Re: veritysetup forward error correction failure
Milan Broz <[email protected]>
| Newsgroups | gmane.linux.kernel.device-mapper.dm-crypt |
|---|---|
| Message-ID | <[email protected]> |
On 18/07/2019 15:49, Tom Eccles wrote: > On 18/07/2019 2:09 pm, Milan Broz wrote: >> On 18/07/2019 13:41, Tom Eccles wrote: >>> On 17/07/2019 8:49 pm, Milan Broz wrote: >>>> If you can still reproduce it, please send version of the utility and >>>> kernel (and --debug output as suggested in another mail) and if you have some >>>> data/hash/fec images that can be used to reproduce it, let me know where I can find it. >>> >>> Attached is a bash script gen_image.sh which should reproduce the issue. >>> find_and_corrupt.c should be in the working directory when gen_image.sh is >>> run. find_and_corrupt.c corrupts the disk image by simply searching for a >>> known string and introducing an error (see the diff outputted by gen_image.sh). >>> >>> See in particular the error and dmesg sample when reading the corrupted file >>> (gen_image.sh:77) and the success when running veritysetup verify >>> (gen_image.sh:86). >>> >>> I have created an issue at https://gitlab.com/cryptsetup/cryptsetup/issues/462 >> >> Thanks. >> >> I think I see the problem, and it is actually not FEC related. >> >> Could you please try to manually allocate loop devices in RW mode (not read-only >> as we have during automatic loop allocation if mapping image is in file) >> over the provided images, and then use these loop device as arguments for >> the veritysetup? >> >> Like >> # losetup /dev/loop0 data8M.img.corrupt >> # losetup /dev/loop1 hash-img >> # losetup /dev/loop2 fec-img >> >> and >> >> # veritysetup open --fec-roots 24 --fec-device /dev/loop2 /dev/loop0 test /dev/loop1 15546e6799bb13608c77fa9cb840682a2dec3cfdb948d942ff3487f537966c01 --debug >> >> Does it correct the data now? For me it prints >> >> kernel: device-mapper: verity: sha256 using implementation "sha256-generic" >> kernel: fec_decode_bufs: 13 callbacks suppressed >> kernel: device-mapper: verity-fec: 7:0: FEC 0: corrected 153 errors >> >> Milan >> > > This is not working for me. ok, I actually just tried dd the whole device, not through the mounted fs. will try it later... But anyway, it seems like a problem with some infrastructure inside dm/block layer and not the FEC algorithm itself (errno -74 is EBADMSG, something that should not be here). m. _______________________________________________ dm-crypt mailing list [email protected] https://www.saout.de/mailman/listinfo/dm-crypt