linux-stable.git/net/core/rtnetlink.c, branch v5.18.2

rtnetlink: Fix handling of disabled L3 stats in RTM_GETSTATS replies

2022-04-14T07:01:26+00:00

When L3 stats are disabled, rtnl_offload_xstats_get_size_stats() returns
size of 0, which is supposed to be an indication that the corresponding
attribute should not be emitted. However, instead, the current code
reserves a 0-byte attribute.

The reason this does not show up as a citation on a kasan kernel is that
netdev_offload_xstats_get(), which is supposed to fill in the data, never
ends up getting called, because rtnl_offload_xstats_get_stats() notices
that the stats are not actually used and skips the call.

Thus a zero-length IFLA_OFFLOAD_XSTATS_L3_STATS attribute ends up in a
response, confusing the userspace.

Fix by skipping the L3-stats related block in rtnl_offload_xstats_fill().

Fixes: 0e7788fd7622 ("net: rtnetlink: Add UAPI for obtaining L3 offload xstats")
Signed-off-by: Petr Machata 
Reviewed-by: Ido Schimmel 
Link: https://lore.kernel.org/r/591b58e7623edc3eb66dd1fcfa8c8f133d090974.1649794741.git.petrm@nvidia.com
Signed-off-by: Paolo Abeni

net: limit altnames to 64k total

2022-03-11T04:15:23+00:00

Property list (altname is a link "property") is wrapped
in a nlattr. nlattrs length is 16bit so practically
speaking the list of properties can't be longer than
that, otherwise user space would have to interpret
broken netlink messages.

Prevent the problem from occurring by checking the length
of the property list before adding new entries.

Reported-by: George Shuklin 
Reviewed-by: David Ahern 
Signed-off-by: Jakub Kicinski

net: account alternate interface name memory

2022-03-11T04:15:20+00:00

George reports that altnames can eat up kernel memory.
We should charge that memory appropriately.

Reported-by: George Shuklin 
Signed-off-by: Jakub Kicinski

net: rtnetlink: fix error handling in rtnl_fill_statsinfo()

2022-03-07T12:26:53+00:00

The clang static analyzer reports this issue
rtnetlink.c:5481:2: warning: Undefined or garbage
  value returned to caller
  return err;
  ^~~~~~~~~~

There is a function level err variable, in the
list_for_each_entry_rcu block there is a shadow
err.  Remove the shadow.

In the same block, the call to nla_nest_start_noflag()
can fail without setting an err.  Set the err
to -EMSGSIZE.

Fixes: 216e690631f5 ("net: rtnetlink: rtnl_fill_statsinfo(): Permit non-EMSGSIZE error returns")
Signed-off-by: Tom Rix 
Reviewed-by: Ido Schimmel 
Reviewed-by: Petr Machata 
Signed-off-by: David S. Miller

net: rtnetlink: Add UAPI toggle for IFLA_OFFLOAD_XSTATS_L3_STATS

2022-03-03T10:37:23+00:00

The offloaded HW stats are designed to allow per-netdevice enablement and
disablement. Add an attribute, IFLA_STATS_SET_OFFLOAD_XSTATS_L3_STATS,
which should be carried by the RTM_SETSTATS message, and expresses a desire
to toggle L3 offload xstats on or off.

As part of the above, add an exported function rtnl_offload_xstats_notify()
that drivers can use when they have installed or deinstalled the counters
backing the HW stats.

At this point, it is possible to enable, disable and query L3 offload
xstats on netdevices. (However there is no driver actually implementing
these.)

Signed-off-by: Petr Machata 
Signed-off-by: Ido Schimmel 
Signed-off-by: David S. Miller

net: rtnetlink: Add RTM_SETSTATS

2022-03-03T10:37:23+00:00

The offloaded HW stats are designed to allow per-netdevice enablement and
disablement. These stats are only accessible through RTM_GETSTATS, and
therefore should be toggled by a RTM_SETSTATS message. Add it, and the
necessary skeleton handler.

Signed-off-by: Petr Machata 
Signed-off-by: Ido Schimmel 
Signed-off-by: David S. Miller

net: rtnetlink: Add UAPI for obtaining L3 offload xstats

2022-03-03T10:37:23+00:00

Add a new IFLA_STATS_LINK_OFFLOAD_XSTATS child attribute,
IFLA_OFFLOAD_XSTATS_L3_STATS, to carry statistics for traffic that takes
place in a HW router.

The offloaded HW stats are designed to allow per-netdevice enablement and
disablement. Additionally, as a netdevice is configured, it may become or
cease being suitable for binding of a HW counter. Both of these aspects
need to be communicated to the userspace. To that end, add another child
attribute, IFLA_OFFLOAD_XSTATS_HW_S_INFO:

    - attr nest IFLA_OFFLOAD_XSTATS_HW_S_INFO
	- attr nest IFLA_OFFLOAD_XSTATS_L3_STATS
 	    - attr IFLA_OFFLOAD_XSTATS_HW_S_INFO_REQUEST
	      - {0,1} as u8
 	    - attr IFLA_OFFLOAD_XSTATS_HW_S_INFO_USED
	      - {0,1} as u8

Thus this one attribute is a nest that can be used to carry information
about various types of HW statistics, and indexing is very simply done by
wrapping the information for a given statistics suite into the attribute
that carries the suite is the RTM_GETSTATS query. At the same time, because
_HW_S_INFO is nested directly below IFLA_STATS_LINK_OFFLOAD_XSTATS, it is
possible through filtering to request only the metadata about individual
statistics suites, without having to hit the HW to get the actual counters.

Signed-off-by: Petr Machata 
Signed-off-by: Ido Schimmel 
Signed-off-by: David S. Miller

net: rtnetlink: rtnl_fill_statsinfo(): Permit non-EMSGSIZE error returns

2022-03-03T10:37:22+00:00

Obtaining stats for the IFLA_STATS_LINK_OFFLOAD_XSTATS nest involves a HW
access, and can fail for more reasons than just netlink message size
exhaustion. Therefore do not always return -EMSGSIZE on the failure path,
but respect the error code provided by the callee. Set the error explicitly
where it is reasonable to assume -EMSGSIZE as the failure reason.

Signed-off-by: Petr Machata 
Signed-off-by: Ido Schimmel 
Signed-off-by: David S. Miller

net: rtnetlink: Propagate extack to rtnl_offload_xstats_fill()

2022-03-03T10:37:22+00:00

Later patches add handlers for more HW-backed statistics. An extack will be
useful when communicating HW / driver errors to the client. Add the
arguments as appropriate.

Signed-off-by: Petr Machata 
Signed-off-by: Ido Schimmel 
Signed-off-by: David S. Miller

net: rtnetlink: RTM_GETSTATS: Allow filtering inside nests

2022-03-03T10:37:22+00:00

The filter_mask field of RTM_GETSTATS header determines which top-level
attributes should be included in the netlink response. This saves
processing time by only including the bits that the user cares about
instead of always dumping everything. This is doubly important for
HW-backed statistics that would typically require a trip to the device to
fetch the stats.

So far there was only one HW-backed stat suite per attribute. However,
IFLA_STATS_LINK_OFFLOAD_XSTATS is a nest, and will gain a new stat suite in
the following patches. It would therefore be advantageous to be able to
filter within that nest, and select just one or the other HW-backed
statistics suite.

Extend rtnetlink so that RTM_GETSTATS permits attributes in the payload.
The scheme is as follows:

    - RTM_GETSTATS
	- struct if_stats_msg
	- attr nest IFLA_STATS_GET_FILTERS
	    - attr IFLA_STATS_LINK_OFFLOAD_XSTATS
		- u32 filter_mask

This scheme reuses the existing enumerators by nesting them in a dedicated
context attribute. This is covered by policies as usual, therefore a
gradual opt-in is possible. Currently only IFLA_STATS_LINK_OFFLOAD_XSTATS
nest has filtering enabled, because for the SW counters the issue does not
seem to be that important.

rtnl_offload_xstats_get_size() and _fill() are extended to observe the
requested filters.

Signed-off-by: Petr Machata 
Signed-off-by: Ido Schimmel 
Signed-off-by: David S. Miller