automatic import of openssh

1 files changed, 295 insertions, 0 deletions

diff --git a/backport-openssh-6.6p1-kuserok.patch b/backport-openssh-6.6p1-kuserok.patch
new file mode 100644
index 0000000..6bab715
--- /dev/null
+++ b/backport-openssh-6.6p1-kuserok.patch
@@ -0,0 +1,295 @@
+diff -up openssh-7.4p1/auth-krb5.c.kuserok openssh-7.4p1/auth-krb5.c
+--- openssh-7.4p1/auth-krb5.c.kuserok	2016-12-23 14:36:07.640465939 +0100
++++ openssh-7.4p1/auth-krb5.c	2016-12-23 14:36:07.644465936 +0100
+Reference:https://src.fedoraproject.org/rpms/openssh/blob/rawhide/f/backport-openssh-6.6p1-kuserok.patch
+@@ -56,6 +56,21 @@
+ 
+ extern ServerOptions	 options;
+ 
++int
++ssh_krb5_kuserok(krb5_context krb5_ctx, krb5_principal krb5_user, const char *client,
++                 int k5login_exists)
++{
++	if (options.use_kuserok || !k5login_exists)
++		return krb5_kuserok(krb5_ctx, krb5_user, client);
++	else {
++		char kuser[65];
++
++		if (krb5_aname_to_localname(krb5_ctx, krb5_user, sizeof(kuser), kuser))
++			return 0;
++		return strcmp(kuser, client) == 0;
++	}
++}
++
+ static int
+ krb5_init(void *context)
+ {
+@@ -160,8 +175,9 @@ auth_krb5_password(Authctxt *authctxt, c
+ 	if (problem)
+ 		goto out;
+ 
+-	if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
+-	    authctxt->pw->pw_name)) {
++	/* Use !options.use_kuserok here to make ssh_krb5_kuserok() not
++	 * depend on the existance of .k5login */
++	if (!ssh_krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user, authctxt->pw->pw_name, !options.use_kuserok)) {
+ 		problem = -1;
+ 		goto out;
+ 	}
+diff -up openssh-7.4p1/gss-serv-krb5.c.kuserok openssh-7.4p1/gss-serv-krb5.c
+--- openssh-7.4p1/gss-serv-krb5.c.kuserok	2016-12-23 14:36:07.640465939 +0100
++++ openssh-7.4p1/gss-serv-krb5.c	2016-12-23 14:36:07.644465936 +0100
+Reference:https://src.fedoraproject.org/rpms/openssh/blob/rawhide/f/backport-openssh-6.6p1-kuserok.patch
+@@ -67,6 +67,7 @@ static int ssh_gssapi_krb5_cmdok(krb5_pr
+     int);
+ 
+ static krb5_context krb_context = NULL;
++extern int ssh_krb5_kuserok(krb5_context, krb5_principal, const char *, int);
+ 
+ /* Initialise the krb5 library, for the stuff that GSSAPI won't do */
+ 
+@@ -92,6 +93,103 @@ ssh_gssapi_krb5_init(void)
+  * Returns true if the user is OK to log in, otherwise returns 0
+  */
+ 
++/* The purpose of the function is to find out if a Kerberos principal is
++ * allowed to log in as the given local user. This is a general problem with
++ * Kerberized services because by design the Kerberos principals are
++ * completely independent from the local user names. This is one of the
++ * reasons why Kerberos is working well on different operating systems like
++ * Windows and UNIX/Linux. Nevertheless a relationship between a Kerberos
++ * principal and a local user name must be established because otherwise every
++ * access would be granted for every principal with a valid ticket.
++ *
++ * Since it is a general issue libkrb5 provides some functions for
++ * applications to find out about the relationship between the Kerberos
++ * principal and a local user name. They are krb5_kuserok() and
++ * krb5_aname_to_localname().
++ *
++ * krb5_kuserok() can be used to "Determine if a principal is authorized to
++ * log in as a local user" (from the MIT Kerberos documentation of this
++ * function). Which is exactly what we are looking for and should be the
++ * preferred choice. It accepts the Kerberos principal and a local user name
++ * and let libkrb5 or its plugins determine if they relate to each other or
++ * not.
++ *
++ * krb5_aname_to_localname() can use used to "Convert a principal name to a
++ * local name" (from the MIT Kerberos documentation of this function). It
++ * accepts a Kerberos principle and returns a local name and it is up to the
++ * application to do any additional checks. There are two issues using
++ * krb5_aname_to_localname(). First, since POSIX user names are case
++ * sensitive, the calling application in general has no other choice than
++ * doing a case-sensitive string comparison between the name returned by
++ * krb5_aname_to_localname() and the name used at the login prompt. When the
++ * users are provided by a case in-sensitive server, e.g. Active Directory,
++ * this might lead to login failures because the user typing the name at the
++ * login prompt might not be aware of the right case. Another issue might be
++ * caused if there are multiple alias names available for a single user. E.g.
++ * the canonical name of a user is user@group.department.example.com but there
++ * exists a shorter login name, e.g. user@example.com, to safe typing at the
++ * login prompt. Here krb5_aname_to_localname() can only return the canonical
++ * name, but if the short alias is used at the login prompt authentication
++ * will fail as well. All this can be avoided by using krb5_kuserok() and
++ * configuring krb5.conf or using a suitable plugin to meet the needs of the
++ * given environment.
++ *
++ * The Fedora and RHEL version of openssh contain two patches which modify the
++ * access control behavior:
++ *  - openssh-6.6p1-kuserok.patch
++ *  - openssh-6.6p1-force_krb.patch
++ *
++ * openssh-6.6p1-kuserok.patch adds a new option KerberosUseKuserok for
++ * sshd_config which controls if krb5_kuserok() is used to check if the
++ * principle is authorized or if krb5_aname_to_localname() should be used.
++ * The reason to add this patch was that krb5_kuserok() by default checks if
++ * a .k5login file exits in the users home-directory. With this the user can
++ * give access to his account for any given principal which might be
++ * in violation with company policies and it would be useful if this can be
++ * rejected. Nevertheless the patch ignores the fact that krb5_kuserok() does
++ * no only check .k5login but other sources as well and checking .k5login can
++ * be disabled for all applications in krb5.conf as well. With this new
++ * option KerberosUseKuserok set to 'no' (and this is the default for RHEL7
++ * and Fedora 21) openssh can only use krb5_aname_to_localname() with the
++ * restrictions mentioned above.
++ *
++ * openssh-6.6p1-force_krb.patch adds a ksu like behaviour to ssh, i.e. when
++ * using GSSAPI authentication only commands configured in the .k5user can be
++ * executed. Here the wrong assumption that krb5_kuserok() only checks
++ * .k5login is made as well. In contrast ksu checks .k5login directly and
++ * does not use krb5_kuserok() which might be more useful for the given
++ * purpose. Additionally this patch is not synced with
++ * openssh-6.6p1-kuserok.patch.
++ *
++ * The current patch tries to restore the usage of krb5_kuserok() so that e.g.
++ * localauth plugins can be used. It does so by adding a forth parameter to
++ * ssh_krb5_kuserok() which indicates whether .k5login exists or not. If it
++ * does not exists krb5_kuserok() is called even if KerberosUseKuserok is set
++ * to 'no' because the intent of the option is to not check .k5login and if it
++ * does not exists krb5_kuserok() returns a result without checking .k5login.
++ * If .k5login does exists and KerberosUseKuserok is 'no' we fall back to
++ * krb5_aname_to_localname(). This is in my point of view an acceptable
++ * limitation and does not break the current behaviour.
++ *
++ * Additionally with this patch ssh_krb5_kuserok() is called in
++ * ssh_gssapi_krb5_cmdok() instead of only krb5_aname_to_localname() is
++ * neither .k5login nor .k5users exists to allow plugin evaluation via
++ * krb5_kuserok() as well.
++ *
++ * I tried to keep the patch as minimal as possible, nevertheless I see some
++ * areas for improvement which, if they make sense, have to be evaluated
++ * carefully because they might change existing behaviour and cause breaks
++ * during upgrade:
++ * - I wonder if disabling .k5login usage make sense in sshd or if it should
++ *   be better disabled globally in krb5.conf
++ * - if really needed openssh-6.6p1-kuserok.patch should be fixed to really
++ *   only disable checking .k5login and maybe .k5users
++ * - the ksu behaviour should be configurable and maybe check the .k5login and
++ *   .k5users files directly like ksu itself does
++ * - to make krb5_aname_to_localname() more useful an option for sshd to use
++ *   the canonical name (the one returned by getpwnam()) instead of the name
++ *   given at the login prompt might be useful */
++
+ static int
+ ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name)
+ {
+@@ -116,7 +214,8 @@ ssh_gssapi_krb5_userok(ssh_gssapi_client
+ 	/* NOTE: .k5login and .k5users must opened as root, not the user,
+ 	 * because if they are on a krb5-protected filesystem, user credentials
+ 	 * to access these files aren't available yet. */
+-	if (krb5_kuserok(krb_context, princ, name) && k5login_exists) {
++	if (ssh_krb5_kuserok(krb_context, princ, name, k5login_exists)
++			&& k5login_exists) {
+ 		retval = 1;
+ 		logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
+ 		    name, (char *)client->displayname.value);
+@@ -190,9 +289,8 @@ ssh_gssapi_krb5_cmdok(krb5_principal pri
+ 	snprintf(file, sizeof(file), "%s/.k5users", pw->pw_dir);
+ 	/* If both .k5login and .k5users DNE, self-login is ok. */
+ 	if (!k5login_exists && (access(file, F_OK) == -1)) {
+-		return (krb5_aname_to_localname(krb_context, principal,
+-		    sizeof(kuser), kuser) == 0) &&
+-		    (strcmp(kuser, luser) == 0);
++                return ssh_krb5_kuserok(krb_context, principal, luser,
++                                        k5login_exists);
+ 	}
+ 	if ((fp = fopen(file, "r")) == NULL) {
+ 		int saved_errno = errno;
+diff -up openssh-7.4p1/servconf.c.kuserok openssh-7.4p1/servconf.c
+--- openssh-7.4p1/servconf.c.kuserok	2016-12-23 14:36:07.630465944 +0100
++++ openssh-7.4p1/servconf.c	2016-12-23 15:11:52.278133344 +0100
+Reference:https://src.fedoraproject.org/rpms/openssh/blob/rawhide/f/backport-openssh-6.6p1-kuserok.patch
+@@ -116,6 +116,7 @@ initialize_server_options(ServerOptions
+ 	options->gss_strict_acceptor = -1;
+ 	options->gss_store_rekey = -1;
+ 	options->gss_kex_algorithms = NULL;
++	options->use_kuserok = -1;
+ 	options->password_authentication = -1;
+ 	options->kbd_interactive_authentication = -1;
+	options->permit_empty_passwd = -1;
+@@ -278,6 +279,8 @@ fill_default_server_options(ServerOption
+ 	if (options->gss_kex_algorithms == NULL)
+ 		options->gss_kex_algorithms = strdup(GSS_KEX_DEFAULT_KEX);
+ #endif
++	if (options->use_kuserok == -1)
++		options->use_kuserok = 1;
+ 	if (options->password_authentication == -1)
+ 		options->password_authentication = 1;
+ 	if (options->kbd_interactive_authentication == -1)
+@@ -399,7 +402,7 @@ typedef enum {
+	sPort, sHostKeyFile, sLoginGraceTime,
+	sPermitRootLogin, sLogFacility, sLogLevel, sLogVerbose,
+	sKerberosAuthentication, sKerberosOrLocalPasswd, sKerberosTicketCleanup,
+-	sKerberosGetAFSToken, sKerberosUniqueCCache,
++	sKerberosGetAFSToken, sKerberosUniqueCCache, sKerberosUseKuserok,
+ 	sPasswordAuthentication,
+ 	sKbdInteractiveAuthentication, sListenAddress, sAddressFamily,
+ 	sPrintMotd, sPrintLastLog, sIgnoreRhosts,
+@@ -478,12 +481,14 @@ static struct {
+ 	{ "kerberosgetafstoken", sUnsupported, SSHCFG_GLOBAL },
+ #endif
+ 	{ "kerberosuniqueccache", sKerberosUniqueCCache, SSHCFG_GLOBAL },
++	{ "kerberosusekuserok", sKerberosUseKuserok, SSHCFG_ALL },
+ #else
+ 	{ "kerberosauthentication", sUnsupported, SSHCFG_ALL },
+ 	{ "kerberosorlocalpasswd", sUnsupported, SSHCFG_GLOBAL },
+ 	{ "kerberosticketcleanup", sUnsupported, SSHCFG_GLOBAL },
+ 	{ "kerberosgetafstoken", sUnsupported, SSHCFG_GLOBAL },
+ 	{ "kerberosuniqueccache", sUnsupported, SSHCFG_GLOBAL },
++	{ "kerberosusekuserok", sUnsupported, SSHCFG_ALL },
+ #endif
+ 	{ "kerberostgtpassing", sUnsupported, SSHCFG_GLOBAL },
+ 	{ "afstokenpassing", sUnsupported, SSHCFG_GLOBAL },
+@@ -1644,6 +1649,10 @@ process_server_config_line(ServerOptions
+		}
+		break;
+
++	case sKerberosUseKuserok:
++		intptr = &options->use_kuserok;
++		goto parse_flag;
++
+	case sMatch:
+		if (cmdline)
+			fatal("Match directive not supported as a command-line "
+@@ -2016,6 +2025,7 @@ copy_set_server_options(ServerOptions *d
+ 	M_CP_INTOPT(client_alive_interval);
+ 	M_CP_INTOPT(ip_qos_interactive);
+ 	M_CP_INTOPT(ip_qos_bulk);
++	M_CP_INTOPT(use_kuserok);
+ 	M_CP_INTOPT(rekey_limit);
+ 	M_CP_INTOPT(rekey_interval);
+ 	M_CP_INTOPT(log_level);
+@@ -2309,6 +2319,7 @@ dump_config(ServerOptions *o)
+ 	dump_cfg_fmtint(sKerberosGetAFSToken, o->kerberos_get_afs_token);
+ # endif
+ 	dump_cfg_fmtint(sKerberosUniqueCCache, o->kerberos_unique_ccache);
++	dump_cfg_fmtint(sKerberosUseKuserok, o->use_kuserok);
+ #endif
+ #ifdef GSSAPI
+	dump_cfg_fmtint(sGssAuthentication, o->gss_authentication);
+diff -up openssh-7.4p1/servconf.h.kuserok openssh-7.4p1/servconf.h
+--- openssh-7.4p1/servconf.h.kuserok	2016-12-23 14:36:07.630465944 +0100
++++ openssh-7.4p1/servconf.h	2016-12-23 14:36:07.645465936 +0100
+Reference:https://src.fedoraproject.org/rpms/openssh/blob/rawhide/f/backport-openssh-6.6p1-kuserok.patch
+@@ -118,6 +118,7 @@ typedef struct {
+ 						 * authenticated with Kerberos. */
+ 	int     kerberos_unique_ccache;		/* If true, the acquired ticket will
+ 						 * be stored in per-session ccache */
++	int	use_kuserok;
+ 	int     gss_authentication;	/* If true, permit GSSAPI authentication */
+ 	int     gss_keyex;		/* If true, permit GSSAPI key exchange */
+ 	int     gss_cleanup_creds;	/* If true, destroy cred cache on logout */
+diff -up openssh-7.4p1/sshd_config.5.kuserok openssh-7.4p1/sshd_config.5
+--- openssh-7.4p1/sshd_config.5.kuserok	2016-12-23 14:36:07.637465940 +0100
++++ openssh-7.4p1/sshd_config.5	2016-12-23 15:14:03.117162222 +0100
+Reference:https://src.fedoraproject.org/rpms/openssh/blob/rawhide/f/backport-openssh-6.6p1-kuserok.patch
+@@ -850,6 +850,10 @@ Specifies whether to automatically destr
+ .Cm no
+ can lead to overwriting previous tickets by subseqent connections to the same
+ user account.
++.It Cm KerberosUseKuserok
++Specifies whether to look at .k5login file for user's aliases.
++The default is
++.Cm yes .
+ .It Cm KexAlgorithms
+ Specifies the available KEX (Key Exchange) algorithms.
+ Multiple algorithms must be comma-separated.
+@@ -1078,6 +1082,7 @@ Available keywords are
+ .Cm IPQoS ,
+ .Cm KbdInteractiveAuthentication ,
+ .Cm KerberosAuthentication ,
++.Cm KerberosUseKuserok ,
+ .Cm LogLevel ,
+ .Cm MaxAuthTries ,
+ .Cm MaxSessions ,
+diff -up openssh-7.4p1/sshd_config.kuserok openssh-7.4p1/sshd_config
+--- openssh-7.4p1/sshd_config.kuserok	2016-12-23 14:36:07.631465943 +0100
++++ openssh-7.4p1/sshd_config	2016-12-23 14:36:07.646465935 +0100
+Reference:https://src.fedoraproject.org/rpms/openssh/blob/rawhide/f/backport-openssh-6.6p1-kuserok.patch
+@@ -73,6 +73,7 @@ ChallengeResponseAuthentication no
+ #KerberosOrLocalPasswd yes
+ #KerberosTicketCleanup yes
+ #KerberosGetAFSToken no
++#KerberosUseKuserok yes
+ 
+ # GSSAPI options
+ #GSSAPIAuthentication no