{"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\/da\/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":"En s\u00e5rbarhed i XFS, der muligg\u00f8r l\u00e6sning af r\u00e5 data fra bloklagringsenheden.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Der XFS-filsystemkode har en s\u00e5rbarhed (CVE-2021-4155), der g\u00f8r det muligt for en lokal, ikke-privilegeret bruger at l\u00e6se data fra ubrugte blokke direkte fra blok-enheden. Alle v\u00e6sentlige versioner af Linux-kernen, der er \u00e6ldre end 5.16 og indeholder XFS-driveren, er udsat for dette problem. Rettelsen blev inkluderet i version 5.16 samt opdateringer til kernen 5.15.14, 5.10.91, 5.4.171, 4.19.225 osv. Status for opdateringer, der l\u00f8ser problemet i distributionerne, kan spores p\u00e5 f\u00f8lgende sider: Debian, RHEL, SUSE, Fedora, Ubuntu, Arch. <\/p>\n

S\u00e5rbarheden skyldes forkert adf\u00e6rd fra to specifikke XFS ioctl(XFS_IOC_ALLOCSP) og ioctl(XFS_IOC_FREESP), som er funktionelt \u00e6kvivalente til det generelle systemkald fallocate(). N\u00e5r filens st\u00f8rrelse \u00f8ges, uden at den er justeret til blokst\u00f8rrelsen, nulstiller ioctl XFS_IOC_ALLOCSP\/XFS_IOC_FREESP ikke de resterende byte til den n\u00e6ste blokgr\u00e6nse. P\u00e5 XFS med en standard blokst\u00f8rrelse p\u00e5 4096 byte kan en angriber l\u00e6se op til 4095 byte af tidligere skrevne data fra hver blok. De angivne omr\u00e5der kan indeholde data fra slettede filer, defragmenterede filer samt filer med deduperede blokke. <\/p>\n

Du kan kontrollere dit system for problemet med en simpel prototype-af exploit. Hvis du efter at have udf\u00f8rt den foresl\u00e5ede kommando-sekvens kan l\u00e6se en tekst af Shakespeare, s\u00e5 er filsystemdriveren s\u00e5rbar. Den oprindelige montering af XFS-partitionen til demonstration kr\u00e6ver superbrugerrettigheder. <\/p>\n

Da ioctl(XFS_IOC_ALLOCSP) og ioctl(XFS_IOC_FREESP) funktionelt set n\u00e6sten ikke adskiller sig fra den standardm\u00e6ssige fallocate(), og den eneste forskel er datal\u00e6kagen, kan deres tilstedev\u00e6relse betragtes som en bagd\u00f8r. P\u00e5 trods af den overordnede politik \u2013 ikke at \u00e6ndre eksisterende gr\u00e6nseflader i kernen \u2013 er det efter Linus' forslag blevet besluttet fuldst\u00e6ndigt at fjerne disse ioctl'er i den n\u00e6ste version.
\n
Kilde: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

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