\u043e 5.13-rc6. \u0412 \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u0430\u0445 \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u043f\u043e\u043a\u0430 \u043e\u0441\u0442\u0430\u0451\u0442\u0441\u044f \u043d\u0435\u0438\u0441\u043f\u0440\u0430\u0432\u043b\u0435\u043d\u043d\u043e\u0439 (RHEL, Fedora, Debian, Ubuntu, SUSE, Arch). \u0412\u044b\u044f\u0432\u0438\u0432\u0448\u0438\u0439 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0438\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u044c \u0441\u043c\u043e\u0433 \u043f\u043e\u0434\u0433\u043e\u0442\u043e\u0432\u0438\u0442\u044c \u044d\u043a\u0441\u043f\u043b\u043e\u0438\u0442 \u0434\u043b\u044f \u043f\u043e\u043b\u0443\u0447\u0435\u043d\u0438\u044f \u043f\u0440\u0430\u0432 root […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":100549,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-100548","post","type-post","status-publish","format-standard","has-post-thumbnail","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\udd47Haavatavus Linuxi tuumas, mis m\u00f5jutab CAN BCM v\u00f5rgu protokolli | ProHoster","description":"Linuxi tuumas avastati haavatavus (CVE-2021-3609), mis v\u00f5imaldab kohalikul kasutajal oma privileege s\u00fcsteemis 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