[pve-devel] [PATCH v2 container 0/2] fix #5160: fix move_mount regression for mount point hotplug

[pve-devel] [PATCH v2 container 0/2] fix #5160: fix move_mount regression for mount point hotplug

[Filip Schauer]

Changes since v1:
* Fix loading of apparmor profile not working in postinst, since the
  profile is not found by dh_apparmor. This is fixed by moving
  pve-container-mounthotplug out of the pve subdirectory.
* Fix a perl undef warning when apparmor changeprofile fails.

Filip Schauer (2):
  fix #5160: fix move_mount regression for mount point hotplug
  fix undef warning when apparmor changeprofile fails

 debian/rules                     | 3 +++
 src/Makefile                     | 3 +++
 src/PVE/LXC.pm                   | 5 +++--
 src/pve-container-debug@.service | 1 +
 src/pve-container-mounthotplug   | 7 +++++++
 src/pve-container@.service       | 1 +
 6 files changed, 18 insertions(+), 2 deletions(-)
 create mode 100644 src/pve-container-mounthotplug

-- 
2.39.2

[pve-devel] [PATCH v2 container 1/2] fix #5160: fix move_mount regression for mount point hotplug

[Filip Schauer]

Set up an Apparmor profile to allow moving mounts for mount point
hotplug.

This fixes a regression caused by
kernel commit 157a3537d6 ("apparmor: Fix regression in mount mediation")

The commit introduced move_mount mediation, which now requires
move_mount to be allowed in the Apparmor profile. Although it is allowed
for most paths in the /usr/bin/lxc-start profile, move_mount is called
with a file descriptor instead of a path in mountpoint_insert_staged,
thus it is not affected by the allow rules in
/etc/apparmor.d/abstractions/lxc/container-base.

To fix this, introduce a new Apparmor profile to allow move_mount on
every mount, specifically for mount point hotplug.

Signed-off-by: Filip Schauer <f.schauer@proxmox.com>
---
 debian/rules                     | 3 +++
 src/Makefile                     | 3 +++
 src/PVE/LXC.pm                   | 2 +-
 src/pve-container-debug@.service | 1 +
 src/pve-container-mounthotplug   | 7 +++++++
 src/pve-container@.service       | 1 +
 6 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 src/pve-container-mounthotplug

diff --git a/debian/rules b/debian/rules
index d999152..f7edccf 100755
--- a/debian/rules
+++ b/debian/rules
@@ -14,3 +14,6 @@
 
 override_dh_installsystemd:
 	dh_installsystemd -ppve-container --no-start --no-enable --no-restart-after-upgrade -r 'system-pve\x2dcontainer.slice'
+
+override_dh_install:
+	dh_apparmor -p pve-container --profile-name=pve-container-mounthotplug
diff --git a/src/Makefile b/src/Makefile
index 5a7a82e..e0b7734 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -4,6 +4,7 @@ PREFIX=${DESTDIR}/usr
 BINDIR=${PREFIX}/bin
 LIBDIR=${PREFIX}/lib
 SBINDIR=${PREFIX}/sbin
+ETCDIR=${DESTDIR}/etc
 MANDIR=${PREFIX}/share/man
 DOCDIR=${PREFIX}/share/doc/${PACKAGE}
 LXC_SCRIPT_DIR=${PREFIX}/share/lxc
@@ -13,6 +14,7 @@ LXC_CONFIG_DIR=${LXC_SCRIPT_DIR}/config
 LXC_COMMON_CONFIG_DIR=${LXC_CONFIG_DIR}/common.conf.d
 LXC_USERNS_CONFIG_DIR=${LXC_CONFIG_DIR}/userns.conf.d
 SERVICEDIR=${DESTDIR}/lib/systemd/system
+APPARMORDDIR=${ETCDIR}/apparmor.d
 PODDIR=${DOCDIR}/pod
 MAN1DIR=${MANDIR}/man1/
 MAN5DIR=${MANDIR}/man5/
@@ -73,6 +75,7 @@ install: pct lxc-pve.conf pct.1 pct.conf.5 pct.bash-completion pct.zsh-completio
 	gzip -9 ${MAN5DIR}/pct.conf.5
 	cd ${MAN5DIR}; ln -s pct.conf.5.gz ct.conf.5.gz
 	install -D -m 0644 10-pve-ct-inotify-limits.conf ${LIBDIR}/sysctl.d/10-pve-ct-inotify-limits.conf
+	install -D -m 0644 pve-container-mounthotplug ${APPARMORDDIR}/pve-container-mounthotplug
 
 pve-userns.seccomp: /usr/share/lxc/config/common.seccomp
 	cp $< $@
diff --git a/src/PVE/LXC.pm b/src/PVE/LXC.pm
index 7883cfb..7db4833 100644
--- a/src/PVE/LXC.pm
+++ b/src/PVE/LXC.pm
@@ -1974,7 +1974,7 @@ sub mountpoint_hotplug :prototype($$$$$) {
 	my $dir = get_staging_mount_path($opt);
 
 	# Now switch our apparmor profile before mounting:
-	my $data = 'changeprofile /usr/bin/lxc-start';
+	my $data = 'changeprofile pve-container-mounthotplug';
 	if (syswrite($aa_fd, $data, length($data)) != length($data)) {
 	    die "failed to change apparmor profile: $!\n";
 	}
diff --git a/src/pve-container-debug@.service b/src/pve-container-debug@.service
index 7cfebaa..cd0895c 100644
--- a/src/pve-container-debug@.service
+++ b/src/pve-container-debug@.service
@@ -13,6 +13,7 @@ Type=simple
 Delegate=yes
 KillMode=mixed
 TimeoutStopSec=120s
+ExecStartPre=/lib/apparmor/profile-load pve-container-mounthotplug
 ExecStart=/usr/bin/lxc-start -F -n %i -o /dev/stderr -l DEBUG
 ExecStop=/usr/share/lxc/pve-container-stop-wrapper %i
 # Environment=BOOTUP=serial
diff --git a/src/pve-container-mounthotplug b/src/pve-container-mounthotplug
new file mode 100644
index 0000000..e6f3903
--- /dev/null
+++ b/src/pve-container-mounthotplug
@@ -0,0 +1,7 @@
+#include <tunables/global>
+
+profile pve-container-mounthotplug flags=(attach_disconnected) {
+  #include <abstractions/lxc/start-container>
+
+  mount options=(move),
+}
diff --git a/src/pve-container@.service b/src/pve-container@.service
index fdc373e..1437858 100644
--- a/src/pve-container@.service
+++ b/src/pve-container@.service
@@ -13,6 +13,7 @@ Type=simple
 Delegate=yes
 KillMode=mixed
 TimeoutStopSec=120s
+ExecStartPre=/lib/apparmor/profile-load pve-container-mounthotplug
 ExecStart=/usr/bin/lxc-start -F -n %i
 ExecStop=/usr/share/lxc/pve-container-stop-wrapper %i
 # Environment=BOOTUP=serial
-- 
2.39.2

[pve-devel] [PATCH v2 container 2/2] fix undef warning when apparmor changeprofile fails

[Filip Schauer]

Fix a "Use of uninitialized value in numeric ne (!=)" warning when
syswrite returns undef when trying to change the apparmor profile.

Signed-off-by: Filip Schauer <f.schauer@proxmox.com>
---
 src/PVE/LXC.pm | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/PVE/LXC.pm b/src/PVE/LXC.pm
index 7db4833..88a9d6f 100644
--- a/src/PVE/LXC.pm
+++ b/src/PVE/LXC.pm
@@ -1975,7 +1975,8 @@ sub mountpoint_hotplug :prototype($$$$$) {
 
 	# Now switch our apparmor profile before mounting:
 	my $data = 'changeprofile pve-container-mounthotplug';
-	if (syswrite($aa_fd, $data, length($data)) != length($data)) {
+	my $data_written = syswrite($aa_fd, $data, length($data));
+	if (!defined($data_written) || $data_written != length($data)) {
 	    die "failed to change apparmor profile: $!\n";
 	}
 	# Check errors on close as well:
-- 
2.39.2

Re: [pve-devel] [PATCH v2 container 1/2] fix #5160: fix move_mount regression for mount point hotplug

[Wolfgang Bumiller]

looks mostly good, just the ExecStartPre= lines in the service files
should be dropped

On Mon, Mar 25, 2024 at 06:28:28PM +0100, Filip Schauer wrote:
> Set up an Apparmor profile to allow moving mounts for mount point
> hotplug.
> 
> This fixes a regression caused by
> kernel commit 157a3537d6 ("apparmor: Fix regression in mount mediation")
> 
> The commit introduced move_mount mediation, which now requires
> move_mount to be allowed in the Apparmor profile. Although it is allowed
> for most paths in the /usr/bin/lxc-start profile, move_mount is called
> with a file descriptor instead of a path in mountpoint_insert_staged,
> thus it is not affected by the allow rules in
> /etc/apparmor.d/abstractions/lxc/container-base.
> 
> To fix this, introduce a new Apparmor profile to allow move_mount on
> every mount, specifically for mount point hotplug.
> 
> Signed-off-by: Filip Schauer <f.schauer@proxmox.com>
> ---
>  debian/rules                     | 3 +++
>  src/Makefile                     | 3 +++
>  src/PVE/LXC.pm                   | 2 +-
>  src/pve-container-debug@.service | 1 +
>  src/pve-container-mounthotplug   | 7 +++++++
>  src/pve-container@.service       | 1 +
>  6 files changed, 16 insertions(+), 1 deletion(-)
>  create mode 100644 src/pve-container-mounthotplug
> 
> diff --git a/debian/rules b/debian/rules
> index d999152..f7edccf 100755
> --- a/debian/rules
> +++ b/debian/rules
> @@ -14,3 +14,6 @@
>  
>  override_dh_installsystemd:
>  	dh_installsystemd -ppve-container --no-start --no-enable --no-restart-after-upgrade -r 'system-pve\x2dcontainer.slice'
> +
> +override_dh_install:
> +	dh_apparmor -p pve-container --profile-name=pve-container-mounthotplug
> diff --git a/src/Makefile b/src/Makefile
> index 5a7a82e..e0b7734 100644
> --- a/src/Makefile
> +++ b/src/Makefile
> @@ -4,6 +4,7 @@ PREFIX=${DESTDIR}/usr
>  BINDIR=${PREFIX}/bin
>  LIBDIR=${PREFIX}/lib
>  SBINDIR=${PREFIX}/sbin
> +ETCDIR=${DESTDIR}/etc
>  MANDIR=${PREFIX}/share/man
>  DOCDIR=${PREFIX}/share/doc/${PACKAGE}
>  LXC_SCRIPT_DIR=${PREFIX}/share/lxc
> @@ -13,6 +14,7 @@ LXC_CONFIG_DIR=${LXC_SCRIPT_DIR}/config
>  LXC_COMMON_CONFIG_DIR=${LXC_CONFIG_DIR}/common.conf.d
>  LXC_USERNS_CONFIG_DIR=${LXC_CONFIG_DIR}/userns.conf.d
>  SERVICEDIR=${DESTDIR}/lib/systemd/system
> +APPARMORDDIR=${ETCDIR}/apparmor.d
>  PODDIR=${DOCDIR}/pod
>  MAN1DIR=${MANDIR}/man1/
>  MAN5DIR=${MANDIR}/man5/
> @@ -73,6 +75,7 @@ install: pct lxc-pve.conf pct.1 pct.conf.5 pct.bash-completion pct.zsh-completio
>  	gzip -9 ${MAN5DIR}/pct.conf.5
>  	cd ${MAN5DIR}; ln -s pct.conf.5.gz ct.conf.5.gz
>  	install -D -m 0644 10-pve-ct-inotify-limits.conf ${LIBDIR}/sysctl.d/10-pve-ct-inotify-limits.conf
> +	install -D -m 0644 pve-container-mounthotplug ${APPARMORDDIR}/pve-container-mounthotplug
>  
>  pve-userns.seccomp: /usr/share/lxc/config/common.seccomp
>  	cp $< $@
> diff --git a/src/PVE/LXC.pm b/src/PVE/LXC.pm
> index 7883cfb..7db4833 100644
> --- a/src/PVE/LXC.pm
> +++ b/src/PVE/LXC.pm
> @@ -1974,7 +1974,7 @@ sub mountpoint_hotplug :prototype($$$$$) {
>  	my $dir = get_staging_mount_path($opt);
>  
>  	# Now switch our apparmor profile before mounting:
> -	my $data = 'changeprofile /usr/bin/lxc-start';
> +	my $data = 'changeprofile pve-container-mounthotplug';
>  	if (syswrite($aa_fd, $data, length($data)) != length($data)) {
>  	    die "failed to change apparmor profile: $!\n";
>  	}
> diff --git a/src/pve-container-debug@.service b/src/pve-container-debug@.service
> index 7cfebaa..cd0895c 100644
> --- a/src/pve-container-debug@.service
> +++ b/src/pve-container-debug@.service
> @@ -13,6 +13,7 @@ Type=simple
>  Delegate=yes
>  KillMode=mixed
>  TimeoutStopSec=120s
> +ExecStartPre=/lib/apparmor/profile-load pve-container-mounthotplug
>  ExecStart=/usr/bin/lxc-start -F -n %i -o /dev/stderr -l DEBUG
>  ExecStop=/usr/share/lxc/pve-container-stop-wrapper %i
>  # Environment=BOOTUP=serial

^ This hunk should be dropped. The entry in d/rules is enough, and this
is the wrong place anyway, as this is triggered when starting a new
container, and not when hotplugging.

> diff --git a/src/pve-container-mounthotplug b/src/pve-container-mounthotplug
> new file mode 100644
> index 0000000..e6f3903
> --- /dev/null
> +++ b/src/pve-container-mounthotplug
> @@ -0,0 +1,7 @@
> +#include <tunables/global>
> +
> +profile pve-container-mounthotplug flags=(attach_disconnected) {
> +  #include <abstractions/lxc/start-container>
> +
> +  mount options=(move),
> +}
> diff --git a/src/pve-container@.service b/src/pve-container@.service
> index fdc373e..1437858 100644
> --- a/src/pve-container@.service
> +++ b/src/pve-container@.service
> @@ -13,6 +13,7 @@ Type=simple
>  Delegate=yes
>  KillMode=mixed
>  TimeoutStopSec=120s
> +ExecStartPre=/lib/apparmor/profile-load pve-container-mounthotplug
>  ExecStart=/usr/bin/lxc-start -F -n %i
>  ExecStop=/usr/share/lxc/pve-container-stop-wrapper %i
>  # Environment=BOOTUP=serial

^ same for this one

Re: [pve-devel] [PATCH v2 container 1/2] fix #5160: fix move_mount regression for mount point hotplug

[Filip Schauer]

Agreed. This appear to be a leftover from testing. A patch v3 with this
removed is available:

https://lists.proxmox.com/pipermail/pve-devel/2024-April/062693.html

On 09/04/2024 10:23, Wolfgang Bumiller wrote:
>> diff --gita/src/pve-container-debug@.service  b/src/pve-container-debug@.service
>> index 7cfebaa..cd0895c 100644
>> ---a/src/pve-container-debug@.service
>> +++b/src/pve-container-debug@.service
>> @@ -13,6 +13,7 @@ Type=simple
>>   Delegate=yes
>>   KillMode=mixed
>>   TimeoutStopSec=120s
>> +ExecStartPre=/lib/apparmor/profile-load pve-container-mounthotplug
>>   ExecStart=/usr/bin/lxc-start -F -n %i -o /dev/stderr -l DEBUG
>>   ExecStop=/usr/share/lxc/pve-container-stop-wrapper %i
>>   # Environment=BOOTUP=serial
> ^ This hunk should be dropped. The entry in d/rules is enough, and this
> is the wrong place anyway, as this is triggered when starting a new
> container, and not when hotplugging.