{"id":100574,"date":"2021-06-22T16:24:20","date_gmt":"2021-06-22T14:24:20","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/uyazvimosti-v-podsisteme-ebpf-pozvolyayushhie-obojti-zashhitu-ot-atak-klassa-spectre"},"modified":"2021-06-22T16:24:20","modified_gmt":"2021-06-22T14:24:20","slug":"uyazvimosti-v-podsisteme-ebpf-pozvolyayushhie-obojti-zashhitu-ot-atak-klassa-spectre","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sq\/blog\/news\/uyazvimosti-v-podsisteme-ebpf-pozvolyayushhie-obojti-zashhitu-ot-atak-klassa-spectre","title":{"rendered":"Vulnerabilitetet n\u00eb n\u00ebn-sistemin e eBPF q\u00eb lejojn\u00eb kalimin e mbrojtjes nga sulmet e klas\u00ebs Spectre.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"
Nj\u00eb dob\u00ebsi \u00ebsht\u00eb zbuluar n\u00eb kernelin Linux (CVE-2021-33624), e cila lejon p\u00ebrdorimin e n\u00ebn\u00ebsis\u00eb eBPF p\u00ebr t\u00eb anashkaluar mbrojtjen nga dob\u00ebsit\u00eb e klas\u00ebs Spectre, duke krijuar mund\u00ebsin\u00eb p\u00ebr t\u00eb p\u00ebrcaktuar p\u00ebrmbajtjen e memories si rezultat i krijimit t\u00eb kushteve p\u00ebr ekzekutimin spekulativ t\u00eb operacioneve t\u00eb caktuara. P\u00ebr nj\u00eb sulm Spectre k\u00ebrkohet nj\u00eb sekuenc\u00eb e caktuar komandash n\u00eb kodin me privilegje q\u00eb \u00e7on n\u00eb ekzekutimin spekulativ t\u00eb instrukcioneve. N\u00ebp\u00ebrmjet manipulimit t\u00eb programeve BPF t\u00eb transferuara p\u00ebr ekzekutim, mund t\u00eb arrihet gjenerimi i instrukcioneve t\u00eb tilla n\u00eb eBPF dhe t\u00eb shfaqen t\u00eb dh\u00ebna p\u00ebrmbajtjeje t\u00eb memories s\u00eb kernelit dhe rajoneve t\u00eb rastit t\u00eb memories fizike p\u00ebrmes kanaleve an\u00ebsore. <\/p>\n
V\u00ebshtir\u00ebsia shkaktohet nga mang\u00ebsit\u00eb n\u00eb verifikuesin e p\u00ebrdorur p\u00ebr identifikimin e gabimeve dhe aktiviteteve t\u00eb papranueshme n\u00eb programet BPF. Verifikuesi kalon n\u00ebp\u00ebr rrug\u00ebt e mundshme t\u00eb ekzekutimit t\u00eb kodit, por injoron deg\u00ebzimet q\u00eb jan\u00eb t\u00eb papranueshme sipas semantik\u00ebs s\u00eb arkitektur\u00ebs s\u00eb grupit t\u00eb komandave. Gjat\u00eb ekzekutimit t\u00eb nj\u00eb programi BPF, deg\u00ebzimet e tilla, t\u00eb cilat nuk jan\u00eb marr\u00eb parasysh nga verifikuesi, mund t\u00eb parashikohen gabimisht nga procesori dhe t\u00eb ekzekutohen n\u00eb m\u00ebnyr\u00eb spekulative. P\u00ebr shembull, kur analizohet operacioni \u201cload\u201d, verifikuesi llogarit se instruksioni p\u00ebrdor nj\u00eb regjist\u00ebr me nj\u00eb adres\u00eb, vlera e s\u00eb cil\u00ebs \u00ebsht\u00eb gjithmon\u00eb brenda kufijve t\u00eb caktuar, por nj\u00eb sulmues mund t\u00eb krijoj\u00eb kushte ku procesori do t\u00eb p\u00ebrpiqet t\u00eb ekzekutoj\u00eb spekulativisht operacionin me nj\u00eb adres\u00eb q\u00eb nuk p\u00ebrputhet me kushtet e kontrollit. <\/p>\n
Problemi shfaqet q\u00eb nga l\u00ebshimi i kernelit 4.15 dhe \u00ebsht\u00eb eliminuar n\u00eb form\u00ebn e patches (1, 2, 3, 4). N\u00eb distribucione, dob\u00ebsia ende mbetet e pap\u00ebrmir\u00ebsuar (Debian, RHEL, Ubuntu, Fedora, SUSE, Arch). <\/p>\n
P\u00ebr m\u00eb tep\u00ebr, mund t\u00eb theksohet nj\u00eb sh\u00ebnim mbi ndikimin n\u00eb performanc\u00eb t\u00eb mjeteve p\u00ebr mbrojtjen nga dob\u00ebsit\u00eb e klas\u00ebs Spectre. N\u00eb sh\u00ebnim jan\u00eb p\u00ebrmbledhur rezultatet e optimizimit t\u00eb debugger-it rr (Record and Replay), i krijuar n\u00eb koh\u00ebn e tij n\u00eb Mozilla p\u00ebr t\u00eb debug-uar gabime t\u00eb v\u00ebshtira p\u00ebr t'u p\u00ebrs\u00ebritur n\u00eb Firefox. Jepja e sistemit t\u00eb thirrjeve, e p\u00ebrdorur p\u00ebr verifikimin e ekzistenc\u00ebs s\u00eb katalog\u00ebve, ka lejuar t\u00eb zvog\u00eblohet ekzekutimi i operacionit \u201crr sources\u201d p\u00ebr projektin testues nga 3 minuta 19 sekonda n\u00eb 36 sekonda. <\/p>\n
Autori i optimizimit vendosi t\u00eb verifikoj\u00eb se sa do t\u00eb ndryshonte performanca pas \u00e7 deaktivizimit t\u00eb mbrojtjes nga Spectre. Pas ngarkimit t\u00eb sistemit me parametrin \u201cmitigations=off\u201d, koha e ekzekutimit t\u00eb \u201crr sources\u201d pa optimizim ishte 2 minuta 5 sekonda (1.6 her\u00eb m\u00eb shpejt), dhe me optimizim \u2014 33 sekonda (9% m\u00eb shpejt). \u00cbsht\u00eb e \u00e7uditshme se \u00e7 deaktivizimi i mbrojtjes nga Spectre jo vet\u00ebm q\u00eb reduktoi koh\u00ebn e ekzekutimit t\u00eb kodit n\u00eb nivelin e b\u00ebrtham\u00ebs (nga 2m9s n\u00eb 1m32s) 1.4 her\u00eb, por gjithashtu reduktoi dyfish koh\u00ebn e ekzekutimit n\u00eb hap\u00ebsir\u00ebn e p\u00ebrdoruesit (nga 1m9s n\u00eb 0m33s), ndoshta p\u00ebr shkak t\u00eb reduktimit t\u00eb efikasitetit t\u00eb pun\u00ebs s\u00eb caches CPU dhe shkarkimit t\u00eb TLB-ve kur mbrojtja nga Spectre ishte e aktivizuar. \n Burimi: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"