fs/vfs: enforce pseudoFS permissions on open()#18891
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acassis merged 1 commit intoMay 17, 2026
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Add inode_checkperm() and integrate it into file_vopen() to enforce UNIX-style read/write permission checks for pseudoFS inodes using effective uid/gid credentials. Skip permission enforcement for mountpoint inodes and allow kernel threads to bypass checks. Signed-off-by: Abhishek Mishra <mishra.abhishek2808@gmail.com>
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Summary
This patch adds centralized UNIX-style permission enforcement for pseudo-filesystem inodes during open() operations. It introduces inode_checkperm() and integrates it into file_vopen() after inode_checkflags() to validate read and write access using inode ownership, permission bits, and the effective uid/gid of the calling task. The implementation supports owner/group/other permission evaluation, bypasses permission checks for kernel threads, and skips mountpoint inodes to avoid affecting mounted filesystems such as FAT, ROMFS, and procfs.
Part of GSoC #18458
Impact
This change introduces the active runtime permission enforcement layer for pseudoFS instead of storing permission metadata. Read-only, write-only, and inaccessible inode modes are now properly enforced during file open operations, returning -EACCES when access is denied.
Testing
NSH
Ostest and checkpatch tests also passed.