Every dlopen_xxx() helper now takes an int log_level argument. It is
passed through to dlopen_many_sym_or_warn() (which in turn propagates it
to dlopen_verbose() for the library-not-installed case), and is used by
the fallback stub when support for the library is not compiled in to
emit a "<lib> support is not compiled in." message at the caller's level.
Callers pass LOG_DEBUG when gracefully degrading, or a higher level when
the failure should surface, and no longer need to log redundantly at the
call site.
As part of this, dlopen_bpf_full() (which already took a log_level) is
merged into dlopen_bpf() rather than keeping both.
The static inline fallbacks used to live in the headers, which required
pulling log.h in from every header that declared a dlopen_xxx(). Move
them into the .c files instead: the declaration is always outside the
#if HAVE_XXX block, the impl sits outside the outer #if HAVE_XXX wrap
with its own internal #if HAVE_XXX/#else/#endif, and apparmor-util.c,
idn-util.c, libmount-util.c and pam-util.c are now always compiled so
they can host their stubs.
Switch all internal callers from the private ELF_NOTE_DLOPEN() macro to
the new public SD_ELF_NOTE_DLOPEN() API from sd-dlopen.h, and remove
the now-redundant macro definitions from dlfcn-util.h.
Signed-off-by: Christian Brauner <brauner@kernel.org>
On top of libcrypt.so.2 and libcrypt.so.1, also try libcrypt.so.1.1
as a third fallback. This is used on debian alpha, and it was
reported that it is intended to ship like that, with a different
SONAME than other architectures:
https://packages.debian.org/sid/alpha/libcrypt1/filelist
Note, this drops logging only test case for crypt_preferred_method(),
as that requires explicitly dlopen() the library. But, we should test
that make_salt() and friends automatically dlopen() it.
libcrypt was no longer built by default since glibc-2.38, and it has been
completely removed since glibc-2.39.
Let's always use libxcrypt, unless when building with musl. As already
major distribution already have libxcrypt-4.4.x, hence let's also bump
the required minimum version to 4.4.0.
libxcrypt cannot be built with musl, hence the previous fallback logic
in libcrypt-util.c are moved to musl/crypt.c.
Note, libxcrypt-4.4.0 was released on 2018-11-20.
See also #38608.
We require at least crypt_r() exists, and it is provided since glibc-2.0
(and dropped in glibc-2.39) or by libxcrypt, and the function is
provided in crypt.h regardless it is provided by glibc or libxcrypt.
Hence, we cannot fallback to unistd.h.
This makes the condition about crypt.h more strict, and stop compilation
earlier when crypt.h does not exist.
Necessary for crypto_random_bytes(), which is used in the branch that
HAVE_CRYPT_GENSALT_RA is false. Unfortunately, our CIs tested only the
other branch.
We currently have a convoluted and complex selection of which random
numbers to use. We can simplify this down to two functions that cover
all of our use cases:
1) Randomness for crypto: this one needs to wait until the RNG is
initialized. So it uses getrandom(0). If that's not available, it
polls on /dev/random, and then reads from /dev/urandom. This function
returns whether or not it was successful, as before.
2) Randomness for other things: this one uses getrandom(GRND_INSECURE).
If it's not available it uses getrandom(GRND_NONBLOCK). And if that
would block, then it falls back to /dev/urandom. And if /dev/urandom
isn't available, it uses the fallback code. It never fails and
doesn't return a value.
These two cases match all the uses of randomness inside of systemd.
I would prefer to make both of these return void, and get rid of the
fallback code, and simply assert in the incredibly unlikely case that
/dev/urandom doesn't exist. But Luca disagrees, so this commit attempts
to instead keep case (1) returning a return value, which all the callers
already check, and fix the fallback code in (2) to be less bad than
before.
For the less bad fallback code for (2), we now use auxval and some
timestamps, together with various counters representing the invocation,
hash it all together and provide the output. Provided that AT_RANDOM is
secure, this construction is probably okay too, though notably it
doesn't have any forward secrecy. Fortunately, it's only used by
random_bytes() and not by crypto_random_bytes().
After https://github.com/systemd/systemd/pull/16981 only the presence of crypt_gensalt_ra
is checked, but there are cases where that function is available but crypt_preferred_method
is not, and they are used in the same ifdef.
Add a check for the latter as well.
Since the loop to check various xcrypt functions is already in place,
adding one more is cheap. And it is nicer to check for the function
directly. People like to backport things, so we might get lucky even
without having libxcrypt.
They are only used under src/home/, but I want to add tests in test-libcrypt-util.c.
And the functions are almost trivial, so I think it is OK to move them to shared.
This lets the libc/xcrypt allocate as much storage area as it needs.
Should fix#16965:
testsuite-46.sh[74]: ==74==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7f3e972e1080 at pc 0x7f3e9be8deed bp 0x7ffce4f28530 sp 0x7ffce4f27ce0
testsuite-46.sh[74]: WRITE of size 131232 at 0x7f3e972e1080 thread T0
testsuite-46.sh[74]: #0 0x7f3e9be8deec (/usr/lib/clang/10.0.1/lib/linux/libclang_rt.asan-x86_64.so+0x9feec)
testsuite-46.sh[74]: #1 0x559cd05a6412 in user_record_make_hashed_password /systemd-meson-build/../build/src/home/user-record-util.c:818:21
testsuite-46.sh[74]: #2 0x559cd058fb03 in create_home /systemd-meson-build/../build/src/home/homectl.c:1112:29
testsuite-46.sh[74]: #3 0x7f3e9b5b3058 in dispatch_verb /systemd-meson-build/../build/src/shared/verbs.c:103:24
testsuite-46.sh[74]: #4 0x559cd058c101 in run /systemd-meson-build/../build/src/home/homectl.c:3325:16
testsuite-46.sh[74]: #5 0x559cd058c00a in main /systemd-meson-build/../build/src/home/homectl.c:3328:1
testsuite-46.sh[74]: #6 0x7f3e9a88b151 in __libc_start_main (/usr/lib/libc.so.6+0x28151)
testsuite-46.sh[74]: #7 0x559cd0583e7d in _start (/usr/bin/homectl+0x24e7d)
testsuite-46.sh[74]: Address 0x7f3e972e1080 is located in stack of thread T0 at offset 32896 in frame
testsuite-46.sh[74]: #0 0x559cd05a60df in user_record_make_hashed_password /systemd-meson-build/../build/src/home/user-record-util.c:789
testsuite-46.sh[74]: This frame has 6 object(s):
testsuite-46.sh[74]: [32, 40) 'priv' (line 790)
testsuite-46.sh[74]: [64, 72) 'np' (line 791)
testsuite-46.sh[74]: [96, 104) 'salt' (line 809)
testsuite-46.sh[74]: [128, 32896) 'cd' (line 810)
testsuite-46.sh[74]: [33152, 33168) '.compoundliteral' <== Memory access at offset 32896 partially underflows this variable
testsuite-46.sh[74]: [33184, 33192) 'new_array' (line 832) <== Memory access at offset 32896 partially underflows this variable
testsuite-46.sh[74]: HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork
testsuite-46.sh[74]: (longjmp and C++ exceptions *are* supported)
testsuite-46.sh[74]: SUMMARY: AddressSanitizer: stack-buffer-overflow (/usr/lib/clang/10.0.1/lib/linux/libclang_rt.asan-x86_64.so+0x9feec)
It seems 'struct crypt_data' is 32896 bytes, but libclang_rt wants more, at least 33168?
We would reject various passwords that glibc accepts, for example ""
or any descrypted password. Accounts with empty password are definitely
useful, for example for testing or in scenarios where a password is not
needed. Also, using weak encryption methods is probably not a good idea,
it's not the job of our nss helpers to decide that: they should just
faithfully forward whatever data is there.
Also rename the function to make it more obvious that the returned answer
is not in any way certain.
This way we can use libxcrypt specific functionality such as
crypt_gensalt() and thus take benefit of the newer algorithms libxcrypt
implements. (Also adds support for a new env var $SYSTEMD_CRYPT_PREFIX
which may be used to select the hash algorithm to use for libxcrypt.)
Also, let's move the weird crypt.h inclusion into libcrypt.h so that
there's a single place for it.
Daan De Meyer
Christian Brauner
Luca Boccassi
Yu Watanabe
Daan De Meyer
Zbigniew Jędrzejewski-Szmek
Jason A. Donenfeld
Luca Boccassi
Lennart Poettering