{"id":100168,"date":"2021-05-14T16:23:07","date_gmt":"2021-05-14T14:23:07","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimosti-v-podsisteme-ebpf-pozvolyayushhie-vypolnit-kod-na-urovne-yadra-linux"},"modified":"2021-05-14T16:23:07","modified_gmt":"2021-05-14T14:23:07","slug":"uyazvimosti-v-podsisteme-ebpf-pozvolyayushhie-vypolnit-kod-na-urovne-yadra-linux","status":"publish","type":"post","link":"https:\/\/prohoster.info\/cs\/blog\/news\/uyazvimosti-v-podsisteme-ebpf-pozvolyayushhie-vypolnit-kod-na-urovne-yadra-linux","title":{"rendered":"Zranitelnosti v podsystemu eBPF, kter\u00e9 umo\u017e\u0148uj\u00ed vykonat k\u00f3d na \u00farovni j\u00e1dra Linuxu.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p>Byly objeveny dv\u011b nov\u00e9 zranitelnosti v podsystemu eBPF, kter\u00fd umo\u017e\u0148uje spou\u0161t\u011bn\u00ed zpracovatel\u016f uvnit\u0159 j\u00e1dra Linux ve speci\u00e1ln\u00ed virtu\u00e1ln\u00ed stroji s JIT. Ob\u011b zranitelnosti umo\u017e\u0148uj\u00ed prov\u00e1d\u011bt vlastn\u00ed k\u00f3d s pr\u00e1vy j\u00e1dra, mimo izolovanou virtu\u00e1ln\u00ed stroj eBPF. Informace o probl\u00e9mech publikoval t\u00fdm Zero Day Initiative, kter\u00fd po\u0159\u00e1d\u00e1 sout\u011b\u017e Pwn2Own, b\u011bhem n\u00ed\u017e byly v tomto roce p\u0159edvedeny t\u0159i \u00fatoky na Ubuntu Linux, p\u0159i nich\u017e byly vyu\u017eity dosud nezn\u00e1m\u00e9 zranitelnosti (nebylo ozn\u00e1meno, zda jsou zranitelnosti v eBPF spojeny s t\u011bmito \u00fatoky).   <\/p>\n<ul>\n<li class=\"l\"> CVE-2021-3490 \u2014 zranitelnost je zp\u016fsobena nedostatkem kontroly p\u0159ete\u010den\u00ed 32bitov\u00fdch hodnot p\u0159i prov\u00e1d\u011bn\u00ed bitov\u00fdch operac\u00ed AND, OR a XOR v eBPF ALU32. \u00dato\u010dn\u00edk m\u016f\u017ee vyu\u017e\u00edt tuto chybu ke \u010dten\u00ed a z\u00e1pisu dat mimo hranice p\u0159id\u011blen\u00e9ho pam\u011b\u0165ov\u00e9ho bloku. Probl\u00e9m s operac\u00ed XOR se projevuje od verze j\u00e1dra 5.7-rc1, a AND a OR \u2014 od vyd\u00e1n\u00ed 5.10-rc1.\n<li class=\"l\"> CVE-2021-3489 \u2014 zranitelnost je zp\u016fsobena chybou v implementaci kruhov\u00e9ho bufferu a souvis\u00ed s t\u00edm, \u017ee funkce bpf_ringbuf_reserve neov\u011b\u0159ovala mo\u017enost, \u017ee velikost p\u0159id\u011blen\u00e9 oblasti pam\u011bti m\u016f\u017ee b\u00fdt men\u0161\u00ed ne\u017e skute\u010dn\u00e1 velikost kruhov\u00e9ho bufferu ringbuf. Probl\u00e9m se projevuje od vyd\u00e1n\u00ed 5.8-rc1.  <\/ul>\n<p>Status opravy zranitelnost\u00ed v distribuc\u00edch lze sledovat na t\u011bchto str\u00e1nk\u00e1ch: Ubuntu, Debian, RHEL, Fedora, SUSE, Arch). Opravy jsou tak\u00e9 k dispozici ve form\u011b patch\u016f (CVE-2021-3489, CVE-2021-3490). Mo\u017enost vyu\u017eit\u00ed probl\u00e9mu z\u00e1vis\u00ed na dostupnosti syst\u00e9mov\u00e9ho vol\u00e1n\u00ed eBPF pro u\u017eivatele. Nap\u0159\u00edklad v z\u00e1kladn\u00ed konfiguraci v RHEL pro zneu\u017eit\u00ed zranitelnosti jsou vy\u017eadov\u00e1na pr\u00e1va CAP_SYS_ADMIN.         <\/p>\n<p>Samostatn\u011b lze zm\u00ednit je\u0161t\u011b jednu zranitelnost v j\u00e1d\u0159e Linux \u2014 CVE-2021-32606, kter\u00e1 umo\u017e\u0148uje m\u00edstn\u00edmu u\u017eivateli zv\u00fd\u0161it sv\u00e9 opr\u00e1vn\u011bn\u00ed na \u00farove\u0148 root. Probl\u00e9m se projevuje od j\u00e1dra Linux 5.11 a je zp\u016fsoben stavem z\u00e1vodu v implementaci protokolu CAN ISOTP, kter\u00fd umo\u017e\u0148uje m\u011bnit parametry vazby na soket kv\u016fli nedostatku spr\u00e1vn\u00e9ho z\u00e1mk\u016f ve funkci isotp_setsockopt() p\u0159i zpracov\u00e1n\u00ed p\u0159\u00edznaku CAN_ISOTP_SF_BROADCAST.    <\/p>\n<p>Po uzav\u0159en\u00ed soketu ISOTP z\u016fst\u00e1v\u00e1 aktivn\u00ed vazba na soket p\u0159\u00edjemce, kter\u00fd m\u016f\u017ee nad\u00e1le pou\u017e\u00edvat s soketem spojen\u00e9 struktury po uvoln\u011bn\u00ed s nimi spojen\u00e9 pam\u011bti (use-after-free v d\u016fsledku vol\u00e1n\u00ed isotp_rcv() na ji\u017e uvoln\u011bn\u00e9 struktu\u0159e isotp_sock). Manipulac\u00ed s daty lze dos\u00e1hnout p\u0159eps\u00e1n\u00ed ukazatele na funkci sk_error_report() a spustit sv\u016fj k\u00f3d na \u00farovni j\u00e1dra.<br \/>\n<br \/>Zdroj: <a content=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/www.opennet.ru\/opennews\/art.shtml?num=55150\">opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>\u0412\u044b\u044f\u0432\u043b\u0435\u043d\u044b \u0434\u0432\u0435 \u043d\u043e\u0432\u044b\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u0432 \u043f\u043e\u0434\u0441\u0438\u0441\u0442\u0435\u043c\u0435 eBPF, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0435\u0439 \u0437\u0430\u043f\u0443\u0441\u043a\u0430\u0442\u044c \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u0447\u0438\u043a\u0438 \u0432\u043d\u0443\u0442\u0440\u0438 \u044f\u0434\u0440\u0430 Linux \u0432 \u0441\u043f\u0435\u0446\u0438\u0430\u043b\u044c\u043d\u043e\u0439 \u0432\u0438\u0440\u0442\u0443\u0430\u043b\u044c\u043d\u043e\u0439 \u043c\u0430\u0448\u0438\u043d\u0435 \u0441 JIT. \u041e\u0431\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0434\u0430\u044e\u0442 \u0432\u043e\u0437\u043c\u043e\u0436\u043d\u043e\u0441\u0442\u044c \u0432\u044b\u043f\u043e\u043b\u043d\u0438\u0442\u044c \u0441\u0432\u043e\u0439 \u043a\u043e\u0434 \u0441 \u043f\u0440\u0430\u0432\u0430\u043c\u0438 \u044f\u0434\u0440\u0430, \u0432\u043d\u0435 \u0438\u0437\u043e\u043b\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u0439 \u0432\u0438\u0440\u0442\u0443\u0430\u043b\u044c\u043d\u043e\u0439 \u043c\u0430\u0448\u0438\u043d\u044b eBPF. \u0418\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044e \u043e \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u0430\u0445 \u043e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043b\u0430 \u043a\u043e\u043c\u0430\u043d\u0434\u0430 Zero Day Initiative, \u043f\u0440\u043e\u0432\u043e\u0434\u044f\u0449\u0430\u044f \u0441\u043e\u0440\u0435\u0432\u043d\u043e\u0432\u0430\u043d\u0438\u044f Pwn2Own, \u0432 \u0445\u043e\u0434\u0435 \u043a\u043e\u0442\u043e\u0440\u044b\u0445 \u0432 \u044d\u0442\u043e\u043c \u0433\u043e\u0434\u0443 \u0431\u044b\u043b\u0438 \u043f\u0440\u043e\u0434\u0435\u043c\u043e\u043d\u0441\u0442\u0440\u0438\u0440\u043e\u0432\u0430\u043d\u044b \u0442\u0440\u0438 \u0430\u0442\u0430\u043a\u0438 [&hellip;]<\/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-100168","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 5.0.3 - aioseo.com -->\n\t<meta name=\"description\" content=\"\u0412\u044b\u044f\u0432\u043b\u0435\u043d\u044b \u0434\u0432\u0435 \u043d\u043e\u0432\u044b\u0435 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