### Background
Various admin operations will be invoked by some userspace task, but the
work will be done on a separate kernel thread at a later time. Snapshots
are an example, which are triggered through zfs_ioc_snapshot() ->
dsl_dataset_snapshot(), but the actual work is from a task dispatched to
dp_sync_taskq.
Many such tasks end up in dsl_enforce_ds_ss_limits(), where various
limits and permissions are enforced. Among other things, it is necessary
to ensure that the invoking task (that is, the user) has permission to
do things. We can't simply check if the running task has permission; it
is a privileged kernel thread, which can do anything.
However, in the general case it's not safe to simply query the task for
its permissions at the check time, as the task may not exist any more,
or its permissions may have changed since it was first invoked. So
instead, we capture the permissions by saving CRED() in the user task,
and then using it for the check through the secpolicy_* functions.
### Current implementation
The current code calls CRED() to get the credential, which gets a
pointer to the cred_t inside the current task and passes it to the
worker task. However, it doesn't take a reference to the cred_t, and so
expects that it won't change, and that the task continues to exist. In
practice that is always the case, because we don't let the calling task
return from the kernel until the work is done.
For Linux, we also take a reference to the current task, because the
Linux credential APIs for the most part do not check an arbitrary
credential, but rather, query what a task can do. See
secpolicy_zfs_proc(). Again, we don't take a reference on the task, just
a pointer to it.
### Changes
We change to calling crhold() on the task credential, and crfree() when
we're done with it. This ensures it stays alive and unchanged for the
duration of the call.
On the Linux side, we change the main policy checking function
priv_policy_ns() to use override_creds()/revert_creds() if necessary to
make the provided credential active in the current task, allowing the
standard task-permission APIs to do the needed check. Since the task
pointer is no longer required, this lets us entirely remove
secpolicy_zfs_proc() and the need to carry a task pointer around as
well.
Sponsored-by: https://despairlabs.com/sponsor/
Signed-off-by: Rob Norris <robn@despairlabs.com>
Reviewed-by: Pavel Snajdr <snajpa@snajpa.net>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Kyle Evans <kevans@FreeBSD.org>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Sponsored-by: https://despairlabs.com/sponsor/
Signed-off-by: Rob Norris <robn@despairlabs.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
This includes the last 12.x release (now EOL) and 13.0 development
versions (<1300139).
Sponsored-by: https://despairlabs.com/sponsor/
Signed-off-by: Rob Norris <robn@despairlabs.com>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
With FreeBSD's switch to git the $FreeBSD$ string is no longer expanded
and they have mostly been removed upstream. Stop using __FBSDID and
remove the no-longer needed sys/cdefs.h includes.
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Brooks Davis <brooks.davis@sri.com>
Closes#15527
The zfs_fsync, zfs_read, and zfs_write function are almost identical
between Linux and FreeBSD. With a little refactoring they can be
moved to the common code which is what is done by this commit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes#11078
This is a step toward being able to vendor the OpenZFS code in FreeBSD.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes#10625
The filesystem_limit and snapshot_limit properties limit the number of
filesystems or snapshots that can be created below this dataset.
According to the manpage, "The limit is not enforced if the user is
allowed to change the limit." Two types of users are allowed to change
the limit:
1. Those that have been delegated the `filesystem_limit` or
`snapshot_limit` permission, e.g. with
`zfs allow USER filesystem_limit DATASET`. This works properly.
2. A user with elevated system privileges (e.g. root). This does not
work - the root user will incorrectly get an error when trying to create
a snapshot/filesystem, if it exceeds the `_limit` property.
The problem is that `priv_policy_ns()` does not work if the `cred_t` is
not that of the current process. This happens when
`dsl_enforce_ds_ss_limits()` is called in syncing context (as part of a
sync task's check func) to determine the permissions of the
corresponding user process.
This commit fixes the issue by passing the `task_struct` (typedef'ed as
a `proc_t`) to syncing context, and then using `has_capability()` to
determine if that process is privileged. Note that we still need to
pass the `cred_t` to syncing context so that we can check if the user
was delegated this permission with `zfs allow`.
This problem only impacts Linux. Wrappers are added to FreeBSD but it
continues to use `priv_check_cred()`, which works on arbitrary `cred_t`.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes#8226Closes#10545
Add the FreeBSD platform code to the OpenZFS repository. As of this
commit the source can be compiled and tested on FreeBSD 11 and 12.
Subsequent commits are now required to compile on FreeBSD and Linux.
Additionally, they must pass the ZFS Test Suite on FreeBSD which is
being run by the CI. As of this commit 1230 tests pass on FreeBSD
and there are no unexpected failures.
Reviewed-by: Sean Eric Fagan <sef@ixsystems.com>
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes#898Closes#8987
