Achọpụtala adịghị ike abụọ na kernel Linux nke na-enye ohere iji usoro eBPF mee ihe iji zere nchebe megide mwakpo Specter v4 (SSB, Speculative Store Bypass). N'iji mmemme BPF na-enweghị ihe ọ bụla, onye na-awakpo nwere ike ịmepụta ọnọdụ maka ịkọ nkọ nke ụfọdụ ọrụ ma chọpụta ọdịnaya nke mpaghara aka ike nke ebe nchekwa kernel. Ndị na-echekwa sistemu eBPF dị na kernel nwetara ohere iji nweta ụdị nrigbu nke na-egosi ikike ịme mwakpo n'omume. Edozila nsogbu ndị a n'ụdị patches (1, 2), nke a ga-etinye na mmelite kernel Linux na-esote. Emebebeghị mmelite na ngwa nkesa (Debian, RHEL, SUSE, Arch, Fedora, Ubuntu).
Usoro ọgụ nke Specter 4 dabere na iweghachi data echekwara na cache processor mgbe ọ tụfuru nsonaazụ nke arụrụ arụ ọrụ mgbe ị na-ahazi ederede na ịgụ ọrụ ọzọ site na iji adreesị na-apụtaghị ìhè. Mgbe a na-agụ ọrụ na-esote ọrụ ide (dịka, mov [rbx + rcx], 0x0; mov rax, [rdx + rsi]), enwere ike mara mwepu nke adreesị ọgụgụ n'ihi ọrụ ndị yiri ya a na-eme (gụọ arụmọrụ bụ. rụrụ ọtụtụ ugboro ugboro na-agụ nwere ike rụrụ site cache) na processor nwere ike speculatively ịrụ na-agụ tupu dee na-echeghị ka dee si indirection offset gbakọọ.
Ọ bụrụ na, mgbe gụchara nkwụghachi ụgwọ, achọpụtara njikọ nke ebe nchekwa maka ide na ịgụ akwụkwọ, onye nrụpụta ga-atụfu nsonaazụ agụpụtagoro enwetagoro wee megharịa ọrụ a. Njirimara a na-enye ohere ịgụ ntụziaka iji nweta uru ochie n'adreesị ụfọdụ mgbe ọrụ ụlọ ahịa emezubeghị. Mgbe ị tụfuchara ọrụ ntule na-enweghị ihe ịga nke ọma, akara nke ogbugbu ya na-anọgide na cache, mgbe nke ahụ gasịrị, otu n'ime ụzọ iji chọpụta ọdịnaya nke cache nwere ike iji weghachite ya dabere na nyocha nke mgbanwe na ohere ịnweta data cache na enweghị nchekwa.
Ihe kpatara adịghị ike nke mbụ (CVE-2021-35477) site na ntụpọ dị na usoro nkwenye mmemme BPF. Iji chebe megide mwakpo Specter 4, onye nyocha na-agbakwunye nkuzi agbakwunyere mgbe ụlọ ahịa nwere nsogbu na ebe nchekwa nke na-echekwa uru efu iji wepụ akara arụ ọrụ gara aga. A na-atụ anya na ọrụ ide ihe na-adịghị mma ga-adị ngwa ngwa ma gbochie igbu egbu n'ihi na ọ dabere na ntụnye aka na etiti nchịkọta BPF. Ma n'ezie, ọ tụgharịrị na ọ ga-ekwe omume ịmepụta ọnọdụ n'okpuru ntụziaka nke na-eduga n'ịkọ nkọcha na-achịkwa ka e gbuo tupu arụ ọrụ ụlọ ahịa.
Ihe ọghọm nke abụọ (CVE-2021-3455) bụ n'ihi eziokwu ahụ bụ na mgbe onye nyocha BPF na-achọpụta ọrụ nchekwa ebe nchekwa nwere ike ịdị ize ndụ, ọ naghị eburu n'uche ebe a na-akpọghị aha nke ngwugwu BPF, ọrụ mbụ na-edeghị ya nke na-adịghị echebe ya. Njirimara a na-eduga na ohere nke ịrụ ọrụ ọgụgụ isi, dabere na ebe nchekwa na-enweghị mmalite, tupu ịme ntụziaka ụlọ ahịa. A na-ekenye ebe nchekwa ọhụrụ maka nchịkọta BPF na-enyochaghị ọdịnaya nke dị na ebe nchekwa ekenyela, na e nwere ụzọ tupu mmemme BPF na-agba ọsọ iji gbanwee ọdịnaya nke mpaghara ebe nchekwa nke a ga-ekenye ya maka nchịkọta BPF.
isi: opennet.ru