Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

make path matching in devfs rules consistent and sane (and safer)

Before this change path matching had the following features:
- for device nodes the patterns were matched against full path
- in the above case '/' in a path could be matched by a wildcard
- for directories and links only the last component was matched

So, for example, a pattern like 're*' could match the following entries:
- re0 device
- responder/u0 device
- zvol/recpool directory

Although it was possible to work around this behavior (once it was spotted
and understood), it was very confusing and contrary to documentation.

Now we always match a full path for all types of devfs entries (devices,
directories, links) and a '/' has to be matched explicitly.
This behavior follows the shell globbing rules.

This change is originally developed by Jaakko Heinonen.
Many thanks!

PR: kern/122838
Submitted by: jh
MFC after: 4 weeks

Introduce the "ruleset=number" option for devfs(5) mounts.
Add support for updating the devfs mount (currently only changing the
ruleset number is supported).
Check mnt_optnew with vfs_filteropt(9).

This new option sets the specified ruleset number as the active ruleset
of the new devfs mount and applies all its rules at mount time. If the
specified ruleset doesn't exist, a new empty ruleset is created.

MFC after: 1 month

- fix duplicate "a a" in some comments

Submitted by: eadler
Approved by: simon
MFC after: 3 days

- Assert that dm_lock is exclusively held in devfs_rules_apply() and
in devfs_vmkdir() while adding the entry to de_list of the parent.
- Apply devfs rules to newly created directories and symbolic links.

PR: kern/125034
Submitted by: Mateusz Guzik (original version)

Handle the special ruleset 0 in devfs_ruleset_use(). An attempt set the
current ruleset to 0 with command "devfs ruleset 0" triggered a KASSERT
in devfs_ruleset_create().

PR: kern/125030
Submitted by: Mateusz Guzik

Add new make_dev_p(9) flag MAKEDEV_ETERNAL to inform devfs that created
cdev will never be destroyed. Propagate the flag to devfs vnodes as
VV_ETERNVALDEV. Use the flags to avoid acquiring devmtx and taking a
thread reference on such nodes.

In collaboration with: pho
MFC after: 1 month

Get pointer to devfs_ruleset struct after garbage collection has been
performed. Otherwise if ruleset is used by given mountpoint and is empty
it's freed by devfs_ruleset_reap and pointer becomes bogus.

Submitted by: Mateusz Guzik <mjguzik@gmail.com>
PR: kern/124853

Do not dereference cdev->si_cdevsw, use the dev_refthread() to properly
obtain the reference. In particular, this fixes the panic reported in
the PR. Remove the comments stating that this needs to be done.

PR: kern/119422
MFC after: 1 week

Sweep kernel replacing suser(9) calls with priv(9) calls, assigning
specific privilege names to a broad range of privileges. These may
require some future tweaking.

Sponsored by: nCircle Network Security, Inc.
Obtained from: TrustedBSD Project
Discussed on: arch@
Reviewed (at least in part) by: mlaier, jmg, pjd, bde, ceri,
Alex Lyashkov <umka at sevcity dot net>,
Skip Ford <skip dot ford at verizon dot net>,
Antoine Brodin <antoine dot brodin at laposte dot net>

Remove the NDEVFSINO and NDEVFSOVERFLOW options which no longer exists in
DEVFS.

Remove the opt_devfs.h file now that it is empty.

When returning EIO from DEVFSIO_RADD ioctl, drop the exclusive rule
lock. Otherwise the system comes to a rather sudden and grinding
halt.

MFC after: 1 week

Make rule zero really magical, that way we don't have to do anything
when we mount and get zero cost if no rules are used in a mountpoint.

Add code to deref rules on unmount.

Switch from SLIST to TAILQ.

Drop SYSINIT, use SX_SYSINIT and static initializer of TAILQ instead.

Drop goto, a break will do.

Reduce double pointers to single pointers.

Combine reaping and destroying rulesets.

Avoid memory leaks in a some error cases.

Rewamp DEVFS internals pretty severely [1].

Give DEVFS a proper inode called struct cdev_priv. It is important
to keep in mind that this "inode" is shared between all DEVFS
mountpoints, therefore it is protected by the global device mutex.

Link the cdev_priv's into a list, protected by the global device
mutex. Keep track of each cdev_priv's state with a flag bit and
of references from mountpoints with a dedicated usecount.

Reap the benefits of much improved kernel memory allocator and the
generally better defined device driver APIs to get rid of the tables
of pointers + serial numbers, their overflow tables, the atomics
to muck about in them and all the trouble that resulted in.

This makes RAM the only limit on how many devices we can have.

The cdev_priv is actually a super struct containing the normal cdev
as the "public" part, and therefore allocation and freeing has moved
to devfs_devs.c from kern_conf.c.

The overall responsibility is (to be) split such that kern/kern_conf.c
is the stuff that deals with drivers and struct cdev and fs/devfs
handles filesystems and struct cdev_priv and their private liason
exposed only in devfs_int.h.

Move the inode number from cdev to cdev_priv and allocate inode
numbers properly with unr. Local dirents in the mountpoints
(directories, symlinks) allocate inodes from the same pool to
guarantee against overlaps.

Various other fields are going to migrate from cdev to cdev_priv
in the future in order to hide them. A few fields may migrate
from devfs_dirent to cdev_priv as well.

Protect the DEVFS mountpoint with an sx lock instead of lockmgr,
this lock also protects the directory tree of the mountpoint.

Give each mountpoint a unique integer index, allocated with unr.
Use it into an array of devfs_dirent pointers in each cdev_priv.
Initially the array points to a single element also inside cdev_priv,
but as more devfs instances are mounted, the array is extended with
malloc(9) as necessary when the filesystem populates its directory
tree.

Retire the cdev alias lists, the cdev_priv now know about all the
relevant devfs_dirents (and their vnodes) and devfs_revoke() will
pick them up from there. We still spelunk into other mountpoints
and fondle their data without 100% good locking. It may make better
sense to vector the revoke event into the tty code and there do a
destroy_dev/make_dev on the tty's devices, but that's for further
study.

Lots of shuffling of stuff and churn of bits for no good reason[2].

XXX: There is still nothing preventing the dev_clone EVENTHANDLER
from being invoked at the same time in two devfs mountpoints. It
is not obvious what the best course of action is here.

XXX: comment out an if statement that lost its body, until I can
find out what should go there so it doesn't do damage in the meantime.

XXX: Leave in a few extra malloc types and KASSERTS to help track
down any remaining issues.

Much testing provided by: Kris
Much confusion caused by (races in): md(4)

[1] You are not supposed to understand anything past this point.

[2] This line should simplify life for the peanut gallery.

Protect the devfs rule internal global lists with a sx lock, the per
mount locks are not enough. Finer granularity (x)locking could be
implemented, but I prefer to keep it simple for now.

Absolve devfs_rule.c from locking responsibility and call it with
all necessary locking held.

Close a race which could result in unwarranted "ruleset %d already
running" panics.

Previously, recursion through the "include" feature was prevented by
marking each ruleset as "running" when applied. This doesn't work for
the case where two DEVFS instances try to apply the same ruleset at
the same time.

Instead introduce the sysctl vfs.devfs.rule_depth (default == 1) which
limits how many levels of "include" we will traverse.

Be aware that traversal of "include" is recursive and kernel stack
size is limited.

MFC: after 3 days

Eliminate effectively unused dm_basedir field from devfs_mount.

Remove kernelside support for devfs rules filtering on major numbers.

XXX mark two places where we do not hold a threadcount on the dev when
frobbing the cdevsw.

In both cases we examine only the cdevsw and it is a good question if we
weren't better off copying those properties into the cdev in the first
place. This question will be revisited.

Do the dreaded s/dev_t/struct cdev */
Bump __FreeBSD_version accordingly.

White-space align a struct definition.
Move a SYSINIT to the file where it belongs.

Fix style(9) of my previous commit.

Noticed by: nate
Approved by: nate, rwatson (mentor)

Allow devfs path rules to work on directories. Without this fix,
devfs rule add path fd unhide
is a no-op, while it should unhide the fd subdirectory.

Approved by: phk, rwatson (mentor)
PR: kern/60897

Back out M_* changes, per decision of the TRB.

Approved by: trb

NODEVFS cleanup: remove #ifdefs.

Remove M_TRYWAIT/M_WAITOK/M_WAIT. Callers should use 0.
Merge M_NOWAIT/M_DONTWAIT into a single flag M_NOWAIT.

Add symlink support to devfs_rule_matchpath(). This allows the user
to unhide symlinks as well as hide them.

Fix comments and one resulting code confusion about the type of the
"command" argument to VOP_IOCTL.

Spotted by: FlexeLint.

Treat the pathptrn field as a real pattern with the aid of fnmatch().

Unimplement panic(8) by making sure that we don't recurse into a
ruleset. If we do, that means there's a ruleset loop (10 includes 20
include 30 includes 10), which will quickly cause a double fault due
to stack overflow (since "include" is implemented by recursion).
(Previously, we only checked that X didn't include X.)

Introduce the DEVFS "rule" subsystem. DEVFS rules permit the
administrator to define certain properties of new devfs nodes before
they become visible to the userland. Both static (e.g., /dev/speaker)
and dynamic (e.g., /dev/bpf*, some removable devices) nodes are
supported. Each DEVFS mount may have a different ruleset assigned to
it, permitting different policies to be implemented for things like
jails.

Approved by: phk