1 # $OpenBSD: limit-keytype.sh,v 1.5 2018/03/12 00:52:57 djm Exp $
2 # Placed in the Public Domain.
4 tid="restrict pubkey type"
6 rm -f $OBJ/authorized_keys_$USER $OBJ/user_ca_key* $OBJ/user_key*
7 rm -f $OBJ/authorized_principals_$USER $OBJ/cert_user_key*
9 mv $OBJ/sshd_proxy $OBJ/sshd_proxy.orig
10 mv $OBJ/ssh_proxy $OBJ/ssh_proxy.orig
13 ${SSHKEYGEN} -q -N '' -t ed25519 -f $OBJ/user_ca_key ||\
14 fatal "ssh-keygen failed"
16 # Make some keys and a certificate.
17 ${SSHKEYGEN} -q -N '' -t ed25519 -f $OBJ/user_key1 || \
18 fatal "ssh-keygen failed"
19 ${SSHKEYGEN} -q -N '' -t rsa -f $OBJ/user_key2 || \
20 fatal "ssh-keygen failed"
21 ${SSHKEYGEN} -q -N '' -t rsa -f $OBJ/user_key3 || \
22 fatal "ssh-keygen failed"
23 ${SSHKEYGEN} -q -N '' -t dsa -f $OBJ/user_key4 || \
24 fatal "ssh-keygen failed"
25 ${SSHKEYGEN} -q -s $OBJ/user_ca_key -I "regress user key for $USER" \
26 -z $$ -n ${USER},mekmitasdigoat $OBJ/user_key3 ||
27 fatal "couldn't sign user_key1"
28 # Copy the private key alongside the cert to allow better control of when
30 mv $OBJ/user_key3-cert.pub $OBJ/cert_user_key3.pub
32 grep -v IdentityFile $OBJ/ssh_proxy.orig > $OBJ/ssh_proxy
34 opts="-oProtocol=2 -F $OBJ/ssh_proxy -oIdentitiesOnly=yes"
35 certopts="$opts -i $OBJ/user_key3 -oCertificateFile=$OBJ/cert_user_key3.pub"
37 echo mekmitasdigoat > $OBJ/authorized_principals_$USER
38 cat $OBJ/user_key1.pub > $OBJ/authorized_keys_$USER
39 cat $OBJ/user_key2.pub >> $OBJ/authorized_keys_$USER
43 grep -v "Protocol" $OBJ/sshd_proxy.orig
45 echo "AuthenticationMethods publickey"
46 echo "TrustedUserCAKeys $OBJ/user_ca_key.pub"
47 echo "AuthorizedPrincipalsFile $OBJ/authorized_principals_%u"
56 # Check we can log in with all key types.
57 ${SSH} $certopts proxy true || fatal "cert failed"
58 ${SSH} $opts -i $OBJ/user_key1 proxy true || fatal "key1 failed"
59 ${SSH} $opts -i $OBJ/user_key2 proxy true || fatal "key2 failed"
61 # Allow plain Ed25519 and RSA. The certificate should fail.
62 verbose "allow rsa,ed25519"
64 "PubkeyAcceptedKeyTypes rsa-sha2-256,rsa-sha2-512,ssh-rsa,ssh-ed25519"
65 ${SSH} $certopts proxy true && fatal "cert succeeded"
66 ${SSH} $opts -i $OBJ/user_key1 proxy true || fatal "key1 failed"
67 ${SSH} $opts -i $OBJ/user_key2 proxy true || fatal "key2 failed"
70 verbose "allow ed25519"
71 prepare_config "PubkeyAcceptedKeyTypes ssh-ed25519"
72 ${SSH} $certopts proxy true && fatal "cert succeeded"
73 ${SSH} $opts -i $OBJ/user_key1 proxy true || fatal "key1 failed"
74 ${SSH} $opts -i $OBJ/user_key2 proxy true && fatal "key2 succeeded"
76 # Allow all certs. Plain keys should fail.
77 verbose "allow cert only"
78 prepare_config "PubkeyAcceptedKeyTypes *-cert-v01@openssh.com"
79 ${SSH} $certopts proxy true || fatal "cert failed"
80 ${SSH} $opts -i $OBJ/user_key1 proxy true && fatal "key1 succeeded"
81 ${SSH} $opts -i $OBJ/user_key2 proxy true && fatal "key2 succeeded"
83 # Allow RSA in main config, Ed25519 for non-existent user.
84 verbose "match w/ no match"
85 prepare_config "PubkeyAcceptedKeyTypes rsa-sha2-256,rsa-sha2-512,ssh-rsa" \
86 "Match user x$USER" "PubkeyAcceptedKeyTypes +ssh-ed25519"
87 ${SSH} $certopts proxy true && fatal "cert succeeded"
88 ${SSH} $opts -i $OBJ/user_key1 proxy true && fatal "key1 succeeded"
89 ${SSH} $opts -i $OBJ/user_key2 proxy true || fatal "key2 failed"
91 # Allow only DSA in main config, Ed25519 for user.
92 verbose "match w/ matching"
93 prepare_config "PubkeyAcceptedKeyTypes ssh-dss" \
94 "Match user $USER" "PubkeyAcceptedKeyTypes +ssh-ed25519"
95 ${SSH} $certopts proxy true || fatal "cert failed"
96 ${SSH} $opts -i $OBJ/user_key1 proxy true || fatal "key1 failed"
97 ${SSH} $opts -i $OBJ/user_key4 proxy true && fatal "key4 succeeded"