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dumpon.8: Update minimum key size language dumpon(8) has not accepted 1024-bit RSA keys since prior to r339784 (2018-10). The manual page language was not updated at that time (oops). The minimum accepted is 2048 bits, which is also a good default choice. Sponsored by: Dell EMC Isilon
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
Update the example added in r348082 to specify a dump device priority. Event: Waterloo Hackathon 2019
Provide an example of using dhclient-script(5) to configure netdump. Reviewed by: cem MFC after: 1 week Event: Waterloo Hackathon 2019 Differential Revision: https://reviews.freebsd.org/D20345
List-ify kernel dump device configuration Allow users to specify multiple dump configurations in a prioritized list. This enables fallback to secondary device(s) if primary dump fails. E.g., one might configure a preference for netdump, but fallback to disk dump as a second choice if netdump is unavailable. This change does not list-ify netdump configuration, which is tracked separately from ordinary disk dumps internally; only one netdump configuration can be made at a time, for now. It also does not implement IPv6 netdump. savecore(8) is already capable of scanning and iterating multiple devices from /etc/fstab or passed on the command line. This change doesn't update the rc or loader variables 'dumpdev' in any way; it can still be set to configure a single dump device, and rc.d/savecore still uses it as a single device. Only dumpon(8) is updated to be able to configure the more complicated configurations for now. As part of revving the ABI, unify netdump and disk dump configuration ioctl / structure, and leave room for ipv6 netdump as a future possibility. Backwards-compatibility ioctls are added to smooth ABI transition, especially for developers who may not keep kernel and userspace perfectly synced. Reviewed by: markj, scottl (earlier version) Relnotes: maybe Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D19996
Change dumpon(8)'s handling of -g. Rather than using a special value to denote "use the default router", treat the absence of the -g option to mean the same thing. The in-kernel netdump client will always attempt to reach the server directly before falling back to the configured gateway anyway. This change makes it cleaner to support a hostname value for -g. Reviewed by: cem MFC after: 3 days Differential Revision: https://reviews.freebsd.org/D18025
dumpon.8: Significantly revamp page Start with a short summary and cover the options in a standard list style. Organize sections by common focus and prioritize more useful information closer to the top. Flesh out authors, history, caveats, and security considerations sections. Reviewed by: markj, eadler (previous version) Differential Revision: https://reviews.freebsd.org/D17679
dumpon(8): Provide seatbelt against weak RSA keys The premise of dumpon -k foo.pem is that dump contents will be confidential except to anyone holding the corresponding RSA private key. This guarantee breaks down when weak RSA keys are used. Small RSA keys (e.g. 512 bits) can be broken on a single personal computer in tractible time. Marginal RSA keys (768 bits) can be broken by EC2 and a few dollars. Even 1024 bit keys can probably be broken by sophisticated and wealthy attackers. NIST SP800-57 (2016) recommends a minimum of 2048 bit RSA keys, and estimates this provides 112 bits of security. It would also be good to protect users from weak values of 'e' (i.e., 3) and perhaps sanity check that their public key .pem does not accidentally contain their private key as well. These considerations are left as future work. Reviewed by: markj, darius AT dons.net.au (previous version) Discussed with: bjk Differential Revision: https://reviews.freebsd.org/D17678
dumpon(8): improve the examples a bit While here, remove extraneous extraneous Pp Reviewed by: jhb (older version)
dumpon: point to better kernel debug symbols. The objdir is temporary, and the current example points to GENERIC. Instead point to the installed location of the debug symbols that are supposed to match the kernel you are using. PR: 223993 Submitted by: Trond.Endrestol@ximalas.info
Add netdump support to dumpon(8). A new usage is added so that parameters for netdump may be specified. Specifically, one configures an interface for netdump with: # dumpon -c <client IP> -s <server IP> [-g <gateway IP>] <iface name> Reviewed by: bdrewery, cem (earlier versions), sbruno MFC after: 1 month Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D15254
Add support for zstd-compressed user and kernel core dumps. This works similarly to the existing gzip compression support, but zstd is typically faster and gives better compression ratios. Support for this functionality must be configured by adding ZSTDIO to one's kernel configuration file. dumpon(8)'s new -Z option is used to configure zstd compression for kernel dumps. savecore(8) now recognizes and saves zstd-compressed kernel dumps with a .zst extension. Submitted by: cem (original version) Relnotes: yes Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D13101, https://reviews.freebsd.org/D13633
Add support for compressed kernel dumps. When using a kernel built with the GZIO config option, dumpon -z can be used to configure gzip compression using the in-kernel copy of zlib. This is useful on systems with large amounts of RAM, which require a correspondingly large dump device. Recovery of compressed dumps is also faster since fewer bytes need to be copied from the dump device. Because we have no way of knowing the final size of a compressed dump until it is written, the kernel will always attempt to dump when compression is configured, regardless of the dump device size. If the dump is aborted because we run out of space, an error is reported on the console. savecore(8) is modified to handle compressed dumps and save them to vmcore.<index>.gz, as it does when given the -z option. A new rc.conf variable, dumpon_flags, is added. Its value is added to the boot-time dumpon(8) invocation that occurs when a dump device is configured in rc.conf. Reviewed by: cem (earlier version) Discussed with: def, rgrimes Relnotes: yes Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D11723
Renumber copyright clause 4 Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96
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
dumpon(8) appears to be present in FreeBSD 2.0.5, despite initial import of man page listed FreeBSD 2.1. PR: 212445 Approved by: bcr (mentor) MFC after: 4 days Differential Revision: https://reviews.freebsd.org/D8105
Revert r156046. We support setting dumpdev via loader tunable again. Also change default disk name to ada. MFC after: 3 weeks
Adapt to the fact that minidumps are now on by default. PR: 177188
Document that you can use -v along with -l. Noticed by: pjd
Add an option to display the current dump device via dumpon -l. MFC after: 2 weeks
It has not been possible to specify a dumpdev in loader.conf since 2002, so don't raise false hopes here.
- Mention the size of the additional header PR: docs/85867 Submitted by: dinoex MFC after: 1 week
Sort sections.
Verify that the specified device is at least as large as hw.physmem.
Wrap some long lines (no content changes)
`off' is a keyword, not a parameter name. Obtained from: DragonFly
Remove advertising clause from University of California Regent's license, per letter dated July 22, 1999. Approved by: core, imp
Bring the dumpon(8) man page closer to reality:
- dumpon utility has not used kern.dumpdev sysctl
since rev. 1.14 (sbin/dumpon/dumpon.c) when phk@
updated it to use the DIOCSKERNELDUMP ioctl [1]
- remove obsolete reference to sysctl(3)
While I am there, fix two style nits:
- use .Nm instead of `dumpon'
- change NOTES to IMPLEMENTATION NOTES, to bring
it in line with recommended section headings in
mdoc(7)
Original patch by: Martin Faxer <gmh003532brfmasthugget.se> [1]
PR: docs/39293
Approved and Reviewed by: des (mentor), re (scottl, bmah)
s/filesystem/file system/g as discussed on -developers
Improve wording even more.
Replace the 'at least the amount of physical memory + 64K' with a better explanation in regards to sizing the dump device.
The .Nm utility
Update dumpon manual page to explain single/multi-user usability PR: 36465 No Objections from: ru
CG hard sentence breaks. Submitted by: ru
Don't use `you'. Submitted by: ru
Allow dump device be configured as early as possible using loader(8) tunable. This allows obtaining crash dumps from the panics occured during late stages of kernel initialisation before system enters into single-user mode. MFC after: 2 weeks
Typo.
Remove whitespace at EOL.
mdoc(7) police: removed HISTORY info from the .Os call.
mdoc(7) police: removed history info from the .Os FreeBSD call.
mdoc(7) police: use the new features of the Nm macro.
* Clarify text on choosing a dump device * Remove the text which states only devices with minor number 1 can be used - this is no longer true. * Mention that dumpon(8) cannot be used to capture dumps from panics during kernel initialization. * /dev/wd -> /dev/ad PR: 19848 Submitted by: Udo Erdelhoff <ue@nathan.ruhr.de> Reviewed by: sheldonh
Back out the new advice introduced in the previous commit, which at least one reviewer is now unhappy with, since it contains incomplete and misleading advice that is not easy to correct. The net effect of this commit and the previous commit is to simply remove all discussion of setting dumpdev to catch crash dumps prior to entering user mode.
Update instructions for setting the dump device prior to multi-user mode. Reported by: dcs Submitted by: asmodai
$Id$ -> $FreeBSD$
Use current names for swap devices. PR: docs/11708 Submitted by: Matthew D. Fuller <fullermd@over-yonder.net>
Sort cross references.
Capitalize at the start of sentence. Add rcsid. Remove unused #includes. Use `dumpon' instead of argv[0].
Correct manual page, based on feedback from Bruce Evans. Reviewed by: Bruce Evans <bde@freebsd.org>
Manual page fix: add cross references, refer to ``dumpdev'' variable in "/etc/rc.conf". PR: 6117 Submitted by: Mark Mayo <mark@vmunix.com>
Revert $FreeBSD$ to $Id$
Make the long-awaited change from $Id$ to $FreeBSD$ This will make a number of things easier in the future, as well as (finally!) avoiding the Id-smashing problem which has plagued developers for so long. Boy, I'm glad we're not using sup anymore. This update would have been insane otherwise.
Use the .Fx macro where appropriate.
Fixed some minor formatting problems to silence manck some more. Corrected some bogus cross references to man pages that we don't/won't have and either deleted them, or found a more appropriate man page that we do have. Various other minor changes to silence manck. Manck is currently down to about 200 lines of errors, down from the 500 - 600+ when I started all this.
My utility to specify where you want crash dumps to go. More user and kernel support to follow.
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