package/openssh: add libxcrypt optional dependency for sshd
When glibc was bumped to version 2.39 in commit
b5680f53d60acf8ff6010082f873438a39bd5d97 it removed the deprecated
libcrypt support.
As glibc's libcrypt was providing sshd's libcrypt dependency this broke
the sshd password authentification at runtime using glibc version 2.39.
# sshpass -p testpwd ssh -oStrictHostKeyChecking=no localhost /bin/true
Permission denied, please try again.
Without libcrypt, OpenSSH >= 6.2 fall back to using openssl's DES_crypt
function on platorms that don't have a native crypt() function [1].
Note that DES_crypt is deprecated since openssl 3.0 [2] [3].
"Use of the low level DES functions has been informally discouraged for a
long time. We now formally deprecate them.
Applications should instead use the EVP APIs, e.g. EVP_EncryptInit_ex,
EVP_EncryptUpdate, EVP_EncryptFinal_ex, and the equivalently named decrypt
functions."
Also DES_crypt is provided by openssl only if
BR2_PACKAGE_LIBOPENSSL_ENABLE_DES is enabled. Otherwise crypt() is
never defined:
sd-compat.a(xcrypt.o): in function `xcrypt':
xcrypt.c:(.text+0x48): undefined reference to `crypt'
It's not clear why the password authentification fail with openssl's
DES_crypt but since it's deprecated we use libxcrypt to provide
a working crypt() function for glibc based toolchains.
[1] https://github.com/openssh/openssh-portable/blob/V_9_7/openbsd-compat/xcrypt.c#L57
[2] https://github.com/openssl/openssl/commit/c6fec81b88131d08c1022504ccf6effa95497afb
[3] https://www.openssl.org/docs/man3.2/man3/DES_crypt.html
Fixes:
https://gitlab.com/buildroot.org/buildroot/-/jobs/6623402147
Signed-off-by: Romain Naour <romain.naour@smile.fr>
Romain Naour