MFC r337272:

Fix some filemon path logging issues.

MFC r304008:

Avoid taking PROC_LOCK in syscalls if not being traced.

MFC r300809,r300890,r300891:

r300809:
filemon exec: Use imgp->execpath rather than vn_fullpath(9).
r300890:
exec: Cease tracing if credentials will change with the new image.
r300891:
Write to the log using the tracer's credentials.

MFC r300892,r300893,r301130,r301404,r301414,r301460:

r300892:
Rename function to be less generic.
r300893:
Don't truncate existing error when writing the log.
r301130:
Enable filemon on all architectures.
r301404:
Support all architectures by just using sysent.
r301414:
Fix build after r301404.
r301460:
Cleanup COMPAT_FREEBSD32 support.

MFC r297156,r297157,r297158,r297159,r297161,r297172,r297200,r297201,r297202,
r297203,r297256:

r297156:
Track filemon usage via a proc.p_filemon pointer rather than its own lists.
r297157:
Stop tracking stat(2).
r297158:
Consolidate open(2) and openat(2) code.
r297159:
Use curthread for vn_fullpath.
r297161:
Attempt to use the namecache for openat(2) path resolution.
r297172:
Consolidate common link(2) logic.
r297200:
Follow-up r297156: Close the log in filemon_dtr rather than in the last
reference.
r297201:
Return any log write failure encountered when closing the filemon fd.
r297202:
Remove unused done argument to copyinstr(9).
r297203:
Handle copyin failures.
r297256:
Remove unneeded return left from refactoring.

Relnotes: yes (filemon stability/performance updates)
Sponsored by: EMC / Isilon Storage Division

MFC r296148:

Remove old compatibility checks.

MFC r296286,r296470,r296472,r296473,r296575:

r296286:
Remove filemon->lock wrappers.
r296470:
Only call bwillwrite() for logging to vnodes, as other fo_write() calls do.
r296472:
Require kldunload -f to unload.
r296473:
Add missing break for r296472.
r296575:
FILEMON_SET_FD: Disallow changing the fd.

MFC r294933,r294949,r294952,r294953,r294957,r294965,r294967,r294968,r295017,
r295026,r295027,r295029,r295030,r295649:

r294933:
Drop any previous fd when setting a new one.
r294949:
filemon_ioctl: Handle error from devfs_get_cdevpriv(9).
r294952:
filemon_ioctl: Lock the associated filemon handle before writing to it.
r294953:
filemon_comment has nothing to do with wrappers so move it out of
filemon_wrapper.c.
r294957:
filemon_dtr: Lock the associated filemon handle before writing to it.
r294965:
filemon: Use process_exit EVENTHANDLER to capture process exit.
r294967:
filemon: Trace fork via process_fork event.
r294968:
Follow-up r294967: Mark flags unused.
r295017:
filemon: Use process_exec EVENTHANDLER to capture sys_execve.
r295026:
filemon_open: Don't record a process to trace here.
r295027:
filemon: Track the process pointer rather than a pid.
r295029:
Document the purpose and non-purpose of filemon(4).
r295030:
Note the double fork behavior with filemon.
r295649:
filemon: Fix panic when fork1() is called from kproc_create().

Approved by: re (marius)

MFC r290170:

Remove unneeded NULL as this is initialized with M_ZERO.

MFC r290374:

Remove unneeded mutex.h include, missed in r287155.

MFC r287151,r287152,r287153,r287155:

r287151:
Move common locking for filemon_inuse and struct filemon* to
filemon_pid_check().
r287152:
Remove unneeded inuse list locking in filemon_comment().
r287153:
Avoid taking proctree_lock and searching parents in wrappers if not needed.
r287155:
Fix filemon locking races.

Relnotes: yes (race fixes)
Sponsored by: EMC / Isilon Storage Division

Latest clang uses openat(2).

If the pathname is absolute or dirfd is AT_FDCWD we can
handle it exactly like open(2).
Otherwise we output an A record to indicate that the path of
an open directory needs to be used (earlier in the trace).

Also filemon_pid_check needs to hold proctree_lock
and use proc_realparent()

Differential Revision: D2810
Reviewed by: jhb
Approved by: re

Merge r263233 from HEAD to stable/10:

Update kernel inclusions of capability.h to use capsicum.h instead; some
further refinement is required as some device drivers intended to be
portable over FreeBSD versions rely on __FreeBSD_version to decide whether
to include capability.h.

Sponsored by: Google, Inc.

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Change the cap_rights_t type from uint64_t to a structure that we can extend
in the future in a backward compatible (API and ABI) way.

The cap_rights_t represents capability rights. We used to use one bit to
represent one right, but we are running out of spare bits. Currently the new
structure provides place for 114 rights (so 50 more than the previous
cap_rights_t), but it is possible to grow the structure to hold at least 285
rights, although we can make it even larger if 285 rights won't be enough.

The structure definition looks like this:

struct cap_rights {
uint64_t cr_rights[CAP_RIGHTS_VERSION + 2];
};

The initial CAP_RIGHTS_VERSION is 0.

The top two bits in the first element of the cr_rights[] array contain total
number of elements in the array - 2. This means if those two bits are equal to
0, we have 2 array elements.

The top two bits in all remaining array elements should be 0.
The next five bits in all array elements contain array index. Only one bit is
used and bit position in this five-bits range defines array index. This means
there can be at most five array elements in the future.

To define new right the CAPRIGHT() macro must be used. The macro takes two
arguments - an array index and a bit to set, eg.

#define CAP_PDKILL CAPRIGHT(1, 0x0000000000000800ULL)

We still support aliases that combine few rights, but the rights have to belong
to the same array element, eg:

#define CAP_LOOKUP CAPRIGHT(0, 0x0000000000000400ULL)
#define CAP_FCHMOD CAPRIGHT(0, 0x0000000000002000ULL)

#define CAP_FCHMODAT (CAP_FCHMOD | CAP_LOOKUP)

There is new API to manage the new cap_rights_t structure:

cap_rights_t *cap_rights_init(cap_rights_t *rights, ...);
void cap_rights_set(cap_rights_t *rights, ...);
void cap_rights_clear(cap_rights_t *rights, ...);
bool cap_rights_is_set(const cap_rights_t *rights, ...);

bool cap_rights_is_valid(const cap_rights_t *rights);
void cap_rights_merge(cap_rights_t *dst, const cap_rights_t *src);
void cap_rights_remove(cap_rights_t *dst, const cap_rights_t *src);
bool cap_rights_contains(const cap_rights_t *big, const cap_rights_t *little);

Capability rights to the cap_rights_init(), cap_rights_set(),
cap_rights_clear() and cap_rights_is_set() functions are provided by
separating them with commas, eg:

cap_rights_t rights;

cap_rights_init(&rights, CAP_READ, CAP_WRITE, CAP_FSTAT);

There is no need to terminate the list of rights, as those functions are
actually macros that take care of the termination, eg:

#define cap_rights_set(rights, ...) \
__cap_rights_set((rights), __VA_ARGS__, 0ULL)
void __cap_rights_set(cap_rights_t *rights, ...);

Thanks to using one bit as an array index we can assert in those functions that
there are no two rights belonging to different array elements provided
together. For example this is illegal and will be detected, because CAP_LOOKUP
belongs to element 0 and CAP_PDKILL to element 1:

cap_rights_init(&rights, CAP_LOOKUP | CAP_PDKILL);

Providing several rights that belongs to the same array's element this way is
correct, but is not advised. It should only be used for aliases definition.

This commit also breaks compatibility with some existing Capsicum system calls,
but I see no other way to do that. This should be fine as Capsicum is still
experimental and this change is not going to 9.x.

Sponsored by: The FreeBSD Foundation

- Use pget(PGET_CANDEBUG | PGET_NOTWEXIT) to determine if the specified
PID is valid for monitoring in FILEMON_SET_PID ioctl.

- Set the monitored PID to -1 when the process exits.

Suggested by: jilles
Tested by: sjg
MFC after: 3 days

Add p_candebug() check to FILEMON_SET_PID ioctl.

Discussed with: sjg
MFC after: 3 days

Build fix: Only <sys/cdefs.h> should be included before __FBSDID().
<sys/param.h> needs to be included after any "opt_foo.h" headers so it
sees the same set of defined macros as other headers.

Match the options of the kernel.

A little bit easier to read.

Iterate rather than use recursion. We can blow out the kernel stack if there
is a long chain of fork(2)s.

Desupport pre-FreeBSD 7.1.

There's no need to make filemon specific to i386 and amd64. All
LP64 architectures define elf64_freebsd_sysvec and all ILP32
architectures define elf32_freebsd_sysvec.

Add the 'filemon' device. 'filemon' is a kernel module that provides a device
interface for processes to record system calls of its children.

Submitted by: Juniper Networks.