[PATCH] cap_inode_getsecurity: use d_find_any_alias() instead of d_find_alias()

[Amir Goldstein]

On Fri, Jun 29, 2018 at 5:53 AM, Serge E. Hallyn <serge at hallyn.com> wrote:
> On Fri, Jun 29, 2018 at 09:57:11AM +0800, Eddie.Horng wrote:
>> On Thu, 2018-06-28 at 13:28 -0500, Serge E. Hallyn wrote:
>> > Ah - I just tried his reproducer, and in fact got:
>> >
>> > 0 ✓ serge at sl ~/test $ getcap execveat
>> > execveat = cap_sys_admin+ep
>> > 0 ✓ serge at sl ~/test $ ./execveat
>> > execveat: Bad file descriptor
>> >
>> > on ext4, with 4.15.0-22-generic #24~16.04.1-Ubuntu
>> >
>> > Without the filecap, it works.
>> >
>> > -serge
>>
>> The simple reproducer expected /bin/echo exists in the same
>> dir of execveat executable and does not check the return fd
>> of open("echo", ...). I'm not sure if you run into this case,
>> but I tried to run execveat without echo exists, got same result:
>> "execveat: Bad file descriptor".
>
> Hah!  Yes, i was in too much of a hurry;  I ran it once with
> ./echo existing and no caps, that worked;  then i set the caps
> on execveat instead of ./echo, and echo had gotten deleted by the
> previous test causing the failure like you said.
>
> So, the same thing does happen with setuid anyway, so while that
> seems worth addressing one day,
>

Serge,

I misunderstood the bottom line.

Can the problem be reproduced on local fs with/without caps?
and if so, what is missing from reproducer script for that.

Thanks,
Amir.
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