[src/trunk]: src/sys/net wg: Use m_pullup to make message header contiguous b...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/d941c3014564
branches:  trunk
changeset: 937798:d941c3014564
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Thu Aug 27 02:53:47 2020 +0000

description:
wg: Use m_pullup to make message header contiguous before processing.

diffstat:

 sys/net/if_wg.c |  93 +++++++++++++++++++++++++++++++++-----------------------
 1 files changed, 54 insertions(+), 39 deletions(-)

diffs (148 lines):

diff -r 8b64f47c7e17 -r d941c3014564 sys/net/if_wg.c
--- a/sys/net/if_wg.c   Thu Aug 27 02:52:33 2020 +0000
+++ b/sys/net/if_wg.c   Thu Aug 27 02:53:47 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_wg.c,v 1.25 2020/08/27 02:52:33 riastradh Exp $     */
+/*     $NetBSD: if_wg.c,v 1.26 2020/08/27 02:53:47 riastradh Exp $     */
 
 /*
  * Copyright (C) Ryota Ozaki <ozaki.ryota%gmail.com@localhost>
@@ -41,7 +41,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_wg.c,v 1.25 2020/08/27 02:52:33 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_wg.c,v 1.26 2020/08/27 02:53:47 riastradh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_inet.h"
@@ -2343,11 +2343,7 @@
        bool success, free_encrypted_buf = false, ok;
        struct mbuf *n;
 
-       if (m->m_len < sizeof(struct wg_msg_data)) {
-               m = m_pullup(m, sizeof(struct wg_msg_data));
-               if (m == NULL)
-                       return;
-       }
+       KASSERT(m->m_len >= sizeof(struct wg_msg_data));
        wgmd = mtod(m, struct wg_msg_data *);
 
        KASSERT(wgmd->wgmd_type == WG_MSG_TYPE_DATA);
@@ -2573,42 +2569,63 @@
        wg_put_session(wgs, &psref);
 }
 
-static bool
-wg_validate_msg_length(struct wg_softc *wg, const struct mbuf *m)
+static struct mbuf *
+wg_validate_msg_header(struct wg_softc *wg, struct mbuf *m)
 {
-       struct wg_msg *wgm;
-       size_t mlen;
-
-       mlen = m_length(m);
-       if (__predict_false(mlen < sizeof(struct wg_msg)))
-               return false;
-
-       wgm = mtod(m, struct wg_msg *);
-       switch (wgm->wgm_type) {
+       struct wg_msg wgm;
+       size_t mbuflen;
+       size_t msglen;
+
+       /*
+        * Get the mbuf chain length.  It is already guaranteed, by
+        * wg_overudp_cb, to be large enough for a struct wg_msg.
+        */
+       mbuflen = m_length(m);
+       KASSERT(mbuflen >= sizeof(struct wg_msg));
+
+       /*
+        * Copy the message header (32-bit message type) out -- we'll
+        * worry about contiguity and alignment later.
+        */
+       m_copydata(m, 0, sizeof(wgm), &wgm);
+       switch (wgm.wgm_type) {
        case WG_MSG_TYPE_INIT:
-               if (__predict_true(mlen >= sizeof(struct wg_msg_init)))
-                       return true;
+               msglen = sizeof(struct wg_msg_init);
                break;
        case WG_MSG_TYPE_RESP:
-               if (__predict_true(mlen >= sizeof(struct wg_msg_resp)))
-                       return true;
+               msglen = sizeof(struct wg_msg_resp);
                break;
        case WG_MSG_TYPE_COOKIE:
-               if (__predict_true(mlen >= sizeof(struct wg_msg_cookie)))
-                       return true;
+               msglen = sizeof(struct wg_msg_cookie);
                break;
        case WG_MSG_TYPE_DATA:
-               if (__predict_true(mlen >= sizeof(struct wg_msg_data)))
-                       return true;
+               msglen = sizeof(struct wg_msg_data);
                break;
        default:
                WG_LOG_RATECHECK(&wg->wg_ppsratecheck, LOG_DEBUG,
-                   "Unexpected msg type: %u\n", wgm->wgm_type);
-               return false;
+                   "Unexpected msg type: %u\n", wgm.wgm_type);
+               goto error;
+       }
+
+       /* Verify the mbuf chain is long enough for this type of message.  */
+       if (__predict_false(mbuflen < msglen)) {
+               WG_DLOG("Invalid msg size: mbuflen=%lu type=%u\n", mbuflen,
+                   wgm.wgm_type);
+               goto error;
        }
-       WG_DLOG("Invalid msg size: mlen=%lu type=%u\n", mlen, wgm->wgm_type);
-
-       return false;
+
+       /* Make the message header contiguous if necessary.  */
+       if (__predict_false(m->m_len < msglen)) {
+               m = m_pullup(m, msglen);
+               if (m == NULL)
+                       return NULL;
+       }
+
+       return m;
+
+error:
+       m_freem(m);
+       return NULL;
 }
 
 static void
@@ -2616,14 +2633,12 @@
     const struct sockaddr *src)
 {
        struct wg_msg *wgm;
-       bool valid;
-
-       valid = wg_validate_msg_length(wg, m);
-       if (!valid) {
-               m_freem(m);
+
+       m = wg_validate_msg_header(wg, m);
+       if (__predict_false(m == NULL))
                return;
-       }
-
+
+       KASSERT(m->m_len >= sizeof(struct wg_msg));
        wgm = mtod(m, struct wg_msg *);
        switch (wgm->wgm_type) {
        case WG_MSG_TYPE_INIT:
@@ -2639,7 +2654,7 @@
                wg_handle_msg_data(wg, m, src);
                break;
        default:
-               /* wg_validate_msg_length should already reject this case */
+               /* wg_validate_msg_header should already reject this case */
                break;
        }
 }