- Fix use of DNS in the panic environment (bsc#1183070):

* kdump-avoid-endless-loop-on-EAI_AGAIN.patch: Avoid an endless
    loop when resolving a hostname fails with EAI_AGAIN.
  * kdump-install-real-resolv.conf.patch: Install /etc/resolv.conf
    using its resolved path.

OBS-URL: https://build.opensuse.org/package/show/Kernel:kdump/kdump?expand=0&rev=211

kdump-avoid-endless-loop-on-EAI_AGAIN.patch

@@ -0,0 +1,102 @@
+From: Petr Pavlu <petr.pavlu@suse.com>
+Date: Thu Mar 25 12:48:54 2021 +0100
+Subject: Avoid an endless loop when resolving a hostname fails with EAI_AGAIN
+References: bsc#1183070
+Upstream: merged
+Git-commit: 716883423f45acf3271c200353dce074d6ffc5be
+
+Method Routable::resolve() invokes function getaddrinfo() to obtain a
+network address for a given hostname. This operation can fail with the
+error code EAI_AGAIN to indicate that the name server encountered a
+temporary failure. Routable::resolve() reacts to this situation by
+calling getaddrinfo() again which can result in an endless loop if the
+function continues to return this error code. It is not guaranteed that
+the underlying reason for EAI_AGAIN will go away in some bounded time.
+
+The patch removes the EAI_AGAIN loop in Routable::resolve() and updates
+the retry code in Routable::check() to repeatedly attempt resolving a
+hostname until it succeeds or a specified timeout for network operations
+is reached.
+
+---
+ kdumptool/routable.cc |   38 ++++++++++++++++++++++++++++++--------
+ 1 file changed, 30 insertions(+), 8 deletions(-)
+
+--- a/kdumptool/routable.cc
++++ b/kdumptool/routable.cc
+@@ -17,6 +17,7 @@
+  * 02110-1301, USA.
+  */
+ 
++#include <algorithm>
+ #include <string.h>
+ 
+ #include <unistd.h>
+@@ -36,6 +37,8 @@
+ #include "stringutil.h"
+ #include "debug.h"
+ 
++using std::min;
++
+ //{{{ NetLink ------------------------------------------------------------------
+ 
+ #define NETLINK_DEF_RECV_MAX	1024
+@@ -470,9 +473,7 @@ bool Routable::resolve(void)
+     memset(&hints, 0, sizeof hints);
+     hints.ai_family = AF_UNSPEC;
+     hints.ai_socktype = SOCK_RAW;
+-    do {
+-	res = getaddrinfo(raw_host.c_str(), NULL, &hints, &m_ai);
+-    } while (res == EAI_AGAIN);
++    res = getaddrinfo(raw_host.c_str(), NULL, &hints, &m_ai);
+ 
+     if (res == 0)
+ 	return true;
+@@ -480,7 +481,8 @@ bool Routable::resolve(void)
+     if (res == EAI_SYSTEM)
+ 	throw KSystemError("Name resolution failed", errno);
+ 
+-    if (res != EAI_NONAME && res != EAI_FAIL && res != EAI_NODATA)
++    if (res != EAI_NONAME && res != EAI_FAIL && res != EAI_NODATA &&
++        res != EAI_AGAIN)
+ 	throw KGaiError("Name resolution failed", res);
+ 
+     return false;
+@@ -489,13 +491,33 @@ bool Routable::resolve(void)
+ // -----------------------------------------------------------------------------
+ bool Routable::check(int timeout)
+ {
++    // Resolve the target hostname. An attempt is made regularly until the
++    // hostname can be resolved or a specified timeout for network operations
++    // is reached.
++    struct timespec tstop;
++    clock_gettime(CLOCK_MONOTONIC, &tstop);
++    tstop.tv_sec += timeout;
++
++    while (!resolve()) {
++        struct timespec tsnow;
++        clock_gettime(CLOCK_MONOTONIC, &tsnow);
++        int interval = (tstop.tv_sec - tsnow.tv_sec) * 1000;
++        interval += (tstop.tv_nsec - tsnow.tv_nsec) / 1000000L;
++        if (interval <= 0)
++            return false;
++
++        // Sleep, at most for 1 second.
++        struct timespec wait_period;
++        interval = min(interval, 1000);
++        wait_period.tv_sec = interval / 1000;
++        wait_period.tv_nsec = (interval % 1000) * 1000 * 1000;
++        nanosleep(&wait_period, NULL);
++    }
++
++    // Check there is an existing route.
+     NetLink nl(RTMGRP_IPV4_ROUTE | RTMGRP_IPV6_ROUTE);
+     nl.setTimeout(timeout);
+ 
+-    while (!resolve())
+-	if (nl.waitRouteChange() != 0)
+-	    return false;
+-
+     while (!hasRoute())
+ 	if (nl.waitRouteChange() != 0)
+ 	    return false;

kdump-install-real-resolv.conf.patch

@@ -0,0 +1,36 @@
+From: Petr Pavlu <petr.pavlu@suse.com>
+Date: Thu Mar 25 12:43:32 2021 +0100
+Subject: Install /etc/resolv.conf using its resolved path
+References: bsc#1183070
+Upstream: merged
+Git-commit: b8439e03d4479f3ffa4b42961a5da18f4b819122
+
+Resolve /etc/resolv.conf first to install directly the target file if it
+is a symlink. This simplifies the setup and avoids any problems when the
+real resolv.conf could be in a location that gets hidden by a mount done
+in the kdump environment, for instance, /etc/resolv.conf ->
+/run/netconfig/resolv.conf with tmpfs getting mounted on /run.
+
+---
+ init/module-setup.sh |   10 +++++++++-
+ 1 file changed, 9 insertions(+), 1 deletion(-)
+
+--- a/init/module-setup.sh
++++ b/init/module-setup.sh
+@@ -308,7 +308,15 @@ install() {
+ 
+     inst_multiple makedumpfile makedumpfile-R.pl kdumptool \
+ 	$KDUMP_REQUIRED_PROGRAMS
+-    inst_simple /etc/resolv.conf
++
++    # Install /etc/resolv.conf to provide initial DNS configuration. The file
++    # is resolved first to install directly the target file if it is a symlink.
++    # The real resolv.conf could be in a location that gets hidden by a mount
++    # done in the kdump environment, for instance, /etc/resolv.conf ->
++    # /run/netconfig/resolv.conf with tmpfs getting mounted on /run.
++    local resolv=$(realpath /etc/resolv.conf)
++    inst_simple "$resolv" /etc/resolv.conf
++
+     inst_simple /usr/share/zoneinfo/UTC
+     inst_simple /etc/localtime
+ }

kdump.changes

@@ -1,3 +1,12 @@
+-------------------------------------------------------------------
+Fri May 28 10:33:45 UTC 2021 - Petr Tesařík <ptesarik@suse.com>
+
+- Fix use of DNS in the panic environment (bsc#1183070):
+  * kdump-avoid-endless-loop-on-EAI_AGAIN.patch: Avoid an endless
+    loop when resolving a hostname fails with EAI_AGAIN.
+  * kdump-install-real-resolv.conf.patch: Install /etc/resolv.conf
+    using its resolved path.
+
 -------------------------------------------------------------------
 Fri May 28 09:51:58 UTC 2021 - Petr Tesařík <ptesarik@suse.com>
 

kdump.spec

@@ -39,6 +39,8 @@ Patch11:        %{name}-mounts.cc-Include-sys-ioctl.h.patch
 Patch12:        %{name}-Add-bootdev-to-dracut-command-line.patch
 Patch13:        %{name}-do-not-iterate-past-end-of-string.patch
 Patch14:        %{name}-fix-incorrect-exit-code-checking.patch
+Patch15:        %{name}-avoid-endless-loop-on-EAI_AGAIN.patch
+Patch16:        %{name}-install-real-resolv.conf.patch
 BuildRequires:  asciidoc
 BuildRequires:  cmake
 BuildRequires:  gcc-c++
@@ -97,6 +99,8 @@ after a crash dump has occured.
 %patch12 -p1
 %patch13 -p1
 %patch14 -p1
+%patch15 -p1
+%patch16 -p1
 
 %build
 export CXXFLAGS="%{optflags} -std=c++11"