From: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
To: Florian Weimer <fweimer@redhat.com>, linux-man@vger.kernel.org
Cc: mtk.manpages@gmail.com, libc-alpha@sourceware.org,
Carlos O'Donell <carlos@redhat.com>
Subject: Re: [PATCH] rtld-audit.7: Clarify la_version handshake
Date: Fri, 25 Sep 2020 12:47:06 +0200 [thread overview]
Message-ID: <299e6651-fa82-8350-f36f-e578e8180859@gmail.com> (raw)
In-Reply-To: <87k0wifdi2.fsf@oldenburg2.str.redhat.com>
On 9/25/20 10:48 AM, Florian Weimer wrote:
> Returning its argument without further checks is almost always
> wrong for la_version.
>
> Signed-off-by: Florian Weimer <fweimer@redhat.com>
Hello Florian,
I've applied this patch locally. I'll merge into master
in a few hours. Perhaps in the meantime there are acks/reviews
that come in.
Cheers,
Michael
> ---
> man7/rtld-audit.7 | 36 +++++++++++++++++++++++++-----------
> 1 file changed, 25 insertions(+), 11 deletions(-)
>
> diff --git a/man7/rtld-audit.7 b/man7/rtld-audit.7
> index b1b7dfebc..21cc339d0 100644
> --- a/man7/rtld-audit.7
> +++ b/man7/rtld-audit.7
> @@ -70,17 +70,30 @@ the auditing library.
> When invoking this function, the dynamic linker passes, in
> .IR version ,
> the highest version of the auditing interface that the linker supports.
> -If necessary, the auditing library can check that this version
> -is sufficient for its requirements.
> .PP
> -As its function result,
> -this function should return the version of the auditing interface
> -that this auditing library expects to use (returning
> +A typical implementation of this function simply returns the constant
> +.BR LAV_CURRENT ,
> +which indicates the version of
> +.I <link.h>
> +that was used to build the audit module. If the dynamic linker does
> +not support this version of the audit interface, it will refuse to
> +activate this audit module. If the function returns zero, the dynamic
> +linker also does not activate this audit module.
> +.PP
> +In order to enable backwards compatibility with older dynamic linkers,
> +an audit module can examine the
> +.I version
> +argument and return an earlier version than
> +.BR LAV_CURRENT ,
> +assuming the module can adjust its implementation to match the
> +requirements of the previous version of the audit interface. The
> +.B la_version
> +function should not return the value of
> .I version
> -is acceptable).
> -If the returned value is 0,
> -or a version that is greater than that supported by the dynamic linker,
> -then the audit library is ignored.
> +without further checks because it could correspond to an interface
> +that does not match the
> +.I <link.h>
> +definitions used to build the audit module.
> .SS la_objsearch()
> \&
> .nf
> @@ -508,9 +521,10 @@ This is reportedly fixed in glibc 2.10.
> unsigned int
> la_version(unsigned int version)
> {
> - printf("la_version(): %u\en", version);
> + printf("la_version(): version = %u; LAV_CURRENT = %u\en",
> + version, LAV_CURRENT);
>
> - return version;
> + return LAV_CURRENT;
> }
>
> char *
>
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
next prev parent reply other threads:[~2020-09-25 10:47 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-25 8:48 Florian Weimer
2020-09-25 10:47 ` Michael Kerrisk (man-pages) [this message]
2020-09-25 16:14 ` Carlos O'Donell
2020-09-25 17:17 ` Michael Kerrisk (man-pages)
-- strict thread matches above, loose matches on Subject: below --
2020-09-23 11:38 Florian Weimer
2020-09-23 11:45 ` Andreas Schwab
2020-09-23 11:47 ` Florian Weimer
2020-09-23 11:52 ` Andreas Schwab
2020-09-23 20:15 ` Ben Coyote Woodard
2020-09-24 1:30 ` Carlos O'Donell
2020-09-25 8:45 ` Florian Weimer
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=299e6651-fa82-8350-f36f-e578e8180859@gmail.com \
--to=mtk.manpages@gmail.com \
--cc=carlos@redhat.com \
--cc=fweimer@redhat.com \
--cc=libc-alpha@sourceware.org \
--cc=linux-man@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).