On Tue, Mar 07, 2023 at 02:32:04PM +0100, David Marchand wrote:
> On Tue, Mar 7, 2023 at 2:06 PM Aaron Conole <[email protected]> wrote:
> >
> > Open vSwitch generally tries to let the underlying operating system
> > managed the low level details of hardware, for example DMA mapping,
> > bus arbitration, etc. However, when using DPDK, the underlying
> > operating system yields control of many of these details to userspace
> > for management.
> >
> > In the case of some DPDK port drivers, configuring rte_flow or even
> > allocating resources may require access to iopl/ioperm calls, which
> > are guarded by the CAP_SYS_RAWIO privilege on linux systems. These
> > calls are dangerous, and can allow a process to completely compromise
> > a system. However, they are needed in the case of some userspace
> > driver code which manages the hardware (for example, the mlx
> > implementation of backend support for rte_flow).
> >
> > Here, we create an opt-in flag passed to the command line to allow
> > this access. We need to do this before ever accessing the database,
> > because we want to drop all privileges asap, and cannot wait for
> > a connection to the database to be established and functional before
> > dropping. There may be distribution specific ways to do capability
> > management as well (using for example, systemd), but they are not
> > as universal to the vswitchd as a flag.
> >
> > Reviewed-by: Simon Horman <[email protected]>
> > Signed-off-by: Aaron Conole <[email protected]>
> > ---
> > NEWS | 4 ++++
> > lib/daemon-unix.c | 29 +++++++++++++++++++++--------
> > lib/daemon-windows.c | 3 ++-
> > lib/daemon.c | 2 +-
> > lib/daemon.h | 4 ++--
> > ovsdb/ovsdb-client.c | 6 +++---
> > ovsdb/ovsdb-server.c | 4 ++--
> > tests/test-netflow.c | 2 +-
> > tests/test-sflow.c | 2 +-
> > tests/test-unixctl.c | 2 +-
> > utilities/ovs-ofctl.c | 4 ++--
> > utilities/ovs-testcontroller.c | 4 ++--
> > vswitchd/ovs-vswitchd.8.in | 8 ++++++++
> > vswitchd/ovs-vswitchd.c | 11 ++++++++++-
> > 14 files changed, 60 insertions(+), 25 deletions(-)
> >
> > diff --git a/NEWS b/NEWS
> > index 85b3496214..65f35dcdd5 100644
> > --- a/NEWS
> > +++ b/NEWS
> > @@ -10,6 +10,10 @@ Post-v3.1.0
> > in order to create OVSDB sockets with access mode of 0770.
> > - QoS:
> > * Added new configuration option 'jitter' for a linux-netem QoS type.
> > + - DPDK:
> > + * ovs-vswitchd will keep the CAP_SYS_RAWIO capability when started
> > + with the --hw-rawio-access command line option. This allows the
> > + process extra privileges when mapping physical interconnect memory.
> >
> >
> > v3.1.0 - 16 Feb 2023
> > diff --git a/lib/daemon-unix.c b/lib/daemon-unix.c
> > index 1a7ba427d7..a080facddc 100644
> > --- a/lib/daemon-unix.c
> > +++ b/lib/daemon-unix.c
> > @@ -88,7 +88,8 @@ static bool switch_user = false;
> > static uid_t uid;
> > static gid_t gid;
> > static char *user = NULL;
> > -static void daemon_become_new_user__(bool access_datapath);
> > +static void daemon_become_new_user__(bool access_datapath,
> > + bool access_hardware_ports);
> >
> > static void check_already_running(void);
> > static int lock_pidfile(FILE *, int command);
> > @@ -443,13 +444,13 @@ monitor_daemon(pid_t daemon_pid)
> > * daemonize_complete()) or that it failed to start up (by exiting with a
> > * nonzero exit code). */
> > void
> > -daemonize_start(bool access_datapath)
> > +daemonize_start(bool access_datapath, bool access_hardware_ports)
> > {
> > assert_single_threaded();
> > daemonize_fd = -1;
> >
> > if (switch_user) {
> > - daemon_become_new_user__(access_datapath);
> > + daemon_become_new_user__(access_datapath, access_hardware_ports);
> > switch_user = false;
> > }
> >
> > @@ -807,7 +808,8 @@ daemon_become_new_user_unix(void)
> > /* Linux specific implementation of daemon_become_new_user()
> > * using libcap-ng. */
> > static void
> > -daemon_become_new_user_linux(bool access_datapath OVS_UNUSED)
> > +daemon_become_new_user_linux(bool access_datapath OVS_UNUSED,
> > + bool access_hardware_ports OVS_UNUSED)
> > {
> > #if defined __linux__ && HAVE_LIBCAPNG
> > int ret;
> > @@ -827,6 +829,16 @@ daemon_become_new_user_linux(bool access_datapath
> > OVS_UNUSED)
> > ret = capng_update(CAPNG_ADD, cap_sets, CAP_NET_ADMIN)
> > || capng_update(CAPNG_ADD, cap_sets, CAP_NET_RAW)
> > || capng_update(CAPNG_ADD, cap_sets,
> > CAP_NET_BROADCAST);
> > +#ifdef DPDK_NETDEV
> > + if (access_hardware_ports && !ret) {
> > + ret = capng_update(CAPNG_ADD, cap_sets, CAP_SYS_RAWIO);
> > + VLOG_INFO("CAP_SYS_RAWIO enabled.");
Perhaps "The Linux capability CAP_SYS_RAWIO is enabled."
> > + }
> > +#else
> > + if (access_hardware_ports) {
> > + VLOG_WARN("Dropped CAP_SYS_RAWIO request (no
> > drivers).");
>
> Does it mean we drop the capability? or do we drop the drop?
> I don't really have a better wording but the current log had me
> reading it a few times.
Same here. Perhaps:
"No driver requires Linux capability CAP_SYS_RAWIO, disabling it."
my $0.02
fbl
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