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-rw-r--r--src/tls/tls_bio_ops.c296
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diff --git a/src/tls/tls_bio_ops.c b/src/tls/tls_bio_ops.c
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+/*++
+/* NAME
+/* tls_bio_ops 3
+/* SUMMARY
+/* TLS network basic I/O management
+/* SYNOPSIS
+/* #define TLS_INTERNAL
+/* #include <tls.h>
+/*
+/* int tls_bio_connect(fd, timeout, context)
+/* int fd;
+/* int timeout;
+/* TLS_SESS_STATE *context;
+/*
+/* int tls_bio_accept(fd, timeout, context)
+/* int fd;
+/* int timeout;
+/* TLS_SESS_STATE *context;
+/*
+/* int tls_bio_shutdown(fd, timeout, context)
+/* int fd;
+/* int timeout;
+/* TLS_SESS_STATE *context;
+/*
+/* int tls_bio_read(fd, buf, len, timeout, context)
+/* int fd;
+/* void *buf;
+/* int len;
+/* int timeout;
+/* TLS_SESS_STATE *context;
+/*
+/* int tls_bio_write(fd, buf, len, timeout, context)
+/* int fd;
+/* void *buf;
+/* int len;
+/* int timeout;
+/* TLS_SESS_STATE *context;
+/* DESCRIPTION
+/* This module enforces VSTREAM-style timeouts on non-blocking
+/* I/O while performing TLS handshake or input/output operations.
+/*
+/* The Postfix VSTREAM read/write routines invoke the
+/* tls_bio_read/write routines to send and receive plain-text
+/* data. In addition, this module provides tls_bio_connect/accept
+/* routines that trigger the initial TLS handshake. The
+/* tls_bio_xxx routines invoke the corresponding SSL routines
+/* that translate the requests into TLS protocol messages.
+/*
+/* Whenever an SSL operation indicates that network input (or
+/* output) needs to happen, the tls_bio_xxx routines wait for
+/* the network to become readable (or writable) within the
+/* timeout limit, then retry the SSL operation. This works
+/* because the network socket is in non-blocking mode.
+/*
+/* tls_bio_connect() performs the SSL_connect() operation.
+/*
+/* tls_bio_accept() performs the SSL_accept() operation.
+/*
+/* tls_bio_shutdown() performs the SSL_shutdown() operation.
+/*
+/* tls_bio_read() performs the SSL_read() operation.
+/*
+/* tls_bio_write() performs the SSL_write() operation.
+/*
+/* Arguments:
+/* .IP fd
+/* Network socket.
+/* .IP buf
+/* Read/write buffer.
+/* .IP len
+/* Read/write request size.
+/* .IP timeout
+/* Read/write timeout.
+/* .IP TLScontext
+/* TLS session state.
+/* DIAGNOSTICS
+/* A result value > 0 means successful completion.
+/*
+/* A result value < 0 means that the requested operation did
+/* not complete due to TLS protocol failure, system call
+/* failure, or for any reason described under "in addition"
+/* below.
+/*
+/* A result value of 0 from tls_bio_shutdown() means that the
+/* operation is in progress. A result value of 0 from other
+/* tls_bio_ops(3) operations means that the remote party either
+/* closed the network connection or that it sent a TLS shutdown
+/* request.
+/*
+/* Upon return from the tls_bio_ops(3) routines the global
+/* errno value is non-zero when the requested operation did not
+/* complete due to system call failure.
+/*
+/* In addition, the result value is set to -1, and the global
+/* errno value is set to ETIMEDOUT, when some network read/write
+/* operation did not complete within the time limit.
+/* LICENSE
+/* .ad
+/* .fi
+/* This software is free. You can do with it whatever you want.
+/* The original author kindly requests that you acknowledge
+/* the use of his software.
+/* AUTHOR(S)
+/* Originally written by:
+/* Lutz Jaenicke
+/* BTU Cottbus
+/* Allgemeine Elektrotechnik
+/* Universitaetsplatz 3-4
+/* D-03044 Cottbus, Germany
+/*
+/* Updated by:
+/* Wietse Venema
+/* IBM T.J. Watson Research
+/* P.O. Box 704
+/* Yorktown Heights, NY 10598, USA
+/*
+/* Victor Duchovni
+/* Morgan Stanley
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <sys/time.h>
+
+#ifndef timersub
+/* res = a - b */
+#define timersub(a, b, res) do { \
+ (res)->tv_sec = (a)->tv_sec - (b)->tv_sec; \
+ (res)->tv_usec = (a)->tv_usec - (b)->tv_usec; \
+ if ((res)->tv_usec < 0) { \
+ (res)->tv_sec--; \
+ (res)->tv_usec += 1000000; \
+ } \
+ } while (0)
+#endif
+
+#ifdef USE_TLS
+
+/* Utility library. */
+
+#include <msg.h>
+#include <iostuff.h>
+
+/* TLS library. */
+
+#define TLS_INTERNAL
+#include <tls.h>
+
+/* tls_bio - perform SSL input/output operation with extreme prejudice */
+
+int tls_bio(int fd, int timeout, TLS_SESS_STATE *TLScontext,
+ int (*hsfunc) (SSL *),
+ int (*rfunc) (SSL *, void *, int),
+ int (*wfunc) (SSL *, const void *, int),
+ void *buf, int num)
+{
+ const char *myname = "tls_bio";
+ int status;
+ int err;
+ int enable_deadline;
+ struct timeval time_left; /* amount of time left */
+ struct timeval time_deadline; /* time of deadline */
+ struct timeval time_now; /* time after SSL_mumble() call */
+
+ /*
+ * Compensation for interface mis-match: With VSTREAMs, timeout <= 0
+ * means wait forever; with the read/write_wait() calls below, we need to
+ * specify timeout < 0 instead.
+ *
+ * Safety: no time limit means no deadline.
+ */
+ if (timeout <= 0) {
+ timeout = -1;
+ enable_deadline = 0;
+ }
+
+ /*
+ * Deadline management is simpler than with VSTREAMs, because we don't
+ * need to decrement a per-stream time limit. We just work within the
+ * budget that is available for this tls_bio() call.
+ */
+ else {
+ enable_deadline =
+ vstream_fstat(TLScontext->stream, VSTREAM_FLAG_DEADLINE);
+ if (enable_deadline) {
+ GETTIMEOFDAY(&time_deadline);
+ time_deadline.tv_sec += timeout;
+ }
+ }
+
+ /*
+ * If necessary, retry the SSL handshake or read/write operation after
+ * handling any pending network I/O.
+ */
+ for (;;) {
+
+ /*
+ * Flush the per-thread SSL error queue. Otherwise, errors from other
+ * code that also uses TLS may confuse SSL_get_error(3).
+ */
+ ERR_clear_error();
+
+ if (hsfunc)
+ status = hsfunc(TLScontext->con);
+ else if (rfunc)
+ status = rfunc(TLScontext->con, buf, num);
+ else if (wfunc)
+ status = wfunc(TLScontext->con, buf, num);
+ else
+ msg_panic("%s: nothing to do here", myname);
+ err = SSL_get_error(TLScontext->con, status);
+
+ /*
+ * Correspondence between SSL_ERROR_* error codes and tls_bio_(read,
+ * write, accept, connect, shutdown) return values (for brevity:
+ * retval).
+ *
+ * SSL_ERROR_NONE corresponds with retval > 0. With SSL_(read, write)
+ * this is the number of plaintext bytes sent or received. With
+ * SSL_(accept, connect, shutdown) this means that the operation was
+ * completed successfully.
+ *
+ * SSL_ERROR_WANT_(WRITE, READ) start a new loop iteration, or force
+ * (retval = -1, errno = ETIMEDOUT) when the time limit is exceeded.
+ *
+ * All other SSL_ERROR_* cases correspond with retval <= 0. With
+ * SSL_(read, write, accept, connect) retval == 0 means that the
+ * remote party either closed the network connection or that it
+ * requested TLS shutdown; with SSL_shutdown() retval == 0 means that
+ * our own shutdown request is in progress. With all operations
+ * retval < 0 means that there was an error. In the latter case,
+ * SSL_ERROR_SYSCALL means that error details are returned via the
+ * errno value.
+ *
+ * Find out if we must retry the operation and/or if there is pending
+ * network I/O.
+ *
+ * XXX If we're the first to invoke SSL_shutdown(), then the operation
+ * isn't really complete when the call returns. We could hide that
+ * anomaly here and repeat the call.
+ */
+ switch (err) {
+ case SSL_ERROR_WANT_WRITE:
+ case SSL_ERROR_WANT_READ:
+ if (enable_deadline) {
+ GETTIMEOFDAY(&time_now);
+ timersub(&time_deadline, &time_now, &time_left);
+ timeout = time_left.tv_sec + (time_left.tv_usec > 0);
+ if (timeout <= 0) {
+ errno = ETIMEDOUT;
+ return (-1);
+ }
+ }
+ if (err == SSL_ERROR_WANT_WRITE) {
+ if (write_wait(fd, timeout) < 0)
+ return (-1); /* timeout error */
+ } else {
+ if (read_wait(fd, timeout) < 0)
+ return (-1); /* timeout error */
+ }
+ break;
+
+ /*
+ * Unhandled cases: SSL_ERROR_WANT_(ACCEPT, CONNECT, X509_LOOKUP)
+ * etc. Historically, Postfix silently treated these as ordinary
+ * I/O errors so we don't really know how common they are. For
+ * now, we just log a warning.
+ */
+ default:
+ msg_warn("%s: unexpected SSL_ERROR code %d", myname, err);
+ /* FALLTHROUGH */
+
+ /*
+ * With tls_timed_read() and tls_timed_write() the caller is the
+ * VSTREAM library module which is unaware of TLS, so we log the
+ * TLS error stack here. In a better world, each VSTREAM I/O
+ * object would provide an error reporting method in addition to
+ * the timed_read and timed_write methods, so that we would not
+ * need to have ad-hoc code like this.
+ */
+ case SSL_ERROR_SSL:
+ if (rfunc || wfunc)
+ tls_print_errors();
+ /* FALLTHROUGH */
+ case SSL_ERROR_ZERO_RETURN:
+ case SSL_ERROR_NONE:
+ errno = 0; /* avoid bogus warnings */
+ /* FALLTHROUGH */
+ case SSL_ERROR_SYSCALL:
+ return (status);
+ }
+ }
+}
+
+#endif