[PATCH 20.11] doc: add more instructions for running as non-root

[Xueming(Steven) Li]

Sorry, my bad, applied now.

Thanks!

> -----Original Message-----
> From: Xueming(Steven) Li
> Sent: Tuesday, August 9, 2022 11:09 PM
> To: Dmitry Kozlyuk <dkozlyuk at nvidia.com>; stable at dpdk.org
> Cc: Bruce Richardson <bruce.richardson at intel.com>
> Subject: RE: [PATCH 20.11] doc: add more instructions for running as non-root
> 
> 
> 
> > -----Original Message-----
> > From: Dmitry Kozlyuk <dkozlyuk at nvidia.com>
> > Sent: Monday, August 1, 2022 8:19 PM
> > To: stable at dpdk.org
> > Cc: Xueming(Steven) Li <xuemingl at nvidia.com>; Bruce Richardson
> > <bruce.richardson at intel.com>
> > Subject: [PATCH 20.11] doc: add more instructions for running as
> > non-root
> >
> > [ upstream commit 979bb5d493fbbce77eaaf2b4a01ee98f93f76dd9 ]
> >
> > The guide to run DPDK applications as non-root in Linux did not
> > provide specific instructions to configure the required access and did not explain why each bit is needed.
> > The latter is important because running as non-root is one of the ways to tighten security and grant minimal permissions.
> >
> > Signed-off-by: Dmitry Kozlyuk <dkozlyuk at nvidia.com>
> > Acked-by: Bruce Richardson <bruce.richardson at intel.com>
> > ---
> > Upstream commit references things missing from 21.11:
> 
> Maybe this is the root cause that the patch can't merge, please retry with 20.11:
> 	https://github.com/steevenlee/dpdk
> 	Branch: 20.11
> 
> > new dpdk-hugepages.py options and memory mapping documentation.
> > The script call replaced with a direct mount command.
> > Documentation reference is dropped as non-essential.
> >
> >  doc/guides/linux_gsg/enable_func.rst | 85
> > +++++++++++++++++++---------
> >  1 file changed, 58 insertions(+), 27 deletions(-)
> >
> > diff --git a/doc/guides/linux_gsg/enable_func.rst
> > b/doc/guides/linux_gsg/enable_func.rst
> > index 25f87f6b1a..7538d04d97 100644
> > --- a/doc/guides/linux_gsg/enable_func.rst
> > +++ b/doc/guides/linux_gsg/enable_func.rst
> > @@ -66,13 +66,62 @@ The application can then determine what action to
> > take, if any, if the HPET is n  Running DPDK Applications Without Root
> > Privileges
> >  -------------------------------------------------
> >
> > -In order to run DPDK as non-root, the following Linux filesystem objects'
> > -permissions should be adjusted to ensure that the Linux account being used to -run the DPDK application has access to them:
> > +The following sections describe generic requirements and
> > +configuration for running DPDK applications as non-root.
> > +There may be additional requirements documented for some drivers.
> >
> > -*   All directories which serve as hugepage mount points, for example, ``/dev/hugepages``
> > +Hugepages
> > +~~~~~~~~~
> >
> > -*   If the HPET is to be used,  ``/dev/hpet``
> > +Hugepages must be reserved as root before running the application as
> > +non-root, for example::
> > +
> > +  sudo dpdk-hugepages.py --reserve 1G
> > +
> > +If multi-process is not required, running with ``--in-memory``
> > +bypasses the need to access hugepage mount point and files within it.
> > +Otherwise, hugepage directory must be made accessible for writing to
> > +the unprivileged user.
> > +A good way for managing multiple applications using hugepages is to
> > +mount the filesystem with group permissions and add a supplementary
> > +group to each application or container.
> > +
> > +One option is to mount manually::
> > +
> > +  mount -t hugetlbfs -o pagesize=1G,uid=`id -u`,gid=`id -g` nodev
> > + $HOME/huge-1G
> > +
> > +In production environment, the OS can manage mount points (`systemd
> > +example <https://github.com/systemd/systemd/blob/main/units/dev-hugepages.mount>`_).
> > +
> > +The ``hugetlb`` filesystem has additional options to guarantee or
> > +limit the amount of memory that is possible to allocate using the mount point.
> > +Refer to the `documentation <https://www.kernel.org/doc/Documentation/vm/hugetlbpage.txt>`_.
> > +
> > +.. note::
> > +
> > +   Using ``vfio-pci`` kernel driver, if applicable, can eliminate the need
> > +   for physical addresses and therefore eliminate the permission requirements
> > +   described below.
> > +
> > +If the driver requires using physical addresses (PA), the executable
> > +file must be granted additional capabilities:
> > +
> > +* ``SYS_ADMIN`` to read ``/proc/self/pagemaps``
> > +* ``IPC_LOCK`` to lock hugepages in memory
> > +
> > +.. code-block:: console
> > +
> > +   setcap cap_ipc_lock,cap_sys_admin+ep <executable>
> > +
> > +If physical addresses are not accessible, the following message will
> > +appear during EAL initialization::
> > +
> > +  EAL: rte_mem_virt2phy(): cannot open /proc/self/pagemap: Permission
> > + denied
> > +
> > +It is harmless in case PA are not needed.
> > +
> > +Resource Limits
> > +~~~~~~~~~~~~~~~
> >
> >  When running as non-root user, there may be some additional resource
> > limits  that are imposed by the system. Specifically, the following resource limits may @@ -87,8 +136,10 @@ need to be adjusted in order
> to ensure normal DPDK operation:
> >  The above limits can usually be adjusted by editing  ``/etc/security/limits.conf`` file, and rebooting.
> >
> > -Additionally, depending on which kernel driver is in use, the
> > relevant -resources also should be accessible by the user running the DPDK application.
> > +Device Control
> > +~~~~~~~~~~~~~~
> > +
> > +If the HPET is to be used, ``/dev/hpet`` permissions must be adjusted.
> >
> >  For ``vfio-pci`` kernel driver, the following Linux file system objects'
> >  permissions should be adjusted:
> > @@ -98,26 +149,6 @@ permissions should be adjusted:
> >  * The directories under ``/dev/vfio`` that correspond to IOMMU group numbers of
> >    devices intended to be used by DPDK, for example, ``/dev/vfio/50``
> >
> > -.. note::
> > -
> > -    The instructions below will allow running DPDK with ``igb_uio`` or
> > -    ``uio_pci_generic`` drivers as non-root with older Linux kernel versions.
> > -    However, since version 4.0, the kernel does not allow unprivileged processes
> > -    to read the physical address information from the pagemaps file, making it
> > -    impossible for those processes to be used by non-privileged users. In such
> > -    cases, using the VFIO driver is recommended.
> > -
> > -For ``igb_uio`` or ``uio_pci_generic`` kernel drivers, the following Linux file -system objects' permissions should be adjusted:
> > -
> > -*   The userspace-io device files in  ``/dev``, for example,  ``/dev/uio0``, ``/dev/uio1``, and so on
> > -
> > -*   The userspace-io sysfs config and resource files, for example for ``uio0``::
> > -
> > -       /sys/class/uio/uio0/device/config
> > -       /sys/class/uio/uio0/device/resource*
> > -
> > -
> >  Power Management and Power Saving Functionality
> >  -----------------------------------------------
> >
> > --
> > 2.25.1