Attachment 2090 Details for Bug 1402 – 05 audit server key destruction suitable for 5.9p1

[patch] 05 audit server key destruction suitable for 5.9p1

openssh-5.9p1-audit5.patch (text/plain), 15.63 KB, created by jchadima on 2011-09-18 12:49:50 AEST

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Creator: jchadima

Created: 2011-09-18 12:49:50 AEST

Size: 15.63 KB

patch

obsolete

>diff -up openssh-5.9p1/audit-bsm.c.audit5 openssh-5.9p1/audit-bsm.c
>--- openssh-5.9p1/audit-bsm.c.audit5	2011-09-13 22:07:31.262575526 +0200
>+++ openssh-5.9p1/audit-bsm.c	2011-09-13 22:07:33.268491813 +0200
>@@ -414,4 +414,22 @@ audit_session_key_free_body(int ctos, pi
> {
> 	/* not implemented */
> }
>+
>+void
>+audit_destroy_sensitive_data(const char *fp)
>+{
>+	/* not implemented */
>+}
>+
>+void
>+audit_destroy_sensitive_data(const char *fp, pid_t pid, uid_t uid)
>+{
>+	/* not implemented */
>+}
>+
>+void
>+audit_generate_ephemeral_server_key(const char *fp)
>+{
>+	/* not implemented */
>+}
> #endif /* BSM */
>diff -up openssh-5.9p1/audit-linux.c.audit5 openssh-5.9p1/audit-linux.c
>--- openssh-5.9p1/audit-linux.c.audit5	2011-09-13 22:07:31.400584308 +0200
>+++ openssh-5.9p1/audit-linux.c	2011-09-13 22:07:33.357460348 +0200
>@@ -350,4 +350,50 @@ audit_session_key_free_body(int ctos, pi
> 		error("cannot write into audit");
> }
> 
>+void
>+audit_destroy_sensitive_data(const char *fp, pid_t pid, uid_t uid)
>+{
>+	char buf[AUDIT_LOG_SIZE];
>+	int audit_fd, audit_ok;
>+
>+	snprintf(buf, sizeof(buf), "op=destroy kind=server fp=%s direction=? spid=%jd suid=%jd ",
>+		fp, (intmax_t)pid, (intmax_t)uid);
>+	audit_fd = audit_open();
>+	if (audit_fd < 0) {
>+		if (errno != EINVAL && errno != EPROTONOSUPPORT &&
>+					 errno != EAFNOSUPPORT)
>+			error("cannot open audit");
>+		return;
>+	}
>+	audit_ok = audit_log_user_message(audit_fd, AUDIT_CRYPTO_KEY_USER,
>+			buf, NULL,
>+			listening_for_clients() ? NULL : get_remote_ipaddr(),
>+			NULL, 1);
>+	audit_close(audit_fd);
>+	/* do not abort if the error is EPERM and sshd is run as non root user */
>+	if ((audit_ok < 0) && ((audit_ok != -1) || (getuid() == 0)))
>+		error("cannot write into audit");
>+}
>+
>+void
>+audit_generate_ephemeral_server_key(const char *fp)
>+{
>+	char buf[AUDIT_LOG_SIZE];
>+	int audit_fd, audit_ok;
>+
>+	snprintf(buf, sizeof(buf), "op=create kind=server fp=%s direction=? ", fp);
>+	audit_fd = audit_open();
>+	if (audit_fd < 0) {
>+		if (errno != EINVAL && errno != EPROTONOSUPPORT &&
>+					 errno != EAFNOSUPPORT)
>+			error("cannot open audit");
>+		return;
>+	}
>+	audit_ok = audit_log_user_message(audit_fd, AUDIT_CRYPTO_KEY_USER,
>+			buf, NULL, 0, NULL, 1);
>+	audit_close(audit_fd);
>+	/* do not abort if the error is EPERM and sshd is run as non root user */
>+	if ((audit_ok < 0) && ((audit_ok != -1) || (getuid() == 0)))
>+		error("cannot write into audit");
>+}
> #endif /* USE_LINUX_AUDIT */
>diff -up openssh-5.9p1/audit.c.audit5 openssh-5.9p1/audit.c
>--- openssh-5.9p1/audit.c.audit5	2011-09-13 22:07:31.495458797 +0200
>+++ openssh-5.9p1/audit.c	2011-09-13 22:07:33.478458341 +0200
>@@ -290,5 +290,24 @@ audit_session_key_free_body(int ctos, pi
> 	debug("audit session key discard euid %u direction %d from pid %ld uid %u",
> 		(unsigned)geteuid(), ctos, (long)pid, (unsigned)uid);
> }
>+
>+/*
>+ * This will be called on destroy private part of the server key
>+ */
>+void
>+audit_destroy_sensitive_data(const char *fp, pid_t pid, uid_t uid)
>+{
>+	debug("audit destroy sensitive data euid %d fingerprint %s from pid %ld uid %u",
>+		geteuid(), fp, (long)pid, (unsigned)uid);
>+}
>+
>+/*
>+ * This will be called on generation of the ephemeral server key
>+ */
>+void
>+audit_generate_ephemeral_server_key(const char *)
>+{
>+	debug("audit create ephemeral server key euid %d fingerprint %s", geteuid(), fp);
>+}
> # endif  /* !defined CUSTOM_SSH_AUDIT_EVENTS */
> #endif /* SSH_AUDIT_EVENTS */
>diff -up openssh-5.9p1/audit.h.audit5 openssh-5.9p1/audit.h
>--- openssh-5.9p1/audit.h.audit5	2011-09-13 22:07:31.616459125 +0200
>+++ openssh-5.9p1/audit.h	2011-09-13 22:07:33.612458074 +0200
>@@ -48,6 +48,8 @@ enum ssh_audit_event_type {
> };
> typedef enum ssh_audit_event_type ssh_audit_event_t;
> 
>+int	listening_for_clients(void);
>+
> void	audit_connection_from(const char *, int);
> void	audit_event(ssh_audit_event_t);
> void	audit_count_session_open(void);
>@@ -64,5 +66,7 @@ void	audit_unsupported_body(int);
> void	audit_kex_body(int, char *, char *, char *, pid_t, uid_t);
> void	audit_session_key_free(int ctos);
> void	audit_session_key_free_body(int ctos, pid_t, uid_t);
>+void	audit_destroy_sensitive_data(const char *, pid_t, uid_t);
>+void	audit_generate_ephemeral_server_key(const char *);
> 
> #endif /* _SSH_AUDIT_H */
>diff -up openssh-5.9p1/key.c.audit5 openssh-5.9p1/key.c
>--- openssh-5.9p1/key.c.audit5	2011-09-13 22:07:23.054490740 +0200
>+++ openssh-5.9p1/key.c	2011-09-13 22:07:33.721583661 +0200
>@@ -1799,6 +1799,30 @@ key_demote(const Key *k)
> }
> 
> int
>+key_is_private(const Key *k)
>+{
>+	switch (k->type) {
>+	case KEY_RSA_CERT_V00:
>+	case KEY_RSA_CERT:
>+	case KEY_RSA1:
>+	case KEY_RSA:
>+		return k->rsa->d != NULL;
>+	case KEY_DSA_CERT_V00:
>+	case KEY_DSA_CERT:
>+	case KEY_DSA:
>+		return k->dsa->priv_key != NULL;
>+#ifdef OPENSSL_HAS_ECC
>+	case KEY_ECDSA_CERT:
>+	case KEY_ECDSA:
>+		return EC_KEY_get0_private_key(k->ecdsa) != NULL;
>+#endif
>+	default:
>+		fatal("key_is_private: bad key type %d", k->type);
>+		return 1;
>+	}
>+}
>+
>+int
> key_is_cert(const Key *k)
> {
> 	if (k == NULL)
>diff -up openssh-5.9p1/key.h.audit5 openssh-5.9p1/key.h
>--- openssh-5.9p1/key.h.audit5	2011-09-13 22:07:23.160459285 +0200
>+++ openssh-5.9p1/key.h	2011-09-13 22:07:33.847459341 +0200
>@@ -109,6 +109,7 @@ Key	*key_generate(int, u_int);
> Key	*key_from_private(const Key *);
> int	 key_type_from_name(char *);
> int	 key_is_cert(const Key *);
>+int	 key_is_private(const Key *k);
> int	 key_type_plain(int);
> int	 key_to_certified(Key *, int);
> int	 key_drop_cert(Key *);
>diff -up openssh-5.9p1/monitor.c.audit5 openssh-5.9p1/monitor.c
>--- openssh-5.9p1/monitor.c.audit5	2011-09-13 22:07:32.285495537 +0200
>+++ openssh-5.9p1/monitor.c	2011-09-13 22:10:04.148554239 +0200
>@@ -114,6 +114,8 @@ extern Buffer auth_debug;
> extern int auth_debug_init;
> extern Buffer loginmsg;
> 
>+extern void destroy_sensitive_data(int);
>+
> /* State exported from the child */
> 
> struct {
>@@ -191,6 +193,7 @@ int mm_answer_audit_end_command(int, Buf
> int mm_answer_audit_unsupported_body(int, Buffer *);
> int mm_answer_audit_kex_body(int, Buffer *);
> int mm_answer_audit_session_key_free_body(int, Buffer *);
>+int mm_answer_audit_server_key_free(int, Buffer *);
> #endif
> 
> static int monitor_read_log(struct monitor *);
>@@ -244,6 +247,7 @@ struct mon_table mon_dispatch_proto20[]
>     {MONITOR_REQ_AUDIT_UNSUPPORTED, MON_PERMIT, mm_answer_audit_unsupported_body},
>     {MONITOR_REQ_AUDIT_KEX, MON_PERMIT, mm_answer_audit_kex_body},
>     {MONITOR_REQ_AUDIT_SESSION_KEY_FREE, MON_PERMIT, mm_answer_audit_session_key_free_body},
>+    {MONITOR_REQ_AUDIT_SERVER_KEY_FREE, MON_PERMIT, mm_answer_audit_server_key_free},
> #endif
> #ifdef BSD_AUTH
>     {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery},
>@@ -285,6 +289,7 @@ struct mon_table mon_dispatch_postauth20
>     {MONITOR_REQ_AUDIT_UNSUPPORTED, MON_PERMIT, mm_answer_audit_unsupported_body},
>     {MONITOR_REQ_AUDIT_KEX, MON_PERMIT, mm_answer_audit_kex_body},
>     {MONITOR_REQ_AUDIT_SESSION_KEY_FREE, MON_PERMIT, mm_answer_audit_session_key_free_body},
>+    {MONITOR_REQ_AUDIT_SERVER_KEY_FREE, MON_PERMIT, mm_answer_audit_server_key_free},
> #endif
>     {0, 0, NULL}
> };
>@@ -319,6 +324,7 @@ struct mon_table mon_dispatch_proto15[]
>     {MONITOR_REQ_AUDIT_UNSUPPORTED, MON_PERMIT, mm_answer_audit_unsupported_body},
>     {MONITOR_REQ_AUDIT_KEX, MON_PERMIT, mm_answer_audit_kex_body},
>     {MONITOR_REQ_AUDIT_SESSION_KEY_FREE, MON_PERMIT, mm_answer_audit_session_key_free_body},
>+    {MONITOR_REQ_AUDIT_SERVER_KEY_FREE, MON_PERMIT, mm_answer_audit_server_key_free},
> #endif
>     {0, 0, NULL}
> };
>@@ -334,6 +340,7 @@ struct mon_table mon_dispatch_postauth15
>     {MONITOR_REQ_AUDIT_UNSUPPORTED, MON_PERMIT, mm_answer_audit_unsupported_body},
>     {MONITOR_REQ_AUDIT_KEX, MON_PERMIT, mm_answer_audit_kex_body},
>     {MONITOR_REQ_AUDIT_SESSION_KEY_FREE, MON_PERMIT, mm_answer_audit_session_key_free_body},
>+    {MONITOR_REQ_AUDIT_SERVER_KEY_FREE, MON_PERMIT, mm_answer_audit_server_key_free},
> #endif
>     {0, 0, NULL}
> };
>@@ -1716,6 +1723,8 @@ mm_answer_term(int sock, Buffer *req)
> 		sshpam_cleanup();
> #endif
> 
>+	destroy_sensitive_data(0);
>+
> 	while (waitpid(pmonitor->m_pid, &status, 0) == -1)
> 		if (errno != EINTR)
> 			exit(1);
>@@ -2470,4 +2479,25 @@ mm_answer_audit_session_key_free_body(in
> 	mm_request_send(sock, MONITOR_ANS_AUDIT_SESSION_KEY_FREE, m);
> 	return 0;
> }
>+
>+int
>+mm_answer_audit_server_key_free(int sock, Buffer *m)
>+{
>+	int len;
>+	char *fp;
>+	pid_t pid;
>+	uid_t uid;
>+
>+	fp = buffer_get_string(m, &len);
>+	pid = buffer_get_int64(m);
>+	uid = buffer_get_int64(m);
>+
>+	audit_destroy_sensitive_data(fp, pid, uid);
>+
>+	xfree(fp);
>+	buffer_clear(m);
>+
>+	mm_request_send(sock, MONITOR_ANS_AUDIT_SERVER_KEY_FREE, m);
>+	return 0;
>+}
> #endif /* SSH_AUDIT_EVENTS */
>diff -up openssh-5.9p1/monitor.h.audit5 openssh-5.9p1/monitor.h
>--- openssh-5.9p1/monitor.h.audit5	2011-09-13 22:07:32.385522626 +0200
>+++ openssh-5.9p1/monitor.h	2011-09-13 22:07:34.098459356 +0200
>@@ -64,6 +64,7 @@ enum monitor_reqtype {
> 	MONITOR_REQ_AUDIT_UNSUPPORTED, MONITOR_ANS_AUDIT_UNSUPPORTED,
> 	MONITOR_REQ_AUDIT_KEX, MONITOR_ANS_AUDIT_KEX,
> 	MONITOR_REQ_AUDIT_SESSION_KEY_FREE, MONITOR_ANS_AUDIT_SESSION_KEY_FREE,
>+	MONITOR_REQ_AUDIT_SERVER_KEY_FREE, MONITOR_ANS_AUDIT_SERVER_KEY_FREE,
> 	MONITOR_REQ_TERM,
> 	MONITOR_REQ_JPAKE_STEP1, MONITOR_ANS_JPAKE_STEP1,
> 	MONITOR_REQ_JPAKE_GET_PWDATA, MONITOR_ANS_JPAKE_GET_PWDATA,
>diff -up openssh-5.9p1/monitor_wrap.c.audit5 openssh-5.9p1/monitor_wrap.c
>--- openssh-5.9p1/monitor_wrap.c.audit5	2011-09-13 22:07:32.510521163 +0200
>+++ openssh-5.9p1/monitor_wrap.c	2011-09-13 22:07:34.610458275 +0200
>@@ -1559,4 +1559,20 @@ mm_audit_session_key_free_body(int ctos,
> 				  &m);
> 	buffer_free(&m);
> }
>+
>+void
>+mm_audit_destroy_sensitive_data(const char *fp, pid_t pid, uid_t uid)
>+{
>+	Buffer m;
>+
>+	buffer_init(&m);
>+	buffer_put_cstring(&m, fp);
>+	buffer_put_int64(&m, pid);
>+	buffer_put_int64(&m, uid);
>+
>+	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUDIT_SERVER_KEY_FREE, &m);
>+	mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_AUDIT_SERVER_KEY_FREE,
>+				  &m);
>+	buffer_free(&m);
>+}
> #endif /* SSH_AUDIT_EVENTS */
>diff -up openssh-5.9p1/monitor_wrap.h.audit5 openssh-5.9p1/monitor_wrap.h
>--- openssh-5.9p1/monitor_wrap.h.audit5	2011-09-13 22:07:32.607520810 +0200
>+++ openssh-5.9p1/monitor_wrap.h	2011-09-13 22:07:34.716458214 +0200
>@@ -81,6 +81,7 @@ void mm_audit_end_command(int, const cha
> void mm_audit_unsupported_body(int);
> void mm_audit_kex_body(int, char *, char *, char *, pid_t, uid_t);
> void mm_audit_session_key_free_body(int, pid_t, uid_t);
>+void mm_audit_destroy_sensitive_data(const char *, pid_t, uid_t);
> #endif
> 
> struct Session;
>diff -up openssh-5.9p1/session.c.audit5 openssh-5.9p1/session.c
>--- openssh-5.9p1/session.c.audit5	2011-09-13 22:07:32.973544819 +0200
>+++ openssh-5.9p1/session.c	2011-09-13 22:07:34.849585578 +0200
>@@ -136,7 +136,7 @@ extern int log_stderr;
> extern int debug_flag;
> extern u_int utmp_len;
> extern int startup_pipe;
>-extern void destroy_sensitive_data(void);
>+extern void destroy_sensitive_data(int);
> extern Buffer loginmsg;
> 
> /* original command from peer. */
>@@ -1633,7 +1633,7 @@ do_child(Session *s, const char *command
> 	int r = 0;
> 
> 	/* remove hostkey from the child's memory */
>-	destroy_sensitive_data();
>+	destroy_sensitive_data(1);
> 	/* Don't audit this - both us and the parent would be talking to the
> 	   monitor over a single socket, with no synchronization. */
> 	packet_destroy_all(0, 1);
>diff -up openssh-5.9p1/sshd.c.audit5 openssh-5.9p1/sshd.c
>--- openssh-5.9p1/sshd.c.audit5	2011-09-13 22:07:33.106516378 +0200
>+++ openssh-5.9p1/sshd.c	2011-09-13 22:07:34.989470331 +0200
>@@ -254,7 +254,7 @@ Buffer loginmsg;
> struct passwd *privsep_pw = NULL;
> 
> /* Prototypes for various functions defined later in this file. */
>-void destroy_sensitive_data(void);
>+void destroy_sensitive_data(int);
> void demote_sensitive_data(void);
> 
> static void do_ssh1_kex(void);
>@@ -273,6 +273,15 @@ close_listen_socks(void)
> 	num_listen_socks = -1;
> }
> 
>+/*
>+ * Is this process listening for clients (i.e. not specific to any specific
>+ * client connection?)
>+ */
>+int listening_for_clients(void)
>+{
>+	return num_listen_socks > 0;
>+}
>+
> static void
> close_startup_pipes(void)
> {
>@@ -533,22 +542,47 @@ sshd_exchange_identification(int sock_in
> 	}
> }
> 
>-/* Destroy the host and server keys.  They will no longer be needed. */
>+/*
>+ * Destroy the host and server keys.  They will no longer be needed.  Careful,
>+ * this can be called from cleanup_exit() - i.e. from just about anywhere.
>+ */
> void
>-destroy_sensitive_data(void)
>+destroy_sensitive_data(int privsep)
> {
> 	int i;
>+	pid_t pid;
>+	uid_t uid;
> 
> 	if (sensitive_data.server_key) {
> 		key_free(sensitive_data.server_key);
> 		sensitive_data.server_key = NULL;
> 	}
>+	pid = getpid();
>+	uid = getuid();
> 	for (i = 0; i < options.num_host_key_files; i++) {
> 		if (sensitive_data.host_keys[i]) {
>+			char *fp;
>+
>+			if (key_is_private(sensitive_data.host_keys[i]))
>+				fp = key_fingerprint(sensitive_data.host_keys[i],
>+					FIPS_mode() ? SSH_FP_SHA1 : SSH_FP_MD5,
>+					SSH_FP_HEX);
>+			else
>+				fp = NULL;
> 			key_free(sensitive_data.host_keys[i]);
> 			sensitive_data.host_keys[i] = NULL;
>+			if (fp != NULL) {
>+				if (privsep)
>+					PRIVSEP(audit_destroy_sensitive_data(fp,
>+						pid, uid));
>+				else
>+					audit_destroy_sensitive_data(fp,
>+						pid, uid);
>+				xfree(fp);
>+			}
> 		}
>-		if (sensitive_data.host_certificates[i]) {
>+		if (sensitive_data.host_certificates
>+		    && sensitive_data.host_certificates[i]) {
> 			key_free(sensitive_data.host_certificates[i]);
> 			sensitive_data.host_certificates[i] = NULL;
> 		}
>@@ -562,6 +596,8 @@ void
> demote_sensitive_data(void)
> {
> 	Key *tmp;
>+	pid_t pid;
>+	uid_t uid;
> 	int i;
> 
> 	if (sensitive_data.server_key) {
>@@ -570,13 +606,27 @@ demote_sensitive_data(void)
> 		sensitive_data.server_key = tmp;
> 	}
> 
>+	pid = getpid();
>+	uid = getuid();
> 	for (i = 0; i < options.num_host_key_files; i++) {
> 		if (sensitive_data.host_keys[i]) {
>+			char *fp;
>+
>+			if (key_is_private(sensitive_data.host_keys[i]))
>+				fp = key_fingerprint(sensitive_data.host_keys[i],
>+					FIPS_mode() ? SSH_FP_SHA1 : SSH_FP_MD5,
>+					SSH_FP_HEX);
>+			else
>+				fp = NULL;
> 			tmp = key_demote(sensitive_data.host_keys[i]);
> 			key_free(sensitive_data.host_keys[i]);
> 			sensitive_data.host_keys[i] = tmp;
> 			if (tmp->type == KEY_RSA1)
> 				sensitive_data.ssh1_host_key = tmp;
>+			if (fp != NULL) {
>+				audit_destroy_sensitive_data(fp, pid, uid);
>+				xfree(fp);
>+			}
> 		}
> 		/* Certs do not need demotion */
> 	}
>@@ -1145,6 +1195,7 @@ server_accept_loop(int *sock_in, int *so
> 		if (received_sigterm) {
> 			logit("Received signal %d; terminating.",
> 			    (int) received_sigterm);
>+			destroy_sensitive_data(0);
> 			close_listen_socks();
> 			unlink(options.pid_file);
> 			exit(received_sigterm == SIGTERM ? 0 : 255);
>@@ -2050,7 +2101,7 @@ main(int ac, char **av)
> 		privsep_postauth(authctxt);
> 		/* the monitor process [priv] will not return */
> 		if (!compat20)
>-			destroy_sensitive_data();
>+			destroy_sensitive_data(0);
> 	}
> 
> 	packet_set_timeout(options.client_alive_interval,
>@@ -2061,6 +2112,7 @@ main(int ac, char **av)
> 
> 	/* The connection has been terminated. */
> 	packet_destroy_all(1, 1);
>+	destroy_sensitive_data(1);
> 
> 	packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
> 	packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
>@@ -2289,7 +2341,7 @@ do_ssh1_kex(void)
> 			session_id[i] = session_key[i] ^ session_key[i + 16];
> 	}
> 	/* Destroy the private and public keys. No longer. */
>-	destroy_sensitive_data();
>+	destroy_sensitive_data(0);
> 
> 	if (use_privsep)
> 		mm_ssh1_session_id(session_id);
>@@ -2392,6 +2444,8 @@ cleanup_exit(int i)
> 	if (the_authctxt)
> 		do_cleanup(the_authctxt);
> 	is_privsep_child = use_privsep && pmonitor != NULL && !mm_is_monitor();
>+	if (sensitive_data.host_keys != NULL)
>+		destroy_sensitive_data(is_privsep_child);
> 	packet_destroy_all(1, is_privsep_child);
> #ifdef SSH_AUDIT_EVENTS
> 	/* done after do_cleanup so it can cancel the PAM auth 'thread' */

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