Commit Graph

76 Commits

Author SHA1 Message Date
Eric Biggers d171c85d74 fsverity: use register_sysctl_init() to avoid kmemleak warning
commit ee5814dddefbaa181cb247a75676dd5103775db1 upstream.

Since the fsverity sysctl registration runs as a builtin initcall, there
is no corresponding sysctl deregistration and the resulting struct
ctl_table_header is not used.  This can cause a kmemleak warning just
after the system boots up.  (A pointer to the ctl_table_header is stored
in the fsverity_sysctl_header static variable, which kmemleak should
detect; however, the compiler can optimize out that variable.)  Avoid
the kmemleak warning by using register_sysctl_init() which is intended
for use by builtin initcalls and uses kmemleak_not_leak().

Reported-by: Yi Zhang <yi.zhang@redhat.com>
Closes: https://lore.kernel.org/r/CAHj4cs8DTSvR698UE040rs_pX1k-WVe7aR6N2OoXXuhXJPDC-w@mail.gmail.com
Cc: stable@vger.kernel.org
Reviewed-by: Joel Granados <j.granados@samsung.com>
Link: https://lore.kernel.org/r/20240501025331.594183-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-06-16 13:47:33 +02:00
Eric Biggers 919dc32095 fsverity: skip PKCS#7 parser when keyring is empty
If an fsverity builtin signature is given for a file but the
".fs-verity" keyring is empty, there's no real reason to run the PKCS#7
parser.  Skip this to avoid the PKCS#7 attack surface when builtin
signature support is configured into the kernel but is not being used.

This is a hardening improvement, not a fix per se, but I've added
Fixes and Cc stable to get it out to more users.

Fixes: 432434c9f8 ("fs-verity: support builtin file signatures")
Cc: stable@vger.kernel.org
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lore.kernel.org/r/20230820173237.2579-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-08-20 10:33:43 -07:00
Eric Biggers 456ae5fe9b fsverity: move sysctl registration out of signature.c
Currently the registration of the fsverity sysctls happens in
signature.c, which couples it to CONFIG_FS_VERITY_BUILTIN_SIGNATURES.

This makes it hard to add new sysctls unrelated to builtin signatures.

Also, some users have started checking whether the directory
/proc/sys/fs/verity exists as a way to tell whether fsverity is
supported.  This isn't the intended method; instead, the existence of
/sys/fs/$fstype/features/verity should be checked, or users should just
try to use the fsverity ioctls.  Regardless, it should be made to work
as expected without a dependency on CONFIG_FS_VERITY_BUILTIN_SIGNATURES.

Therefore, move the sysctl registration into init.c.  With
CONFIG_FS_VERITY_BUILTIN_SIGNATURES, nothing changes.  Without it, but
with CONFIG_FS_VERITY, an empty list of sysctls is now registered.

Link: https://lore.kernel.org/r/20230705212743.42180-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-07-11 22:57:03 -07:00
Eric Biggers e77000ccc5 fsverity: simplify handling of errors during initcall
Since CONFIG_FS_VERITY is a bool, not a tristate, fs/verity/ can only be
builtin or absent entirely; it can't be a loadable module.  Therefore,
the error code that gets returned from the fsverity_init() initcall is
never used.  If any part of the initcall does fail, which should never
happen, the kernel will be left in a bad state.

Following the usual convention for builtin code, just panic the kernel
if any of part of the initcall fails.

Link: https://lore.kernel.org/r/20230705212743.42180-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-07-11 22:49:18 -07:00
Eric Biggers 5d37a11980 fsverity: explicitly check that there is no algorithm 0
Since libfsverity and some other code would break if 0 is ever allocated
as an FS_VERITY_HASH_ALG_* value, make fsverity_check_hash_algs()
explicitly check that there is no algorithm 0.

Link: https://lore.kernel.org/r/20230705211719.37713-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-07-11 22:49:18 -07:00
Eric Biggers 672d6ef4c7 fsverity: improve documentation for builtin signature support
fsverity builtin signatures (CONFIG_FS_VERITY_BUILTIN_SIGNATURES) aren't
the only way to do signatures with fsverity, and they have some major
limitations.  Yet, more users have tried to use them, e.g. recently by
https://github.com/ostreedev/ostree/pull/2640.  In most cases this seems
to be because users aren't sufficiently familiar with the limitations of
this feature and what the alternatives are.

Therefore, make some updates to the documentation to try to clarify the
properties of this feature and nudge users in the right direction.

Note that the Integrity Policy Enforcement (IPE) LSM, which is not yet
upstream, is planned to use the builtin signatures.  (This differs from
IMA, which uses its own signature mechanism.)  For that reason, my
earlier patch "fsverity: mark builtin signatures as deprecated"
(https://lore.kernel.org/r/20221208033548.122704-1-ebiggers@kernel.org),
which marked builtin signatures as "deprecated", was controversial.

This patch therefore stops short of marking the feature as deprecated.
I've also revised the language to focus on better explaining the feature
and what its alternatives are.

Link: https://lore.kernel.org/r/20230620041937.5809-1-ebiggers@kernel.org
Reviewed-by: Colin Walters <walters@verbum.org>
Reviewed-by: Luca Boccassi <bluca@debian.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-06-20 22:47:55 -07:00
Eric Biggers 74836ecbc5 fsverity: rework fsverity_get_digest() again
Address several issues with the calling convention and documentation of
fsverity_get_digest():

- Make it provide the hash algorithm as either a FS_VERITY_HASH_ALG_*
  value or HASH_ALGO_* value, at the caller's choice, rather than only a
  HASH_ALGO_* value as it did before.  This allows callers to work with
  the fsverity native algorithm numbers if they want to.  HASH_ALGO_* is
  what IMA uses, but other users (e.g. overlayfs) should use
  FS_VERITY_HASH_ALG_* to match fsverity-utils and the fsverity UAPI.

- Make it return the digest size so that it doesn't need to be looked up
  separately.  Use the return value for this, since 0 works nicely for
  the "file doesn't have fsverity enabled" case.  This also makes it
  clear that no other errors are possible.

- Rename the 'digest' parameter to 'raw_digest' and clearly document
  that it is only useful in combination with the algorithm ID.  This
  hopefully clears up a point of confusion.

- Export it to modules, since overlayfs will need it for checking the
  fsverity digests of lowerdata files
  (https://lore.kernel.org/r/dd294a44e8f401e6b5140029d8355f88748cd8fd.1686565330.git.alexl@redhat.com).

Acked-by: Mimi Zohar <zohar@linux.ibm.com> # for the IMA piece
Link: https://lore.kernel.org/r/20230612190047.59755-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-06-14 10:41:07 -07:00
Eric Biggers 13e2408d02 fsverity: simplify error handling in verify_data_block()
Clean up the error handling in verify_data_block() to (a) eliminate the
'err' variable which has caused some confusion because the function
actually returns a bool, (b) reduce the compiled code size slightly, and
(c) execute one fewer branch in the success case.

Link: https://lore.kernel.org/r/20230604022312.48532-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-06-04 05:56:11 -07:00
Eric Biggers d1f0c5ea04 fsverity: don't use bio_first_page_all() in fsverity_verify_bio()
bio_first_page_all(bio)->mapping->host is not compatible with large
folios, since the first page of the bio is not necessarily the head page
of the folio, and therefore it might not have the mapping pointer set.

Therefore, move the dereference of ->mapping->host into
verify_data_blocks(), which works with a folio.

(Like the commit that this Fixes, this hasn't actually been tested with
large folios yet, since the filesystems that use fs/verity/ don't
support that yet.  But based on code review, I think this is needed.)

Fixes: 5d0f0e57ed ("fsverity: support verifying data from large folios")
Link: https://lore.kernel.org/r/20230604022101.48342-1-ebiggers@kernel.org
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-06-04 05:56:11 -07:00
Eric Biggers 32ab3c5e62 fsverity: constify fsverity_hash_alg
Now that fsverity_hash_alg doesn't have an embedded mempool, it can be
'const' almost everywhere.  Add it.

Link: https://lore.kernel.org/r/20230604022348.48658-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-06-04 05:56:11 -07:00
Eric Biggers 8fcd94add6 fsverity: use shash API instead of ahash API
The "ahash" API, like the other scatterlist-based crypto APIs such as
"skcipher", comes with some well-known limitations.  First, it can't
easily be used with vmalloc addresses.  Second, the request struct can't
be allocated on the stack.  This adds complexity and a possible failure
point that needs to be worked around, e.g. using a mempool.

The only benefit of ahash over "shash" is that ahash is needed to access
traditional memory-to-memory crypto accelerators, i.e. drivers/crypto/.
However, this style of crypto acceleration has largely fallen out of
favor and been superseded by CPU-based acceleration or inline crypto
engines.  Also, ahash needs to be used asynchronously to take full
advantage of such hardware, but fs/verity/ has never done this.

On all systems that aren't actually using one of these ahash-only crypto
accelerators, ahash just adds unnecessary overhead as it sits between
the user and the underlying shash algorithms.

Also, XFS is planned to cache fsverity Merkle tree blocks in the
existing XFS buffer cache.  As a result, it will be possible for a
single Merkle tree block to be split across discontiguous pages
(https://lore.kernel.org/r/20230405233753.GU3223426@dread.disaster.area).
This data will need to be hashed.  It is easiest to work with a vmapped
address in this case.  However, ahash is incompatible with this.

Therefore, let's convert fs/verity/ from ahash to shash.  This
simplifies the code, and it should also slightly improve performance for
everyone who wasn't actually using one of these ahash-only crypto
accelerators, i.e. almost everyone (or maybe even everyone)!

Link: https://lore.kernel.org/r/20230516052306.99600-1-ebiggers@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-06-04 05:54:28 -07:00
Eric Biggers 0483913921 fsverity: reject FS_IOC_ENABLE_VERITY on mode 3 fds
Commit 56124d6c87 ("fsverity: support enabling with tree block size <
PAGE_SIZE") changed FS_IOC_ENABLE_VERITY to use __kernel_read() to read
the file's data, instead of direct pagecache accesses.

An unintended consequence of this is that the
'WARN_ON_ONCE(!(file->f_mode & FMODE_READ))' in __kernel_read() became
reachable by fuzz tests.  This happens if FS_IOC_ENABLE_VERITY is called
on a fd opened with access mode 3, which means "ioctl access only".

Arguably, FS_IOC_ENABLE_VERITY should work on ioctl-only fds.  But
ioctl-only fds are a weird Linux extension that is rarely used and that
few people even know about.  (The documentation for FS_IOC_ENABLE_VERITY
even specifically says it requires O_RDONLY.)  It's probably not
worthwhile to make the ioctl internally open a new fd just to handle
this case.  Thus, just reject the ioctl on such fds for now.

Fixes: 56124d6c87 ("fsverity: support enabling with tree block size < PAGE_SIZE")
Reported-by: syzbot+51177e4144d764827c45@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=2281afcbbfa8fdb92f9887479cc0e4180f1c6b28
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230406215106.235829-1-ebiggers@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-04-11 19:23:23 -07:00
Eric Biggers 39049b69ec fsverity: explicitly check for buffer overflow in build_merkle_tree()
The new Merkle tree construction algorithm is a bit fragile in that it
may overflow the 'root_hash' array if the tree actually generated does
not match the calculated tree parameters.

This should never happen unless there is a filesystem bug that allows
the file size to change despite deny_write_access(), or a bug in the
Merkle tree logic itself.  Regardless, it's fairly easy to check for
buffer overflow here, so let's do so.

This is a robustness improvement only; this case is not currently known
to be reachable.  I've added a Fixes tag anyway, since I recommend that
this be included in kernels that have the mentioned commit.

Fixes: 56124d6c87 ("fsverity: support enabling with tree block size < PAGE_SIZE")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230328041505.110162-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-04-11 19:23:23 -07:00
Eric Biggers 8eb8af4b3d fsverity: use WARN_ON_ONCE instead of WARN_ON
As per Linus's suggestion
(https://lore.kernel.org/r/CAHk-=whefxRGyNGzCzG6BVeM=5vnvgb-XhSeFJVxJyAxAF8XRA@mail.gmail.com),
use WARN_ON_ONCE instead of WARN_ON.  This barely adds any extra
overhead, and it makes it so that if any of these ever becomes reachable
(they shouldn't, but that's the point), the logs can't be flooded.

Link: https://lore.kernel.org/r/20230406181542.38894-1-ebiggers@kernel.org
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-04-11 19:23:15 -07:00
Luis Chamberlain 1238c8b91c fs-verity: simplify sysctls with register_sysctl()
register_sysctl_paths() is only needed if your child (directories) have
entries but this does not so just use register_sysctl() so to do away
with the path specification.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20230302202826.776286-10-mcgrof@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-03-27 21:17:02 -07:00
Eric Biggers a075bacde2 fsverity: don't drop pagecache at end of FS_IOC_ENABLE_VERITY
The full pagecache drop at the end of FS_IOC_ENABLE_VERITY is causing
performance problems and is hindering adoption of fsverity.  It was
intended to solve a race condition where unverified pages might be left
in the pagecache.  But actually it doesn't solve it fully.

Since the incomplete solution for this race condition has too much
performance impact for it to be worth it, let's remove it for now.

Fixes: 3fda4c617e ("fs-verity: implement FS_IOC_ENABLE_VERITY ioctl")
Cc: stable@vger.kernel.org
Reviewed-by: Victor Hsieh <victorhsieh@google.com>
Link: https://lore.kernel.org/r/20230314235332.50270-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-03-15 22:50:41 -07:00
Nathan Huckleberry f959325e6a fsverity: Remove WQ_UNBOUND from fsverity read workqueue
WQ_UNBOUND causes significant scheduler latency on ARM64/Android.  This
is problematic for latency sensitive workloads, like I/O
post-processing.

Removing WQ_UNBOUND gives a 96% reduction in fsverity workqueue related
scheduler latency and improves app cold startup times by ~30ms.
WQ_UNBOUND was also removed from the dm-verity workqueue for the same
reason [1].

This code was tested by running Android app startup benchmarks and
measuring how long the fsverity workqueue spent in the runnable state.

Before
Total workqueue scheduler latency: 553800us
After
Total workqueue scheduler latency: 18962us

[1]: https://lore.kernel.org/all/20230202012348.885402-1-nhuck@google.com/

Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Fixes: 8a1d0f9cac ("fs-verity: add data verification hooks for ->readpages()")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230310193325.620493-1-nhuck@google.com
Signed-off-by: Eric Biggers <ebiggers@google.com>
2023-03-14 16:16:36 -07:00
Eric Biggers 5d0f0e57ed fsverity: support verifying data from large folios
Try to make fs/verity/verify.c aware of large folios.  This includes
making fsverity_verify_bio() support the case where the bio contains
large folios, and adding a function fsverity_verify_folio() which is the
equivalent of fsverity_verify_page().

There's no way to actually test this with large folios yet, but I've
tested that this doesn't cause any regressions.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20230127221529.299560-1-ebiggers@kernel.org
2023-01-27 14:46:31 -08:00
Eric Biggers 56124d6c87 fsverity: support enabling with tree block size < PAGE_SIZE
Make FS_IOC_ENABLE_VERITY support values of
fsverity_enable_arg::block_size other than PAGE_SIZE.

To make this possible, rework build_merkle_tree(), which was reading
data and hash pages from the file and assuming that they were the same
thing as "blocks".

For reading the data blocks, just replace the direct pagecache access
with __kernel_read(), to naturally read one block at a time.

(A disadvantage of the above is that we lose the two optimizations of
hashing the pagecache pages in-place and forcing the maximum readahead.
That shouldn't be very important, though.)

The hash block reads are a bit more difficult to handle, as the only way
to do them is through fsverity_operations::read_merkle_tree_page().

Instead, let's switch to the single-pass tree construction algorithm
that fsverity-utils uses.  This eliminates the need to read back any
hash blocks while the tree is being built, at the small cost of an extra
block-sized memory buffer per Merkle tree level.  This is probably what
I should have done originally.

Taken together, the above two changes result in page-size independent
code that is also a bit simpler than what we had before.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Andrey Albershteyn <aalbersh@redhat.com>
Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20221223203638.41293-8-ebiggers@kernel.org
2023-01-09 19:06:06 -08:00
Eric Biggers 5306892a50 fsverity: support verification with tree block size < PAGE_SIZE
Add support for verifying data from verity files whose Merkle tree block
size is less than the page size.  The main use case for this is to allow
a single Merkle tree block size to be used across all systems, so that
only one set of fsverity file digests and signatures is needed.

To do this, eliminate various assumptions that the Merkle tree block
size and the page size are the same:

- Make fsverity_verify_page() a wrapper around a new function
  fsverity_verify_blocks() which verifies one or more blocks in a page.

- When a Merkle tree block is needed, get the corresponding page and
  only verify and use the needed portion.  (The Merkle tree continues to
  be read and cached in page-sized chunks; that doesn't need to change.)

- When the Merkle tree block size and page size differ, use a bitmap
  fsverity_info::hash_block_verified to keep track of which Merkle tree
  blocks have been verified, as PageChecked cannot be used directly.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Andrey Albershteyn <aalbersh@redhat.com>
Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20221223203638.41293-7-ebiggers@kernel.org
2023-01-09 19:06:03 -08:00
Eric Biggers f45555bf23 fsverity: replace fsverity_hash_page() with fsverity_hash_block()
In preparation for allowing the Merkle tree block size to differ from
PAGE_SIZE, replace fsverity_hash_page() with fsverity_hash_block().  The
new function is similar to the old one, but it operates on the block at
the given offset in the page instead of on the full page.

(For now, all callers still pass a full page.)

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Andrey Albershteyn <aalbersh@redhat.com>
Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20221223203638.41293-6-ebiggers@kernel.org
2023-01-09 19:06:01 -08:00
Eric Biggers 55eed69cc8 fsverity: use EFBIG for file too large to enable verity
Currently, there is an implementation limit where files can't have more
than 8 Merkle tree levels.  With SHA-256 and 4K blocks, this limit is
never reached, since a file would need to be larger than 2**64 bytes to
need 9 levels.  However, with SHA-512, 9 levels are needed for files
larger than about 1.15 EB, which is possible on btrfs.  Therefore, this
limit technically became reachable when btrfs added fsverity support.

Meanwhile, support for merkle_tree_block_size < PAGE_SIZE will introduce
another implementation limit on file size, resulting from the use of an
in-memory bitmap to track which Merkle tree blocks have been verified.

In any case, currently FS_IOC_ENABLE_VERITY fails with EINVAL when the
file is too large.  This is undocumented, and also ambiguous since
EINVAL can mean other things too.  Let's change the error code to EFBIG,
which is much clearer, and document it.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Andrey Albershteyn <aalbersh@redhat.com>
Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20221223203638.41293-5-ebiggers@kernel.org
2023-01-09 19:05:59 -08:00
Eric Biggers 579a12f78d fsverity: store log2(digest_size) precomputed
Add log_digestsize to struct merkle_tree_params so that it can be used
in verify.c.  Also save memory by using u8 for all the log_* fields.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Andrey Albershteyn <aalbersh@redhat.com>
Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20221223203638.41293-4-ebiggers@kernel.org
2023-01-09 19:05:56 -08:00
Eric Biggers 9098f36b73 fsverity: simplify Merkle tree readahead size calculation
First, calculate max_ra_pages more efficiently by using the bio size.

Second, calculate the number of readahead pages from the hash page
index, instead of calculating it ahead of time using the data page
index.  This ends up being a bit simpler, especially since level 0 is
last in the tree, so we can just limit the readahead to the tree size.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Andrey Albershteyn <aalbersh@redhat.com>
Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20221223203638.41293-3-ebiggers@kernel.org
2023-01-09 19:05:54 -08:00
Eric Biggers 284d5db5f9 fsverity: use unsigned long for level_start
fs/verity/ isn't consistent with whether Merkle tree block indices are
'unsigned long' or 'u64'.  There's no real point to using u64 for them,
though, since (a) a Merkle tree with over ULONG_MAX blocks would only be
needed for a file larger than MAX_LFS_FILESIZE, and (b) for reads, the
status of all Merkle tree blocks has to be tracked in memory.

Therefore, let's make things a bit more efficient on 32-bit systems by
using 'unsigned long[]' for merkle_tree_params::level_start, instead of
'u64[]'.  Also, to be extra safe, explicitly check that there aren't
more than ULONG_MAX Merkle tree blocks.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Andrey Albershteyn <aalbersh@redhat.com>
Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20221223203638.41293-2-ebiggers@kernel.org
2023-01-09 19:05:47 -08:00
Eric Biggers 86f66569ba fsverity: remove debug messages and CONFIG_FS_VERITY_DEBUG
I've gotten very little use out of these debug messages, and I'm not
aware of anyone else having used them.

Indeed, sprinkling pr_debug around is not really a best practice these
days, especially for filesystem code.  Tracepoints are used instead.

Let's just remove these and start from a clean slate.

This change does not affect info, warning, and error messages.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20221215060420.60692-1-ebiggers@kernel.org
2023-01-01 15:46:48 -08:00
Eric Biggers 72ea15f0dd fsverity: pass pos and size to ->write_merkle_tree_block
fsverity_operations::write_merkle_tree_block is passed the index of the
block to write and the log base 2 of the block size.  However, all
implementations of it use these parameters only to calculate the
position and the size of the block, in bytes.

Therefore, make ->write_merkle_tree_block take 'pos' and 'size'
parameters instead of 'index' and 'log_blocksize'.

Suggested-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20221214224304.145712-5-ebiggers@kernel.org
2023-01-01 15:46:48 -08:00
Eric Biggers 9642946c6c fsverity: optimize fsverity_cleanup_inode() on non-verity files
Make fsverity_cleanup_inode() an inline function that checks for
non-NULL ->i_verity_info, then (if needed) calls
__fsverity_cleanup_inode() to do the real work.  This reduces the
overhead on non-verity files.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20221214224304.145712-4-ebiggers@kernel.org
2023-01-01 15:46:48 -08:00
Eric Biggers 01d90c07a5 fsverity: optimize fsverity_prepare_setattr() on non-verity files
Make fsverity_prepare_setattr() an inline function that does the
IS_VERITY() check, then (if needed) calls __fsverity_prepare_setattr()
to do the real work.  This reduces the overhead on non-verity files.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20221214224304.145712-3-ebiggers@kernel.org
2023-01-01 15:46:48 -08:00
Eric Biggers a6528a960b fsverity: optimize fsverity_file_open() on non-verity files
Make fsverity_file_open() an inline function that does the IS_VERITY()
check, then (if needed) calls __fsverity_file_open() to do the real
work.  This reduces the overhead on non-verity files.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20221214224304.145712-2-ebiggers@kernel.org
2023-01-01 15:46:48 -08:00
Eric Biggers a4bbf53d88 fsverity: simplify fsverity_get_digest()
Instead of looking up the algorithm by name in hash_algo_name[] to get
its hash_algo ID, just store the hash_algo ID in the fsverity_hash_alg
struct.  Verify at boot time that every fsverity_hash_alg has a valid
hash_algo ID with matching digest size.

Remove an unnecessary memset() of the whole digest array to 0 before the
digest is copied into it.

Finally, remove the pr_debug statement.  There is already a pr_debug for
the fsverity digest when the file is opened.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Link: https://lore.kernel.org/r/20221129045139.69803-1-ebiggers@kernel.org
2022-11-29 21:07:41 -08:00
Eric Biggers 98dc08bae6 fsverity: stop using PG_error to track error status
As a step towards freeing the PG_error flag for other uses, change ext4
and f2fs to stop using PG_error to track verity errors.  Instead, if a
verity error occurs, just mark the whole bio as failed.  The coarser
granularity isn't really a problem since it isn't any worse than what
the block layer provides, and errors from a multi-page readahead aren't
reported to applications unless a single-page read fails too.

f2fs supports compression, which makes the f2fs changes a bit more
complicated than desired, but the basic premise still works.

Note: there are still a few uses of PageError in f2fs, but they are on
the write path, so they are unrelated and this patch doesn't touch them.

Reviewed-by: Chao Yu <chao@kernel.org>
Acked-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20221129070401.156114-1-ebiggers@kernel.org
2022-11-28 23:15:10 -08:00
Linus Torvalds 76e4503534 for-6.1-tag
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Merge tag 'for-6.1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs updates from David Sterba:
 "There's a bunch of performance improvements, most notably the FIEMAP
  speedup, the new block group tree to speed up mount on large
  filesystems, more io_uring integration, some sysfs exports and the
  usual fixes and core updates.

  Summary:

  Performance:

   - outstanding FIEMAP speed improvement
      - algorithmic change how extents are enumerated leads to orders of
        magnitude speed boost (uncached and cached)
      - extent sharing check speedup (2.2x uncached, 3x cached)
      - add more cancellation points, allowing to interrupt seeking in
        files with large number of extents
      - more efficient hole and data seeking (4x uncached, 1.3x cached)
      - sample results:
	    256M, 32K extents:   4s ->  29ms  (~150x)
	    512M, 64K extents:  30s ->  59ms  (~550x)
	    1G,  128K extents: 225s -> 120ms (~1800x)

   - improved inode logging, especially for directories (on dbench
     workload throughput +25%, max latency -21%)

   - improved buffered IO, remove redundant extent state tracking,
     lowering memory consumption and avoiding rb tree traversal

   - add sysfs tunable to let qgroup temporarily skip exact accounting
     when deleting snapshot, leading to a speedup but requiring a rescan
     after that, will be used by snapper

   - support io_uring and buffered writes, until now it was just for
     direct IO, with the no-wait semantics implemented in the buffered
     write path it now works and leads to speed improvement in IOPS
     (2x), throughput (2.2x), latency (depends, 2x to 150x)

   - small performance improvements when dropping and searching for
     extent maps as well as when flushing delalloc in COW mode
     (throughput +5MB/s)

  User visible changes:

   - new incompatible feature block-group-tree adding a dedicated tree
     for tracking block groups, this allows a much faster load during
     mount and avoids seeking unlike when it's scattered in the extent
     tree items
      - this reduces mount time for many-terabyte sized filesystems
      - conversion tool will be provided so existing filesystem can also
        be updated in place
      - to reduce test matrix and feature combinations requires no-holes
        and free-space-tree (mkfs defaults since 5.15)

   - improved reporting of super block corruption detected by scrub

   - scrub also tries to repair super block and does not wait until next
     commit

   - discard stats and tunables are exported in sysfs
     (/sys/fs/btrfs/FSID/discard)

   - qgroup status is exported in sysfs
     (/sys/sys/fs/btrfs/FSID/qgroups/)

   - verify that super block was not modified when thawing filesystem

  Fixes:

   - FIEMAP fixes
      - fix extent sharing status, does not depend on the cached status
        where merged
      - flush delalloc so compressed extents are reported correctly

   - fix alignment of VMA for memory mapped files on THP

   - send: fix failures when processing inodes with no links (orphan
     files and directories)

   - fix race between quota enable and quota rescan ioctl

   - handle more corner cases for read-only compat feature verification

   - fix missed extent on fsync after dropping extent maps

  Core:

   - lockdep annotations to validate various transactions states and
     state transitions

   - preliminary support for fs-verity in send

   - more effective memory use in scrub for subpage where sector is
     smaller than page

   - block group caching progress logic has been removed, load is now
     synchronous

   - simplify end IO callbacks and bio handling, use chained bios
     instead of own tracking

   - add no-wait semantics to several functions (tree search, nocow,
     flushing, buffered write

   - cleanups and refactoring

  MM changes:

   - export balance_dirty_pages_ratelimited_flags"

* tag 'for-6.1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (177 commits)
  btrfs: set generation before calling btrfs_clean_tree_block in btrfs_init_new_buffer
  btrfs: drop extent map range more efficiently
  btrfs: avoid pointless extent map tree search when flushing delalloc
  btrfs: remove unnecessary next extent map search
  btrfs: remove unnecessary NULL pointer checks when searching extent maps
  btrfs: assert tree is locked when clearing extent map from logging
  btrfs: remove unnecessary extent map initializations
  btrfs: remove the refcount warning/check at free_extent_map()
  btrfs: add helper to replace extent map range with a new extent map
  btrfs: move open coded extent map tree deletion out of inode eviction
  btrfs: use cond_resched_rwlock_write() during inode eviction
  btrfs: use extent_map_end() at btrfs_drop_extent_map_range()
  btrfs: move btrfs_drop_extent_cache() to extent_map.c
  btrfs: fix missed extent on fsync after dropping extent maps
  btrfs: remove stale prototype of btrfs_write_inode
  btrfs: enable nowait async buffered writes
  btrfs: assert nowait mode is not used for some btree search functions
  btrfs: make btrfs_buffered_write nowait compatible
  btrfs: plumb NOWAIT through the write path
  btrfs: make lock_and_cleanup_extent_if_need nowait compatible
  ...
2022-10-06 17:36:48 -07:00
Boris Burkov 38622010a6 btrfs: send: add support for fs-verity
Preserve the fs-verity status of a btrfs file across send/recv.

There is no facility for installing the Merkle tree contents directly on
the receiving filesystem, so we package up the parameters used to enable
verity found in the verity descriptor. This gives the receive side
enough information to properly enable verity again. Note that this means
that receive will have to re-compute the whole Merkle tree, similar to
how compression worked before encoded_write.

Since the file becomes read-only after verity is enabled, it is
important that verity is added to the send stream after any file writes.
Therefore, when we process a verity item, merely note that it happened,
then actually create the command in the send stream during
'finish_inode_if_needed'.

This also creates V3 of the send stream format, without any format
changes besides adding the new commands and attributes.

Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
2022-09-26 12:27:55 +02:00
Eric Biggers 8377e8a24b fs-verity: use kmap_local_page() instead of kmap()
Convert the use of kmap() to its recommended replacement
kmap_local_page().  This avoids the overhead of doing a non-local
mapping, which is unnecessary in this case.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Link: https://lore.kernel.org/r/20220818224010.43778-1-ebiggers@kernel.org
2022-08-19 15:19:55 -07:00
Eric Biggers c987918a3f fs-verity: use memcpy_from_page()
Replace extract_hash() with the memcpy_from_page() helper function.

This is simpler, and it has the side effect of replacing the use of
kmap_atomic() with its recommended replacement kmap_local_page().

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Link: https://lore.kernel.org/r/20220818223903.43710-1-ebiggers@kernel.org
2022-08-19 15:19:55 -07:00
Eric Biggers 8da572c52a fs-verity: mention btrfs support
btrfs supports fs-verity since Linux v5.15.  Document this.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: David Sterba <dsterba@suse.com>
Link: https://lore.kernel.org/r/20220610000616.18225-1-ebiggers@kernel.org
2022-07-15 23:42:30 -07:00
Linus Torvalds fdaf9a5840 Page cache changes for 5.19
- Appoint myself page cache maintainer
 
  - Fix how scsicam uses the page cache
 
  - Use the memalloc_nofs_save() API to replace AOP_FLAG_NOFS
 
  - Remove the AOP flags entirely
 
  - Remove pagecache_write_begin() and pagecache_write_end()
 
  - Documentation updates
 
  - Convert several address_space operations to use folios:
    - is_dirty_writeback
    - readpage becomes read_folio
    - releasepage becomes release_folio
    - freepage becomes free_folio
 
  - Change filler_t to require a struct file pointer be the first argument
    like ->read_folio
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Merge tag 'folio-5.19' of git://git.infradead.org/users/willy/pagecache

Pull page cache updates from Matthew Wilcox:

 - Appoint myself page cache maintainer

 - Fix how scsicam uses the page cache

 - Use the memalloc_nofs_save() API to replace AOP_FLAG_NOFS

 - Remove the AOP flags entirely

 - Remove pagecache_write_begin() and pagecache_write_end()

 - Documentation updates

 - Convert several address_space operations to use folios:
     - is_dirty_writeback
     - readpage becomes read_folio
     - releasepage becomes release_folio
     - freepage becomes free_folio

 - Change filler_t to require a struct file pointer be the first
   argument like ->read_folio

* tag 'folio-5.19' of git://git.infradead.org/users/willy/pagecache: (107 commits)
  nilfs2: Fix some kernel-doc comments
  Appoint myself page cache maintainer
  fs: Remove aops->freepage
  secretmem: Convert to free_folio
  nfs: Convert to free_folio
  orangefs: Convert to free_folio
  fs: Add free_folio address space operation
  fs: Convert drop_buffers() to use a folio
  fs: Change try_to_free_buffers() to take a folio
  jbd2: Convert release_buffer_page() to use a folio
  jbd2: Convert jbd2_journal_try_to_free_buffers to take a folio
  reiserfs: Convert release_buffer_page() to use a folio
  fs: Remove last vestiges of releasepage
  ubifs: Convert to release_folio
  reiserfs: Convert to release_folio
  orangefs: Convert to release_folio
  ocfs2: Convert to release_folio
  nilfs2: Remove comment about releasepage
  nfs: Convert to release_folio
  jfs: Convert to release_folio
  ...
2022-05-24 19:55:07 -07:00
Linus Torvalds 0350785b0a integrity-v5.19
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Merge tag 'integrity-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

Pull IMA updates from Mimi Zohar:
 "New is IMA support for including fs-verity file digests and signatures
  in the IMA measurement list as well as verifying the fs-verity file
  digest based signatures, both based on policy.

  In addition, are two bug fixes:

   - avoid reading UEFI variables, which cause a page fault, on Apple
     Macs with T2 chips.

   - remove the original "ima" template Kconfig option to address a boot
     command line ordering issue.

  The rest is a mixture of code/documentation cleanup"

* tag 'integrity-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  integrity: Fix sparse warnings in keyring_handler
  evm: Clean up some variables
  evm: Return INTEGRITY_PASS for enum integrity_status value '0'
  efi: Do not import certificates from UEFI Secure Boot for T2 Macs
  fsverity: update the documentation
  ima: support fs-verity file digest based version 3 signatures
  ima: permit fsverity's file digests in the IMA measurement list
  ima: define a new template field named 'd-ngv2' and templates
  fs-verity: define a function to return the integrity protected file digest
  ima: use IMA default hash algorithm for integrity violations
  ima: fix 'd-ng' comments and documentation
  ima: remove the IMA_TEMPLATE Kconfig option
  ima: remove redundant initialization of pointer 'file'.
2022-05-24 13:50:39 -07:00
Zhang Jianhua e6af1bb077 fs-verity: Use struct_size() helper in enable_verity()
Follow the best practice for allocating a variable-sized structure.

Signed-off-by: Zhang Jianhua <chris.zjh@huawei.com>
[ebiggers: adjusted commit message]
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20220519022450.2434483-1-chris.zjh@huawei.com
2022-05-19 09:53:33 -07:00
Zhang Jianhua b0487ede1f fs-verity: remove unused parameter desc_size in fsverity_create_info()
The parameter desc_size in fsverity_create_info() is useless and it is
not referenced anywhere. The greatest meaning of desc_size here is to
indecate the size of struct fsverity_descriptor and futher calculate the
size of signature. However, the desc->sig_size can do it also and it is
indeed, so remove it.

Therefore, it is no need to acquire desc_size by fsverity_get_descriptor()
in ensure_verity_info(), so remove the parameter desc_ret in
fsverity_get_descriptor() too.

Signed-off-by: Zhang Jianhua <chris.zjh@huawei.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20220518132256.2297655-1-chris.zjh@huawei.com
2022-05-18 11:01:31 -07:00
Matthew Wilcox (Oracle) 2ebdd1df31 mm/readahead: Convert page_cache_async_readahead to take a folio
Removes a couple of calls to compound_head and saves a few bytes.
Also convert verity's read_file_data_page() to be folio-based.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2022-05-08 14:45:56 -04:00
Mimi Zohar 246d921646 fs-verity: define a function to return the integrity protected file digest
Define a function named fsverity_get_digest() to return the verity file
digest and the associated hash algorithm (enum hash_algo).

This assumes that before calling fsverity_get_digest() the file must have
been opened, which is even true for the IMA measure/appraise on file
open policy rule use case (func=FILE_CHECK).  do_open() calls vfs_open()
immediately prior to ima_file_check().

Acked-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2022-05-01 16:39:36 -04:00
Matthew Wilcox (Oracle) 704528d895 fs: Remove ->readpages address space operation
All filesystems have now been converted to use ->readahead, so
remove the ->readpages operation and fix all the comments that
used to refer to it.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
2022-04-01 13:45:33 -04:00
Eric Biggers 80f6e3080b fs-verity: fix signed integer overflow with i_size near S64_MAX
If the file size is almost S64_MAX, the calculated number of Merkle tree
levels exceeds FS_VERITY_MAX_LEVELS, causing FS_IOC_ENABLE_VERITY to
fail.  This is unintentional, since as the comment above the definition
of FS_VERITY_MAX_LEVELS states, it is enough for over U64_MAX bytes of
data using SHA-256 and 4K blocks.  (Specifically, 4096*128**8 >= 2**64.)

The bug is actually that when the number of blocks in the first level is
calculated from i_size, there is a signed integer overflow due to i_size
being signed.  Fix this by treating i_size as unsigned.

This was found by the new test "generic: test fs-verity EFBIG scenarios"
(https://lkml.kernel.org/r/b1d116cd4d0ea74b9cd86f349c672021e005a75c.1631558495.git.boris@bur.io).

This didn't affect ext4 or f2fs since those have a smaller maximum file
size, but it did affect btrfs which allows files up to S64_MAX bytes.

Reported-by: Boris Burkov <boris@bur.io>
Fixes: 3fda4c617e ("fs-verity: implement FS_IOC_ENABLE_VERITY ioctl")
Fixes: fd2d1acfca ("fs-verity: add the hook for file ->open()")
Cc: <stable@vger.kernel.org> # v5.4+
Reviewed-by: Boris Burkov <boris@bur.io>
Link: https://lore.kernel.org/r/20210916203424.113376-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2021-09-22 10:56:34 -07:00
Ard Biesheuvel e3a606f2c5 fsverity: relax build time dependency on CRYPTO_SHA256
CONFIG_CRYPTO_SHA256 denotes the generic C implementation of the SHA-256
shash algorithm, which is selected as the default crypto shash provider
for fsverity. However, fsverity has no strict link time dependency, and
the same shash could be exposed by an optimized implementation, and arm64
has a number of those (scalar, NEON-based and one based on special crypto
instructions). In such cases, it makes little sense to require that the
generic C implementation is incorporated as well, given that it will never
be called.

To address this, relax the 'select' clause to 'imply' so that the generic
driver can be omitted from the build if desired.

Acked-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2021-04-22 17:31:32 +10:00
Linus Torvalds 7d6beb71da idmapped-mounts-v5.12
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Merge tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

Pull idmapped mounts from Christian Brauner:
 "This introduces idmapped mounts which has been in the making for some
  time. Simply put, different mounts can expose the same file or
  directory with different ownership. This initial implementation comes
  with ports for fat, ext4 and with Christoph's port for xfs with more
  filesystems being actively worked on by independent people and
  maintainers.

  Idmapping mounts handle a wide range of long standing use-cases. Here
  are just a few:

   - Idmapped mounts make it possible to easily share files between
     multiple users or multiple machines especially in complex
     scenarios. For example, idmapped mounts will be used in the
     implementation of portable home directories in
     systemd-homed.service(8) where they allow users to move their home
     directory to an external storage device and use it on multiple
     computers where they are assigned different uids and gids. This
     effectively makes it possible to assign random uids and gids at
     login time.

   - It is possible to share files from the host with unprivileged
     containers without having to change ownership permanently through
     chown(2).

   - It is possible to idmap a container's rootfs and without having to
     mangle every file. For example, Chromebooks use it to share the
     user's Download folder with their unprivileged containers in their
     Linux subsystem.

   - It is possible to share files between containers with
     non-overlapping idmappings.

   - Filesystem that lack a proper concept of ownership such as fat can
     use idmapped mounts to implement discretionary access (DAC)
     permission checking.

   - They allow users to efficiently changing ownership on a per-mount
     basis without having to (recursively) chown(2) all files. In
     contrast to chown (2) changing ownership of large sets of files is
     instantenous with idmapped mounts. This is especially useful when
     ownership of a whole root filesystem of a virtual machine or
     container is changed. With idmapped mounts a single syscall
     mount_setattr syscall will be sufficient to change the ownership of
     all files.

   - Idmapped mounts always take the current ownership into account as
     idmappings specify what a given uid or gid is supposed to be mapped
     to. This contrasts with the chown(2) syscall which cannot by itself
     take the current ownership of the files it changes into account. It
     simply changes the ownership to the specified uid and gid. This is
     especially problematic when recursively chown(2)ing a large set of
     files which is commong with the aforementioned portable home
     directory and container and vm scenario.

   - Idmapped mounts allow to change ownership locally, restricting it
     to specific mounts, and temporarily as the ownership changes only
     apply as long as the mount exists.

  Several userspace projects have either already put up patches and
  pull-requests for this feature or will do so should you decide to pull
  this:

   - systemd: In a wide variety of scenarios but especially right away
     in their implementation of portable home directories.

         https://systemd.io/HOME_DIRECTORY/

   - container runtimes: containerd, runC, LXD:To share data between
     host and unprivileged containers, unprivileged and privileged
     containers, etc. The pull request for idmapped mounts support in
     containerd, the default Kubernetes runtime is already up for quite
     a while now: https://github.com/containerd/containerd/pull/4734

   - The virtio-fs developers and several users have expressed interest
     in using this feature with virtual machines once virtio-fs is
     ported.

   - ChromeOS: Sharing host-directories with unprivileged containers.

  I've tightly synced with all those projects and all of those listed
  here have also expressed their need/desire for this feature on the
  mailing list. For more info on how people use this there's a bunch of
  talks about this too. Here's just two recent ones:

      https://www.cncf.io/wp-content/uploads/2020/12/Rootless-Containers-in-Gitpod.pdf
      https://fosdem.org/2021/schedule/event/containers_idmap/

  This comes with an extensive xfstests suite covering both ext4 and
  xfs:

      https://git.kernel.org/brauner/xfstests-dev/h/idmapped_mounts

  It covers truncation, creation, opening, xattrs, vfscaps, setid
  execution, setgid inheritance and more both with idmapped and
  non-idmapped mounts. It already helped to discover an unrelated xfs
  setgid inheritance bug which has since been fixed in mainline. It will
  be sent for inclusion with the xfstests project should you decide to
  merge this.

  In order to support per-mount idmappings vfsmounts are marked with
  user namespaces. The idmapping of the user namespace will be used to
  map the ids of vfs objects when they are accessed through that mount.
  By default all vfsmounts are marked with the initial user namespace.
  The initial user namespace is used to indicate that a mount is not
  idmapped. All operations behave as before and this is verified in the
  testsuite.

  Based on prior discussions we want to attach the whole user namespace
  and not just a dedicated idmapping struct. This allows us to reuse all
  the helpers that already exist for dealing with idmappings instead of
  introducing a whole new range of helpers. In addition, if we decide in
  the future that we are confident enough to enable unprivileged users
  to setup idmapped mounts the permission checking can take into account
  whether the caller is privileged in the user namespace the mount is
  currently marked with.

  The user namespace the mount will be marked with can be specified by
  passing a file descriptor refering to the user namespace as an
  argument to the new mount_setattr() syscall together with the new
  MOUNT_ATTR_IDMAP flag. The system call follows the openat2() pattern
  of extensibility.

  The following conditions must be met in order to create an idmapped
  mount:

   - The caller must currently have the CAP_SYS_ADMIN capability in the
     user namespace the underlying filesystem has been mounted in.

   - The underlying filesystem must support idmapped mounts.

   - The mount must not already be idmapped. This also implies that the
     idmapping of a mount cannot be altered once it has been idmapped.

   - The mount must be a detached/anonymous mount, i.e. it must have
     been created by calling open_tree() with the OPEN_TREE_CLONE flag
     and it must not already have been visible in the filesystem.

  The last two points guarantee easier semantics for userspace and the
  kernel and make the implementation significantly simpler.

  By default vfsmounts are marked with the initial user namespace and no
  behavioral or performance changes are observed.

  The manpage with a detailed description can be found here:

      1d7b902e28

  In order to support idmapped mounts, filesystems need to be changed
  and mark themselves with the FS_ALLOW_IDMAP flag in fs_flags. The
  patches to convert individual filesystem are not very large or
  complicated overall as can be seen from the included fat, ext4, and
  xfs ports. Patches for other filesystems are actively worked on and
  will be sent out separately. The xfstestsuite can be used to verify
  that port has been done correctly.

  The mount_setattr() syscall is motivated independent of the idmapped
  mounts patches and it's been around since July 2019. One of the most
  valuable features of the new mount api is the ability to perform
  mounts based on file descriptors only.

  Together with the lookup restrictions available in the openat2()
  RESOLVE_* flag namespace which we added in v5.6 this is the first time
  we are close to hardened and race-free (e.g. symlinks) mounting and
  path resolution.

  While userspace has started porting to the new mount api to mount
  proper filesystems and create new bind-mounts it is currently not
  possible to change mount options of an already existing bind mount in
  the new mount api since the mount_setattr() syscall is missing.

  With the addition of the mount_setattr() syscall we remove this last
  restriction and userspace can now fully port to the new mount api,
  covering every use-case the old mount api could. We also add the
  crucial ability to recursively change mount options for a whole mount
  tree, both removing and adding mount options at the same time. This
  syscall has been requested multiple times by various people and
  projects.

  There is a simple tool available at

      https://github.com/brauner/mount-idmapped

  that allows to create idmapped mounts so people can play with this
  patch series. I'll add support for the regular mount binary should you
  decide to pull this in the following weeks:

  Here's an example to a simple idmapped mount of another user's home
  directory:

	u1001@f2-vm:/$ sudo ./mount --idmap both:1000:1001:1 /home/ubuntu/ /mnt

	u1001@f2-vm:/$ ls -al /home/ubuntu/
	total 28
	drwxr-xr-x 2 ubuntu ubuntu 4096 Oct 28 22:07 .
	drwxr-xr-x 4 root   root   4096 Oct 28 04:00 ..
	-rw------- 1 ubuntu ubuntu 3154 Oct 28 22:12 .bash_history
	-rw-r--r-- 1 ubuntu ubuntu  220 Feb 25  2020 .bash_logout
	-rw-r--r-- 1 ubuntu ubuntu 3771 Feb 25  2020 .bashrc
	-rw-r--r-- 1 ubuntu ubuntu  807 Feb 25  2020 .profile
	-rw-r--r-- 1 ubuntu ubuntu    0 Oct 16 16:11 .sudo_as_admin_successful
	-rw------- 1 ubuntu ubuntu 1144 Oct 28 00:43 .viminfo

	u1001@f2-vm:/$ ls -al /mnt/
	total 28
	drwxr-xr-x  2 u1001 u1001 4096 Oct 28 22:07 .
	drwxr-xr-x 29 root  root  4096 Oct 28 22:01 ..
	-rw-------  1 u1001 u1001 3154 Oct 28 22:12 .bash_history
	-rw-r--r--  1 u1001 u1001  220 Feb 25  2020 .bash_logout
	-rw-r--r--  1 u1001 u1001 3771 Feb 25  2020 .bashrc
	-rw-r--r--  1 u1001 u1001  807 Feb 25  2020 .profile
	-rw-r--r--  1 u1001 u1001    0 Oct 16 16:11 .sudo_as_admin_successful
	-rw-------  1 u1001 u1001 1144 Oct 28 00:43 .viminfo

	u1001@f2-vm:/$ touch /mnt/my-file

	u1001@f2-vm:/$ setfacl -m u:1001:rwx /mnt/my-file

	u1001@f2-vm:/$ sudo setcap -n 1001 cap_net_raw+ep /mnt/my-file

	u1001@f2-vm:/$ ls -al /mnt/my-file
	-rw-rwxr--+ 1 u1001 u1001 0 Oct 28 22:14 /mnt/my-file

	u1001@f2-vm:/$ ls -al /home/ubuntu/my-file
	-rw-rwxr--+ 1 ubuntu ubuntu 0 Oct 28 22:14 /home/ubuntu/my-file

	u1001@f2-vm:/$ getfacl /mnt/my-file
	getfacl: Removing leading '/' from absolute path names
	# file: mnt/my-file
	# owner: u1001
	# group: u1001
	user::rw-
	user:u1001:rwx
	group::rw-
	mask::rwx
	other::r--

	u1001@f2-vm:/$ getfacl /home/ubuntu/my-file
	getfacl: Removing leading '/' from absolute path names
	# file: home/ubuntu/my-file
	# owner: ubuntu
	# group: ubuntu
	user::rw-
	user:ubuntu:rwx
	group::rw-
	mask::rwx
	other::r--"

* tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: (41 commits)
  xfs: remove the possibly unused mp variable in xfs_file_compat_ioctl
  xfs: support idmapped mounts
  ext4: support idmapped mounts
  fat: handle idmapped mounts
  tests: add mount_setattr() selftests
  fs: introduce MOUNT_ATTR_IDMAP
  fs: add mount_setattr()
  fs: add attr_flags_to_mnt_flags helper
  fs: split out functions to hold writers
  namespace: only take read lock in do_reconfigure_mnt()
  mount: make {lock,unlock}_mount_hash() static
  namespace: take lock_mount_hash() directly when changing flags
  nfs: do not export idmapped mounts
  overlayfs: do not mount on top of idmapped mounts
  ecryptfs: do not mount on top of idmapped mounts
  ima: handle idmapped mounts
  apparmor: handle idmapped mounts
  fs: make helpers idmap mount aware
  exec: handle idmapped mounts
  would_dump: handle idmapped mounts
  ...
2021-02-23 13:39:45 -08:00
Eric Biggers 07c9900131 fs-verity: support reading signature with ioctl
Add support for FS_VERITY_METADATA_TYPE_SIGNATURE to
FS_IOC_READ_VERITY_METADATA.  This allows a userspace server program to
retrieve the built-in signature (if present) of a verity file for
serving to a client which implements fs-verity compatible verification.
See the patch which introduced FS_IOC_READ_VERITY_METADATA for more
details.

The ability for userspace to read the built-in signatures is also useful
because it allows a system that is using the in-kernel signature
verification to migrate to userspace signature verification.

This has been tested using a new xfstest which calls this ioctl via a
new subcommand for the 'fsverity' program from fsverity-utils.

Link: https://lore.kernel.org/r/20210115181819.34732-7-ebiggers@kernel.org
Reviewed-by: Victor Hsieh <victorhsieh@google.com>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
2021-02-07 14:51:19 -08:00
Eric Biggers 947191ac8c fs-verity: support reading descriptor with ioctl
Add support for FS_VERITY_METADATA_TYPE_DESCRIPTOR to
FS_IOC_READ_VERITY_METADATA.  This allows a userspace server program to
retrieve the fs-verity descriptor of a file for serving to a client
which implements fs-verity compatible verification.  See the patch which
introduced FS_IOC_READ_VERITY_METADATA for more details.

"fs-verity descriptor" here means only the part that userspace cares
about because it is hashed to produce the file digest.  It doesn't
include the signature which ext4 and f2fs append to the
fsverity_descriptor struct when storing it on-disk, since that way of
storing the signature is an implementation detail.  The next patch adds
a separate metadata_type value for retrieving the signature separately.

This has been tested using a new xfstest which calls this ioctl via a
new subcommand for the 'fsverity' program from fsverity-utils.

Link: https://lore.kernel.org/r/20210115181819.34732-6-ebiggers@kernel.org
Reviewed-by: Victor Hsieh <victorhsieh@google.com>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
2021-02-07 14:51:17 -08:00
Eric Biggers 622699cfe6 fs-verity: support reading Merkle tree with ioctl
Add support for FS_VERITY_METADATA_TYPE_MERKLE_TREE to
FS_IOC_READ_VERITY_METADATA.  This allows a userspace server program to
retrieve the Merkle tree of a verity file for serving to a client which
implements fs-verity compatible verification.  See the patch which
introduced FS_IOC_READ_VERITY_METADATA for more details.

This has been tested using a new xfstest which calls this ioctl via a
new subcommand for the 'fsverity' program from fsverity-utils.

Link: https://lore.kernel.org/r/20210115181819.34732-5-ebiggers@kernel.org
Reviewed-by: Victor Hsieh <victorhsieh@google.com>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
2021-02-07 14:51:14 -08:00