Apparently unpriv clients expect to be able to auth via PAM. Kinda
sucks. But it is what it is. Hence open this up.
This shouldn't be too bad in effect since clients after all need to
provide security creds for unlocking the home dir, in order to misuse
this.
Fixes: #15072
Let's create a string cell for the unit if possible (since there can
only be one unit right now, and the JSON alternative output then
generates a string instead of an array for us), an empty cell if empty.
This adds the --exit-idle-time argument that causes
systemd-socket-proxyd to exit when there has been an idle period. An
open connection prevents the idle period from starting, even if there is
no activity on that connection.
When combined with another service that uses StopWhenUnneeded=, the
proxy exiting can trigger a resource-intensive process to exit. So
although the proxy may consume minimal resources, significant resources
can be saved indirectly.
Fixes#2106
The old version of this command will delete everything under the new home directory (including `.identity`), rendering the directory unusable with homed.
Having taken a look at https://github.com/systemd/systemd/runs/645252074?check_suite_focus=true
where fuzz-journal-remote failed with
```
AddressSanitizer:DEADLYSIGNAL
=================================================================
==16==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7f864f98948e bp 0x7ffde5c6b7c0 sp 0x7ffde5c6b560 T0)
==16==The signal is caused by a READ memory access.
==16==Hint: address points to the zero page.
SCARINESS: 10 (null-deref)
#0 0x7f864f98948e in output_short /work/build/../../src/systemd/src/shared/logs-show.c
#1 0x7f864f984624 in show_journal_entry /work/build/../../src/systemd/src/shared/logs-show.c:1154:15
#2 0x7f864f984b63 in show_journal /work/build/../../src/systemd/src/shared/logs-show.c:1239:21
#3 0x4cabab in LLVMFuzzerTestOneInput /work/build/../../src/systemd/src/fuzz/fuzz-journal-remote.c:67:21
#4 0x51fd16 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/libfuzzer/FuzzerLoop.cpp:556:15
#5 0x51c330 in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool*) /src/libfuzzer/FuzzerLoop.cpp:470:3
#6 0x523700 in fuzzer::Fuzzer::ReadAndExecuteSeedCorpora(std::__1::vector<fuzzer::SizedFile, fuzzer::fuzzer_allocator<fuzzer::SizedFile> >&) /src/libfuzzer/FuzzerLoop.cpp:765:7
#7 0x5246cd in fuzzer::Fuzzer::Loop(std::__1::vector<fuzzer::SizedFile, fuzzer::fuzzer_allocator<fuzzer::SizedFile> >&) /src/libfuzzer/FuzzerLoop.cpp:792:3
#8 0x4de3d1 in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/libfuzzer/FuzzerDriver.cpp:824:6
#9 0x4cfb47 in main /src/libfuzzer/FuzzerMain.cpp:19:10
#10 0x7f864e69782f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
#11 0x41f2a8 in _start (out/fuzz-journal-remote+0x41f2a8)
AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /work/build/../../src/systemd/src/shared/logs-show.c in output_short
==16==ABORTING
MS: 0 ; base unit: 0000000000000000000000000000000000000000
0x44,0x3d,0xa,0x5f,0x5f,0x52,0x45,0x41,0x4c,0x54,0x49,0x4d,0x45,0x5f,0x54,0x49,0x4d,0x45,0x53,0x54,0x41,0x4d,0x50,0x3d,0x31,0xa,0xa,
D=\x0a__REALTIME_TIMESTAMP=1\x0a\x0a
artifact_prefix='./'; Test unit written to ./crash-d635b9dd31cceff3c912fd45e1a58d7e90f0ad73
Base64: RD0KX19SRUFMVElNRV9USU1FU1RBTVA9MQoK
```
I was wondering why it hadn't been caught by the compiler even though clang should have failed to compile it with
```
../src/shared/logs-show.c:624:25: warning: null passed to a callee that requires a non-null argument [-Wnonnull]
print_multiline(f, 4 + fieldlen + 1, 0, OUTPUT_FULL_WIDTH, 0, false,
^
../src/shared/logs-show.c:161:24: note: callee declares array parameter as static here
size_t highlight[static 2]) {
^ ~~~~~~~~~~
../src/shared/logs-show.c:1239:21: warning: null passed to a callee that requires a non-null argument [-Wnonnull]
r = show_journal_entry(f, j, mode, n_columns, flags, NULL, NULL, ellipsized);
^ ~~~~
../src/shared/logs-show.c:1133:30: note: callee declares array parameter as static here
const size_t highlight[static 2],
^ ~~~~~~~~~~
2 warnings generated.
```
Given that judging by https://github.com/systemd/systemd/issues/13039 it doesn't seem to be
the first time issues like that have been missed I think it would be better to turn nonnull on
and get around false positives on a case-by-case basis with DISABLE_WARNING_NONNULL .. REENABLE_WARNING
Reopens https://github.com/systemd/systemd/issues/6119
Let's use "!*" instead of "!!" as invalid password string.
Generally, any invalid password string can be used to for locking an
account, according to shadow(5). To temporarily lock a password of an
account it is commonly implemented to prefix the original password with
a single "!", so that it can later on be unlocked again by removing the
"!", restoring the original password. Thus, the "!" marker is an
indicator for a locked password; the act of prefixing "!" to a
password string is the locking operation; and the removal of a "!"
prefix is the unlock operation. (This is also suggested in shadow(5)).
If we want to entirely lock an account we previously used "!!" as
password string. This is nice since it indicates the password is locked.
However, it is less than ideal, since applying the password unlock
operation once will change the string to "!", which is still a locked
password. Unlocking the password a second time will result in "", i.e.
the empty password, which will in many cases allow logging in without
password. And that's a problem. Hopefully, tools do not allow such
duplicate unlocking, but it's still not a nice property.
By changing our password string to "!*" we get different behaviour: the
password will appear locked. When it is unlocked the password is "*"
which is an invalid password. In that case the password is hence
unlocked but invalid, which is a much better state to be in than the
above.
This is paranoia hardening. Not more. There's no report that anyone
every unlocked an account twice and people could log in.
I'm not sure if the LogTarget property is sufficiently general to be made into
a property that can be generally implemented. It is very closely tied to the internal
systemd logic. The other two seem fine thoough.
This has the advantage that the executables are always in place and we don't
need any units to exist on the bus, so we can eventually hook this up into
a normal build system. (Probably as a build time check.)
In all the other cases, I think the code was clearer with the static table.
Here, not so much. And because of the existing dump code, the vtables cannot
be made static and need to remain exported. I still think it's worth to do the
change to have the cmdline introspection, but I'm disappointed with how this
came out.
Lennart Poettering