Commit Graph

12 Commits

Author SHA1 Message Date
Conrad Meyer
8298529226 EKCD: Add Chacha20 encryption mode
Add Chacha20 mode to Encrypted Kernel Crash Dumps.

Chacha20 does not require messages to be multiples of block size, so it is
valid to use the cipher on non-block-sized messages without the explicit
padding AES-CBC would require.  Therefore, allow use with simultaneous dump
compression.  (Continue to disallow use of AES-CBC EKCD with compression.)

dumpon(8) gains a -C cipher flag to select between chacha and aes-cbc.
It defaults to chacha if no -C option is provided.  The man page documents this
behavior.

Relnotes:	sure
Sponsored by:	Dell EMC Isilon
2019-05-23 20:12:24 +00:00
Jung-uk Kim
3548eb3aab Make decryptcore(8) buildable. 2018-09-19 07:07:03 +00:00
Mariusz Zaborski
7672a0148f Convert cap_enter() < 0 && errno != ENOSYS to caph_enter() < 0.
No functional change intended.
2018-06-19 23:43:14 +00:00
Mariusz Zaborski
8586c17750 Bump date after r328535.
Submitted by:	def@
2018-01-29 09:27:32 +00:00
Konrad Witaszczyk
02670b9048 Fix misspelling of encryptedcore.
PR:		223991
Submitted by:	Trond Endrestol <Trond.Endrestol@ximalas.info>
Approved by:	pjd (mentor)
2018-01-29 09:21:08 +00:00
Bryan Drewery
ea825d0274 DIRDEPS_BUILD: Update dependencies.
Sponsored by:	Dell EMC Isilon
2017-10-31 00:07:04 +00:00
Bryan Drewery
6106a50ee6 DIRDEPS_BUILD: Connect new directories.
Sponsored by:	Dell EMC Isilon
2017-05-09 01:48:14 +00:00
Enji Cooper
22289a8c3d sbin: normalize paths using SRCTOP-relative paths or :H when possible
This simplifies make logic/output

MFC after:	1 month
Sponsored by:	Dell EMC Isilon
2017-03-04 11:33:01 +00:00
Konrad Witaszczyk
4b30cd46a5 Don't decrypt a core if a vmcore file already exists by default.
Allow to change this behaviour using the -f flag.

Approved by:	pjd (mentor)
2017-02-08 23:17:23 +00:00
Konrad Witaszczyk
3c7ccf15c7 Fix bugs found by Coverity in decryptcore(8) and savecore(8):
- Perform final decryption and write decrypted data in case of non-block aligned
input data;
- Use strlcpy(3) instead of strncpy(3) to verify if paths aren't too long;
- Check errno after calling unlink(2) instead of calling stat(2) in order to
verify if a decrypted core was created by a child process;
- Free dumpkey.

Reported by:	Coverity, cem, pfg
Suggested by:	cem
CID:		1366936, 1366942, 1366951, 1366952
Approved by:	pjd (mentor)
2017-02-04 14:10:16 +00:00
Christian Brueffer
c519c3c308 Language and mdoc cleanup. 2016-12-13 18:15:11 +00:00
Konrad Witaszczyk
480f31c214 Add support for encrypted kernel crash dumps.
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
2016-12-10 16:20:39 +00:00