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Fix host-based authentication with rsa keys

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Resolves: rhbz#2088916

Signed-off-by: Zoltan Fridrich <zfridric@redhat.com>
This commit is contained in:
Zoltan Fridrich 2022-07-11 17:44:53 +02:00
parent 9bf7b4f39d
commit fd0d5a4f44
2 changed files with 160 additions and 0 deletions
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151
openssh-8.7p1-host-based-auth.patch Normal file
View File

@ -0,0 +1,151 @@
diff --color -rup a/sshconnect2.c b/sshconnect2.c
--- a/sshconnect2.c 2022-07-11 17:00:02.618575727 +0200
+++ b/sshconnect2.c 2022-07-11 17:03:05.096085690 +0200
@@ -2288,9 +2288,9 @@ userauth_hostbased(struct ssh *ssh)
if (authctxt->sensitive->keys[i] == NULL ||
authctxt->sensitive->keys[i]->type == KEY_UNSPEC)
continue;
- if (match_pattern_list(
+ if (!sshkey_match_keyname_to_sigalgs(
sshkey_ssh_name(authctxt->sensitive->keys[i]),
- authctxt->active_ktype, 0) != 1)
+ authctxt->active_ktype))
continue;
/* we take and free the key */
private = authctxt->sensitive->keys[i];
@@ -2316,7 +2316,8 @@ userauth_hostbased(struct ssh *ssh)
error_f("sshkey_fingerprint failed");
goto out;
}
- debug_f("trying hostkey %s %s", sshkey_ssh_name(private), fp);
+ debug_f("trying hostkey %s %s using sigalg %s",
+ sshkey_ssh_name(private), fp, authctxt->active_ktype);
/* figure out a name for the client host */
lname = get_local_name(ssh_packet_get_connection_in(ssh));
diff --color -rup a/sshkey.c b/sshkey.c
--- a/sshkey.c 2022-07-11 17:00:02.609575554 +0200
+++ b/sshkey.c 2022-07-11 17:12:30.905976443 +0200
@@ -252,6 +252,29 @@ sshkey_ecdsa_nid_from_name(const char *n
return -1;
}
+int
+sshkey_match_keyname_to_sigalgs(const char *keyname, const char *sigalgs)
+{
+ int ktype;
+
+ if (sigalgs == NULL || *sigalgs == '\0' ||
+ (ktype = sshkey_type_from_name(keyname)) == KEY_UNSPEC)
+ return 0;
+ else if (ktype == KEY_RSA) {
+ return match_pattern_list("ssh-rsa", sigalgs, 0) == 1 ||
+ match_pattern_list("rsa-sha2-256", sigalgs, 0) == 1 ||
+ match_pattern_list("rsa-sha2-512", sigalgs, 0) == 1;
+ } else if (ktype == KEY_RSA_CERT) {
+ return match_pattern_list("ssh-rsa-cert-v01@openssh.com",
+ sigalgs, 0) == 1 ||
+ match_pattern_list("rsa-sha2-256-cert-v01@openssh.com",
+ sigalgs, 0) == 1 ||
+ match_pattern_list("rsa-sha2-512-cert-v01@openssh.com",
+ sigalgs, 0) == 1;
+ } else
+ return match_pattern_list(keyname, sigalgs, 0) == 1;
+}
+
char *
sshkey_alg_list(int certs_only, int plain_only, int include_sigonly, char sep)
{
diff --color -rup a/sshkey.h b/sshkey.h
--- a/sshkey.h 2022-07-11 17:00:02.603575438 +0200
+++ b/sshkey.h 2022-07-11 17:13:01.052556879 +0200
@@ -194,6 +194,10 @@ int sshkey_is_cert(const struct sshkey
int sshkey_is_sk(const struct sshkey *);
int sshkey_type_is_cert(int);
int sshkey_type_plain(int);
+
+/* Returns non-zero if key name match sigalgs pattern list. (handles RSA) */
+int sshkey_match_keyname_to_sigalgs(const char *, const char *);
+
int sshkey_to_certified(struct sshkey *);
int sshkey_drop_cert(struct sshkey *);
int sshkey_cert_copy(const struct sshkey *, struct sshkey *);
diff --color -rup a/ssh-keysign.c b/ssh-keysign.c
--- a/ssh-keysign.c 2021-08-20 06:03:49.000000000 +0200
+++ b/ssh-keysign.c 2022-07-11 17:00:23.306973667 +0200
@@ -62,7 +62,7 @@
extern char *__progname;
static int
-valid_request(struct passwd *pw, char *host, struct sshkey **ret,
+valid_request(struct passwd *pw, char *host, struct sshkey **ret, char **pkalgp,
u_char *data, size_t datalen)
{
struct sshbuf *b;
@@ -75,6 +75,8 @@ valid_request(struct passwd *pw, char *h
if (ret != NULL)
*ret = NULL;
+ if (pkalgp != NULL)
+ *pkalgp = NULL;
fail = 0;
if ((b = sshbuf_from(data, datalen)) == NULL)
@@ -122,8 +124,6 @@ valid_request(struct passwd *pw, char *h
fail++;
} else if (key->type != pktype)
fail++;
- free(pkalg);
- free(pkblob);
/* client host name, handle trailing dot */
if ((r = sshbuf_get_cstring(b, &p, &len)) != 0)
@@ -154,8 +154,19 @@ valid_request(struct passwd *pw, char *h
if (fail)
sshkey_free(key);
- else if (ret != NULL)
- *ret = key;
+ else {
+ if (ret != NULL) {
+ *ret = key;
+ key = NULL;
+ }
+ if (pkalgp != NULL) {
+ *pkalgp = pkalg;
+ pkalg = NULL;
+ }
+ }
+ sshkey_free(key);
+ free(pkalg);
+ free(pkblob);
return (fail ? -1 : 0);
}
@@ -170,7 +181,7 @@ main(int argc, char **argv)
struct passwd *pw;
int r, key_fd[NUM_KEYTYPES], i, found, version = 2, fd;
u_char *signature, *data, rver;
- char *host, *fp;
+ char *host, *fp, *pkalg;
size_t slen, dlen;
if (pledge("stdio rpath getpw dns id", NULL) != 0)
@@ -258,7 +269,7 @@ main(int argc, char **argv)
if ((r = sshbuf_get_string(b, &data, &dlen)) != 0)
fatal_r(r, "%s: buffer error", __progname);
- if (valid_request(pw, host, &key, data, dlen) < 0)
+ if (valid_request(pw, host, &key, &pkalg, data, dlen) < 0)
fatal("%s: not a valid request", __progname);
free(host);
@@ -279,7 +290,7 @@ main(int argc, char **argv)
}
if ((r = sshkey_sign(keys[i], &signature, &slen, data, dlen,
- NULL, NULL, NULL, 0)) != 0)
+ pkalg, NULL, NULL, 0)) != 0)
fatal_r(r, "%s: sshkey_sign failed", __progname);
free(data);

9
openssh.spec
View File

@ -240,6 +240,12 @@ Patch1003: openssh-8.7p1-mem-leak.patch
# upstream MR:
# https://github.com/openssh-gsskex/openssh-gsskex/pull/21
Patch1004: openssh-8.7p1-gssapi-auth.patch
# Fix host-based authentication with rsa keys
# upstream commits:
# 7aa7b096cf2bafe2777085abdeed5ce00581f641
# d9dbb5d9a0326e252d3c7bc13beb9c2434f59409
# fdb1d58d0d3888b042e5a500f6ce524486aaf782
Patch1005: openssh-8.7p1-host-based-auth.patch
License: BSD
Requires: /sbin/nologin
@ -433,6 +439,7 @@ popd
%patch1002 -p1 -b .ssh-manpage
%patch1003 -p1 -b .mem-leak
%patch1004 -p1 -b .gssapi-auth
%patch1005 -p1 -b .host-based-auth
%patch100 -p1 -b .coverity
@ -722,6 +729,8 @@ test -f %{sysconfig_anaconda} && \
Related: rhbz#2068423
- Fix gssapi authentication failures
Resolves: rhbz#2091023
- Fix host-based authentication with rsa keys
Resolves: rhbz#2088916
* Wed Jun 29 2022 Dmitry Belyavskiy <dbelyavs@redhat.com> - 8.7p1-10
- Set minimal value of RSA key length via configuration option