Comment 0 for bug 1669712

Introducing valid usernames with trailing newline characters triggers the removal of valid LDB cache entries

Reproducer:

1. Request a valid user and confirm it's cached:
ubuntu@ubuntu:~⟫ sudo sss_cache -E; getent passwd 'ad1'
ad1:*:1500:1500:ad1:/home/ad:/bin/bash

ubuntu@ubuntu:~⟫ sudo ldbsearch -H /var/lib/sss/db/cache_UBUNTU.TEST.ldb -b name=ad1,cn=users,cn=UBUNTU.TEST,cn=sysdb | grep entries
asq: Unable to register control with rootdse!
# 1 entries

2. Request an invalid username:
ubuntu@ubuntu:~⟫ sudo sss_cache -E; getent passwd 'ad1
'

3. Confirm the cache entry has disappeared:
ubuntu@ubuntu:~⟫ sudo ldbsearch -H /var/lib/sss/db/cache_UBUNTU.TEST.ldb -b name=ad1,cn=users,cn=UBUNTU.TEST,cn=sysdb | grep entries
asq: Unable to register control with rootdse!
# 0 entries

This is an excerpt from the logs of the request with the newline char:

(Tue Feb 28 16:07:40 2017) [sssd[be[UBUNTU.TEST]]] [be_get_account_info] (0x0200): Got request for [0x1001][FAST BE_REQ_USER][1][name=ad1
]

(Tue Feb 28 16:08:33 2017) [sssd[be[UBUNTU.TEST]]] [sdap_get_generic_ext_step] (0x0400): calling ldap_search_ext with [(&(sAMAccountName=ad1
)(objectclass=user)(sAMAccountName=*)(&(uidNumber=*)(!(uidNumber=0))))][CN=Users,DC=ubuntu,DC=test].
(Tue Feb 28 16:08:33 2017) [sssd[be[UBUNTU.TEST]]] [sdap_get_users_done] (0x0040): Failed to retrieve users
(Tue Feb 28 16:08:33 2017) [sssd[nss]] [sss_ncache_set_str] (0x0400): Adding [NCE/USER/UBUNTU.TEST/ad1
] to negative cache
(Tue Feb 28 16:08:33 2017) [sssd[nss]] [nss_cmd_getpwnam_search] (0x0040): No results for getpwnam call

At this point, the ldb entry removal request for ad1 (without \n) takes place via sysdb_delete_user.

Adding '\n' to the character list in sss_filter_sanitize_ex() seems to fix this issue.

Upstream bug: https://pagure.io/SSSD/sssd/issue/3317