Add the needed assert changes to make the code clean
for the new check-pointer-deref script.
Note that for `_cmp()` functions its a bit of a question
if we want `assert()` or `POINTER_MAY_BE_NULL()` here. The
former is more correct but it adds a (small) runtime hit. If
we use POINTER_MAY_BE_NULL() it is compiled out but strictly
speaking it is wrong (so at least we would need a comment).
There's no need to pass in a boolean to decide whether we use
namespace_enter_delegated() or not. Instead, we can just check if we
have CAP_SYS_ADMIN in our own user namespace. If we don't, then we have
to insist on a child user namespace being passed in and we have to enter
it first to get CAP_SYS_ADMIN as without CAP_SYS_ADMIN we wouldn't be
able
to call setns() in the first place. If we do have CAP_SYS_ADMIN, we can
always enter the other namespaces first before entering the user
namespace.
Additionally, we don't fail anymore if we can't reset the UID/GID since
a
root user might not always be available in every user namespace we might
enter.
There's no need to pass in a boolean to decide whether we use
namespace_enter_delegated() or not. Instead, we can just check if we
have CAP_SYS_ADMIN in our own user namespace. If we don't, then we have
to insist on a child user namespace being passed in and we have to enter
it first to get CAP_SYS_ADMIN as without CAP_SYS_ADMIN we wouldn't be able
to call setns() in the first place. If we do have CAP_SYS_ADMIN, we can
always enter the other namespaces first before entering the user namespace.
Additionally, we don't fail anymore if we can't reset the UID/GID since a
root user might not always be available in every user namespace we might
enter.
Calling mlockall in an unprivileged process most notably had the effect
of making systemd-cryptenroll OOM while trying to open a normal-sized
argon2 keyslot due to it hitting RLIMIT_MEMLOCK.
Previously, if execution failed, we'd log at error level both from the
child and the parent, and we were using a bogus variable for the argument
name:
$ build/systemd-inhibit list
Failed to execute : No such file or directory
list failed with exit status 1.
In general, we can and should assume that the program the user is calling
is well behaved, so it'll log the error on its own if appropriate. So we
shouldn't log on "normal errors", but only if the child is terminated by
a signal.
And since the program name is controlled by the user, use quotes everywhere
to avoid ambiguity.
Now:
$ build/systemd-inhibit false
(nothing)
$ build/systemd-inhibit bash -c 'kill -SEGV $$'
src/basic/process-util.c:895: 'bash' terminated by signal SEGV.
Allow CPUSchedulingPolicy to be set to "ext". SCHED_EXT is a new
scheduling policy in Linux v6.12 that allows processes to be scheduled
using custom BPF schedulers instead of the default in-kernel ones.
Selectively setting the SCHED_EXT policy is useful for systems running
in "partial mode" where not all processes are run using a custom
scheduler.
Fallback to SCHED_OTHER and print an error message for systems where
SCHED_EXT isn't available.
Note that we still have to block SIGCHLD so that
we can be certain the process is not reaped before
we get the pidfd to it. safe_fork() and friends are
used in libsystemd where we don't control how the
SIGCHLD signal is configured. Specifically, kernel
autoreaping could be enabled which is why we have
to block SIGCHLD until we get the pidfd so that the
kernel cannot autoreap the process before we get
the pidfd.
* Specifying all 3 of FORK_DEATHSIG_SIG{KILL,TERM,INT} for
the middle man makes zero sense. Use SIGKILL only.
* Make sure operations on except_fds work sensibly - close/pack/
de-ocloexecify fds only in the second level, so that the namespace
fds remain usable across first safe_fork().
* Fire FORK_NEW_*NS after attaching to the desired namespaces,
not already in the outer process.
* Insist on PDEATHSIG being enabled to ensure propagation of killing.
* Suppress more redundant flags.
While blocking dlopen() in child generally makes sense, it does
also lead to misery - in the very case of extension/cred refreshing
it then enforces loading of libcryptsetup/libacl in pid1, which
are otherwise never used. Let's add a flag to opt out hence, but
still prohibit it in namespace_fork/enter().
We have dropped cgroup v1 support in v258. When running on cgroup v2,
cg_get_path_and_check() with SYSTEMD_CGROUP_CONTROLLER as controller is
equivalent with checking if we are running on cgroup v2 and then
cg_get_path(). As we can assume we are running on cgroup v2, then the
check is not necessary anymore, thus we can replace
cg_get_path_and_check() with cg_get_path().
Then, move syscall definitions to the wrapper, and prototypes are moved
to relevant headers.
This also adds checks for add_key() and request_key(), as one day
glibc may be going to add some of them separatedly.
The check for fspick in meson.build is dropped, as it is currently
unused in our code.
This also moves
- basic/missing_bpf.h -> include/override/linux/bpf.h,
- basic/missing_keyctl.h -> include/override/linux/keyctl.h.
- Drop effectively unused "terminator" param, imply whitespace
- Make ret param optional
- Return ENODATA if the requested key is not found, rather than
ENOENT
- Turn ENOENT -> ENOSYS if /proc/ is not mounted
- Don't skip whitespaces before ':', nothing needs this handling
anyways
- Remove the special treatment for all "0"s. We don't actually
use this for capabilities given pidref_get_capability() exists
- Switch away from read_full_virtual_file() - files using "field"
scheme under /proc/ seem all to be "seq_file"s (refer to
da65941c3e for details on file types)
This introduce LOG_ITEM() macro that checks arbitrary formats in
log_struct().
Then, drop _printf_ attribute from log_struct_internal(), as it does not
help so much, and compiler checked only the first format string.
Hopefully, this silences false-positive warnings by Coverity.
This used to be relevant since in old versions of glibc an internal
cache is maintained, while we might sidestep their invalidation
with raw_clone(). After glibc 2.25 getpid() is a trivial wrapper
for the syscall, and hence there's no need to have a separate
raw_getpid().
Let's switch things around, and move the internals of safe_fork_full() into
pidref_safe_fork_full() and make safe_fork_full() a trivial wrapper on top
of pidref_safe_fork_full().
Note that this drops a lot of "const" qualifiers on PidRef arguments.
That's because pidref_is_self() suddenly might end changing the PidRef
because it acquires the pidfd ID.
We had this previously already with pidfd_equal(), but this amplifies
the problem.
I guess we C's "const" doesn't really work for stuff that contains
caches, that is just conceptually constant, but not actually.
Michael Vogt
Mike Yuan
Daan De Meyer
Yu Watanabe
cyclopentane
Zbigniew Jędrzejewski-Szmek
Daan De Meyer
Matt Fleming
Lennart Poettering