This reverts PR #23269 and its follow-up commit. Especially,
2299b1cae3 (partially), and
3cf63830ac.
The PR was merged without final approval, and has several issues:
- The NetLabel for static addresses are not assigned, as labels are
stored in the Address objects managed by Network, instead of Link.
- If NetLabel is specified for a static address, then the address
section will be invalid and the address will not be configured,
- It should be implemented with Request object,
- There is no test about the feature.
New directive `NetLabel=` provides a method for integrating dynamic network
configuration into Linux NetLabel subsystem rules, used by Linux security
modules (LSMs) for network access control. The option expects a whitespace
separated list of NetLabel labels. The labels must conform to lexical
restrictions of LSM labels. When an interface is configured with IP addresses,
the addresses and subnetwork masks will be appended to the NetLabel Fallback
Peer Labeling rules. They will be removed when the interface is
deconfigured. Failures to manage the labels will be ignored.
Example:
```
[DHCP]
NetLabel=system_u:object_r:localnet_peer_t:s0
```
With the above rules for interface `eth0`, when the interface is configured with
an IPv4 address of 10.0.0.0/8, `systemd-networkd` performs the equivalent of
`netlabelctl` operation
```
$ sudo netlabelctl unlbl add interface eth0 address:10.0.0.0/8 label:system_u:object_r:localnet_peer_t:s0
```
Result:
```
$ sudo netlabelctl -p unlbl list
...
interface: eth0
address: 10.0.0.0/8
label: "system_u:object_r:localnet_peer_t:s0"
...
```
Since we don't need the error value, and the buffer is allocated with a fixed
size, the whole logic provided by in_addr_to_string() becomes unnecessary, so
it's enough to wrap inet_ntop() directly.
inet_ntop() can only fail with ENOSPC. But we specify a buffer that is supposed
to be large enough, so this should never fail. A bunch of tests of this are added.
This allows all the wrappers like strna(), strnull(), strempty() to be dropped.
The guard of 'if (DEBUG_LOGGING)' can be dropped from around log_debug(),
because log_debug() implements the check outside of the function call. But
log_link_debug() does not, so it we need it to avoid unnecessary evaluation of
the formatting.
It's pretty useful to be able to access the bytes generically, without
acknowledging a specific family, hence let's a third way to access an
in_addr_union.
In subsequent commits, calls to if_nametoindex() will be replaced by a wrapper
that falls back to alternative name resolution over netlink. netlink support
requires libsystemd (for sd-netlink), and we don't want to add any functions
that require netlink in basic/. So stuff that calls if_nametoindex() for user
supplied interface names, and everything that depends on that, needs to be
moved.
The DHCP client should not pre-filter addresses beyond what RFC
requires. If a client's user (like networkd) wishes to skip/filter
certain addresses, it's their responsibility.
The point of this is that the DHCP library does not hide/abstract
information that might be relevant for certain users. For example,
NetworkManager exposes DHCP options in its API. When doing that, the
options should be close to the actual lease.
This is related to commit d9ec2e632d
(dhcp4: filter bogus DNS/NTP server addresses silently).
Mike Yuan
Daan De Meyer
Yu Watanabe
Zbigniew Jędrzejewski-Szmek
Topi Miettinen
Lennart Poettering
Andreas Rammhold
Thomas Haller