tarfs: Inherit mnt_iosize_max from the lower vnode

There is no obvious reason to use a value smaller than that.

Reviewed by: des, kib
MFC after: 1 week
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D44627

tarfs: Fix 32-bit build.

MFC after: 3 days
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: bapt
Differential Revision: https://reviews.freebsd.org/D44613

tarfs: Ignore global extended headers.

Previously, we would error out if we encountered a global extended
header, because we don't know what it means. This doesn't really
matter though, and traditionally, tar implementations have either
ignored them or treated them as plain files, so just ignore them.
This allows tarfs to mount tar files created by `git archive`.

MFC after: 3 days
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: kevans
Differential Revision: https://reviews.freebsd.org/D44600

tarfs: Support paths that spill into exthdrs.

MFC after: 3 days
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: kevans
Differential Revision: https://reviews.freebsd.org/D44599

tarfs: Fix checksum on 32-bit platforms.

MFC after: 3 days
Fixes: b56872332e47786afc09515a4daaf1388da4d73c
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: bapt
Differential Revision: https://reviews.freebsd.org/D44261

tarfs: Fix checksum calculation.

The checksum code assumed that struct ustar_header filled an entire
block and calculcated the checksum based on the size of the structure.
The header is in fact only 500 bytes long while the checksum covers
the entire block (“logical record” in POSIX terms). Add padding and
an assertion, and clean up the checksum code.

MFC after: 3 days
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: imp
Differential Revision: https://reviews.freebsd.org/D44226

tarfs: Remove unnecessary hack and obsolete comment.

MFC after: 3 days
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: allanjude
Differential Revision: https://reviews.freebsd.org/D44203

tarfs: Avoid overflow in exthdr calculation.

MFC after: 3 days
PR: 277420
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D44202

tarfs: Improve validation of numeric fields.

MFC after: 3 days
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: sjg, allanjude
Differential Revision: https://reviews.freebsd.org/D44166

tarfs: Fix two input validation issues.

* Reject hard or soft links with an empty target path. Currently, a
debugging kernel will hit an assertion in tarfs_lookup_path() while
a non-debugging kernel will happily create a link to the mount root.

* Use a temporary variable to store the result of the link target path,
and copy it to tnp->other only once we have found it to be valid.
Otherwise we error out after creating a reference to the target but
before incrementing the target's reference count, which results in a
use-after-free situation in the cleanup code.

* Correctly return ENOENT from tarfs_lookup_path() if the requested
path was not found and create_dirs is false. Luckily, existing
callers did not rely solely on the return value.

MFC after: 3 days
PR: 277360
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: sjg
Differential Revision: https://reviews.freebsd.org/D44161

tarfs_mount allow control of vfs_mountedfrom

We default to passing the path of the tar file to vfs_mountedfrom
so we can tell where a filesystem was mounted from.
However this can make the output of mount(8) hard to read.

Allow things like:

mount -t tarfs -o as=`basename $tar` $tar /mnt

so "as" is recorded instead of $tar

Reviewed by: des
Sponsored by: Juniper Networks
Differential Revision: https://reviews.freebsd.org/D39273

tarfs: Fix backtracking during node creation.

Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D39082

tarfs: Support tar files which include file modes with permissions.

Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D39020

tarfs: Correctly track link count.

Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D39019

tarfs: Set mountedfrom correctly.

Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: sjg, kib
Differential Revision: https://reviews.freebsd.org/D38930

tarfs: Really prevent descending into a non-directory.

The previous fix was incorrect: we need to verify that the current node, if it exists, is not a directory, but we were checking the parent node instead. Address this, add more tests, and fix the test cleanup routines.

PR: 269519, 269561
Fixes: ae6cff89738b
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D38645

tarfs: Don't panic if the parent of a new node is not a directory.

PR: 269519
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D38587

tarfs: Fix issues revealed by static analysis and testing.

* tarfs_alloc_mount(): Remove an unnecessary null check (CID 1504505) and an unused variable.

* tarfs_alloc_one(): Verify that the file size is not negative (CID 1504506). While there, also validate the mode, owner and group.

* tarfs_vget(), tarfs_zio_init(): Explicitly ignore return value from getnewvnode(), which cannot fail (CID 1504508)

* tarfs_lookup_path(): Fix a case where a specially-crafted tarball could trigger a null pointer dereference by first descending into, and then backing out of, a previously unknown directory. (CID 1504515)

* mktar: Construct a tarball that triggers the aforementioned null pointer dereference.

Reported by: Coverity
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: imp, kib
Differential Revision: https://reviews.freebsd.org/D38463

tarfs: Fix 32-bit build.

Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.

Add tarfs, a filesystem backed by tarballs.

Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Reviewed by: pauamma, imp
Differential Revision: https://reviews.freebsd.org/D37753