This is a security feature, and we thus shouldn't derive the random MACs
from a potentially guessable source. MAC addresses are after all facing
to the outside, and can be interacted with from untrusted environments.
Hence, let's generate them the same way as we generate UUIDs: from
getrandom() or /dev/urandom, and optionally with RDRAND if that's
supported.
RDRAND should be fine, since this is not cryptographic key material, but
ultimately public information. We just want to make sure conflicts are
not likely.
Previously we'd generate the MACs via rand(), which means given the
short seed they are a little bit too guessable, making collisions too
likely. See #14355 in particular.
Fixes: #14355
(Note that #14355 was already fixed by
a0f11d1d11, but I think we should do
better even, and not rely on rand() and uninitialized random pools)
When setting flow control attributes of an interface we first acquire
the current settings and then add in the new settings before applying
them again. This only works on interfaces that implement the ethtool
ioctls. on others we'll see an ugly "Could not set flow control of"
message, simply because we issue the SIOCETHTOOL ioctl once, for getting
the data. In particular we'll get it for the "lo" interface all the
time, which sucks hard. Let's get rid of it.
Prompted by the discussions in #15180.
This is a bit more complex than I hoped, since for PID 1 we need to pass
in the synethetic environment block in we generate on demand.
The function sd_device_get_property_value has some paths where it exits without
touching the n pointer. In those cases, n remained uninitialized until it was
eventually read inside isempty where it caused the segmentation fault.
Fixes#15078
Two releases ago we started warning about this, and I think it is now to turn
this into a hard error. People get bitten by this every once in a while, and
there doesn't see to be any legitimate use case where the same .link or
.network files should be applied to _all_ interfaces, since in particular that
configuration would apply both to lo and any other interfaces. And if for
whatever reason that is actually desired, OriginalName=* or Name=* can be
easily added to silence the warning and achieve the effect.
(The case described in #12098 is particularly nasty: 'echo -n >foo.network'
creates a mask file, 'echo >foo.network' creates a "match all" file.)
Fixes#717, #12098 for realz now.
This is for 6d36464065. It turns out that this is causing more problems than
expected. Let's retroactively introduce naming scheme v241 to conditionalize
this change.
Follow-up for #12792 and 6d36464065. See also
https://bugzilla.suse.com/show_bug.cgi?id=1136600.
$ SYSTEMD_LOG_LEVEL=debug NET_NAMING_SCHEME=v240 build/udevadm test-builtin net_setup_link /sys/class/net/br11
$ SYSTEMD_LOG_LEVEL=debug NET_NAMING_SCHEME=v241 build/udevadm test-builtin net_setup_link /sys/class/net/br11
...
@@ -20,11 +20,13 @@
link_config: could not set ethtool features for br11
Could not set offload features of br11: Operation not permitted
br11: Device has name_assign_type=3
-Using interface naming scheme 'v240'.
+Using interface naming scheme 'v241'.
br11: Policy *keep*: keeping existing userspace name
br11: Device has addr_assign_type=1
-br11: No stable identifying information found
-br11: Could not generate persistent MAC: No data available
+br11: Using "br11" as stable identifying information
+br11: Using generated persistent MAC address
+Could not set Alias=, MACAddress= or MTU= on br11: Operation not permitted
+br11: Could not apply link config, ignoring: Operation not permitted
Unload module index
Unloaded link configuration context.
ID_NET_DRIVER=bridge
This is in preparation for later changes. Let's change the documentation of
net.naming-scheme= to also say that it applies to MAC addresses. This commit
doesn't actually implement that though.
This suppress the following warning:
```
systemd-udevd[437]: Config file /usr/lib/systemd/network/99-default.link
applies to device based on potentially unpredictable interface name 'wlan0'
```
Follow-up for 84ea567eb4.
The comment in udev-builtin-net_id.c (removed in grandparent commit) showed the
property without the prefix. I assume that was always the intent, because it
doesn't make much sense to concatenate anything to an arbitrary user-specified
field.
In order to properly and predictably name netdevsim netdevices,
introduce a separate implementation, as the netdevices reside on a
specific netdevsim bus. Note that this applies only to netdevsim devices
created using sysfs, because those expose phys_port_name attribute.
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
We have a few cases or reported issues which are about a timeout to parse
the input in 25 s. In all cases, the input is a few hundred kb. We don't really
care if the config parsers are super efficent, so let's set a limit on the input
size to avoid triggering such issues. The parsers often contain quadratic
algorithms. This is OK, because the numbers of elements are almost always very
small in real use. Rewriting the code to use more complicated data structures
to speed this up would not only complicate the code, but also pessimize behaviour
for the overwhelmingly common case of small samples. Note that in all those
cases, the input data is trusted. We care about memory correctness, and not
not so much about efficiency.
The size checks are done twice: using options for libfuzzer, and using an
internal check for afl. Those should be changed together. I didn't use a define,
because there is no easy mechanism to share the define between the two files.
