Dumpers may wish to print messages from an initialization hook; this
change ensures that such messages aren't mixed with output from the
generic dump code.
MFC after: 1 week
Enable the hardclock-based watchdog previously conditional on the
SW_WATCHDOG option whenever hardware watchdogs are not found, and
watchdogd attempts to enable the watchdog. The SW_WATCHDOG option
still causes the sofware watchdog to be enabled even if there is a
hardware watchdog. This does not change the other software-based
watchdog enabled by the --softtimeout option to watchdogd.
Note that the code to reprime the watchdog during kernel core dumps is
no longer conditional on SW_WATCHDOG. I think this was previously a bug.
Reviewed by: imp alfred bjk
MFC after: 1 week
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D13713
All of the kernel dump implementations keep track of the current offset
("dumplo") within the dump device. However, except for textdumps, they
all write the dump sequentially, so we can reduce code duplication by
having the MI code keep track of the current offset. The new
dump_append() API can be used to write at the current offset.
This is needed to implement support for kernel dump compression in the
MI kernel dump code.
Also simplify dump_encrypted_write() somewhat: use dump_write() instead
of duplicating its bounds checks, and get rid of the redundant offset
tracking.
Reviewed by: cem
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D11722
This helps simplify the code in kern_shutdown.c and reduces the number
of globally visible functions.
No functional change intended.
Reviewed by: cem, def
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D11603
dump_start() and dump_finish() are responsible for writing kernel dump
headers, optionally writing the key when encryption is enabled, and
initializing the initial offset into the dump device.
Also remove the unused dump_pad(), and make some functions static now that
they're only called from kern_shutdown.c.
No functional change intended.
Reviewed by: cem, def
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D11584
Changes include modifications in kernel crash dump routines, dumpon(8) and
savecore(8). A new tool called decryptcore(8) was added.
A new DIOCSKERNELDUMP I/O control was added to send a kernel crash dump
configuration in the diocskerneldump_arg structure to the kernel.
The old DIOCSKERNELDUMP I/O control was renamed to DIOCSKERNELDUMP_FREEBSD11 for
backward ABI compatibility.
dumpon(8) generates an one-time random symmetric key and encrypts it using
an RSA public key in capability mode. Currently only AES-256-CBC is supported
but EKCD was designed to implement support for other algorithms in the future.
The public key is chosen using the -k flag. The dumpon rc(8) script can do this
automatically during startup using the dumppubkey rc.conf(5) variable. Once the
keys are calculated dumpon sends them to the kernel via DIOCSKERNELDUMP I/O
control.
When the kernel receives the DIOCSKERNELDUMP I/O control it generates a random
IV and sets up the key schedule for the specified algorithm. Each time the
kernel tries to write a crash dump to the dump device, the IV is replaced by
a SHA-256 hash of the previous value. This is intended to make a possible
differential cryptanalysis harder since it is possible to write multiple crash
dumps without reboot by repeating the following commands:
# sysctl debug.kdb.enter=1
db> call doadump(0)
db> continue
# savecore
A kernel dump key consists of an algorithm identifier, an IV and an encrypted
symmetric key. The kernel dump key size is included in a kernel dump header.
The size is an unsigned 32-bit integer and it is aligned to a block size.
The header structure has 512 bytes to match the block size so it was required to
make a panic string 4 bytes shorter to add a new field to the header structure.
If the kernel dump key size in the header is nonzero it is assumed that the
kernel dump key is placed after the first header on the dump device and the core
dump is encrypted.
Separate functions were implemented to write the kernel dump header and the
kernel dump key as they need to be unencrypted. The dump_write function encrypts
data if the kernel was compiled with the EKCD option. Encrypted kernel textdumps
are not supported due to the way they are constructed which makes it impossible
to use the CBC mode for encryption. It should be also noted that textdumps don't
contain sensitive data by design as a user decides what information should be
dumped.
savecore(8) writes the kernel dump key to a key.# file if its size in the header
is nonzero. # is the number of the current core dump.
decryptcore(8) decrypts the core dump using a private RSA key and the kernel
dump key. This is performed by a child process in capability mode.
If the decryption was not successful the parent process removes a partially
decrypted core dump.
Description on how to encrypt crash dumps was added to the decryptcore(8),
dumpon(8), rc.conf(5) and savecore(8) manual pages.
EKCD was tested on amd64 using bhyve and i386, mipsel and sparc64 using QEMU.
The feature still has to be tested on arm and arm64 as it wasn't possible to run
FreeBSD due to the problems with QEMU emulation and lack of hardware.
Designed by: def, pjd
Reviewed by: cem, oshogbo, pjd
Partial review: delphij, emaste, jhb, kib
Approved by: pjd (mentor)
Differential Revision: https://reviews.freebsd.org/D4712
(And 4Kn minidump support, but only for amd64.)
Make sure all I/O to the dump device is of the native sector size. To
that end, we keep a native sector sized buffer associated with dump
devices (di->blockbuf) and use it to pad smaller objects as needed (e.g.
kerneldumpheader).
Add dump_write_pad() as a convenience API to dump smaller objects with
zero padding. (Rather than pull in NPM leftpad, we wrote our own.)
Savecore(1) has been updated to deal with these dumps. The format for
512-byte sector dumps should remain backwards compatible.
Minidumps for other architectures are left as an exercise for the
reader.
PR: 194279
Submitted by: ambrisko@
Reviewed by: cem (earlier version), rpokala
Tested by: rpokala (4Kn/512 except 512 fulldump), cem (512 fulldump)
Relnotes: yes
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D5848
- While at it, arrange #ifndefs in kern_dump.c more intelligently; it's
rather confusing to have multiple competing and/or unused functions in
the kernel.
code in sys/kern/kern_dump.c. Most dumpsys() implementations are nearly
identical and simply redefine a number of constants and helper subroutines;
a generic implementation will make it easier to implement features around
kernel core dumps. This change does not alter any minidump code and should
have no functional impact.
PR: 193873
Differential Revision: https://reviews.freebsd.org/D904
Submitted by: Conrad Meyer <conrad.meyer@isilon.com>
Reviewed by: jhibbits (earlier version)
Sponsored by: EMC / Isilon Storage Division
