UBUNTU: SAUCE: overlayfs: Propogate nosuid from lower and upper mounts
An overlayfs mount using an upper or lower directory from a
nosuid filesystem bypasses this restriction. Change this so
that if any lower or upper directory is nosuid at mount time the
overlayfs superblock is marked nosuid. This requires some
additions at the vfs level since nosuid currently only applies to
mounts, so a SB_I_NOSUID flag is added along with a helper
function to check a path for nosuid in both the mount and the
superblock.
UBUNTU: SAUCE: overlayfs: Be more careful about copying up sxid files
When an overlayfs filesystem's lowerdir is on a nosuid filesystem
but the upperdir is not, it's possible to copy up an sxid file or
stick directory into upperdir without changing the mode by
opening the file rw in the overlayfs mount without writing to it.
This makes it possible to bypass the nosuid restriction on the
lowerdir mount.
It's a bad idea in general to let the mounter copy up a sxid file
if the mounter wouldn't have had permission to create the sxid
file in the first place. Therefore change ovl_set_xattr to
exclude these bits when initially setting the mode, then set the
full mode after setting the user for the inode. This allows copy
up for non-sxid files to work as before but causes copy up to
fail for the cases where the user could not have created the sxid
inode in upperdir.
UBUNTU: SAUCE: overlayfs: Skip permission checking for trusted.overlayfs.* xattrs
The original mounter had CAP_SYS_ADMIN in the user namespace
where the mount happened, and the vfs has validated that the user
has permission to do the requested operation. This is sufficient
for allowing the kernel to write these specific xattrs, so we can
bypass the permission checks for these xattrs.
To support this, export __vfs_setxattr_noperm and add an similar
__vfs_removexattr_noperm which is also exported. Use these when
setting or removing trusted.overlayfs.* xattrs.
In the mark_source_chains function (net/ipv4/netfilter/ip_tables.c) it
is possible for a user-supplied ipt_entry structure to have a large
next_offset field. This field is not bounds checked prior to writing a
counter value at the supplied offset.
Problem is that xt_entry_foreach() macro stops iterating once e->next_offset
is out of bounds, assuming this is the last entry.
With malformed data thats not necessarily the case so we can
write outside of allocated area later as we might not have walked the
entire blob.
Fix this by simplifying mark_source_chains -- it already has to check
if nextoff is in range to catch invalid jumps, so just do the check
when we move to a next entry as well.
Also, check that the offset meets the xtables_entry alignment.
Reported-by: Ben Hawkes <email address hidden>
Signed-off-by: Florian Westphal <email address hidden>
Signed-off-by: Chris J. Arges <email address hidden>
Acked-by: Brad Figg <email address hidden>
Signed-off-by: Brad Figg <email address hidden>
Signed-off-by: Tim Gardner <email address hidden>
UBUNTU: SAUCE: (no-up) ACPI: Disable Windows 8 compatibility for some Lenovo ThinkPads
The AML implementation for brightness control on several ThinkPads
contains a workaround to meet a Windows 8 requirement of 101 brightness
levels [1]. The implementation is flawed, as only 16 of the brighness
values reported by _BCL affect a change in brightness. _BCM silently
discards the rest of the values. Disabling Windows 8 compatibility on
these machines reverts them to the old behavior, making _BCL only report
the 16 brightness levels which actually work. Add a quirk to do this
along with a dmi callback to disable Win8 compatibility.
