{"id":102964,"date":"2022-01-14T21:37:17","date_gmt":"2022-01-14T19:37:17","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/%d1%83%d1%8f%d0%b7%d0%b2%d0%b8%d0%bc%d0%be%d1%81%d1%82%d1%8c-%d0%b2-xfs-%d0%bf%d0%be%d0%b7%d0%b2%d0%be%d0%bb%d1%8f%d1%8e%d1%89%d0%b0%d1%8f-%d1%87%d0%b8%d1%82%d0%b0%d1%82%d1%8c-%d1%81%d1%8b%d1%80"},"modified":"2022-01-14T21:37:17","modified_gmt":"2022-01-14T19:37:17","slug":"%d1%83%d1%8f%d0%b7%d0%b2%d0%b8%d0%bc%d0%be%d1%81%d1%82%d1%8c-%d0%b2-xfs-%d0%bf%d0%be%d0%b7%d0%b2%d0%be%d0%bb%d1%8f%d1%8e%d1%89%d0%b0%d1%8f-%d1%87%d0%b8%d1%82%d0%b0%d1%82%d1%8c-%d1%81%d1%8b%d1%80","status":"publish","type":"post","link":"https:\/\/prohoster.info\/ro\/blog\/news\/%d1%83%d1%8f%d0%b7%d0%b2%d0%b8%d0%bc%d0%be%d1%81%d1%82%d1%8c-%d0%b2-xfs-%d0%bf%d0%be%d0%b7%d0%b2%d0%be%d0%bb%d1%8f%d1%8e%d1%89%d0%b0%d1%8f-%d1%87%d0%b8%d1%82%d0%b0%d1%82%d1%8c-%d1%81%d1%8b%d1%80","title":{"rendered":"O vulnerabilitate \u00een XFS, care permite citirea datelor brute de pe dispozitivul de stocare.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

A fost descoperit\u0103 o vulnerabilitate \u00een codul sistemului de fi\u0219iere XFS (CVE-2021-4155), care permite unui utilizator local f\u0103r\u0103 privilegii s\u0103 citeasc\u0103 datele blocurilor neutilizate direct de pe dispozitivul bloc. Toate versiunile semnificative ale nucleului Linux mai vechi de 5.16, care con\u021bin driverul XFS, sunt afectate de aceast\u0103 problem\u0103. Corec\u021bia a fost inclus\u0103 \u00een versiunea 5.16, precum \u0219i \u00een actualiz\u0103rile nucleelor 5.15.14, 5.10.91, 5.4.171, 4.19.225 etc. Starea form\u0103rii actualiz\u0103rilor cu rezolvarea problemei \u00een distribu\u021bii poate fi urm\u0103rit\u0103 pe aceste pagini: Debian, RHEL, SUSE, Fedora, Ubuntu, Arch. <\/p>\n

Vulnerabilitatea este cauzat\u0103 de comportamentul incorect al celor dou\u0103 ioctl(XFS_IOC_ALLOCSP) \u0219i ioctl(XFS_IOC_FREESP) specifice XFS, care sunt echivalente func\u021bionale cu apelul de sistem fallocate() la nivel de nucleu. C\u00e2nd dimensiunea fi\u0219ierului este crescut\u0103, f\u0103r\u0103 a fi aliniat\u0103 la dimensiunea blocului, ioctl XFS_IOC_ALLOCSP\/XFS_IOC_FREESP nu reseteaz\u0103 octe\u021bii r\u0103ma\u0219i p\u00e2n\u0103 la urm\u0103toarea limit\u0103 a blocului. Astfel, pe XFS cu o dimensiune standard a blocului de 4096 de octe\u021bi, un atacator poate citi p\u00e2n\u0103 la 4095 de octe\u021bi din datele scrise anterior din fiecare bloc. \u00cen zonele specificate pot fi con\u021binute datele fi\u0219ierelor \u0219terse, fi\u0219ierele defragmentate, precum \u0219i fi\u0219ierele cu blocuri deduplicate. <\/p>\n

\u00ce\u021bi po\u021bi verifica sistemul pentru a identifica problema printr-un prototip simplu de exploit. Dac\u0103, dup\u0103 executarea secven\u021bei de comenzi propuse, reu\u0219e\u0219ti s\u0103 cite\u0219ti un text de Shakespeare, driverul FS este vulnerabil. Montarea ini\u021bial\u0103 a parti\u021biei XFS pentru demonstra\u021bie necesit\u0103 drepturi de superutilizator. <\/p>\n

Deoarece ioctl(XFS_IOC_ALLOCSP) \u0219i ioctl(XFS_IOC_FREESP) sunt practic identice din punct de vedere func\u021bional cu standardul fallocate(), diferen\u021ba lor principal\u0103 fiind scurgerea de date, prezen\u021ba acestora pare a fi un backdoor. \u00cen ciuda politicii generale de a nu modifica interfe\u021bele existente \u00een nucleu, ca urmare a propunerii lui Linus, s-a decis eliminarea complet\u0103 a acestor ioctl-uri \u00een urm\u0103toarea versiune.
\n
Sursa: opennet.ro<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

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