This commit is contained in:
Joel Savitz 2021-05-18 15:38:43 -04:00
parent 8f7988d00c
commit 36b0af9c9e
3 changed files with 17 additions and 150 deletions

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@ -1,100 +0,0 @@
From cdee6bd650a35075515d4fe2bb67657811c9640c Mon Sep 17 00:00:00 2001
From: Joe Lawrence <joe.lawrence@redhat.com>
Date: Mon, 16 Nov 2020 15:21:59 -0500
Subject: [PATCH] kpatch: wait for module ref counts on unload
There exists a very small timing window in which "kpatch unload" gets to
its "rmmod" step before the kpatch-patch module's reference count has
cleared and the "rmmod" fails.
This is only a transient problem, but we can adopt code from upstream
livepatch kselftests which wait for the module refcounts to settle
before moving onto "rmmod".
A small wrinkle is that this is not supported by the older kpatch.ko
core. The price for circumventing the activeness safety check via
KPATCH_FORCE_UNSAFE is that it must leave the kpatch patch modules in
place (see e1890e627a9b ("prevent rmmod of forced modules")).
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
kpatch/kpatch | 40 ++++++++++++++++++++++++++++++++++++++--
1 file changed, 38 insertions(+), 2 deletions(-)
diff --git a/kpatch/kpatch b/kpatch/kpatch
index bca8f41..b35b742 100755
--- a/kpatch/kpatch
+++ b/kpatch/kpatch
@@ -28,6 +28,7 @@ SCRIPTDIR="$(readlink -f "$(dirname "$(type -p "$0")")")"
VERSION="0.9.2"
POST_ENABLE_WAIT=15 # seconds
POST_SIGNAL_WAIT=60 # seconds
+MODULE_REF_WAIT=15 # seconds
# How many times to try loading the patch if activeness safety check fails.
MAX_LOAD_ATTEMPTS=5
@@ -125,6 +126,10 @@ find_core_module() {
return 1
}
+kpatch_core_loaded() {
+ grep -q -e "T kpatch_register" /proc/kallsyms
+}
+
core_loaded () {
grep -q -e "T klp_enable_patch" -e "T kpatch_register" /proc/kallsyms
}
@@ -265,6 +270,31 @@ wait_for_patch_transition() {
return 1
}
+module_ref_count() {
+ local modname="$1"
+ [[ $(cat "/sys/module/$modname/refcnt" 2>/dev/null) != "0" ]]
+}
+
+wait_for_zero_module_ref_count() {
+ local modname="$1"
+ local i=0
+
+ # We can't rely on a zero refcount with kpatch.ko as it
+ # implements KPATCH_FORCE_UNSAFE with an additional reference on
+ # kpatch-patch modules to avoid potential crashes.
+ kpatch_core_loaded && return 0
+
+ module_ref_count "$modname" || return 0
+
+ echo "waiting (up to $MODULE_REF_WAIT seconds) for module refcount..."
+ for (( i=0; i<MODULE_REF_WAIT; i++ )); do
+ module_ref_count "$modname" || return 0
+ sleep 1s
+ done
+
+ return 1
+}
+
load_module () {
local module="$1"
@@ -381,10 +411,16 @@ disable_patch_strict () {
}
remove_module () {
- echo "unloading patch module: $1"
+ local modname="$1"
+
+ if ! wait_for_zero_module_ref_count "$modname"; then
+ die "failed to unload module $modname (refcnt)"
+ fi
+
+ echo "unloading patch module: $modname"
# ignore any error here because rmmod can fail if the module used
# KPATCH_FORCE_UNSAFE.
- rmmod "$1" 2> /dev/null || return 0
+ rmmod "$modname" 2> /dev/null || return 0
}
unload_module () {
--
2.25.4

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@ -1,39 +0,0 @@
From 73f6d5cdb2a4ce78cec6f49517116a3c7616f393 Mon Sep 17 00:00:00 2001
From: Joe Lawrence <joe.lawrence@redhat.com>
Date: Thu, 12 Nov 2020 15:15:47 -0500
Subject: [PATCH] Makefile: set install permission modes
By default, the install command will apply rwxr-xr-x permissions (how
intuitive). Give the command expected file modes to avoid rpmbuild
complaints like this:
*** WARNING: ./usr/lib/python3.9/site-packages/dnf-plugins/kpatch.py is executable but has no shebang, removing executable bit
*** WARNING: ./etc/dnf/plugins/kpatch.conf is executable but has no shebang, removing executable bit
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
Makefile | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/Makefile b/Makefile
index fb92d06..77c8eb5 100644
--- a/Makefile
+++ b/Makefile
@@ -23,11 +23,11 @@ all: $(TARGETS)
install: $(TARGETS)
install -d $(MANDIR)
- install man/dnf.kpatch.8.gz $(MANDIR)
+ install -m 644 man/dnf.kpatch.8.gz $(MANDIR)
install -d $(CONFDIR)
- install conf/kpatch.conf $(CONFDIR)
+ install -m 644 conf/kpatch.conf $(CONFDIR)
install -d $(DNFPLUGINDIR)
- install kpatch.py $(DNFPLUGINDIR)
+ install -m 644 kpatch.py $(DNFPLUGINDIR)
%.gz: %
gzip --keep $^
--
2.25.4

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@ -1,8 +1,8 @@
%define kpatch_dnf_ver 0.2
%define kpatch_dnf_ver 0.3
Name: kpatch
Version: 0.9.2
Release: 5%{?dist}
Version: 0.9.3
Release: 1%{?dist}
Summary: Dynamic kernel patch manager
Group: System Environment/Kernel
@ -15,11 +15,11 @@ Source1: kpatch-dnf-v%{kpatch_dnf_ver}.tar.gz
Patch0: 0001-contrib-disable-upstart-kpatch.conf-install.patch
Patch1: 0002-kpatch-clarify-unload-unsupport.patch
# Upstream backports
Patch100: 0100-kpatch-wait-for-module-ref-counts-on-unload.patch
# Upstream backports (inactive -- for future reference)
#Patch100: 0100-kpatch-wait-for-module-ref-counts-on-unload.patch
# kpatch-dnf backports
Patch200: 0200-Makefile-set-install-permission-modes.patch
# kpatch-dnf backports (inactive -- for future reference)
#Patch200: 0200-foo-bar-etcetera.patch
Requires: bash kmod binutils
Recommends: kpatch-dnf
@ -49,12 +49,15 @@ kpatch-patch packages updates.
%setup -q
%patch0 -p1
%patch1 -p1
%patch100 -p1
# Use this to apply upstream patches to kpatch (inactive)
#%patch100 -p1
%setup -D -T -a 1
cd kpatch-dnf-%{kpatch_dnf_ver}
%patch200 -p1
cd ..
# Use this to apply patches to kpatch-dnf (inactive)
#cd kpatch-dnf-%{kpatch_dnf_ver}
#%patch200 -p1
#cd ..
%build
make -C man
@ -85,6 +88,9 @@ echo "To enable automatic kpatch-patch subscription, run:"
echo -e "\t$ dnf kpatch auto"
%changelog
* Tue May 18 2021 Joel Savitz <jsavitz@redhat.com> - 0.9.3-1
- Rebase to latest upstream
* Fri Apr 16 2021 Mohan Boddu <mboddu@redhat.com> - 0.9.2-5
- Rebuilt for RHEL 9 BETA on Apr 15th 2021. Related: rhbz#1947937