configure | 9 ++++- meson.build | 10 +++++- meson_options.txt | 3 ++ qemu-nbd.c | 33 +++++++++++++++++++ tests/docker/dockerfiles/centos8.docker | 1 + tests/docker/dockerfiles/fedora.docker | 1 + tests/docker/dockerfiles/opensuse-leap.docker | 1 + tests/docker/dockerfiles/ubuntu1804.docker | 1 + tests/docker/dockerfiles/ubuntu2004.docker | 1 + 9 files changed, 58 insertions(+), 2 deletions(-)
Under SELinux, Unix domain sockets have two labels. One is on the
disk and can be set with commands such as chcon(1). There is a
different label stored in memory (called the process label). This can
only be set by the process creating the socket. When using SELinux +
SVirt and wanting qemu to be able to connect to a qemu-nbd instance,
you must set both labels correctly first.
For qemu-nbd the options to set the second label are awkward. You can
create the socket in a wrapper program and then exec into qemu-nbd.
Or you could try something with LD_PRELOAD.
This commit adds the ability to set the label straightforwardly on the
command line, via the new --selinux-label flag. (The name of the flag
is the same as the equivalent nbdkit option.)
A worked example showing how to use the new option can be found in
this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1984938
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1984938
Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
---
configure | 9 ++++-
meson.build | 10 +++++-
meson_options.txt | 3 ++
qemu-nbd.c | 33 +++++++++++++++++++
tests/docker/dockerfiles/centos8.docker | 1 +
tests/docker/dockerfiles/fedora.docker | 1 +
tests/docker/dockerfiles/opensuse-leap.docker | 1 +
tests/docker/dockerfiles/ubuntu1804.docker | 1 +
tests/docker/dockerfiles/ubuntu2004.docker | 1 +
9 files changed, 58 insertions(+), 2 deletions(-)
diff --git a/configure b/configure
index b5965b159f..7e04bd485f 100755
--- a/configure
+++ b/configure
@@ -443,6 +443,7 @@ fuse="auto"
fuse_lseek="auto"
multiprocess="auto"
slirp_smbd="$default_feature"
+selinux="auto"
malloc_trim="auto"
gio="$default_feature"
@@ -1578,6 +1579,10 @@ for opt do
;;
--disable-slirp-smbd) slirp_smbd=no
;;
+ --enable-selinux) selinux="enabled"
+ ;;
+ --disable-selinux) selinux="disabled"
+ ;;
*)
echo "ERROR: unknown option $opt"
echo "Try '$0 --help' for more information"
@@ -1965,6 +1970,7 @@ disabled with --disable-FEATURE, default is enabled if available
multiprocess Out of process device emulation support
gio libgio support
slirp-smbd use smbd (at path --smbd=*) in slirp networking
+ selinux SELinux support in qemu-nbd
NOTE: The object files are built at the place where configure is launched
EOF
@@ -5220,7 +5226,8 @@ if test "$skip_meson" = no; then
-Dattr=$attr -Ddefault_devices=$default_devices -Dvirglrenderer=$virglrenderer \
-Ddocs=$docs -Dsphinx_build=$sphinx_build -Dinstall_blobs=$blobs \
-Dvhost_user_blk_server=$vhost_user_blk_server -Dmultiprocess=$multiprocess \
- -Dfuse=$fuse -Dfuse_lseek=$fuse_lseek -Dguest_agent_msi=$guest_agent_msi -Dbpf=$bpf\
+ -Dfuse=$fuse -Dfuse_lseek=$fuse_lseek -Dguest_agent_msi=$guest_agent_msi -Dbpf=$bpf \
+ -Dselinux=$selinux \
$(if test "$default_features" = no; then echo "-Dauto_features=disabled"; fi) \
-Dtcg_interpreter=$tcg_interpreter \
$cross_arg \
diff --git a/meson.build b/meson.build
index 2f377098d7..2d7206233e 100644
--- a/meson.build
+++ b/meson.build
@@ -1064,6 +1064,11 @@ keyutils = dependency('libkeyutils', required: false,
has_gettid = cc.has_function('gettid')
+# libselinux
+selinux = dependency('libselinux',
+ required: get_option('selinux'),
+ method: 'pkg-config', kwargs: static_kwargs)
+
# Malloc tests
malloc = []
@@ -1291,6 +1296,7 @@ config_host_data.set('CONFIG_FUSE', fuse.found())
config_host_data.set('CONFIG_FUSE_LSEEK', fuse_lseek.found())
config_host_data.set('CONFIG_X11', x11.found())
config_host_data.set('CONFIG_CFI', get_option('cfi'))
+config_host_data.set('CONFIG_SELINUX', selinux.found())
config_host_data.set('QEMU_VERSION', '"@0@"'.format(meson.project_version()))
config_host_data.set('QEMU_VERSION_MAJOR', meson.project_version().split('.')[0])
config_host_data.set('QEMU_VERSION_MINOR', meson.project_version().split('.')[1])
@@ -2739,7 +2745,8 @@ if have_tools
qemu_io = executable('qemu-io', files('qemu-io.c'),
dependencies: [block, qemuutil], install: true)
qemu_nbd = executable('qemu-nbd', files('qemu-nbd.c'),
- dependencies: [blockdev, qemuutil, gnutls], install: true)
+ dependencies: [blockdev, qemuutil, gnutls, selinux],
+ install: true)
subdir('storage-daemon')
subdir('contrib/rdmacm-mux')
@@ -3104,6 +3111,7 @@ summary_info += {'libpmem support': libpmem.found()}
summary_info += {'libdaxctl support': libdaxctl.found()}
summary_info += {'libudev': libudev.found()}
summary_info += {'FUSE lseek': fuse_lseek.found()}
+summary_info += {'selinux': selinux.found()}
summary(summary_info, bool_yn: true, section: 'Dependencies')
if not supported_cpus.contains(cpu)
diff --git a/meson_options.txt b/meson_options.txt
index a9a9b8f4c6..a5938500a3 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -155,3 +155,6 @@ option('slirp', type: 'combo', value: 'auto',
option('fdt', type: 'combo', value: 'auto',
choices: ['disabled', 'enabled', 'auto', 'system', 'internal'],
description: 'Whether and how to find the libfdt library')
+
+option('selinux', type: 'feature', value: 'auto',
+ description: 'SELinux support in qemu-nbd')
diff --git a/qemu-nbd.c b/qemu-nbd.c
index 26ffbf15af..003ba2492e 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -47,6 +47,10 @@
#include "trace/control.h"
#include "qemu-version.h"
+#ifdef CONFIG_SELINUX
+#include <selinux/selinux.h>
+#endif
+
#ifdef __linux__
#define HAVE_NBD_DEVICE 1
#else
@@ -64,6 +68,7 @@
#define QEMU_NBD_OPT_FORK 263
#define QEMU_NBD_OPT_TLSAUTHZ 264
#define QEMU_NBD_OPT_PID_FILE 265
+#define QEMU_NBD_OPT_SELINUX_LABEL 266
#define MBR_SIZE 512
@@ -116,6 +121,9 @@ static void usage(const char *name)
" --fork fork off the server process and exit the parent\n"
" once the server is running\n"
" --pid-file=PATH store the server's process ID in the given file\n"
+#ifdef CONFIG_SELINUX
+" --selinux-label=LABEL set SELinux process label on listening socket\n"
+#endif
#if HAVE_NBD_DEVICE
"\n"
"Kernel NBD client support:\n"
@@ -532,6 +540,8 @@ int main(int argc, char **argv)
{ "trace", required_argument, NULL, 'T' },
{ "fork", no_argument, NULL, QEMU_NBD_OPT_FORK },
{ "pid-file", required_argument, NULL, QEMU_NBD_OPT_PID_FILE },
+ { "selinux-label", required_argument, NULL,
+ QEMU_NBD_OPT_SELINUX_LABEL },
{ NULL, 0, NULL, 0 }
};
int ch;
@@ -558,6 +568,7 @@ int main(int argc, char **argv)
int old_stderr = -1;
unsigned socket_activation;
const char *pid_file_name = NULL;
+ const char *selinux_label = NULL;
BlockExportOptions *export_opts;
#ifdef CONFIG_POSIX
@@ -747,6 +758,9 @@ int main(int argc, char **argv)
case QEMU_NBD_OPT_PID_FILE:
pid_file_name = optarg;
break;
+ case QEMU_NBD_OPT_SELINUX_LABEL:
+ selinux_label = optarg;
+ break;
}
}
@@ -938,6 +952,16 @@ int main(int argc, char **argv)
} else {
backlog = MIN(shared, SOMAXCONN);
}
+ if (sockpath && selinux_label) {
+#ifdef CONFIG_SELINUX
+ if (setsockcreatecon_raw(selinux_label) == -1) {
+ error_report("Cannot set SELinux socket create context "
+ "to %s: %s",
+ selinux_label, strerror(errno));
+ exit(EXIT_FAILURE);
+ }
+#endif
+ }
saddr = nbd_build_socket_address(sockpath, bindto, port);
if (qio_net_listener_open_sync(server, saddr, backlog,
&local_err) < 0) {
@@ -945,6 +969,15 @@ int main(int argc, char **argv)
error_report_err(local_err);
exit(EXIT_FAILURE);
}
+ if (sockpath && selinux_label) {
+#ifdef CONFIG_SELINUX
+ if (setsockcreatecon_raw(NULL) == -1) {
+ error_report("Cannot clear SELinux socket create context: %s",
+ strerror(errno));
+ exit(EXIT_FAILURE);
+ }
+#endif
+ }
} else {
size_t i;
/* See comment in check_socket_activation above. */
diff --git a/tests/docker/dockerfiles/centos8.docker b/tests/docker/dockerfiles/centos8.docker
index 46398c61ee..7f135f8e8c 100644
--- a/tests/docker/dockerfiles/centos8.docker
+++ b/tests/docker/dockerfiles/centos8.docker
@@ -51,6 +51,7 @@ ENV PACKAGES \
libpng-devel \
librbd-devel \
libseccomp-devel \
+ libselinux-devel \
libslirp-devel \
libssh-devel \
libtasn1-devel \
diff --git a/tests/docker/dockerfiles/fedora.docker b/tests/docker/dockerfiles/fedora.docker
index eec1add7f6..c6fd7e1113 100644
--- a/tests/docker/dockerfiles/fedora.docker
+++ b/tests/docker/dockerfiles/fedora.docker
@@ -53,6 +53,7 @@ ENV PACKAGES \
libpng-devel \
librbd-devel \
libseccomp-devel \
+ libselinux-devel \
libslirp-devel \
libssh-devel \
libtasn1-devel \
diff --git a/tests/docker/dockerfiles/opensuse-leap.docker b/tests/docker/dockerfiles/opensuse-leap.docker
index 5a8bee0289..3bbdb67f4f 100644
--- a/tests/docker/dockerfiles/opensuse-leap.docker
+++ b/tests/docker/dockerfiles/opensuse-leap.docker
@@ -55,6 +55,7 @@ ENV PACKAGES \
libpulse-devel \
librbd-devel \
libseccomp-devel \
+ libselinux-devel \
libspice-server-devel \
libssh-devel \
libtasn1-devel \
diff --git a/tests/docker/dockerfiles/ubuntu1804.docker b/tests/docker/dockerfiles/ubuntu1804.docker
index 0880bf3e29..450fd06d0d 100644
--- a/tests/docker/dockerfiles/ubuntu1804.docker
+++ b/tests/docker/dockerfiles/ubuntu1804.docker
@@ -60,6 +60,7 @@ ENV PACKAGES \
libsdl2-dev \
libsdl2-image-dev \
libseccomp-dev \
+ libselinux-dev \
libsnappy-dev \
libspice-protocol-dev \
libspice-server-dev \
diff --git a/tests/docker/dockerfiles/ubuntu2004.docker b/tests/docker/dockerfiles/ubuntu2004.docker
index 39de63d012..15a026be09 100644
--- a/tests/docker/dockerfiles/ubuntu2004.docker
+++ b/tests/docker/dockerfiles/ubuntu2004.docker
@@ -60,6 +60,7 @@ ENV PACKAGES \
libsdl2-dev \
libsdl2-image-dev \
libseccomp-dev \
+ libselinux-dev \
libslirp-dev \
libsnappy-dev \
libspice-protocol-dev \
--
2.31.1
Am 23.07.2021 um 12:33 hat Richard W.M. Jones geschrieben: > Under SELinux, Unix domain sockets have two labels. One is on the > disk and can be set with commands such as chcon(1). There is a > different label stored in memory (called the process label). This can > only be set by the process creating the socket. When using SELinux + > SVirt and wanting qemu to be able to connect to a qemu-nbd instance, > you must set both labels correctly first. > > For qemu-nbd the options to set the second label are awkward. You can > create the socket in a wrapper program and then exec into qemu-nbd. > Or you could try something with LD_PRELOAD. > > This commit adds the ability to set the label straightforwardly on the > command line, via the new --selinux-label flag. (The name of the flag > is the same as the equivalent nbdkit option.) > > A worked example showing how to use the new option can be found in > this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > Signed-off-by: Richard W.M. Jones <rjones@redhat.com> I suppose this would also be relevant for the built-in NBD server, especially in the context of qemu-storage-daemon? If so, is this something specific to NBD sockets, or would it actually make sense to have it as a generic option in UnixSocketAddress? Kevin
On Fri, Jul 23, 2021 at 06:18:55PM +0200, Kevin Wolf wrote: > Am 23.07.2021 um 12:33 hat Richard W.M. Jones geschrieben: > > Under SELinux, Unix domain sockets have two labels. One is on the > > disk and can be set with commands such as chcon(1). There is a > > different label stored in memory (called the process label). This can > > only be set by the process creating the socket. When using SELinux + > > SVirt and wanting qemu to be able to connect to a qemu-nbd instance, > > you must set both labels correctly first. > > > > For qemu-nbd the options to set the second label are awkward. You can > > create the socket in a wrapper program and then exec into qemu-nbd. > > Or you could try something with LD_PRELOAD. > > > > This commit adds the ability to set the label straightforwardly on the > > command line, via the new --selinux-label flag. (The name of the flag > > is the same as the equivalent nbdkit option.) > > > > A worked example showing how to use the new option can be found in > > this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > > > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > Signed-off-by: Richard W.M. Jones <rjones@redhat.com> > > I suppose this would also be relevant for the built-in NBD server, > especially in the context of qemu-storage-daemon? > > If so, is this something specific to NBD sockets, or would it actually > make sense to have it as a generic option in UnixSocketAddress? For other NBD sockets, most likely. I'm not sure about Unix sockets in general (as in: I know they also have the two label thing, but I don't know if there's a situation where SVirt protects other sockets apart from NBD sockets). I'm sure Dan will know ... By the way although it appears that setsockcreatecon_raw is setting a global flag, it seems to actually use a thread-local variable, so implementing this (although still ugly) would not require locks. https://github.com/SELinuxProject/selinux/blob/32611aea6543e3a8f32635857e37b4332b0b5c99/libselinux/src/procattr.c#L347 Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top
On Fri, Jul 23, 2021 at 06:18:55PM +0200, Kevin Wolf wrote: > Am 23.07.2021 um 12:33 hat Richard W.M. Jones geschrieben: > > Under SELinux, Unix domain sockets have two labels. One is on the > > disk and can be set with commands such as chcon(1). There is a > > different label stored in memory (called the process label). This can > > only be set by the process creating the socket. When using SELinux + > > SVirt and wanting qemu to be able to connect to a qemu-nbd instance, > > you must set both labels correctly first. > > > > For qemu-nbd the options to set the second label are awkward. You can > > create the socket in a wrapper program and then exec into qemu-nbd. > > Or you could try something with LD_PRELOAD. > > > > This commit adds the ability to set the label straightforwardly on the > > command line, via the new --selinux-label flag. (The name of the flag > > is the same as the equivalent nbdkit option.) > > > > A worked example showing how to use the new option can be found in > > this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > > > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > Signed-off-by: Richard W.M. Jones <rjones@redhat.com> > > I suppose this would also be relevant for the built-in NBD server, > especially in the context of qemu-storage-daemon? It depends on the usage scenario really. nbdkit / qemu-nbd are not commonly run under any SELinux policy, so then end up being unconfined_t. A QEMU NBD client can't connect to an unconfined_t socket, so we need to override it with this arg. In the case of qemu system emulator, under libvirt, it will already have a svirt_t type, so in that case there is no need to override the type for the socket. For qsd there's not really any strong practice established but i expect most current usage is unconfined_t too and would benefit from setting label. > If so, is this something specific to NBD sockets, or would it actually > make sense to have it as a generic option in UnixSocketAddress? It is applicable to inet sockets too in fact. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
On Fri, Jul 23, 2021 at 05:38:06PM +0100, Daniel P. Berrangé wrote: > On Fri, Jul 23, 2021 at 06:18:55PM +0200, Kevin Wolf wrote: > > Am 23.07.2021 um 12:33 hat Richard W.M. Jones geschrieben: > > > Under SELinux, Unix domain sockets have two labels. One is on the > > > disk and can be set with commands such as chcon(1). There is a > > > different label stored in memory (called the process label). This can > > > only be set by the process creating the socket. When using SELinux + > > > SVirt and wanting qemu to be able to connect to a qemu-nbd instance, > > > you must set both labels correctly first. > > > > > > For qemu-nbd the options to set the second label are awkward. You can > > > create the socket in a wrapper program and then exec into qemu-nbd. > > > Or you could try something with LD_PRELOAD. > > > > > > This commit adds the ability to set the label straightforwardly on the > > > command line, via the new --selinux-label flag. (The name of the flag > > > is the same as the equivalent nbdkit option.) > > > > > > A worked example showing how to use the new option can be found in > > > this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > > > > > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > > Signed-off-by: Richard W.M. Jones <rjones@redhat.com> > > > > I suppose this would also be relevant for the built-in NBD server, > > especially in the context of qemu-storage-daemon? > > It depends on the usage scenario really. nbdkit / qemu-nbd are > not commonly run under any SELinux policy, so then end up being > unconfined_t. A QEMU NBD client can't connect to an unconfined_t > socket, so we need to override it with this arg. > > In the case of qemu system emulator, under libvirt, it will > already have a svirt_t type, so in that case there is no need > to override the type for the socket. > > For qsd there's not really any strong practice established > but i expect most current usage is unconfined_t too and > would benefit from setting label. > > > If so, is this something specific to NBD sockets, or would it actually > > make sense to have it as a generic option in UnixSocketAddress? > > It is applicable to inet sockets too in fact. So now that 6.2 is open, should I queue the patch as is, or wait for a v3 that makes the option more generic to all socket usage? -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
Ping On Wed, Aug 25, 2021 at 02:35:04PM -0500, Eric Blake wrote: > On Fri, Jul 23, 2021 at 05:38:06PM +0100, Daniel P. Berrangé wrote: > > On Fri, Jul 23, 2021 at 06:18:55PM +0200, Kevin Wolf wrote: > > > Am 23.07.2021 um 12:33 hat Richard W.M. Jones geschrieben: > > > > Under SELinux, Unix domain sockets have two labels. One is on the > > > > disk and can be set with commands such as chcon(1). There is a > > > > different label stored in memory (called the process label). This can > > > > only be set by the process creating the socket. When using SELinux + > > > > SVirt and wanting qemu to be able to connect to a qemu-nbd instance, > > > > you must set both labels correctly first. > > > > > > > > For qemu-nbd the options to set the second label are awkward. You can > > > > create the socket in a wrapper program and then exec into qemu-nbd. > > > > Or you could try something with LD_PRELOAD. > > > > > > > > This commit adds the ability to set the label straightforwardly on the > > > > command line, via the new --selinux-label flag. (The name of the flag > > > > is the same as the equivalent nbdkit option.) > > > > > > > > A worked example showing how to use the new option can be found in > > > > this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > > > > > > > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > > > Signed-off-by: Richard W.M. Jones <rjones@redhat.com> > > > > > > I suppose this would also be relevant for the built-in NBD server, > > > especially in the context of qemu-storage-daemon? > > > > It depends on the usage scenario really. nbdkit / qemu-nbd are > > not commonly run under any SELinux policy, so then end up being > > unconfined_t. A QEMU NBD client can't connect to an unconfined_t > > socket, so we need to override it with this arg. > > > > In the case of qemu system emulator, under libvirt, it will > > already have a svirt_t type, so in that case there is no need > > to override the type for the socket. > > > > For qsd there's not really any strong practice established > > but i expect most current usage is unconfined_t too and > > would benefit from setting label. > > > > > If so, is this something specific to NBD sockets, or would it actually > > > make sense to have it as a generic option in UnixSocketAddress? > > > > It is applicable to inet sockets too in fact. > > So now that 6.2 is open, should I queue the patch as is, or wait for a > v3 that makes the option more generic to all socket usage? > -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
24.09.2021 22:23, Eric Blake wrote: > Ping > > On Wed, Aug 25, 2021 at 02:35:04PM -0500, Eric Blake wrote: >> On Fri, Jul 23, 2021 at 05:38:06PM +0100, Daniel P. Berrangé wrote: >>> On Fri, Jul 23, 2021 at 06:18:55PM +0200, Kevin Wolf wrote: >>>> Am 23.07.2021 um 12:33 hat Richard W.M. Jones geschrieben: >>>>> Under SELinux, Unix domain sockets have two labels. One is on the >>>>> disk and can be set with commands such as chcon(1). There is a >>>>> different label stored in memory (called the process label). This can >>>>> only be set by the process creating the socket. When using SELinux + >>>>> SVirt and wanting qemu to be able to connect to a qemu-nbd instance, >>>>> you must set both labels correctly first. >>>>> >>>>> For qemu-nbd the options to set the second label are awkward. You can >>>>> create the socket in a wrapper program and then exec into qemu-nbd. >>>>> Or you could try something with LD_PRELOAD. >>>>> >>>>> This commit adds the ability to set the label straightforwardly on the >>>>> command line, via the new --selinux-label flag. (The name of the flag >>>>> is the same as the equivalent nbdkit option.) >>>>> >>>>> A worked example showing how to use the new option can be found in >>>>> this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 >>>>> >>>>> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 >>>>> Signed-off-by: Richard W.M. Jones <rjones@redhat.com> >>>> >>>> I suppose this would also be relevant for the built-in NBD server, >>>> especially in the context of qemu-storage-daemon? >>> >>> It depends on the usage scenario really. nbdkit / qemu-nbd are >>> not commonly run under any SELinux policy, so then end up being >>> unconfined_t. A QEMU NBD client can't connect to an unconfined_t >>> socket, so we need to override it with this arg. >>> >>> In the case of qemu system emulator, under libvirt, it will >>> already have a svirt_t type, so in that case there is no need >>> to override the type for the socket. >>> >>> For qsd there's not really any strong practice established >>> but i expect most current usage is unconfined_t too and >>> would benefit from setting label. >>> >>>> If so, is this something specific to NBD sockets, or would it actually >>>> make sense to have it as a generic option in UnixSocketAddress? >>> >>> It is applicable to inet sockets too in fact. If so, should patch at least be changed to call setsockcreatecon_raw() for inet sockets as well? With current code selinux_label is silently ignored in that case. >> >> So now that 6.2 is open, should I queue the patch as is, or wait for a >> v3 that makes the option more generic to all socket usage? >> > -- Best regards, Vladimir
On Fri, Jul 23, 2021 at 11:33:03AM +0100, Richard W.M. Jones wrote: > Under SELinux, Unix domain sockets have two labels. One is on the > disk and can be set with commands such as chcon(1). There is a > different label stored in memory (called the process label). This can > only be set by the process creating the socket. When using SELinux + > SVirt and wanting qemu to be able to connect to a qemu-nbd instance, > you must set both labels correctly first. > > For qemu-nbd the options to set the second label are awkward. You can > create the socket in a wrapper program and then exec into qemu-nbd. > Or you could try something with LD_PRELOAD. > > This commit adds the ability to set the label straightforwardly on the > command line, via the new --selinux-label flag. (The name of the flag > is the same as the equivalent nbdkit option.) > > A worked example showing how to use the new option can be found in > this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > Signed-off-by: Richard W.M. Jones <rjones@redhat.com> > --- I'm making one tweak to your patch before sending the pull request: > +++ b/qemu-nbd.c > @@ -64,6 +68,7 @@ > #define QEMU_NBD_OPT_FORK 263 > #define QEMU_NBD_OPT_TLSAUTHZ 264 > #define QEMU_NBD_OPT_PID_FILE 265 > +#define QEMU_NBD_OPT_SELINUX_LABEL 266 > > #define MBR_SIZE 512 > > @@ -116,6 +121,9 @@ static void usage(const char *name) > " --fork fork off the server process and exit the parent\n" > " once the server is running\n" > " --pid-file=PATH store the server's process ID in the given file\n" > +#ifdef CONFIG_SELINUX > +" --selinux-label=LABEL set SELinux process label on listening socket\n" > +#endif The new option is only conditionally advertised under --help (qemu-nbd lacks a stable machine-parseable output, so scraping --help output will have to do for now)... > #if HAVE_NBD_DEVICE > "\n" > "Kernel NBD client support:\n" > @@ -532,6 +540,8 @@ int main(int argc, char **argv) > { "trace", required_argument, NULL, 'T' }, > { "fork", no_argument, NULL, QEMU_NBD_OPT_FORK }, > { "pid-file", required_argument, NULL, QEMU_NBD_OPT_PID_FILE }, > + { "selinux-label", required_argument, NULL, > + QEMU_NBD_OPT_SELINUX_LABEL }, ...but is unconditionally supported as a long option even when support was not compiled in... > { NULL, 0, NULL, 0 } > }; > int ch; > @@ -558,6 +568,7 @@ int main(int argc, char **argv) > int old_stderr = -1; > unsigned socket_activation; > const char *pid_file_name = NULL; > + const char *selinux_label = NULL; > BlockExportOptions *export_opts; > > #ifdef CONFIG_POSIX > @@ -747,6 +758,9 @@ int main(int argc, char **argv) > case QEMU_NBD_OPT_PID_FILE: > pid_file_name = optarg; > break; > + case QEMU_NBD_OPT_SELINUX_LABEL: > + selinux_label = optarg; > + break; > } > } > > @@ -938,6 +952,16 @@ int main(int argc, char **argv) > } else { > backlog = MIN(shared, SOMAXCONN); > } > + if (sockpath && selinux_label) { > +#ifdef CONFIG_SELINUX > + if (setsockcreatecon_raw(selinux_label) == -1) { > + error_report("Cannot set SELinux socket create context " > + "to %s: %s", > + selinux_label, strerror(errno)); > + exit(EXIT_FAILURE); > + } > +#endif ...but here we silently ignore it if support is not compiled in. Better is to issue an error message about using an unsupported option, so I'll squash this in: diff --git i/qemu-nbd.c w/qemu-nbd.c index 5dc82c419255..94f8ec07c064 100644 --- i/qemu-nbd.c +++ w/qemu-nbd.c @@ -962,6 +962,9 @@ int main(int argc, char **argv) selinux_label, strerror(errno)); exit(EXIT_FAILURE); } +#else + error_report("SELinux support not enabled in this binary"); + exit(EXIT_FAILURE); #endif } saddr = nbd_build_socket_address(sockpath, bindto, port); @@ -978,6 +981,9 @@ int main(int argc, char **argv) strerror(errno)); exit(EXIT_FAILURE); } +#else + error_report("SELinux support not enabled in this binary"); + exit(EXIT_FAILURE); #endif } } else { -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
On Mon, Sep 27, 2021 at 04:18:34PM -0500, Eric Blake wrote: > On Fri, Jul 23, 2021 at 11:33:03AM +0100, Richard W.M. Jones wrote: > > Under SELinux, Unix domain sockets have two labels. One is on the > > disk and can be set with commands such as chcon(1). There is a > > different label stored in memory (called the process label). This can > > only be set by the process creating the socket. When using SELinux + > > SVirt and wanting qemu to be able to connect to a qemu-nbd instance, > > you must set both labels correctly first. > > > > For qemu-nbd the options to set the second label are awkward. You can > > create the socket in a wrapper program and then exec into qemu-nbd. > > Or you could try something with LD_PRELOAD. > > > > This commit adds the ability to set the label straightforwardly on the > > command line, via the new --selinux-label flag. (The name of the flag > > is the same as the equivalent nbdkit option.) > > > > A worked example showing how to use the new option can be found in > > this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > > > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > Signed-off-by: Richard W.M. Jones <rjones@redhat.com> > > --- > > I'm making one tweak to your patch before sending the pull request: > > > +++ b/qemu-nbd.c > > @@ -64,6 +68,7 @@ > > #define QEMU_NBD_OPT_FORK 263 > > #define QEMU_NBD_OPT_TLSAUTHZ 264 > > #define QEMU_NBD_OPT_PID_FILE 265 > > +#define QEMU_NBD_OPT_SELINUX_LABEL 266 > > > > #define MBR_SIZE 512 > > > > @@ -116,6 +121,9 @@ static void usage(const char *name) > > " --fork fork off the server process and exit the parent\n" > > " once the server is running\n" > > " --pid-file=PATH store the server's process ID in the given file\n" > > +#ifdef CONFIG_SELINUX > > +" --selinux-label=LABEL set SELinux process label on listening socket\n" > > +#endif > > The new option is only conditionally advertised under --help (qemu-nbd > lacks a stable machine-parseable output, so scraping --help output > will have to do for now)... > > > #if HAVE_NBD_DEVICE > > "\n" > > "Kernel NBD client support:\n" > > @@ -532,6 +540,8 @@ int main(int argc, char **argv) > > { "trace", required_argument, NULL, 'T' }, > > { "fork", no_argument, NULL, QEMU_NBD_OPT_FORK }, > > { "pid-file", required_argument, NULL, QEMU_NBD_OPT_PID_FILE }, > > + { "selinux-label", required_argument, NULL, > > + QEMU_NBD_OPT_SELINUX_LABEL }, > > ...but is unconditionally supported as a long option even when support > was not compiled in... > > > { NULL, 0, NULL, 0 } > > }; > > int ch; > > @@ -558,6 +568,7 @@ int main(int argc, char **argv) > > int old_stderr = -1; > > unsigned socket_activation; > > const char *pid_file_name = NULL; > > + const char *selinux_label = NULL; > > BlockExportOptions *export_opts; > > > > #ifdef CONFIG_POSIX > > @@ -747,6 +758,9 @@ int main(int argc, char **argv) > > case QEMU_NBD_OPT_PID_FILE: > > pid_file_name = optarg; > > break; > > + case QEMU_NBD_OPT_SELINUX_LABEL: > > + selinux_label = optarg; > > + break; > > } > > } > > > > @@ -938,6 +952,16 @@ int main(int argc, char **argv) > > } else { > > backlog = MIN(shared, SOMAXCONN); > > } > > + if (sockpath && selinux_label) { > > +#ifdef CONFIG_SELINUX > > + if (setsockcreatecon_raw(selinux_label) == -1) { > > + error_report("Cannot set SELinux socket create context " > > + "to %s: %s", > > + selinux_label, strerror(errno)); > > + exit(EXIT_FAILURE); > > + } > > +#endif > > ...but here we silently ignore it if support is not compiled in. > Better is to issue an error message about using an unsupported option, > so I'll squash this in: > > diff --git i/qemu-nbd.c w/qemu-nbd.c > index 5dc82c419255..94f8ec07c064 100644 > --- i/qemu-nbd.c > +++ w/qemu-nbd.c > @@ -962,6 +962,9 @@ int main(int argc, char **argv) > selinux_label, strerror(errno)); > exit(EXIT_FAILURE); > } > +#else > + error_report("SELinux support not enabled in this binary"); > + exit(EXIT_FAILURE); > #endif > } > saddr = nbd_build_socket_address(sockpath, bindto, port); > @@ -978,6 +981,9 @@ int main(int argc, char **argv) > strerror(errno)); > exit(EXIT_FAILURE); > } > +#else > + error_report("SELinux support not enabled in this binary"); > + exit(EXIT_FAILURE); > #endif > } > } else { > Good idea, thanks. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/
On Fri, Jul 23, 2021 at 11:33:03AM +0100, Richard W.M. Jones wrote: > Under SELinux, Unix domain sockets have two labels. One is on the > disk and can be set with commands such as chcon(1). There is a > different label stored in memory (called the process label). This can > only be set by the process creating the socket. When using SELinux + > SVirt and wanting qemu to be able to connect to a qemu-nbd instance, > you must set both labels correctly first. > > For qemu-nbd the options to set the second label are awkward. You can > create the socket in a wrapper program and then exec into qemu-nbd. > Or you could try something with LD_PRELOAD. > > This commit adds the ability to set the label straightforwardly on the > command line, via the new --selinux-label flag. (The name of the flag > is the same as the equivalent nbdkit option.) > > A worked example showing how to use the new option can be found in > this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > Signed-off-by: Richard W.M. Jones <rjones@redhat.com> > --- > configure | 9 ++++- > meson.build | 10 +++++- > meson_options.txt | 3 ++ > qemu-nbd.c | 33 +++++++++++++++++++ > tests/docker/dockerfiles/centos8.docker | 1 + > tests/docker/dockerfiles/fedora.docker | 1 + > tests/docker/dockerfiles/opensuse-leap.docker | 1 + > tests/docker/dockerfiles/ubuntu1804.docker | 1 + > tests/docker/dockerfiles/ubuntu2004.docker | 1 + > 9 files changed, 58 insertions(+), 2 deletions(-) Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
On Fri, Jul 23, 2021 at 11:47:51AM +0100, Daniel P. Berrangé wrote: > On Fri, Jul 23, 2021 at 11:33:03AM +0100, Richard W.M. Jones wrote: > > Under SELinux, Unix domain sockets have two labels. One is on the > > disk and can be set with commands such as chcon(1). There is a > > different label stored in memory (called the process label). This can > > only be set by the process creating the socket. When using SELinux + > > SVirt and wanting qemu to be able to connect to a qemu-nbd instance, > > you must set both labels correctly first. > > > > For qemu-nbd the options to set the second label are awkward. You can > > create the socket in a wrapper program and then exec into qemu-nbd. > > Or you could try something with LD_PRELOAD. > > > > This commit adds the ability to set the label straightforwardly on the > > command line, via the new --selinux-label flag. (The name of the flag > > is the same as the equivalent nbdkit option.) > > > > A worked example showing how to use the new option can be found in > > this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > > > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > Signed-off-by: Richard W.M. Jones <rjones@redhat.com> > > --- > > configure | 9 ++++- > > meson.build | 10 +++++- > > meson_options.txt | 3 ++ > > qemu-nbd.c | 33 +++++++++++++++++++ > > tests/docker/dockerfiles/centos8.docker | 1 + > > tests/docker/dockerfiles/fedora.docker | 1 + > > tests/docker/dockerfiles/opensuse-leap.docker | 1 + > > tests/docker/dockerfiles/ubuntu1804.docker | 1 + > > tests/docker/dockerfiles/ubuntu2004.docker | 1 + > > 9 files changed, 58 insertions(+), 2 deletions(-) > > Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Thanks. This is a new feature, so it doesn't qualify for inclusion in 6.1, but I'm queuing it through my NBD tree to go in as soon as upstream reopens for 6.2. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
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