out verbatim to the disk: see ffs_sbput() in sys/ufs/ffs/ffs_subr.c.
It contains a pointer to the fs_summary_info structure. This pointer
value inadvertently causes garbage to be stored. It is garbage because
the pointer to the fs_summary_info structure is the address the then
current stack or heap. Although a mere pointer does not reveal anything
useful (like a part of a private key) to an attacker, garbage output
deteriorates reproducibility.

This commit zeros out the pointer to the fs_summary_info structure
before writing the out the superblock.

Reviewed by:  kib
Tested by:    Peter Holm
PR:           246983
Sponsored by: Netflix

fs_summary_info structure. This change was originally done
by the CheriBSD project as they need larger pointers that
do not fit in the existing superblock.

This cleanup of the superblock eases the task of the commit
that immediately follows this one.

Suggested by: brooks
Reviewed by:  kib
PR:           246983
Sponsored by: Netflix

module from that file into ffs_vfsops.c.  This fixes the build for kernel
configs that don't include FFS.

PR:		247256
Submitted by:	glebius
Reviewed by:	mckusick (earlier version)
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D25285

the underlying media fails or becomes inaccessible. For example
when a USB flash memory card hosting a UFS filesystem is unplugged.

The strategy for handling disk I/O errors when soft updates are
enabled is to stop writing to the disk of the affected file system
but continue to accept I/O requests and report that all future
writes by the file system to that disk actually succeed. Then
initiate an asynchronous forced unmount of the affected file system.

There are two cases for disk I/O errors:

   - ENXIO, which means that this disk is gone and the lower layers
     of the storage stack already guarantee that no future I/O to
     this disk will succeed.

   - EIO (or most other errors), which means that this particular
     I/O request has failed but subsequent I/O requests to this
     disk might still succeed.

For ENXIO, we can just clear the error and continue, because we
know that the file system cannot affect the on-disk state after we
see this error. For EIO or other errors, we arrange for the geom_vfs
layer to reject all future I/O requests with ENXIO just like is
done when the geom_vfs is orphaned. In both cases, the file system
code can just clear the error and proceed with the forcible unmount.

This new treatment of I/O errors is needed for writes of any buffer
that is involved in a dependency. Most dependencies are described
by a structure attached to the buffer's b_dep field. But some are
created and processed as a result of the completion of the dependencies
attached to the buffer.

Clearing of some dependencies require a read. For example if there
is a dependency that requires an inode to be written, the disk block
containing that inode must be read, the updated inode copied into
place in that buffer, and the buffer then written back to disk.

Often the needed buffer is already in memory and can be used. But
if it needs to be read from the disk, the read will fail, so we
fabricate a buffer full of zeroes and pretend that the read succeeded.
This zero'ed buffer can be updated and written back to disk.

The only case where a buffer full of zeros causes the code to do
the wrong thing is when reading an inode buffer containing an inode
that still has an inode dependency in memory that will reinitialize
the effective link count (i_effnlink) based on the actual link count
(i_nlink) that we read. To handle this case we now store the i_nlink
value that we wrote in the inode dependency so that it can be
restored into the zero'ed buffer thus keeping the tracking of the
inode link count consistent.

Because applications depend on knowing when an attempt to write
their data to stable storage has failed, the fsync(2) and msync(2)
system calls need to return errors if data fails to be written to
stable storage. So these operations return ENXIO for every call
made on files in a file system where we have otherwise been ignoring
I/O errors.

Coauthered by: mckusick
Reviewed by:   kib
Tested by:     Peter Holm
Approved by:   mckusick (mentor)
Sponsored by:  Netflix
Differential Revision:  https://reviews.freebsd.org/D24088

when a superblock check-hash error is detected. This change clarifies
a mount that failed due to media hardware failures (EIO) from a mount
that failed due to media errors (EINTEGRITY) that can be corrected by
running fsck(8).

Sponsored by: Netflix

Same automation.

No functional change.

filesystems that have block pointers that are out-of-range for their
filesystem. These out-of-range block pointers are corrected by
fsck(8) so are only encountered when an unchecked filesystem is
mounted.

A new "untrusted" flag has been added to the generic mount interface
that can be set when mounting media of unknown provenance or integrity.
For example, a daemon that automounts a filesystem on a flash drive
when it is plugged into a system.

This commit adds a test to UFS/FFS that validates all block numbers
before using them. Because checking for out-of-range blocks adds
unnecessary overhead to normal operation, the tests are only done
when the filesystem is mounted as an "untrusted" filesystem.

Reported by:  Christopher Krah, Thomas Barabosch, and Jan-Niclas Hilgert of Fraunhofer FKIE
Reported as:  FS-14-UFS-3: Out of bounds read in write-2 (ffs_alloccg)
Reviewed by:  kib
Sponsored by: Netflix

rename the source to gsb_crc32.c.

This is a prerequisite of unifying kernel zlib instances.

PR:		229763
Submitted by:	Yoshihiro Ota <ota at j.email.ne.jp>
Differential Revision:	https://reviews.freebsd.org/D20193

the check-hash fails. Prior to the fix in -r342133 the inode with the
zeroed out check-hash was written back to disk causing further confusion.

Reported by:  Gary Jennejohn (gj)
Sponsored by: Netflix

before copying in the inode so that the mode and link-count are not set
if the check-hash fails. This change ensures that the vnode will be properly
unwound and recycled rather than being held in the cache.

Initialize the file mode is zero so that if the loading of the inode
fails (for example because of a check-hash failure), the vnode will be
properly unwound and recycled.

Reported by:  Gary Jennejohn (gj)
Sponsored by: Netflix

"panic: softdep_update_inodeblock: bad link count" when releasing
a partially initialized vnode after an inode check-hash failure.

Reported by:  Gary Jennejohn <gljennjohn@gmail.com>
Reported by:  Peter Holm (pho)
Sponsored by: Netflix

check hash to the filesystem inodes. Access attempts to files
associated with an inode with an invalid check hash will fail with
EINVAL (Invalid argument). Access is reestablished after an fsck
is run to find and validate the inodes with invalid check-hashes.
This check avoids a class of filesystem panics related to corrupted
inodes. The hash is done using crc32c.

Note this check-hash is for the inode itself and not any of its
indirect blocks. Check-hash validation may be extended to also
cover indirect block pointers, but that will be a separate (and
more costly) feature.

Check hashes are added only to UFS2 and not to UFS1 as UFS1 is
primarily used in embedded systems with small memories and low-powered
processors which need as light-weight a filesystem as possible.

Reviewed by:  kib
Tested by:    Peter Holm
Sponsored by: Netflix

superblock has a check-hash error, an error message noting the
superblock check-hash failure is printed and the mount fails. The
administrator then runs fsck to repair the filesystem and when
successful, the filesystem can once again be mounted.

This approach fails if the filesystem in question is a root filesystem
from which you are trying to boot. Here, the loader fails when trying
to access the filesystem to get the kernel to boot. So it is necessary
to allow the loader to ignore the superblock check-hash error and make
a best effort to read the kernel. The filesystem may be suffiently
corrupted that the read attempt fails, but there is no harm in trying
since the loader makes no attempt to write to the filesystem.

Once the kernel is loaded and starts to run, it attempts to mount its
root filesystem. Once again, failure means that it breaks to its prompt
to ask where to get its root filesystem. Unless you have an alternate
root filesystem, you are stuck.

Since the root filesystem is initially mounted read-only, it is
safe to make an attempt to mount the root filesystem with the failed
superblock check-hash. Thus, when asked to mount a root filesystem
with a failed superblock check-hash, the kernel prints a warning
message that the root filesystem superblock check-hash needs repair,
but notes that it is ignoring the error and proceeding. It does
mark the filesystem as needing an fsck which prevents it from being
enabled for writing until fsck has been run on it. The net effect
is that the reboot fails to single user, but at least at that point
the administrator has the tools at hand to fix the problem.

Reported by:    Rick Macklem (rmacklem@)
Discussed with: Warner Losh (imp@)
Sponsored by:   Netflix

predates metadata check hashes so that it is done before deciding
whether to compute a check-hash of the superblock.

Reported by:  Rick Macklem <rmacklem@uoguelph.ca>
Sponsored by: Netflix

This corrects a bug that prevented snapshots from being mounted due to a
superblock check-hash failure.

Reported by:  Brennan Vincent <brennan@umanwizard.com>
Tested by:    Peter Holm (pho@)
Sponsored by: Netflix

document the libufs interface for fetching and storing inodes.
The undocumented getino / putino interface has been replaced
with a new getinode / putinode interface.

Convert the utilities that had been using the undocumented
interface to use the new documented interface.

No functional change (as for now the libufs library does not
do inode check-hashes).

Reviewed by:  kib
Tested by:    Peter Holm
Sponsored by: Netflix

check hash to the superblock. If a check hash fails when an attempt
is made to mount a filesystem, the mount fails with EINVAL (Invalid
argument). This avoids a class of filesystem panics related to
corrupted superblocks. The hash is done using crc32c.

Check hases are added only to UFS2 and not to UFS1 as UFS1 is primarily
used in embedded systems with small memories and low-powered processors
which need as light-weight a filesystem as possible.

Reviewed by:  kib
Tested by:    Peter Holm
Sponsored by: Netflix

    Avoid Undefined Behavior in ffs_clusteracct()

    Change the type of 'bit' variable from int to unsigned int and use unsigned
    values consistently.

    sys/ufs/ffs/ffs_subr.c:336:10, shift exponent -1 is negative

    Detected with Kernel Undefined Behavior Sanitizer.

    Reported by <Harry Pantazis>

Submitted by: Pedro Giffuni

to fix the memory leak that I introduced in r328426. Instead of
trying to clear up the possible memory leak in all the clients, I
ensure that it gets cleaned up in the source (e.g., ffs_sbget ensures
that memory is always freed if it returns an error).

The original change in r328426 was a bit sparse in its description.
So I am expanding on its description here (thanks cem@ and rgrimes@
for your encouragement for my longer commit messages).

In preparation for adding check hashing to superblocks, r328426 is
a refactoring of the code to get the reading/writing of the superblock
into one place. Unlike the cylinder group reading/writing which
ends up in two places (ffs_getcg/ffs_geom_strategy in the kernel
and cgget/cgput in libufs), I have the core superblock functions
just in the kernel (ffs_sbfetch/ffs_sbput in ffs_subr.c which is
already imported into utilities like fsck_ffs as well as libufs to
implement sbget/sbput). The ffs_sbfetch and ffs_sbput functions
take a function pointer to do the actual I/O for which there are
four variants:

    ffs_use_bread / ffs_use_bwrite for the in-kernel filesystem

    g_use_g_read_data / g_use_g_write_data for kernel geom clients

    ufs_use_sa_read for the standalone code (stand/libsa/ufs.c
	but not stand/libsa/ufsread.c which is size constrained)

    use_pread / use_pwrite for libufs

Uses of these interfaces are in the UFS filesystem, geoms journal &
label, libsa changes, and libufs. They also permeate out into the
filesystem utilities fsck_ffs, newfs, growfs, clri, dump, quotacheck,
fsirand, fstyp, and quot. Some of these utilities should probably be
converted to directly use libufs (like dumpfs was for example), but
there does not seem to be much win in doing so.

Tested by: Peter Holm (pho@)

restraints when validating one of the backup superblocks.

backup superblocks.

than in the two places that call readsuper().

No semantic change intended.

Reviewed by: kib

Reported and tested by:	allanjude
Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation

ffs_sbget() may return a superblock buffer even if it fails, so the
caller must be prepared to free it in this case. Moreover, when tasting
alternate superblock locations in a loop, ffs_sbget()'s readfunc
callback must free the previously allocated buffer.

Reported and tested by:	pho
Reviewed by:		kib (previous version)
Differential Revision:	https://reviews.freebsd.org/D14390

Specifically reading is done if ffs_sbget() and writing is done
in ffs_sbput(). These functions are exported to libufs via the
sbget() and sbput() functions which then used in the various
filesystem utilities. This work is in preparation for adding
subperblock check hashes.

No functional change intended.

Reviewed by: kib

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

Also renumber license clause to avoid skipping #3

Remove redunand i_dev and i_fs pointers, which are available as
ip->i_ump->um_dev and ip->i_ump->um_fs, and reorder members by size to
reduce padding.  To compensate added derefences, the most often i_ump
access to differentiate between UFS1 and UFS2 dinode layout is
removed, by addition of the new i_flag IN_UFS2.  Overall, this
actually reduces the amount of memory dereferences.

On 64bit machine, original struct inode size is 176, reduced to 152
bytes with the change.

Tested by:	pho (previous version)
Reviewed by:	mckusick
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks

   'buf' is inconvenient and has lead me to some irritating to discover
   bugs over the years.  It also makes it more challenging to refactor
   the buf allocation system.
 - Move swbuf and declare it as an extern in vfs_bio.c.  This is still
   not perfect but better than it was before.
 - Eliminate the unused ffs function that relied on knowledge of the buf
   array.
 - Move the shutdown code that iterates over the buf array into vfs_bio.c.

Reviewed by:	kib
Sponsored by:	EMC / Isilon Storage Division

^/user/gjb/hacking since this is likely to be merged to head/ soon.

Sponsored by:	The FreeBSD Foundation

inclusion of (at least) arm builds with the release.

Sponsored by:	The FreeBSD Foundation

by /etc/rc.d/jail.

   brings in support for an optional intent log which eliminates the need
   for background fsck on unclean shutdown.

Sponsored by:   iXsystems, Yahoo!, and Juniper.
With help from: McKusick and Peter Holm

o remove all of compat except for pwcache and strstuftoll; these might
  end up in libutil or similar so keep them in the subdir
o mv getid.c up to the top level; this looks like something that'll be
  makefs-specific
o eliminate private versions of .h files in sys; use system files instead
o eliminate private ffs_tables.c; use the system version directly (might
  want to adopt const'ification at some point but that's the only diff I
  can see)
o mv remaining code from sys to ffs and strip out unused bits; this now
  becomes part of makefs
o add compat defs and shims to makefs.h
o strip all vestiges of nbtool_config.h, compat_defs.h, etc.
o fixup includes after file shuffling
o rename system #defines that do implicit byte swapping to have an _swap
  suffix; e.g. DIRSIZ -> DIRSIZ_SWAP, cg_inosused -> cg_inosused_swap; if
  we ever add endian-agnostic support to the kernel these can go back to
  their original names
o strip some netbsd'isms that aren't worth shim'ing (e.g. _DIAGASSERT)

Code compiles w/o complaints but is untested.

performance in Xen's HVM mode.