lib: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by: Netflix

Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

pam_exec: fix segfault when authtok is null

According to pam_exec(8), the `expose_authtok` option should be ignored
when the service function is `pam_sm_setcred`. Currently `pam_exec` only
prevent prompt for anth token when `expose_authtok` is set on
`pam_sm_setcred`. This subsequently led to segfault when there isn't an
existing auth token available.

Bug reported on this: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=263893

After reading https://reviews.freebsd.org/rS349556 I am not sure if the
default behaviour supposed to be simply not prompt for authentication
token, or is it to ignore the option entirely as stated in the man page.

This patch is therefore only adding an additional NULL check on the item
`pam_get_item` provide, and exit with `PAM_SYSTEM_ERR` when such item is
NULL.

MFC after: 1 week
Reviewed by: des, khng
Differential Revision: https://reviews.freebsd.org/D35169

Apply tentative fix for clang 11 warning in pam_exec(8):

lib/libpam/modules/pam_exec/pam_exec.c:222:56: error: format specifies type 'char *' but the argument has type 'const void *' [-Werror,-Wformat]
if (asprintf(&envstr, "%s=%s", pam_item_env[i].name, item) < 0)
~~ ^~~~

Changes to the expose_password functionality:

- Implement use_first_pass, allowing expose_password to be used by other
service functions than pam_auth() without prompting a second time.

- Don't prompt for a password during pam_setcred().

PR: 238041
MFC after: 3 weeks

For full Linux-PAM compatibility, add a trailing NUL character when
passing the authentication token to the external program.

Approved by: re (kib)
Submitted by: Thomas Munro <munro@ip9.org>
MFC after: 1 week
Differential Revision: D16950

Add support for Linux-PAM's badly named expose_authtok option.

Submitted by: Thomas Munro <munro@ip9.org>
MFC after: 1 week
Differential Revision: D16171

lib: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using mis-identified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Add options to capture stdout and / or stderr and pass the output on
to the user. There is currently no buffering, so the result may be
somewhat unpredictable if the conversation function adds a newline,
like openpam_ttyconv() does.

Clean up and simplify the environment handling code, which triggered
an inexplicable bug on some systems.

MFC after: 2 weeks

Revert r314780
libpam: extra bounds checking through reallocarray(3).

It appears to be causing brokenness when reporting PAM_* environment
variables. This requires more investigation.

Reported by: lstewart

libpam: extra bounds checking through reallocarray(3).

Reviewed by: des
MFC after: 1 week

Revert r314777: wrong log, the change was to libpam.

libfetch: extra bounds checking through reallocarray(3).

Reviewed by: des
MFC after: 1 week

Fix error messages containing the executed command name

Before, we took the first argument to pam_exec(8). With the addition of
options in front of the command, this could be wrong.

Now, options are parsed before calling _pam_exec() and messages contain
the proper command name.

While here, fix a warning.

Sponsored by: Yakaz (http://www.yakaz.com)

Use program exit status as pam_exec return code (optional)

pam_exec(8) now accepts a new option "return_prog_exit_status". When
set, the program exit status is used as the pam_exec return code. It
allows the program to tell why the step failed (eg. user unknown).
However, if it exits with a code not allowed by the calling PAM service
module function (see $PAM_SM_FUNC below), a warning is logged and
PAM_SERVICE_ERR is returned.

The following changes are related to this new feature but they apply no
matter if the "return_prog_exit_status" option is set or not.

The environment passed to the program is extended:
o $PAM_SM_FUNC contains the name of the PAM service module function
(eg. pam_sm_authenticate).
o All valid PAM return codes' numerical values are available
through variables named after the return code name. For instance,
$PAM_SUCCESS, $PAM_USER_UNKNOWN or $PAM_PERM_DENIED.

pam_exec return code better reflects what went on:
o If the program exits with !0, the return code is now
PAM_PERM_DENIED, not PAM_SYSTEM_ERR.
o If the program fails because of a signal (WIFSIGNALED) or doesn't
terminate normally (!WIFEXITED), the return code is now
PAM_SERVICE_ERR, not PAM_SYSTEM_ERR.
o If a syscall in pam_exec fails, the return code remains
PAM_SYSTEM_ERR.

waitpid(2) is called in a loop. If it returns because of EINTR, do it
again. Before, it would return PAM_SYSTEM_ERR without waiting for the
child to exit.

Several log messages now include the PAM service module function name.

The man page is updated accordingly.

Reviewed by: gleb@, des@
Sponsored by: Yakaz (http://www.yakaz.com)
MFC after: 2 weeks

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

Create the altix project branch. The altix project will add support
for the SGI Altix 350 to FreeBSD/ia64. The hardware used for porting
is a two-module system, consisting of a base compute module and a
CPU expansion module. SGI's NUMAFlex architecture can be an excellent
platform to test CPU affinity and NUMA-aware features in FreeBSD.

Include <stdio.h> for asprintf().

Submitted by: Pawel Worach

- Import the HEAD csup code which is the basis for the cvsmode work.

childerr needs to be volatile so gcc won't optimize it away.

PR: bin/85830
MFC after: 1 week

When (re)allocating space for an array of pointers to char, use
sizeof(*list), not sizeof(**list). (i.e., sizeof(pointer) rather than
sizeof(char)).

It is possible that this buffer overflow is exploitable, but it was
added after RELENG_5 forked and hasn't been MFCed, so this will not
receive an advisory.

Submitted by: Vitezslav Novy
MFC after: 1 day

In addition to the PAM environment, export a handful of useful PAM items.

Suggested by: Ed Maste <emaste@phaedrus.sandvine.ca>

Update copyright.

Export the PAM environment to the child process instead of the "normal"
environment list, which may be unsafe and / or sensitive.

Sponsored by: DARPA, NAI Labs

Just to show that PAM can do almost anything from the ridiculous to the
obscene, or - as they say in New York - sophisticated, add pam_echo(8) and
pam_exec(8) to our ever-lengthening roster of PAM modules.

Sponsored by: DARPA, NAI Labs.