Now really CC Yauheni.

On Wed, Jan 31, 2018 at 9:39 AM, Lucas De Marchi
[off-list ref] wrote:

Hi Ferry,

CC'ing mailing list and Yauheni who worked on fixing modinfo output in
the last release.


On Wed, Jan 31, 2018 at 1:23 AM, Ferry van Steen
[off-list ref] wrote:

quoted

Hi,


sorry, not sure where to file this. There seems to be a bug in either th=

e

quoted

kernel signing modules with a wrong signature algorithm, or modinfo is
reporting it incorrectly. I presume it's the latter.


More details are here: https://bugzilla.redhat.com/show_bug.cgi?id=3D149=

0975

Not showing the output on older versions is a known issue: support for
PKCS#7 sig type was
only added to kmod in v23.

Now for the incorrect info, the problem appears to be in the kernel
implementation:
it appends a PKCS#7, but doens't fill out the struct module_signature
correctly. So in F27 I get this from, e.g.
soundcore.ko:

$ xxd -c 8 -g 1 mod.ko | tail -n6
00004d80: b9 d5 04 00 00 02 00 00  ........   <<<<<<
00004d88: 00 00 00 00 00 02 d3 7e  .......~
00004d90: 4d 6f 64 75 6c 65 20 73  Module s
00004d98: 69 67 6e 61 74 75 72 65  ignature
00004da0: 20 61 70 70 65 6e 64 65   appende
00004da8: 64 7e 0a                 d~.

See line marked above. It should match a struct module_signature. So:
id_type =3D=3D 0x2 // PKCS7
hash =3D=3D 0 // md4
algo =3D=3D 0 // dsa

Looking at scripts/sign-file.c, indeed id_type is the only field that
is filled out.
CC'ing  David Howells as well. Any input here?

Lucas De Marchi

quoted

Thanks in advance and kind regards,


Ferry van Steen
Linux Developer
Ferry.van.Steen@Citrus.nl

Citrus Software
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Lucas De Marchi