{"id":38554,"date":"2019-10-31T22:24:30","date_gmt":"2019-10-31T19:24:30","guid":{"rendered":"https:\/\/prohoster.info\/blog\/v-yadro-linux-5-4-prinyaty-patchi-dlya-ogranicheniya-dostupa-root-k-vnutrennostyam-yadra\/"},"modified":"2019-10-31T22:24:30","modified_gmt":"2019-10-31T19:24:30","slug":"v-yadro-linux-5-4-prinyaty-patchi-dlya-ogranicheniya-dostupa-root-k-vnutrennostyam-yadra","status":"publish","type":"post","link":"https:\/\/prohoster.info\/pt\/blog\/news\/v-yadro-linux-5-4-prinyaty-patchi-dlya-ogranicheniya-dostupa-root-k-vnutrennostyam-yadra","title":{"rendered":"No n\u00facleo do Linux 5.4, foram aceitas corre\u00e7\u00f5es para restringir o acesso do root aos componentes internos do n\u00facleo","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Linus Torvalds aceitou<\/a><\/noindex> A nova vers\u00e3o do n\u00facleo Linux 5.4 inclui um conjunto de patches «lockdown<\/a><\/noindex>\u00ab, proposto<\/a><\/noindex>\tDavid Howells (trabalhando na Red Hat) e Matthew Garrett (Matthew Garrett<\/a><\/noindex>, desenvolvido pelo Google, para restringir o acesso do usu\u00e1rio root ao n\u00facleo. A funcionalidade associada ao «lockdown» foi transformada em um m\u00f3dulo LSM opcional que pode ser carregado (Linux Security Module<\/a><\/noindex>), que estabelece uma barreira entre o UID 0 e o n\u00facleo, limitando certas funcionalidades de baixo n\u00edvel.<\/p>\n

Se um invasor conseguir, atrav\u00e9s de um ataque, executar c\u00f3digo com privil\u00e9gios de root, ele poder\u00e1 executar seu c\u00f3digo tamb\u00e9m a n\u00edvel de n\u00facleo, por exemplo, atrav\u00e9s da substitui\u00e7\u00e3o do n\u00facleo com kexec ou leitura\/escrita de mem\u00f3ria via \/dev\/kmem. A consequ\u00eancia mais \u00f3bvia de tal atividade pode ser a evas\u00e3o<\/a><\/noindex> do UEFI Secure Boot ou a extra\u00e7\u00e3o de dados confidenciais armazenados a n\u00edvel de n\u00facleo.<\/p>\n

Inicialmente, as fun\u00e7\u00f5es de restri\u00e7\u00e3o do root se desenvolveram no contexto de refor\u00e7o da seguran\u00e7a da inicializa\u00e7\u00e3o verificada, e distribui\u00e7\u00f5es j\u00e1 h\u00e1 bastante tempo aplicam patches de terceiros para bloquear a evas\u00e3o do UEFI Secure Boot. Entretanto, tais restri\u00e7\u00f5es n\u00e3o foram inclu\u00eddas no n\u00facleo principal devido a disputas<\/a><\/noindex> em sua implementa\u00e7\u00e3o e preocupa\u00e7\u00f5es sobre a viola\u00e7\u00e3o do funcionamento de sistemas existentes. O m\u00f3dulo «lockdown» incorporou patches j\u00e1 utilizados nas distribui\u00e7\u00f5es, que foram redesenhados na forma de um subsistema separado, n\u00e3o vinculado ao UEFI Secure Boot. <\/p>\n

No modo lockdown, o acesso a \/dev\/mem, \/dev\/kmem, \/dev\/port, \/proc\/kcore, debugfs, modo de teste de kprobes, mmiotrace, tracefs, BPF, PCMCIA CIS (Card Information Structure), algumas interfaces ACPI e registradores MSR do CPU \u00e9 restringido, chamadas kexec_file e kexec_load s\u00e3o bloqueadas, o modo de sono \u00e9 proibido, o uso de DMA para dispositivos PCI \u00e9 limitado, a importa\u00e7\u00e3o de c\u00f3digo ACPI a partir de vari\u00e1veis EFI \u00e9 proibida,
\nmanipula\u00e7\u00f5es com portas de entrada\/sa\u00edda n\u00e3o s\u00e3o permitidas, incluindo altera\u00e7\u00f5es no n\u00famero de interrup\u00e7\u00e3o e na porta de entrada\/sa\u00edda para a porta serial. <\/p>\n

Por padr\u00e3o, o m\u00f3dulo lockdown n\u00e3o est\u00e1 ativo, \u00e9 compilado quando a op\u00e7\u00e3o SECURITY_LOCKDOWN_LSM \u00e9 especificada no kconfig e \u00e9 ativado atrav\u00e9s do par\u00e2metro do n\u00facleo «lockdown=», do arquivo de controle «\\\/sys\\\/kernel\\\/security\\\/lockdown» ou das op\u00e7\u00f5es de compila\u00e7\u00e3o LOCK_DOWN_KERNEL_FORCE_*<\/a><\/noindex>, que podem aceitar os valores «integrity» e «confidentiality». No primeiro caso, as capacidades que permitem modificar o n\u00facleo em funcionamento a partir do espa\u00e7o do usu\u00e1rio s\u00e3o bloqueadas, enquanto no segundo tamb\u00e9m \u00e9 desativada a funcionalidade que pode ser usada para extrair informa\u00e7\u00f5es confidenciais do n\u00facleo.<\/p>\n

\u00c9 importante notar que o lockdown apenas limita as capacidades nativas de acesso ao n\u00facleo, mas n\u00e3o protege contra modifica\u00e7\u00f5es resultantes da explora\u00e7\u00e3o de vulnerabilidades. Para bloquear a inser\u00e7\u00e3o de altera\u00e7\u00f5es no n\u00facleo em funcionamento ao aplicar exploits, o projeto Openwall est\u00e1 em desenvolvimento<\/a><\/noindex> um m\u00f3dulo separado LKRG<\/a><\/noindex> (Linux Kernel Runtime Guard).<\/p>\n

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

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

\u041b\u0438\u043d\u0443\u0441 \u0422\u043e\u0440\u0432\u0430\u043b\u044c\u0434\u0441 \u043f\u0440\u0438\u043d\u044f\u043b \u0432 \u0441\u043e\u0441\u0442\u0430\u0432 \u0431\u0443\u0434\u0443\u0449\u0435\u0433\u043e \u0432\u044b\u043f\u0443\u0441\u043a\u0430 \u044f\u0434\u0440\u0430 Linux 5.4 \u043d\u0430\u0431\u043e\u0440 \u043f\u0430\u0442\u0447\u0435\u0439 «lockdown«, \u043f\u0440\u0435\u0434\u043b\u043e\u0436\u0435\u043d\u043d\u044b\u0439 \u0414\u044d\u0432\u0438\u0434\u043e\u043c \u0425\u043e\u0443\u044d\u043b\u043b\u0441\u043e\u043c (David Howells, \u0440\u0430\u0431\u043e\u0442\u0430\u0435\u0442 \u0432 Red Hat) \u0438 \u041c\u044d\u0442\u044c\u044e \u0413\u0430\u0440\u0440\u0435\u0442\u043e\u043c (Matthew Garrett, \u0440\u0430\u0431\u043e\u0442\u0430\u0435\u0442 \u0432 Google) \u0434\u043b\u044f \u043e\u0433\u0440\u0430\u043d\u0438\u0447\u0435\u043d\u0438\u044f \u0434\u043e\u0441\u0442\u0443\u043f\u0430 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044f root \u043a \u044f\u0434\u0440\u0443. \u0421\u0432\u044f\u0437\u0430\u043d\u043d\u0430\u044f \u0441 «lockdown» \u0444\u0443\u043d\u043a\u0446\u0438\u043e\u043d\u0430\u043b\u044c\u043d\u043e\u0441\u0442\u044c \u0432\u044b\u043d\u0435\u0441\u0435\u043d\u0430 \u0432 \u043e\u043f\u0446\u0438\u043e\u043d\u0430\u043b\u044c\u043d\u043e \u0437\u0430\u0433\u0440\u0443\u0436\u0430\u0435\u043c\u044b\u0439 LSM-\u043c\u043e\u0434\u0443\u043b\u044c (Linux Security Module), \u0443\u0441\u0442\u0430\u043d\u0430\u0432\u043b\u0438\u0432\u0430\u044e\u0449\u0438\u0439 \u0431\u0430\u0440\u044c\u0435\u0440 \u043c\u0435\u0436\u0434\u0443 UID 0 \u0438 […]<\/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-38554","post","type-post","status-publish","format-standard","hentry","category-news"],"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\udd47Patches foram aprovados para o n\u00facleo Linux 5.4 limitando o acesso root aos internals do n\u00facleo | ProHoster","description":"Linus Torvalds aceitou para a pr\u00f3xima 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