Audit race condition resolved (#1308295)
This commit is contained in:
Jakub Jelen
parent
7b15444065
commit
44fc97266b
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@ -0,0 +1,143 @@
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diff --git a/monitor_wrap.c b/monitor_wrap.c
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index 89a1762..fe98e08 100644
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--- a/monitor_wrap.c
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+++ b/monitor_wrap.c
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@@ -1251,4 +1251,48 @@ mm_audit_destroy_sensitive_data(const char *fp, pid_t pid, uid_t uid)
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mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUDIT_SERVER_KEY_FREE, &m);
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buffer_free(&m);
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}
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+
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+int mm_forward_audit_messages(int fdin)
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+{
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+ u_char buf[4];
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+ u_int blen, msg_len;
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+ Buffer m;
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+ int ret = 0;
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+
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+ debug3("%s: entering", __func__);
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+ buffer_init(&m);
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+ do {
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+ blen = atomicio(read, fdin, buf, sizeof(buf));
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+ if (blen == 0) /* closed pipe */
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+ break;
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+ if (blen != sizeof(buf)) {
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+ error("%s: Failed to read the buffer from child", __func__);
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+ ret = -1;
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+ break;
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+ }
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+
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+ msg_len = get_u32(buf);
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+ if (msg_len > 256 * 1024)
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+ fatal("%s: read: bad msg_len %d", __func__, msg_len);
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+ buffer_clear(&m);
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+ buffer_append_space(&m, msg_len);
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+ if (atomicio(read, fdin, buffer_ptr(&m), msg_len) != msg_len) {
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+ error("%s: Failed to read the the buffer conent from the child", __func__);
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+ ret = -1;
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+ break;
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+ }
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+ if (atomicio(vwrite, pmonitor->m_recvfd, buf, blen) != blen ||
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+ atomicio(vwrite, pmonitor->m_recvfd, buffer_ptr(&m), msg_len) != msg_len) {
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+ error("%s: Failed to write the messag to the monitor", __func__);
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+ ret = -1;
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+ break;
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+ }
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+ } while (1);
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+ buffer_free(&m);
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+ return ret;
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+}
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+void mm_set_monitor_pipe(int fd)
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+{
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+ pmonitor->m_recvfd = fd;
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+}
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#endif /* SSH_AUDIT_EVENTS */
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diff --git a/monitor_wrap.h b/monitor_wrap.h
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index e73134e..fbfe395 100644
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--- a/monitor_wrap.h
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+++ b/monitor_wrap.h
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@@ -86,6 +86,8 @@ void mm_audit_unsupported_body(int);
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void mm_audit_kex_body(int, char *, char *, char *, char *, pid_t, uid_t);
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void mm_audit_session_key_free_body(int, pid_t, uid_t);
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void mm_audit_destroy_sensitive_data(const char *, pid_t, uid_t);
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+int mm_forward_audit_messages(int);
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+void mm_set_monitor_pipe(int);
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#endif
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struct Session;
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diff --git a/session.c b/session.c
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index 8949fd1..9afb764 100644
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--- a/session.c
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+++ b/session.c
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@@ -159,6 +159,10 @@ static Session *sessions = NULL;
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login_cap_t *lc;
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#endif
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+#ifdef SSH_AUDIT_EVENTS
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+int paudit[2];
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+#endif
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+
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static int is_child = 0;
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static int have_dev_log = 1;
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@@ -875,6 +879,8 @@ do_exec(Session *s, const char *command)
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}
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if (s->command != NULL && s->ptyfd == -1)
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s->command_handle = PRIVSEP(audit_run_command(s->command));
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+ if (pipe(paudit) < 0)
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+ fatal("pipe: %s", strerror(errno));
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#endif
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if (s->ttyfd != -1)
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ret = do_exec_pty(s, command);
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@@ -890,6 +896,20 @@ do_exec(Session *s, const char *command)
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*/
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buffer_clear(&loginmsg);
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+#ifdef SSH_AUDIT_EVENTS
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+ close(paudit[1]);
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+ if (use_privsep && ret == 0) {
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+ /*
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+ * Read the audit messages from forked child and send them
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+ * back to monitor. We don't want to communicate directly,
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+ * because the messages might get mixed up.
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+ * Continue after the pipe gets closed (all messages sent).
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+ */
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+ ret = mm_forward_audit_messages(paudit[0]);
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+ }
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+ close(paudit[0]);
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+#endif /* SSH_AUDIT_EVENTS */
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+
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return ret;
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}
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@@ -1707,12 +1727,28 @@ do_child(Session *s, const char *command)
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struct passwd *pw = s->pw;
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int r = 0;
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+#ifdef SSH_AUDIT_EVENTS
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+ int pparent = paudit[1];
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+ close(paudit[0]);
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+ /* Hack the monitor pipe to avoid race condition with parent */
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+ if (use_privsep)
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+ mm_set_monitor_pipe(pparent);
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+#endif
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+
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/* remove hostkey from the child's memory */
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- destroy_sensitive_data(1);
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- /* Don't audit this - both us and the parent would be talking to the
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- monitor over a single socket, with no synchronization. */
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+ destroy_sensitive_data(use_privsep);
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+ /*
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+ * We can audit this, because wer hacked the pipe to direct the
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+ * messages over postauth child. But this message requires answer
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+ * which we can't do using one-way pipe.
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+ */
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packet_destroy_all(0, 1);
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+#ifdef SSH_AUDIT_EVENTS
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+ /* Notify parent that we are done */
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+ close(pparent);
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+#endif
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+
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/* Force a password change */
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if (s->authctxt->force_pwchange) {
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do_setusercontext(pw);
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@ -106,6 +106,8 @@ Patch103: openssh-5.8p1-packet.patch
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# https://bugzilla.redhat.com/show_bug.cgi?id=1171248
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# record pfs= field in CRYPTO_SESSION audit event
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Patch200: openssh-6.7p1-audit.patch
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# Audit race condition in forked child (#1310684)
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Patch201: openssh-7.1p2-audit-race-condition.patch
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# --- pam_ssh-agent ---
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# make it build reusing the openssh sources
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@ -473,6 +475,7 @@ popd
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%patch937 -p1 -b .x11-fallback
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%patch200 -p1 -b .audit
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%patch201 -p1 -b .audit-race
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%patch700 -p1 -b .fips
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%patch100 -p1 -b .coverity
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