Kernel TLS

Sat Nov 30 01:40:07 EST 2019

On Fri, 29 Nov 2019 23:37:35 -0500, Jeffrey Walton said:

repl: bad addresses:
	Valentin VidiD <vvidic at valentin-vidic.from.hr> -- no mailbox in address, only a phrase (Valentin VidiD)
> On Fri, Nov 29, 2019 at 3:04 PM Jeffrey Walton <noloader at gmail.com> wrote:
> > ...
> > So now I am at:
> >
> >     $ gcc -Wall -g2 -O1 ktls.c -o ktls
> >     $ ./ktls
> >     setsockopt failed, 524, Unknown error 524
>
> Now open in the Fedora bug tracker:
> https://bugzilla.redhat.com/show_bug.cgi?id=1778348

Looks like the 'unknown error' issue is a glibc strerror() problem. On the
kernel side, git blame says:

 [/usr/src/linux-next] git blame include/linux/errno.h | grep -C 5 524
^1da177e4c3f4 (Linus Torvalds     2005-04-16 15:20:36 -0700 22)
^1da177e4c3f4 (Linus Torvalds     2005-04-16 15:20:36 -0700 23) /* Defined for the NFSv3 protocol */
^1da177e4c3f4 (Linus Torvalds     2005-04-16 15:20:36 -0700 24) #define EBADHANDLE	521	/* Illegal NFS file handle */
^1da177e4c3f4 (Linus Torvalds     2005-04-16 15:20:36 -0700 25) #define ENOTSYNC	522	/* Update synchronization mismatch */
^1da177e4c3f4 (Linus Torvalds     2005-04-16 15:20:36 -0700 26) #define EBADCOOKIE	523	/* Cookie is stale */
^1da177e4c3f4 (Linus Torvalds     2005-04-16 15:20:36 -0700 27) #define ENOTSUPP	524	/* Operation is not supported */
^1da177e4c3f4 (Linus Torvalds     2005-04-16 15:20:36 -0700 28) #define ETOOSMALL	525	/* Buffer or request is too small */
^1da177e4c3f4 (Linus Torvalds     2005-04-16 15:20:36 -0700 29) #define ESERVERFAULT	526	/* An untranslatable error occurred */

So I'm mystified why glibc's strerror() doesn't handle it.
Though I think Alexander is correct on why the kernel returns ENOTSUPP.

I've updated the bugzilla entry.

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