Extended file attributes: Difference between revisions

Revision as of 23:58, 30 July 2023

Revision as of 00:02, 31 July 2023

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| access-date=2017-07-11}}</ref> filesystems support extended attributes (abbreviated ''xattr'') when enabled in the kernel configuration. Any regular file or directory may have extended attributes consisting of a name and associated data. The name must be a [[null-terminated string]] prefixed by a [[namespace]] identifier and a dot character. Currently, four namespaces exist: user, trusted, security and system. The user namespace has no restrictions with regard to naming or contents. The system namespace is primarily used by the kernel for [[access control list]]s. The security namespace is used by [[SELinux]], for example.

Support for the extended attribute concept from a POSIX.1e draft{{cn|date=July 2020}} that had been withdrawn<ref>{{cite webusenet | url=https://groups.google.com/g/comp.security.unix/c/gfyLMetqubs/m/5tBrcPuJA0gJhipaUcdWosAJ | title=Posix.1e? |first=Casey |last=Schaufler |date=2002-04-30 |newsgroup=comp.security.unix}}</ref> in 1997 was added to Linux around 2002.<ref>{{cite web

| title=v2.5.3 git commit log

| url=https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/include/?id=1ea864f1c53bc771294e61cf9be43b1d22e78f4c