[dpdk-stable] [RFC 2/2] nfp: allow for non-root user
Aaron Conole
aconole at redhat.com
Tue Apr 17 21:19:23 CEST 2018
Alejandro Lucero <alejandro.lucero at netronome.com> writes:
> I was just wondering, if device device PCI sysfs resource files or VFIO group /dev files require to change
> permissions for non-root users, does it not make sense to adjust also /var/lock in the system?
For the /dev, we use udev rules - so the correct individual vfio device
files get assigned the correct permissions. No such mechanism exists
for /var/lock as far as I can tell.
Ex. see:
https://github.com/openvswitch/ovs/blob/master/rhel/usr_lib_udev_rules.d_91-vfio.rules
Maybe something similar exists that we could use to generate the lock
file automatically?
> On Tue, Apr 17, 2018 at 4:44 PM, Alejandro Lucero <alejandro.lucero at netronome.com> wrote:
>
> I have seen that VFIO also requires explicitly to set the right permissions for non-root users to VFIO
> groups under /dev/vfio.
>
> I assume then that running OVS or other DPDK apps as non-root is possible, although requiring
> those explicit permissions changes, and therefore this patch is necessary.
>
> Adding stable@ and Thomas for discussing how can this be added to stable DPDK versions even if
> this is not going to be a patch for current DPDK version.
>
> Acked-by: Alejandro Lucero <alejandro.lucero at netronome.com>
>
> On Fri, Apr 13, 2018 at 4:31 PM, Alejandro Lucero <alejandro.lucero at netronome.com> wrote:
>
> On Fri, Apr 13, 2018 at 2:31 PM, Aaron Conole <aconole at redhat.com> wrote:
>
> Alejandro Lucero <alejandro.lucero at netronome.com> writes:
>
> > Again, this patch is correct, but because NFP PMD needs to access
> > /sys/bus/pci/devices/$DEVICE_PCI_STRING/resource$RESOURCE_ID, and these files have
> just
> > read/write accesses for root, I do not know if this is really necessary.
> >
> > Being honest, I have not used a DPDK app with NFP PMD and not being root. Does it
> work
> > with non-root users and other PMDs with same requirements regarding sysfs resource
> files?
>
> We do run as non-root user definitely with Intel PMDs.
>
> I'm not very sure about other vendors, but I think mlx pmd runs as
> non-root user (and it was modified to move off of sysfs for that
> reason[1]).
>
> It is possible to not rely on sysfs resource files if device is attached to VFIO, but I think that is a
> must with UIO.
>
>
> I'll continue to push for more information from the testing side to find
> out though.
>
> [1]: http://dpdk.org/ml/archives/dev/2018-February/090586.html
>
> > On Fri, Apr 13, 2018 at 12:22 AM, Aaron Conole <aconole at redhat.com> wrote:
> >
> > Currently, the nfp lock files are taken from the global lock file
> > location, which will work when the user is running as root. However,
> > some distributions and applications (notably ovs 2.8+ on RHEL/Fedora)
> > run as a non-root user.
> >
> > Signed-off-by: Aaron Conole <aconole at redhat.com>
> > ---
> > drivers/net/nfp/nfp_nfpu.c | 23 ++++++++++++++++++-----
> > 1 file changed, 18 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/net/nfp/nfp_nfpu.c b/drivers/net/nfp/nfp_nfpu.c
> > index 2ed985ff4..ae2e07220 100644
> > --- a/drivers/net/nfp/nfp_nfpu.c
> > +++ b/drivers/net/nfp/nfp_nfpu.c
> > @@ -18,6 +18,22 @@
> > #define NFP_CFG_EXP_BAR 7
> >
> > #define NFP_CFG_EXP_BAR_CFG_BASE 0x30000
> > +#define NFP_LOCKFILE_PATH_FMT "%s/nfp%d"
> > +
> > +/* get nfp lock file path (/var/lock if root, $HOME otherwise) */
> > +static void
> > +nspu_get_lockfile_path(char *buffer, int bufsz, nfpu_desc_t *desc)
> > +{
> > + const char *dir = "/var/lock";
> > + const char *home_dir = getenv("HOME");
> > +
> > + if (getuid() != 0 && home_dir != NULL)
> > + dir = home_dir;
> > +
> > + /* use current prefix as file path */
> > + snprintf(buffer, bufsz, NFP_LOCKFILE_PATH_FMT, dir,
> > + desc->nfp);
> > +}
> >
> > /* There could be other NFP userspace tools using the NSP interface.
> > * Make sure there is no other process using it and locking the access for
> > @@ -30,9 +46,7 @@ nspv_aquire_process_lock(nfpu_desc_t *desc)
> > struct flock lock;
> > char lockname[30];
> >
> > - memset(&lock, 0, sizeof(lock));
> > -
> > - snprintf(lockname, sizeof(lockname), "/var/lock/nfp%d", desc->nfp);
> > + nspu_get_lockfile_path(lockname, sizeof(lockname), desc);
> >
> > /* Using S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH */
> > desc->lock = open(lockname, O_RDWR | O_CREAT, 0666);
> > @@ -106,7 +120,6 @@ nfpu_close(nfpu_desc_t *desc)
> > rte_free(desc->nspu);
> > close(desc->lock);
> >
> > - snprintf(lockname, sizeof(lockname), "/var/lock/nfp%d", desc->nfp);
> > - unlink(lockname);
> > + nspu_get_lockfile_path(lockname, sizeof(lockname), desc);
> > return 0;
> > }
> > --
> > 2.14.3
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