Messages in this thread | | | Date | Mon, 16 Apr 2007 13:03:08 +0200 | From | Miklos Szeredi <> | Subject | [patch 00/10] mount ownership and unprivileged mount syscall (v3) |
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This patchset adds support for keeping mount ownership information in the kernel, and allow unprivileged mount(2) and umount(2) in certain cases.
This can be useful for the following reasons:
- mount(8) can store ownership ("user=XY" option) in the kernel instead, or in addition to storing it in /etc/mtab. For example if private namespaces are used with mount propagations /etc/mtab becomes unworkable, but using /proc/mounts works fine
- fuse won't need a special suid-root mount/umount utility. Plain umount(8) can easily be made to work with unprivileged fuse mounts
- users can use bind mounts without having to pre-configure them in /etc/fstab
The following security measures are taken for unprivileged mounts:
- only allow submounting under mounts which have a special mount flag set - only allow mounting on files/directories writable by the user - limit the number of user mounts - force "nosuid,nodev" mount options
Changes from the previous submissions:
- add mount flags to set/clear mnt_flags individually - add "usermnt" mount flag. If it is set, then allow unprivileged submounts under this mount - make max number of user mounts default to 1024, since now the usermnt flag will prevent user mounts by default
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