Integrate capsicum-test into the FreeBSD test suite

This change takes capsicum-test from upstream and applies some local changes to make the
tests work on FreeBSD when executed via Kyua.

The local modifications are as follows:
1. Make `OpenatTest.WithFlag` pass with the new dot-dot lookup behavior in FreeBSD 12.x+.
2. capsicum-test references a set of helper binaries: `mini-me`, `mini-me.noexec`, and
   `mini-me.setuid`, as part of the execve/fexecve tests, via execve, fexecve, and open.
   It achieves this upstream by assuming `mini-me*` is in the current directory, however,
   in order for Kyua to execute `capsicum-test`, it needs to provide a full path to
   `mini-me*`. In order to achieve this, I made `capsicum-test` cache the executable's
   path from argv[0] in main(..) and use the cached value to compute the path to
   `mini-me*` as part of the execve/fexecve testcases.
3. The capsicum-test test suite assumes that it's always being run on CAPABILITIES enabled
   kernels. However, there's a chance that the test will be run on a host without a
   CAPABILITIES enabled kernel, so we must check for the support before running the tests.
   The way to achieve this is to add the relevant `feature_present("security_capabilities")`
   check to SetupEnvironment::SetUp() and skip the tests when the support is not available.
   While here, add a check for `kern.trap_enotcap` being enabled. As noted by markj@ in
   https://github.com/google/capsicum-test/issues/23, this sysctl being enabled can trigger
   non-deterministic failures. Therefore, the tests should be skipped if this sysctl is
   enabled.

All local changes have been submitted to the capsicum-test project
(https://github.com/google/capsicum-test) and are in various stages of review.
Please see the following pull requests for more details:
1. https://github.com/google/capsicum-test/pull/35
2. https://github.com/google/capsicum-test/pull/41
3. https://github.com/google/capsicum-test/pull/42

Reviewed by:	asomers
Discussed with:	emaste, markj
Approved by:	emaste (mentor)
MFC after:	2 months
Differential Revision: https://reviews.freebsd.org/D19758

1 files changed, 73 insertions, 0 deletions

diff --git a/contrib/capsicum-test/capsicum-freebsd.h b/contrib/capsicum-test/capsicum-freebsd.h
new file mode 100644
index 000000000000..96ceb9b6d5f1
--- /dev/null
+++ b/contrib/capsicum-test/capsicum-freebsd.h
@@ -0,0 +1,73 @@
+#ifndef __CAPSICUM_FREEBSD_H__
+#define __CAPSICUM_FREEBSD_H__
+#ifdef __FreeBSD__
+/************************************************************
+ * FreeBSD Capsicum Functionality.
+ ************************************************************/
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* FreeBSD definitions. */
+#include <errno.h>
+#include <sys/param.h>
+#if __FreeBSD_version >= 1100014 || \
+    (__FreeBSD_version >= 1001511 && __FreeBSD_version < 1100000)
+#include <sys/capsicum.h>
+#else
+#include <sys/capability.h>
+#endif
+#include <sys/procdesc.h>
+
+#if __FreeBSD_version >= 1000000
+#define AT_SYSCALLS_IN_CAPMODE
+#define HAVE_CAP_RIGHTS_GET
+#define HAVE_CAP_RIGHTS_LIMIT
+#define HAVE_PROCDESC_FSTAT
+#define HAVE_CAP_FCNTLS_LIMIT
+// fcntl(2) takes int, cap_fcntls_limit(2) takes uint32_t.
+typedef uint32_t cap_fcntl_t;
+#define HAVE_CAP_IOCTLS_LIMIT
+// ioctl(2) and cap_ioctls_limit(2) take unsigned long.
+typedef unsigned long cap_ioctl_t;
+
+#if __FreeBSD_version >= 1101000
+#define HAVE_OPENAT_INTERMEDIATE_DOTDOT
+#endif
+
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+// Use fexecve_() in tests to allow Linux variant to bypass glibc version.
+#define fexecve_(F, A, E) fexecve(F, A, E)
+
+#ifdef ENOTBENEATH
+#define E_NO_TRAVERSE_CAPABILITY ENOTBENEATH
+#define E_NO_TRAVERSE_O_BENEATH ENOTBENEATH
+#else
+#define E_NO_TRAVERSE_CAPABILITY ENOTCAPABLE
+#define E_NO_TRAVERSE_O_BENEATH ENOTCAPABLE
+#endif
+
+// FreeBSD limits the number of ioctls in cap_ioctls_limit to 256
+#define CAP_IOCTLS_LIMIT_MAX 256
+
+// Too many links
+#define E_TOO_MANY_LINKS EMLINK
+
+// TODO(FreeBSD): uncomment if/when FreeBSD propagates rights on accept.
+// FreeBSD does not generate a capability from accept(cap_fd,...).
+// https://bugs.freebsd.org/201052
+// #define CAP_FROM_ACCEPT
+// TODO(FreeBSD): uncomment if/when FreeBSD propagates rights on sctp_peeloff.
+// FreeBSD does not generate a capability from sctp_peeloff(cap_fd,...).
+// https://bugs.freebsd.org/201052
+// #define CAP_FROM_PEELOFF
+
+#endif  /* __FreeBSD__ */
+
+#endif /*__CAPSICUM_FREEBSD_H__*/