MFC r298565:

Add a new jail OSD method, PR_METHOD_REMOVE. It's called when a jail is
removed from the user perspective, i.e. when the last pr_uref goes away,
even though the jail mail still exist in the dying state. It will also
be called if either PR_METHOD_CREATE or PR_METHOD_SET fail.

MFC r298683:

Delay removing the last jail reference in prison_proc_free, and instead
put it off into the pr_task. This is similar to prison_free, and in fact
uses the same task even though they do something slightly different.

MFC r298566:

Pass the current/new jail to PR_METHOD_CHECK, which pushes the call
until after the jail is found or created. This requires unlocking the
jail for the call and re-locking it afterward, but that works because
nothing in the jail has been changed yet, and other processes won't
change the important fields as long as allprison_lock remains held.

Keep better track of name vs namelc in kern_jail_set. Name should
always be the hierarchical name (relative to the caller), and namelc
the last component.

MFC r298668:

Use crcopysafe in jail_attach.

PR: 48471

MFC r298564:

Remove the PR_REMOVE flag, which was meant as a temporary marker for
a jail that might be seen mid-removal. It hasn't been doing the right
thing since at least the ability to resurrect dying jails, and such
resurrection also makes it unnecessary.

MFH: 285685
Add support to the jail framework to be able to mount linsysfs(5) and linprocfs(5).

PR: 207179
Requested by: thomas@gibfest.dk
Reviewed by: jamie, bapt
Approved by: re (gjb)
Sponsored by: gandi.net
Differential Revision: https://reviews.freebsd.org/D5390

MFC r279361, r279395, r279396:

Allow the kern.osrelease and kern.osreldate sysctl values to be set in a
jail's creation parameters. This allows the kernel version to be reliably
spoofed within the jail whether examined directly with sysctl or
indirectly with the uname -r and -K options.

Export the new osreldate and osrelease jail parms in jail_get(2).

Fix line wrap.

MFC r277855:

Add allow.mount.fdescfs jail flag.

PR: 192951
Submitted by: ruben@verweg.com

MFC r279361, r279395, r279396:

Allow the kern.osrelease and kern.osreldate sysctl values to be set in a
jail's creation parameters. This allows the kernel version to be reliably
spoofed within the jail whether examined directly with sysctl or
indirectly with the uname -r and -K options.

Export the new osreldate and osrelease jail parms in jail_get(2).

Fix line wrap.

MFC r277855:

Add allow.mount.fdescfs jail flag.

PR: 192951
Submitted by: ruben@verweg.com