{"id":41110,"date":"2020-02-05T21:30:57","date_gmt":"2020-02-05T18:30:57","guid":{"rendered":"https:\/\/prohoster.info\/blog\/blog_prohoster\/metody-otklyucheniya-zashhity-lockdown-v-ubuntu-dlya-udalyonnogo-obhoda-uefi-secure-boot"},"modified":"2020-02-05T21:30:57","modified_gmt":"2020-02-05T18:30:57","slug":"metody-otklyucheniya-zashhity-lockdown-v-ubuntu-dlya-udalyonnogo-obhoda-uefi-secure-boot","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sk\/blog\/metody-otklyucheniya-zashhity-lockdown-v-ubuntu-dlya-udalyonnogo-obhoda-uefi-secure-boot","title":{"rendered":"Met\u00f3dy vypnutia ochrany Lockdown v Ubuntu na vzdialen\u00e9 ob\u00eddenie UEFI Secure Boot","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Andrej Konovalov z firmy Google publikoval<\/a><\/noindex> met\u00f3da vzdialen\u00e9ho vypnutia ochrany Lockdown<\/a><\/noindex>, pon\u00fakanej v bal\u00edku s jadrom Linux, dod\u00e1van\u00fdm v Ubuntu (teoreticky navrhnut\u00e9 met\u00f3dy mus\u00edte<\/a><\/noindex> fungova\u0165 s jadrom Fedora a in\u00fdmi distrib\u00faciami, ale neboli testovan\u00e9). <\/p>\n

Lockdown obmedzuje pr\u00edstup pou\u017e\u00edvate\u013ea root k jadru a blokuje cesty ob\u00eddenia UEFI Secure Boot. Napr\u00edklad v re\u017eime lockdown je obmedzen\u00fd pr\u00edstup k \/dev\/mem, \/dev\/kmem, \/dev\/port, \/proc\/kcore, debugfs, re\u017eimu ladenia kprobes, mmiotrace, tracefs, BPF, PCMCIA CIS (Card Information Structure), niektor\u00fdm ACPI rozhran\u00edm a MSR registrami CPU, s\u00fa blokovan\u00e9 volania kexec_file a kexec_load, zakazuje sa prechod do re\u017eimu sp\u00e1nku, obmedzuje sa pou\u017e\u00edvanie DMA pre PCI zariadenia, zakazuje sa import ACPI k\u00f3du z EFI premenn\u00fdch, nie s\u00fa povolen\u00e9 manipul\u00e1cie s vstupno\/v\u00fdstupn\u00fdmi portami, vr\u00e1tane zmeny \u010d\u00edsla preru\u0161enia a vstupno\/v\u00fdstupn\u00e9ho portu pre s\u00e9riov\u00fd port.<\/p>\n

Mechanizmus Lockdown bol ned\u00e1vno pridan\u00fd do hlavnej s\u00fa\u010dasti jadra Linux 5.4<\/a><\/noindex>, ale v dod\u00e1van\u00fdch distrib\u00faci\u00e1ch jadier je st\u00e1le realizovan\u00fd vo forme patchov alebo doplnen\u00fd patchmi. Jedn\u00fdm z rozdielov poskytnut\u00fdch v distrib\u00faci\u00e1ch nadstavieb od zabudovanej v jadre implement\u00e1cie je mo\u017enos\u0165 vypnutia poskytovanej blok\u00e1cie pri fyzickom pr\u00edstupe k syst\u00e9mu. <\/p>\n

V Ubuntu a Fedore je na vypnutie Lockdown predp\u00edsan\u00e1 kombin\u00e1cia kl\u00e1ves Alt+SysRq+X. P\u0159edpokl\u00e1d\u00e1 se, \u017ee kombin\u00e1ciu Alt+SysRq+X je mo\u017en\u00e9 pou\u017ei\u0165 iba pri fyzickom pr\u00edstupe k zariadeniu, a v pr\u00edpade vzdialen\u00e9ho hacku a z\u00edskania pr\u00edstupov\u00fdch pr\u00e1v root \u00fato\u010dn\u00edk nem\u00f4\u017ee vypn\u00fa\u0165 Lockdown a napr\u00edklad na\u010d\u00edta\u0165 do jadra nezaznamenan\u00fd digit\u00e1lne podp\u00edsan\u00fd modul s rootkitom. <\/p>\n

Andrej Konovalov uk\u00e1zal, \u017ee met\u00f3dy potvrdzovania fyzickej pr\u00edtomnosti pou\u017e\u00edvate\u013ea s\u00favisiace s pou\u017e\u00edvan\u00edm kl\u00e1vesnice s\u00fa neefekt\u00edvne. Najjednoduch\u0161\u00ed sp\u00f4sob vypnutia Lockdown by bol softv\u00e9rov\u00fd simul\u00e1cia<\/a><\/noindex> stla\u010denia Alt+SysRq+X cez \/dev\/uinput, ale t\u00e1to mo\u017enos\u0165 je p\u00f4vodne zablokovan\u00e1. Napriek tomu sa podarilo identifikova\u0165 aspo\u0148 \u010fal\u0161ie dva sp\u00f4soby substit\u00facie Alt+SysRq+X. <\/p>\n

Prv\u00fd sp\u00f4sob s\u00favis\u00ed s pou\u017eit\u00edm rozhrania <sysrq-trigger> — na simul\u00e1ciu sta\u010d\u00ed aktivova\u0165 toto rozhranie zap\u00edsan\u00edm <1> do \/proc\/sys\/kernel\/sysrq a n\u00e1sledne zap\u00edsa\u0165 <x> do \/proc\/sysrq-trigger. Uveden\u00e1 diera bola odstr\u00e1nen\u00e1<\/a><\/noindex> bola v decembrovom aktualiz\u00e1cii jadra Ubuntu a vo Fedore 31. Zauj\u00edmav\u00e9 je, \u017ee v\u00fdvoj\u00e1ri, ako v pr\u00edpade \/dev\/uinput, p\u00f4vodne s\u00edce sa sna\u017eili<\/a><\/noindex> zablokova\u0165 t\u00fato met\u00f3du, ale blokovanie nefungovalo kv\u00f4li chyby<\/a><\/noindex> k\u00f3du.<\/p>\n

Druh\u00fd sp\u00f4sob je spojen\u00fd s emul\u00e1ciou kl\u00e1vesnice cez USB\/IP<\/a><\/noindex> a n\u00e1sledn\u00fdm odoslan\u00edm sekvencie Alt+SysRq+X z virtu\u00e1lnej kl\u00e1vesnice. V dod\u00e1vanom jadre Ubuntu je USB\/IP predvolene povolen\u00e9 (CONFIG_USBIP_VHCI_HCD=m a CONFIG_USBIP_CORE=m) a s\u00fa poskytnut\u00e9 potrebn\u00e9 certifikovan\u00e9 digit\u00e1lne moduly usbip_core a vhci_hcd. \u00dato\u010dn\u00edk m\u00f4\u017ee vytvori\u0165<\/a><\/noindex> virtu\u00e1lne USB zariadenie, spusten\u00edm<\/a><\/noindex> sie\u0165ov\u00e9ho spracovate\u013ea na loopback rozhran\u00ed a pripojen\u00edm ho ako vzdialen\u00e9 USB zariadenie pomocou USB\/IP. O tejto met\u00f3de bolo informovan\u00e9<\/a><\/noindex> v\u00fdvoj\u00e1rom Ubuntu, ale oprava zatia\u013e nebola vydan\u00e1.<\/p>\n

<\/a><\/noindex><\/p>\n

Zdroj: opennet.ru<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0410\u043d\u0434\u0440\u0435\u0439 \u041a\u043e\u043d\u043e\u0432\u0430\u043b\u043e\u0432 \u0438\u0437 \u043a\u043e\u043c\u043f\u0430\u043d\u0438\u0438 Google \u043e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043b \u0441\u043f\u043e\u0441\u043e\u0431 \u0443\u0434\u0430\u043b\u0451\u043d\u043d\u043e\u0433\u043e \u043e\u0442\u043a\u043b\u044e\u0447\u0435\u043d\u0438\u044f \u0437\u0430\u0449\u0438\u0442\u044b Lockdown, \u043f\u0440\u0435\u0434\u043b\u0430\u0433\u0430\u0435\u043c\u043e\u0439 \u0432 \u043f\u0430\u043a\u0435\u0442\u0435 \u0441 \u044f\u0434\u0440\u043e\u043c Linux, \u043f\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u043c\u043e\u043c \u0432 Ubuntu (\u0442\u0435\u043e\u0440\u0435\u0442\u0438\u0447\u0435\u0441\u043a\u0438 \u043f\u0440\u0435\u0434\u043b\u043e\u0436\u0435\u043d\u043d\u044b\u0435 \u043c\u0435\u0442\u043e\u0434\u044b \u0434\u043e\u043b\u0436\u043d\u044b \u0440\u0430\u0431\u043e\u0442\u0430\u0442\u044c \u0441 \u044f\u0434\u0440\u043e\u043c Fedora \u0438 \u0434\u0440\u0443\u0433\u0438\u0445 \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u043e\u0432, \u043d\u043e \u043e\u043d\u0438 \u043d\u0435 \u043f\u0440\u043e\u0442\u0435\u0441\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u044b). Lockdown \u043e\u0433\u0440\u0430\u043d\u0438\u0447\u0438\u0432\u0430\u0435\u0442 \u0434\u043e\u0441\u0442\u0443\u043f \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044f root \u043a \u044f\u0434\u0440\u0443 \u0438 \u0431\u043b\u043e\u043a\u0438\u0440\u0443\u0435\u0442 \u043f\u0443\u0442\u0438 \u043e\u0431\u0445\u043e\u0434\u0430 UEFI Secure Boot. \u041d\u0430\u043f\u0440\u0438\u043c\u0435\u0440, \u0432 \u0440\u0435\u0436\u0438\u043c\u0435 lockdown \u043e\u0433\u0440\u0430\u043d\u0438\u0447\u0438\u0432\u0430\u0435\u0442\u0441\u044f \u0434\u043e\u0441\u0442\u0443\u043f […]<\/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":[],"tags":[],"class_list":["post-41110","post","type-post","status-publish","format-standard","hentry"],"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\udd47Sp\u00f4soby vypnutia ochrany Lockdown v Ubuntu pre ob\u00eddenie UEFI Secure Boot | ProHoster","description":"Andrej Konovalov zo spolo\u010dnosti Google publikoval sp\u00f4sob vzdialen\u00e9ho odpojenia 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