On Feb 9, 2015, at 18:43, Mateusz Guzik <mjgu...@gmail.com> wrote:
>
> On Mon, Feb 09, 2015 at 11:13:51PM +0000, Rui Paulo wrote:
>> +notify 10 {
>> + match "system" "kernel";
>> + match "subsystem" "signal";
>> + match "type" "coredump";
>> + action "logger $comm $core";
>> +};
>> +
>> */
>>
> [..]
>> + if (vn_fullpath_global(td, p->p_textvp, &fullpath, &freepath) != 0)
>> + goto out;
>> + snprintf(data, len, "comm=%s", fullpath);
>
> I cannot test it right now, but it looks like immediate privilege
> escalation.
>
> Path is not sanitized in any way and devd passes it to 'sh -c'.
>
> So a file named "a.out; /bin/id; meh" or so should result in execution
> of aforementioned /bin/id.
Well, you can't have a file name with "/" but you're right.
> Another note is that currently devctl is record oriented, but this may
> change at some point and free form userspace text could be used to forge
> new events.
>
> As such is trongly suggest we sanitize this somehow. Maybe a base64 or
> something.
I was trying hard to avoid this issue in unpublished my crash helper, but I
forgot that devd runs execl("sh -c", ....); :-(
It might just be easier to inspect the path names and allow only
[a-z][A-Z][0-9] and '/' before sending the devctl message.
--
Rui Paulo
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