[3/4] doc: give specific instructions for running as non-root
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Commit Message
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.
Cc: stable@dpdk.org
Signed-off-by: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
---
doc/guides/linux_gsg/enable_func.rst | 53 ++++++++++++++++---
.../prog_guide/env_abstraction_layer.rst | 2 +
2 files changed, 49 insertions(+), 6 deletions(-)
Comments
On Wed, 8 Jun 2022 02:49:48 +0300
Dmitry Kozlyuk <dkozlyuk@nvidia.com> wrote:
> 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.
>
> Cc: stable@dpdk.org
>
> Signed-off-by: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
If running with multiple containers it is often better to have OS
take care of mounting huge pages.
https://github.com/systemd/systemd/blob/main/units/dev-hugepages.mount
And a good way for managing multiple applications using hugepages
is to mount device with group permissions and add supplementary
group to each container.
@@ -13,13 +13,46 @@ Enabling Additional Functionality
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 runing 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, for example::
+
+ export HUGEDIR=$HOME/huge-1G
+ mkdir -p $HUGEDIR
+ sudo dpdk-hugepages.py --mount --directory $HUGEDIR --owner `id -u`:`id -g`
+
+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
@@ -34,7 +67,15 @@ 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
+See `Hugepage Mapping <hugepage_mapping>`_
+secton to learn how these limits affect EAL.
+
+Device Control
+~~~~~~~~~~~~~~
+
+If the HPET is to be used, ``/dev/hpet`` permissions must be adjusted.
+
+Depending on which kernel driver is in use, the relevant
resources also should be accessible by the user running the DPDK application.
For ``vfio-pci`` kernel driver, the following Linux file system objects'
@@ -228,6 +228,8 @@ Normally, these options do not need to be changed.
can later be mapped into that preallocated VA space (if dynamic memory mode
is enabled), and can optionally be mapped into it at startup.
+.. _hugepage_mapping:
+
Hugepage Mapping
^^^^^^^^^^^^^^^^