When building with KCOV enabled the compiler will insert function calls
to probes allowing us to trace the execution of the kernel from userspace.
These probes are on function entry (trace-pc) and on comparison operations
(trace-cmp).
Userspace can enable the use of these probes on a single kernel thread with
an ioctl interface. It can allocate space for the probe with KIOSETBUFSIZE,
then mmap the allocated buffer and enable tracing with KIOENABLE, with the
trace mode being passed in as the int argument. When complete KIODISABLE
is used to disable tracing.
The first item in the buffer is the number of trace event that have
happened. Userspace can write 0 to this to reset the tracing, and is
expected to do so on first use.
The format of the buffer depends on the trace mode. When in PC tracing just
the return address of the probe is stored. Under comparison tracing the
comparison type, the two arguments, and the return address are traced. The
former method uses on entry per trace event, while the later uses 4. As
such they are incompatible so only a single mode may be enabled.
KCOV is expected to help fuzzing the kernel, and while in development has
already found a number of issues. It is required for the syzkaller system
call fuzzer [1]. Other kernel fuzzers could also make use of it, either
with the current interface, or by extending it with new modes.
A man page is currently being worked on and is expected to be committed
soon, however having the code in the kernel now is useful for other
developers to use.
[1] https://github.com/google/syzkaller
Submitted by: Mitchell Horne <mhorne063@gmail.com> (Earlier version)
Reviewed by: kib
Testing by: tuexen
Sponsored by: DARPA, AFRL
Sponsored by: The FreeBSD Foundation (Mitchell Horne)
Differential Revision: https://reviews.freebsd.org/D14599
Once a signal's siginfo was copied to 'td_si' as part of the signal
exchange in issignal(), it was never cleared. This caused future
thread events that are reported as SIGTRAP events without signal
information to report the stale siginfo in 'td_si'. For example, if a
debugger created a new process and used SIGSTOP to stop it after
PT_ATTACH, future system call entry / exit events would set PL_FLAG_SI
with the SIGSTOP siginfo in pl_siginfo. This broke 'catch syscall' in
current versions of gdb as it assumed PL_FLAG_SI with SIGTRAP
indicates a breakpoint or single step trap.
Reviewed by: kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D18487
Fix reporting of SS_ONSTACK in nested signal delivery when sigaltstack()
is used on some architectures.
Add a unit test for this. I tested the test by introducing the bug
on amd64. I did not test it on other architectures.
Reviewed by: kib
MFC after: 2 weeks
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D18347
Unconditionally reparenting to PID 1 breaks the procctl(2) reaper
functionality.
Add a regression test for this case.
Reviewed by: kib
Approved by: re (gjb)
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D17589
FreeBSD's mkstemp sets the temporary file's permissions to 600, and has ever
since mkstemp was added in 1987. Coverity's warning is still relevant for
portable programs since OpenGroup does not require that behavior, and POSIX
didn't until 2008. But none of these programs are portable.
umask(2) should always be used prior to mkstemp(3) so the temporary file
won't be created with insecure permissions.
Reported by: Coverity
CID: 1331605 1347173 1375366 1339800 1331604 1296056 1296060
CID: 1296057 1296062
MFC after: 2 weeks
- Add some more cases to the truncation test.
- Remove the "expect fail" annotations.
PR: 131876
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D16562
With r337328, the test hangs becase the sendmsg() call will block until
the receive buffer is at least partially drained. Fix the problem by
using a non-blocking socket and allowing short writes. Also assert
that a SCM_CREDS message was received if one was expected.
PR: 181741
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D16516
Enable the LOCAL_PEERCRED socket option for unix domain stream sockets
created with socketpair(2). Previously, it only worked with unix domain
stream sockets created with socket(2)/listen(2)/connect(2)/accept(2).
PR: 176419
Reported by: Nicholas Wilson <nicholas@nicholaswilson.me.uk>
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D16350
- Remove return statements in functions with a void return type.
- Allocate enough space for the SCM_CREDS and SCM_RIGHTS messages
received in the rights_creds_payload test.
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
If an error occurs while copying a SCM_RIGHTS message to userspace,
we free the mbuf containing externalized rights, leaking them.
PR: 131876
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
A pipe was was left over from a development version of pdeathsig.c and
is not needed.
Process C waits for a signal that'll be generated when process B
exists. Process B waits for process D to send it a byte via pipe_db
before it exits. Process D sends the byte after it has started
ptrace()ing process C. The point of the test is to show that process C
receives the signal because process B exited, even though C has been
reparented to process D. The pipe pipe_cd isn't doing anything useful
(though in an earlier version of the patch it did). Clean that up by
removing the useless pipe.
Submitted by: Thomas Munro
MFC after: 6 days
Differential revision: https://reviews.freebsd.org/D15214
- ptrace__breakpoint_siginfo tests that a SIGTRAP for a software breakpoint
in userland triggers a SIGTRAP with a signal code of TRAP_BRKPT.
- ptrace__step_siginfo tests that a SIGTRAP reported for a step after
stepping via PT_STEP or PT_SETSTEP has a signal code of TRAP_TRACE.
- Use a single list of platforms to define HAVE_BREAKPOINT for platforms
that expose a functional breakpoint() inline to userland. Replace
existing lists of platform tests with HAVE_BREAKPOINT instead.
- Add support for advancing PC past a breakpoint inserted via breakpoint()
to support the existing ptrace__PT_CONTINUE_different_thread test on
non-x86 platforms (x86 advances the PC past the breakpoint instruction,
but other platforms do not). This is implemented by defining a new
SKIP_BREAK macro which accepts a pointer to a 'struct reg' as its sole
argument and modifies the contents to advance the PC. The intention is
to use it in between PT_GETREGS and PT_SETREGS.
Tested on: amd64, i386, mips (after adding a breakpoint() to mips)
MFC after: 1 month
-> PROC_PDEATHSIG_STATUS for consistency with other procctl(2)
operations names.
Requested by: emaste
Sponsored by: The FreeBSD Foundation
MFC after: 13 days
Allow processes to request the delivery of a signal upon death of
their parent process. Supposed consumer of the feature is PostgreSQL.
Submitted by: Thomas Munro
Reviewed by: jilles, mjg
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D15106
It mistakenly believes the 'static' keyword must come first. Fix PPC,
Sparc64, and maybe MIPS world. Fallout from r331279.
Reported by: tinderbox (results come slowly)
The general idea here is to provide userspace programs with well-defined
sources of entropy, in a fashion that doesn't require opening a new file
descriptor (ulimits) or accessing paths (/dev/urandom may be restricted
by chroot or capsicum).
getrandom(2) is the more general API, and comes from the Linux world.
Since our urandom and random devices are identical, the GRND_RANDOM flag
is ignored.
getentropy(3) is added as a compatibility shim for the OpenBSD API.
truss(1) support is included.
Tests for both system calls are provided. Coverage is believed to be at
least as comprehensive as LTP getrandom(2) test coverage. Additionally,
instructions for running the LTP tests directly against FreeBSD are provided
in the "Test Plan" section of the Differential revision linked below. (They
pass, of course.)
PR: 194204
Reported by: David CARLIER <david.carlier AT hardenedbsd.org>
Discussed with: cperciva, delphij, jhb, markj
Relnotes: maybe
Differential Revision: https://reviews.freebsd.org/D14500
Don't declare some types that FreeBSD incorrectly declares.
Fix an incorrect call to open() (missing mode).
ANSIfy prototypes.
Enable SysV message queue, semaphore, and shared memory tests.
With exception of the workaround for union semun, these fixes have been
committed to NetBSD.
Reviewed by: asomers
Approved by: CheriBSD
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D13471
Some of the ptrace tests need to wait for a child process to become a
zombie before preceding. The parent process polls the child process
via the kern.proc.pid sysctl to wait for it to become a zombie.
Previously the code polled until the sysctl failed with ESRCH. Now it
will poll until either the sysctl fails with ESRCH (for compatiblity
with older kernels) or returns a kinfo_proc structure with the ki_stat
field set to SZOMB.
Reported by: Jenkins
Tested by: markj
Discussed with: mjg
MFC after: 1 week
When multiple threads wish to report a tracing event to a debugger,
both threads call ptracestop() and one thread will win the race to be
the reporting thread (p->p_xthread). The debugger uses PT_LWPINFO
with the process ID to determine which thread / LWP is reporting an
event and the details of that event. This event is cleared as a side
effect of the subsequent ptrace event that resumed the process
(PT_CONTINUE, PT_STEP, etc.). However, ptrace() was clearing the
event identified by the LWP ID passed to the resume request even if
that wasn't the 'p_xthread'. This could result in clearing an event
that had not yet been observed by the debugger and leaving the
existing event for 'p_thread' pending so that it was reported a second
time.
Specifically, if the debugger stopped due to a software breakpoint in
one thread, but then switched to another thread that was used to
resume (e.g. if the user switched to a different thread and issued a
step), the resume request (PT_STEP) cleared a pending event (if any)
for the thread being stepped. However, the process immediately
stopped and the first thread reported it's breakpoint event a second
time. The debugger decremented the PC for "both" breakpoint events
which resulted in the PC now pointing into the middle of an
instruction (on x86) and a SIGILL fault when the process was resumed a
second time.
To fix, always clear the pending event for 'p_xthread' when resuming a
process. ptrace() still honors the requested LWP ID when enabling
single-stepping (PT_STEP) or setting a different PC (PT_CONTINUE).
Reported by: GDB testsuite (gdb.threads/continue-pending-status.exp)
Reviewed by: kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D12794
Executable bits should be set at install time instead of in the repo.
Setting executable bits on files triggers false positives with Phabricator.
MFC after: 2 months
- Use "atf_check -x 'cmd1 | cmd2'" instead of "cmd1 | atf_check cmd2". The
two forms are idiomatically similar, but subtly different in the sense of
what program invokes the other, and there could be unwanted side effects
of the latter idiom dealing with forking, pipes, etc.
- Remove chmod and instead source coredump_phnum_restore_state.sh directly.
This avoids the need to check the result of the chmod call.
- Fix indentation in an if-block (4 column space indentation -> hard tab).
The testcase no longer fails on ^/head because readelf has established parity
with binutils' copy of readelf.
This issue is not seen on Jenkins because
`test_suites.FreeBSD.allow_sysctl_side_effects` isn't set in kyua.conf on
the CI host, i.e., the test is skipped.
PR: 215019
Tested with: binutils (amd64-binutils-2.28,1); elftoolchain (r3561M)
It was sending only a long's worth (4 or 8 bytes) of data previously
(instead of the entire buffer) via send(2).
MFC after: 1 week
Reported by: Coverity
CID: 1229966, 1229967, 1230004, 1230005
Sponsored by: Dell EMC Isilon
These command take an int. The tests work by accident on little-endian,
64-bit systems.
PR: 218919
Tested with: qemu-cheri and CheriBSD built for mips64
Reviewed by: asomers, ngie
Obtained from: CheriBSD
MFC after: 1 week
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D10518
available and if that is true make use of them.
Thank you very much to Andrew Turner for providing help and review the patch!
Reviewed by: andrew
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D10499
A couple of the ptrace tests make assumptions about which thread in a
multithreaded process will run after a halt. This makes the tests less
portable across branches, and susceptible to future breakage. Instead,
twiddle thread scheduling and priorities to match the tests'
expectation.
X-MFC with: r313992
Sponsored by: Dell EMC
The ptrace() user has the option of discarding the signal. In such a
case, p_ptevents should not be modified. If the ptrace() user decides to
send a SIGKILL, ptevents will be cleared in ptracestop(). procfs events
do not have the capability to discard the signal, so continue to clear
the mask in that case.
Reviewed by: jhb (initial revision)
MFC after: 1 week
Sponsored by: Dell EMC
Differential Revision: https://reviews.freebsd.org/D9939
