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| author | Miklos Szeredi <mszeredi@redhat.com> | 2017-12-11 11:28:10 +0100 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2017-12-11 11:28:10 +0100 |
| commit | 438c84c2f0c794f75ab55ce65c505b01bfce4480 (patch) | |
| tree | 1473170ca270435dc5165c04d6690b7bcd6718bb /fs/overlayfs/Kconfig | |
| parent | ae64f9bd1d3621b5e60d7363bc20afb46aede215 (diff) | |
ovl: don't follow redirects if redirect_dir=off
Overlayfs is following redirects even when redirects are disabled. If this
is unintentional (probably the majority of cases) then this can be a
problem. E.g. upper layer comes from untrusted USB drive, and attacker
crafts a redirect to enable read access to otherwise unreadable
directories.
If "redirect_dir=off", then turn off following as well as creation of
redirects. If "redirect_dir=follow", then turn on following, but turn off
creation of redirects (which is what "redirect_dir=off" does now).
This is a backward incompatible change, so make it dependent on a config
option.
Reported-by: David Howells <dhowells@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs/Kconfig')
| -rw-r--r-- | fs/overlayfs/Kconfig | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig index cbfc196e5dc5..5ac415466861 100644 --- a/fs/overlayfs/Kconfig +++ b/fs/overlayfs/Kconfig @@ -24,6 +24,16 @@ config OVERLAY_FS_REDIRECT_DIR an overlay which has redirects on a kernel that doesn't support this feature will have unexpected results. +config OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW + bool "Overlayfs: follow redirects even if redirects are turned off" + default y + depends on OVERLAY_FS + help + Disable this to get a possibly more secure configuration, but that + might not be backward compatible with previous kernels. + + For more information, see Documentation/filesystems/overlayfs.txt + config OVERLAY_FS_INDEX bool "Overlayfs: turn on inodes index feature by default" depends on OVERLAY_FS |