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* [Bug network/31476] New: Automatic activation of single-request options break resolv.conf reloading
@ 2024-03-12 6:43 fweimer at redhat dot com
2024-03-12 6:45 ` [Bug network/31476] " fweimer at redhat dot com
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: fweimer at redhat dot com @ 2024-03-12 6:43 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=31476
Bug ID: 31476
Summary: Automatic activation of single-request options break
resolv.conf reloading
Product: glibc
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: network
Assignee: unassigned at sourceware dot org
Reporter: fweimer at redhat dot com
Target Milestone: ---
Flags: security-
Initial report from John Levon:
Issue with stale resolv.conf state
<https://inbox.sourceware.org/libc-alpha/Ze7KCkIzR5PuErba@movementarian.org/>
John traced the lack of reloading to a change in _res.options:
“
I don't understand the first part of the comment, but indeed, ->resp doesn't
match. In particular:
62 return ctx->resp->options == ctx->conf->options
and ctx->resp (aka _resp) has 0x47002c1 whereas ctx->conf has 0x41002c1.
I'm not sure but I suspect the additional RES_SNGLKUP|RES_SNGLKUPREOP may be
due
to this code:
1000 /* There are quite a few broken name servers out
1001 there which don't handle two outstanding
1002 requests from the same source. There are also
1003 broken firewall settings. If we time out after
1004 having received one answer switch to the mode
1005 where we send the second request only once we
1006 have received the first answer. */
1007 if (!single_request)
1008 {
1009 statp->options |= RES_SNGLKUP;
1010 single_request = true;
1011 *gotsomewhere = save_gotsomewhere;
1012 goto retry;
1013 }
1014 else if (!single_request_reopen)
1015 {
1016 statp->options |= RES_SNGLKUPREOP;
1017 single_request_reopen = true;
1018 *gotsomewhere = save_gotsomewhere;
1019 __res_iclose (statp, false);
1020 goto retry_reopen;
1021 }
I'm guessing these got set when the VPN dropped routing to the old nameservers,
but before the next getaddrinfo() came in, thus leading to the match failing.
”
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* [Bug network/31476] Automatic activation of single-request options break resolv.conf reloading
2024-03-12 6:43 [Bug network/31476] New: Automatic activation of single-request options break resolv.conf reloading fweimer at redhat dot com
@ 2024-03-12 6:45 ` fweimer at redhat dot com
2024-03-12 9:32 ` levon at movementarian dot org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: fweimer at redhat dot com @ 2024-03-12 6:45 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=31476
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
See Also| |https://sourceware.org/bugz
| |illa/show_bug.cgi?id=29017
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* [Bug network/31476] Automatic activation of single-request options break resolv.conf reloading
2024-03-12 6:43 [Bug network/31476] New: Automatic activation of single-request options break resolv.conf reloading fweimer at redhat dot com
2024-03-12 6:45 ` [Bug network/31476] " fweimer at redhat dot com
@ 2024-03-12 9:32 ` levon at movementarian dot org
2024-06-10 9:57 ` fweimer at redhat dot com
2024-06-13 16:57 ` fweimer at redhat dot com
3 siblings, 0 replies; 5+ messages in thread
From: levon at movementarian dot org @ 2024-03-12 9:32 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=31476
John Levon <levon at movementarian dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |levon at movementarian dot org
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* [Bug network/31476] Automatic activation of single-request options break resolv.conf reloading
2024-03-12 6:43 [Bug network/31476] New: Automatic activation of single-request options break resolv.conf reloading fweimer at redhat dot com
2024-03-12 6:45 ` [Bug network/31476] " fweimer at redhat dot com
2024-03-12 9:32 ` levon at movementarian dot org
@ 2024-06-10 9:57 ` fweimer at redhat dot com
2024-06-13 16:57 ` fweimer at redhat dot com
3 siblings, 0 replies; 5+ messages in thread
From: fweimer at redhat dot com @ 2024-06-10 9:57 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=31476
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
CC| |fweimer at redhat dot com
Assignee|unassigned at sourceware dot org |fweimer at redhat dot com
--- Comment #1 from Florian Weimer <fweimer at redhat dot com> ---
Patch posted:
[PATCH] resolv: Track single-request fallback via _res._flags (bug 31476)
<https://inbox.sourceware.org/libc-alpha/87ikyhqfwy.fsf@oldenburg.str.redhat.com/>
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* [Bug network/31476] Automatic activation of single-request options break resolv.conf reloading
2024-03-12 6:43 [Bug network/31476] New: Automatic activation of single-request options break resolv.conf reloading fweimer at redhat dot com
` (2 preceding siblings ...)
2024-06-10 9:57 ` fweimer at redhat dot com
@ 2024-06-13 16:57 ` fweimer at redhat dot com
3 siblings, 0 replies; 5+ messages in thread
From: fweimer at redhat dot com @ 2024-06-13 16:57 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=31476
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |2.40
Resolution|--- |FIXED
Status|ASSIGNED |RESOLVED
--- Comment #2 from Florian Weimer <fweimer at redhat dot com> ---
Fixed for 2.40 via:
commit 868ab8923a2ec977faafec97ecafac0c3159c1b2
Author: Florian Weimer <fweimer@redhat.com>
Date: Thu Jun 13 18:56:30 2024 +0200
resolv: Track single-request fallback via _res._flags (bug 31476)
This avoids changing _res.options, which inteferes with change
detection as part of automatic reloading of /etc/resolv.conf.
Reviewed-by: DJ Delorie <dj@redhat.com>
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2024-03-12 6:43 [Bug network/31476] New: Automatic activation of single-request options break resolv.conf reloading fweimer at redhat dot com
2024-03-12 6:45 ` [Bug network/31476] " fweimer at redhat dot com
2024-03-12 9:32 ` levon at movementarian dot org
2024-06-10 9:57 ` fweimer at redhat dot com
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