BPF_PROG_TYPE_CGROUP_SKB is supported since kernel v4.10
(0e33661de493db325435d565a4a722120ae4cbf3) and
BPF_PROG_TYPE_CGROUP_SOCK_ADDR is supported since kernel v4.17
(4fbac77d2d092b475dda9eea66da674369665427).
Our baseline on the kernel is v5.4. The check is not necessary.
After 3988e2489a, the function is a simple
wrapper of bpf_dlopen() with logging. Let's introduce dlopen_bpf_full()
that takes log level, and replace cgroup_bpf_supported() with it.
Currently there are various circular dependencies between headers
in core/. Let's get rid of these by making judicious use of forward
declarations and moving includes into implementation files instead of
having them in header files.
Getting rid of circular header includes simplifies the code and makes
various clang based tooling such as iwyu work much better on our code.
The most important change is getting rid of the manager.h include in
unit.h which is possible thanks to the previous commits. We also move
the OOMPolicy and StatusType enums to unit.h to remove the need for
other unit headers to include manager.h to get access to these enums.
libbpf returns error codes from the kernel unmodified, and we don't understand
them so non-fatal ones are handled as hard errors.
Add a translation helper, and start by translating 524 to EOPNOTSUPP, which is
returned when nsresourced tries to use LSM BPF hooks that are not
implemented on a given arch (in this case, arm64 is misssing trampolines).
Fixes https://github.com/systemd/systemd/issues/32170
This patch fixes an issue where, when not specifiying either at least one
`SocketBindAllow` or `SocketBindDeny` rule, behavior for the bind syscall
filtering would be unexpected.
For example, when trying to bind to a port with only "SocketBindDeny=any"
given, the syscall would succeed:
> systemd-run -t -p "SocketBindDeny=any" nc -l 8080
Expected with this set of rules (also in accordance with the documentation)
would be an Operation not permitted error.
This behavior occurs because a default initialized socket_bind_rule struct
matches what "any" represents. When creating the bpf list all elements get
default initialized, as such represeting "any". Seemingly it is necressarry
to set the size of the map to at least one, as such if no allow rule is
given default initialization and minimal map size cause one any allow rule
to be in the map, causing the behavior observed above.
This patch solves this by introducing a new "match nothing" magic stored in
the rule's address family and setting such a rule as the first one if no
rule is given, making sure that default initialized rule structs are never
used.
Resolves#30556
This refactors the Unit structure a bit: all cgroup-related state fields
are moved to a new structure CGroupRuntime, which is only allocated as
we realize a cgroup.
This is both a nice cleanup and should make unit structures considerably
smaller that have no cgroup associated, because never realized or
because they belong to a unit type that doesn#t have cgroups anyway.
This makes things nicely symmetric:
ExecContext → static user configuration about execution
ExecRuntime → dynamic user state of execution
CGroupContext → static user configuration about cgroups
CGroupRuntime → dynamic user state of cgroups
And each time the XyzContext is part of the unit type structures such as
Service or Slice that need it, but the runtime object is only allocated
when a unit is started.
-1 was used everywhere, but -EBADF or -EBADFD started being used in various
places. Let's make things consistent in the new style.
Note that there are two candidates:
EBADF 9 Bad file descriptor
EBADFD 77 File descriptor in bad state
Since we're initializating the fd, we're just assigning a value that means
"no fd yet", so it's just a bad file descriptor, and the first errno fits
better. If instead we had a valid file descriptor that became invalid because
of some operation or state change, the other errno would fit better.
In some places, initialization is dropped if unnecessary.
- new symbols are available from libbpf 0.6.0 so could be used with
libbpf.so.0, but we're sure the old symbols will be there and this
simplifies code
- detection at runtime should always work, regardless of whether systemd
has been compiled with older or newer libbpf and runs with older or newer
libbpf
When something goes awry, we would get identical log messages from all the
bpf subsystems. E.g. "Failed to load BPF object: %m" appeared 5 times in the
sources. But it is very important to know *which* object we failed to load.
This could be guessed, e.g. from surroudning messages or from filename/line
metadata, but when we get log messages in bug reports, this might not be
available. Let's make the messages distinguishable.
While at it, some messages were adjusted a bit. In particular, we shouldn't use
internal names like BPFProgram which have no meaning outside of the codebase.
Lookup ip protocol in a socket address to allow or deny binding a socket
to the address.
Matching rule is extended with 'protocol' field. If its value is 0
(IPPROTO_IP) ip protocol comparison is omitted and matching is passed to
the next token which is ip ports.
Documentation is updated.
