When some transient unit setting is received over D-Bus, we write it it to a
transient unit file. We escape backslashes and specifiers. For most settings
this is enough, because most settings only do parsing and interpolation of
specifiers. When systemd-run is called (or something equivalent that gives us a
command strv), we write ExecStart=, but when reading it, we not only do parsing
and interpolation of specifiers, but also split on semicolons and do variable
substitution. This results in an ugly situation where the commandline is
interpolated twice, once on the caller side, and once in the manager.
I think we need to treat this as a bug: current behaviour seems to be an
accident of implementation and hard to explain in a reasonable way. If we
*were* doing specifier expansion, then it'd be somewhat reasonable so say that
"the commandline is handled the same as ExecStart=". But since we explicitly
prevent specifier expansion, we best we could say is "the commandline has some
subset of features of ExecStart=". I think this is not useful, and unexpected
by users. Since most people use use a shell to call systemd-run, one level of
variable expansion is already done on the caller side, and having to take into
account another level of expansion (with slightly different rules), creates a
big mental overhead when the commandline needs to include a dollar character or
such. Not doing any expansion is much cleaner and easier to explain or use.
Thus I think it's better to change behaviour here, even though in principle
some people could be relying on current behaviour. I think it's more likely
that nobody noticed, because people generally don't use systemd-run for
complicated commandlines.
Thus this commit adds an additional mode of escaping that prevents variable
explansion and other elements of ExecStart= syntax. I looked over all the
places where unit_escape_setting() is called, and I think that only two need to
be changed to use the new flag.
Fixes#23631.
This was a trivial wrapper that didn't provide any added value. With more
complicated structures like strvs, hashmaps, sets, and arrays, it is possible
to have an empty container. But in case of a list, the list is empty only when
the head is missing.
Also, we generally want the positive condition, so we replace many
if (!LIST_IS_EMPTY(x)) with just if (x).
This reverts PR #22587 and its follow-up commit. More specifically,
2299b1cae3 (partially),
e176f855278d5098d3fecc5aa24ba702147d42e0,
ceb46a31a01b3d3d1d6095d857e29ea214a2776b, and
51bb9076ab8c050bebb64db5035852385accda35.
The PR was merged without final approval, and has several issues:
- OSS fuzz reported issues in the conf parser,
- It calls synchrnous netlink call, it should not be especially in PID1,
- The importance of NFTSet for CGroup and DynamicUser may be
questionable, at least, there was no justification PID1 should support
it.
- For networkd, it should be implemented with Request object,
- There is no test for the feature.
Fixes#23711.
Fixes#23717.
Fixes#23719.
Fixes#23720.
Fixes#23721.
Fixes#23759.
Follow-up for 68acc1afbe.
Before the commit, SystemCallFilter bus property provides only allowed
syscalls if ExecContext.syscall_filter is an allow-list, and vice versa.
After the commit, if the list is allow-list, it contains allowed
syscalls with value `-1`, and denied syscalls with non-negative values.
To keep the backward compatibility, denied syscalls must be dropped in
SystemCallFilter bus property.
New directive `DynamicUserNFTSet=` provides a method for integrating
configuration of dynamic users into firewall rules with NFT sets.
Example:
```
table inet filter {
set u {
typeof meta skuid
}
chain service_output {
meta skuid != @u drop
accept
}
}
```
```
/etc/systemd/system/dunft.service
[Service]
DynamicUser=yes
DynamicUserNFTSet=inet:filter:u
ExecStart=/bin/sleep 1000
[Install]
WantedBy=multi-user.target
```
```
$ sudo nft list set inet filter u
table inet filter {
set u {
typeof meta skuid
elements = { 64864 }
}
}
$ ps -n --format user,group,pid,command -p `pgrep sleep`
USER GROUP PID COMMAND
64864 64864 55158 /bin/sleep 1000
```
Add a new setting that follows the same principle and implementation
as ExtensionImages, but using directories as sources.
It will be used to implement support for extending portable images
with directories, since portable services can already use a directory
as root.
When combined with a tmpfs on /run or /var/lib, allows to create
arbitrary and ephemeral symlinks for StateDirectory or RuntimeDirectory.
This is especially useful when sharing these directories between
different services, to make the same state/runtime directory 'backend'
appear as different names to each service, so that they can be added/removed
to a sharing agreement transparently, without code changes.
An example (simplified, but real) use case:
foo.service:
StateDirectory=foo
bar.service:
StateDirectory=bar
foo.service.d/shared.conf:
StateDirectory=
StateDirectory=shared:foo
bar.service.d/shared.conf:
StateDirectory=
StateDirectory=shared:bar
foo and bar use respectively /var/lib/foo and /var/lib/bar. Then
the orchestration layer decides to stop this sharing, the drop-in
can be removed. The services won't need any update and will keep
working and being able to store state, transparently.
To keep backward compatibility, new DBUS messages are added.
Let's define two helpers strdupa_safe() + strndupa_safe() which do the
same as their non-safe counterparts, except that they abort if called
with allocations larger than ALLOCA_MAX.
This should ensure that all our alloca() based allocations are subject
to this limit.
afaics glibc offers three alloca() based APIs: alloca() itself,
strndupa() + strdupa(). With this we have now replacements for all of
them, that take the limit into account.
This verifies that the argv part of any exec_command parameters that
are sent through dbus is not empty at deserialization time.
There is an additional check in service.c service_verify() that again
checks if all exec_commands are correctly populated, after the service
has been loaded, whether through dbus or otherwise.
Fixes#20933.
Currently there does not exist a way to specify a path relative to which
all binaries executed by Exec should be found. The only way is to
specify the absolute path.
This change implements the functionality to specify a path relative to which
binaries executed by Exec*= can be found.
Closes#6308
With some versions of the compiler, the _cleanup_ attr makes it think
the variable might be freed/closed when uninitialized, even though it
cannot happen. The added cost is small enough to be worth the benefit,
and optimized builds will help reduce it even further.
parse_syscall_and_errno() does not check the validity of syscall name or
syscall group name, but it just split into syscall name and errno.
So, it is not necessary to call it for SystemCallLog=.
Implement directives `NoExecPaths=` and `ExecPaths=` to control `MS_NOEXEC`
mount flag for the file system tree. This can be used to implement file system
W^X policies, and for example with allow-listing mode (NoExecPaths=/) a
compromised service would not be able to execute a shell, if that was not
explicitly allowed.
Example:
[Service]
NoExecPaths=/
ExecPaths=/usr/bin/daemon /usr/lib64 /usr/lib
Closes: #17942.
This adds the ability to specify truncate:PATH for StandardOutput= and
StandardError=, similar to the existing append:PATH. The code is mostly
copied from the related append: code. Fixes#8983.
With new directive SystemCallLog= it's possible to list system calls to be
logged. This can be used for auditing or temporarily when constructing system
call filters.
---
v5: drop intermediary, update HASHMAP_FOREACH_KEY() use
v4: skip useless debug messages, actually parse directive
v3: don't declare unused variables with old libseccomp
v2: fix build without seccomp or old libseccomp
Define explicit action "kill" for SystemCallErrorNumber=.
In addition to errno code, allow specifying "kill" as action for
SystemCallFilter=.
---
v7: seccomp_parse_errno_or_action() returns -EINVAL if !HAVE_SECCOMP
v6: use streq_ptr(), let errno_to_name() handle bad values, kill processes,
init syscall_errno
v5: actually use seccomp_errno_or_action_to_string(), don't fail bus unit
parsing without seccomp
v4: fix build without seccomp
v3: drop log action
v2: action -> number
Zbigniew Jędrzejewski-Szmek
Yu Watanabe
Topi Miettinen
Jan Janssen
Luca Boccassi
Lennart Poettering
Daan De Meyer
Iago López Galeiras
Henri Chain
alexlzhu
Xℹ Ruoyao
Susant Sahani
Lucas Werkmeister