kexec-tools/0001-kdumpctl-Drop-default-kexec-d-option.patch

From 32f9ada4bfa9f9690bdcdb21de40568c81a5ea80 Mon Sep 17 00:00:00 2001
From: Philipp Rudo <prudo@redhat.com>
Date: Fri, 14 Jun 2024 11:48:24 +0200
Subject: [PATCH 1/7] kdumpctl: Drop default kexec '-d' option

Kernel commits cbc2fe9d9cb2 ("kexec_file: add kexec_file flag to control
debug printing") and a85ee18c7900 ("kexec_file: print out debugging
message if required") added debug messages to the kexec_file_load system
call when option -d is provided to the kexec user space tool. As
kexec_file_load is the default and option -d is set by default these
messages are always printed when a crash kernel is loaded. This not only
clutters the kernel log but also potentially leaks confidential kernel
information to users. As the messages are printed to the kernel log, not
stderr, the redirection to /var/log/kdump.log won't catch them. This
will become even more problematic as for RHEL10 the kernel will be built
without support for the kexec_load system call. So kexec_file_load will
be the only choice in the future.

The redirection also caused confusion in a recent bug report. There a
user moved a working /etc/sysconfig/kdump from ppc to s390 with
KEXEC_ARGS containing the --dt-no-old-root option. This option is arch
specific and does not exist on s390. Thus the kexec-tools failed with an
'unrecognized option' error followed by the usage(). The problem was
that the 'unrecognized option' error is printed to stderr, which got
redirected to /var/log/kdump.log, while the usage() is printed to
stdout, which ended up in the systemd journal. This caused confusion as
the user only checked the journal and found the usage() without any
error message.

Thus remove the default -d option and the redirection of stderr to
/var/log/kdump.log for the kexec-tools user space tool.

This commit ultimately reverts 88a8b94 ("kdumpctl: add the '-d' option to
enable the kexec loading debugging messages").

Signed-off-by: Philipp Rudo <prudo@redhat.com>
---
 kdumpctl              | 21 +++------------------
 kexec-kdump-howto.txt |  7 +------
 2 files changed, 4 insertions(+), 24 deletions(-)

diff --git a/kdumpctl b/kdumpctl
index 30eb27d..8dc56e5 100755
--- a/kdumpctl
+++ b/kdumpctl
@@ -5,7 +5,6 @@ KDUMP_KERNELVER=""
 KDUMP_KERNEL=""
 KDUMP_COMMANDLINE=""
 KEXEC_ARGS=""
-KDUMP_LOG_PATH="/var/log"
 MKDUMPRD="/sbin/mkdumprd -f"
 MKFADUMPRD="/sbin/mkfadumprd"
 DRACUT_MODULES_FILE="/usr/lib/dracut/modules.txt"
@@ -17,7 +16,7 @@ TARGET_INITRD=""
 #kdump shall be the default dump mode
 DEFAULT_DUMP_MODE="kdump"
 
-standard_kexec_args="-d -p"
+standard_kexec_args="-p"
 
 # Some default values in case /etc/sysconfig/kdump doesn't include
 KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug"
@@ -696,7 +695,7 @@ function load_kdump_kernel_key()
 # as the currently running kernel.
 load_kdump()
 {
-	local ret uki
+	local uki
 
 	KEXEC_ARGS=$(prepare_kexec_args "${KEXEC_ARGS}")
 	KDUMP_COMMANDLINE=$(prepare_cmdline "${KDUMP_COMMANDLINE}" "${KDUMP_COMMANDLINE_REMOVE}" "${KDUMP_COMMANDLINE_APPEND}")
@@ -713,26 +712,12 @@ load_kdump()
 
 	ddebug "$KEXEC $KEXEC_ARGS $standard_kexec_args --command-line=$KDUMP_COMMANDLINE --initrd=$TARGET_INITRD $KDUMP_KERNEL"
 
-	# The '12' represents an intermediate temporary file descriptor
-	# to store the standard error file descriptor '2', and later
-	# restore the error file descriptor with the file descriptor '12'
-	# and release it.
-	exec 12>&2
-	exec 2>> $KDUMP_LOG_PATH/kdump.log
-	chmod 600 $KDUMP_LOG_PATH/kdump.log
-	PS4='+ $(date "+%Y-%m-%d %H:%M:%S") ${BASH_SOURCE}@${LINENO}: '
-	set -x
-
 	# shellcheck disable=SC2086
 	$KEXEC $KEXEC_ARGS $standard_kexec_args \
 		--command-line="$KDUMP_COMMANDLINE" \
 		--initrd="$TARGET_INITRD" "$KDUMP_KERNEL"
 
-	ret=$?
-	set +x
-	exec 2>&12 12>&-
-
-	if [[ $ret == 0 ]]; then
+	if [[ $? == 0 ]]; then
 		dinfo "kexec: loaded kdump kernel"
 		return 0
 	else
diff --git a/kexec-kdump-howto.txt b/kexec-kdump-howto.txt
index 6741faf..c65d45a 100644
--- a/kexec-kdump-howto.txt
+++ b/kexec-kdump-howto.txt
@@ -1016,12 +1016,7 @@ Debugging Tips
   and the second kernel.
 
   In the first kernel, you can find the historical logs with the journalctl
-  command and check kdump service debugging information. In addition, the
-  'kexec -d' debugging messages are also saved to /var/log/kdump.log in the
-  first kernel. For example:
-
-  [root@ibm-z-109 ~]# ls -al /var/log/kdump.log
-  -rw-r--r--. 1 root root 63238 Oct 28 06:40 /var/log/kdump.log
+  command and check kdump service debugging information.
 
   If you want to get the debugging information of building kdump initramfs, you
   can enable the '--debug' option for the dracut_args in the /etc/kdump.conf, and
-- 
2.45.2