We aren't properly checking the length and null-termination of the strings passed to us from glibc. We need to do the following:

Define a new macro, {{{SSS_NAME_LENGTH}}} and set it to equal {{{LOGIN_NAME_MAX}}} from limits.h on platforms that have it, otherwise set it explicitly to 256.

If the names are too long, we should simply return an error, rather than passing the overlong name through the socket to SSSD.

There is no security exposure here, as the receiving daemon properly terminates everything. It can cause a wasteful amount of memory use, however. So it's a bug that should be fixed.