git: d41caea44ba9 - stable/12 - if_pflog: fix packet length

[Kristof Provost]

The branch stable/12 has been updated by kp:

URL: 
https://cgit.FreeBSD.org/src/commit/?id=d41caea44ba9f676b72d9a27d53de520ef61e196

commit d41caea44ba9f676b72d9a27d53de520ef61e196
Author:     Kristof Provost <k...@freebsd.org>
AuthorDate: 2021-12-02 07:22:34 +0000
Commit:     Kristof Provost <k...@freebsd.org>
CommitDate: 2021-12-11 09:38:55 +0000

    if_pflog: fix packet length
    
    There were two issues with the new pflog packet length.
    The first is that the length is expected to be a multiple of
    sizeof(long), but we'd assumed it had to be a multiple of
    sizeof(uint32_t).
    
    The second is that there's some broken software out there (such as
    Wireshark) that makes incorrect assumptions about the amount of padding.
    That is, Wireshark assumes there's always three bytes of padding, rather
    than however much is needed to get to a multiple of sizeof(long).
    
    Fix this by adding extra padding, and a fake field to maintain
    Wireshark's assumption.
    
    Reported by:    Ozkan KIRIK <ozkan.ki...@gmail.com>
    Tested by:      Ozkan KIRIK <ozkan.ki...@gmail.com>
    MFC after:      1 week
    Sponsored by:   Rubicon Communications, LLC ("Netgate")
    Differential Revision:  https://reviews.freebsd.org/D33236
    
    (cherry picked from commit 6d4baa0d011cb3e78b4b08415568e71c0aab00fe)
---
 sys/net/if_pflog.h        | 8 ++++++--
 sys/netpfil/pf/if_pflog.c | 2 +-
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/sys/net/if_pflog.h b/sys/net/if_pflog.h
index c77d8da1440a..93a69a2bb3a5 100644
--- a/sys/net/if_pflog.h
+++ b/sys/net/if_pflog.h
@@ -31,6 +31,8 @@
 #ifndef _NET_IF_PFLOG_H_
 #define        _NET_IF_PFLOG_H_
 
+#include <net/bpf.h>
+
 #define        PFLOGIFS_MAX    16
 
 #define        PFLOG_RULESET_NAME_SIZE 16
@@ -51,11 +53,13 @@ struct pfloghdr {
        u_int8_t        dir;
        u_int8_t        pad[3];
        u_int32_t       ridentifier;
+       u_int8_t        reserve;        /* Appease broken software like 
Wireshark. */
+       u_int8_t        pad2[3];
 };
 
-#define        PFLOG_HDRLEN            sizeof(struct pfloghdr)
+#define        PFLOG_HDRLEN            BPF_WORDALIGN(offsetof(struct pfloghdr, 
pad2))
 /* minus pad, also used as a signature */
-#define        PFLOG_REAL_HDRLEN       offsetof(struct pfloghdr, pad)
+#define        PFLOG_REAL_HDRLEN       offsetof(struct pfloghdr, pad2)
 
 #ifdef _KERNEL
 struct pf_rule;
diff --git a/sys/netpfil/pf/if_pflog.c b/sys/netpfil/pf/if_pflog.c
index 4853c1301d6f..261c9f2a4087 100644
--- a/sys/netpfil/pf/if_pflog.c
+++ b/sys/netpfil/pf/if_pflog.c
@@ -215,7 +215,7 @@ pflog_packet(struct pfi_kkif *kif, struct mbuf *m, 
sa_family_t af, u_int8_t dir,
                return (0);
 
        bzero(&hdr, sizeof(hdr));
-       hdr.length = PFLOG_HDRLEN;
+       hdr.length = PFLOG_REAL_HDRLEN;
        hdr.af = af;
        hdr.action = rm->action;
        hdr.reason = reason;