git: 8303afca1765 - stable/13 - net: Check per-flow priority code point for untagged traffic

The branch stable/13 has been updated by zlei:

URL: https://cgit.FreeBSD.org/src/commit/?id=8303afca1765148d0069ce5144072b3ae9cab61e

commit 8303afca1765148d0069ce5144072b3ae9cab61e
Author:     Zhenlei Huang <zlei@FreeBSD.org>
AuthorDate: 2023-09-06 10:15:14 +0000
Commit:     Zhenlei Huang <zlei@FreeBSD.org>
CommitDate: 2023-09-20 10:00:37 +0000

    net: Check per-flow priority code point for untagged traffic
    
    Commit 868aabb4708d introduced per-flow priority. There's a defect in the
    logic for untagged traffic, it does not check M_VLANTAG set in the mbuf
    packet header or MTAG_8021Q/MTAG_8021Q_PCP_OUT tag set by firewall, then
    can result missing desired priority in the outbound packets.
    
    For mbuf packet with M_VLANTAG in header, some interfaces happen to work
    due to bug in the drivers mentioned in D39499. As modern interfaces have
    VLAN hardware offloading, the defect is barely noticeable unless the
    feature per-flow priority is widely tested.
    
    As a side effect of this defect, the soft padding to work around buggy
    bridges is bypassed. That may result in regression if soft padding is
    requested.
    
    PR:             273431
    Discussed with: kib
    Fixes:  868aabb4708d Add IP(V6)_VLAN_PCP to set 802.1 priority per-flow
    MFC after:      1 week
    Differential Revision:  https://reviews.freebsd.org/D39536
    
    (cherry picked from commit 49d6743da15fe378782e43776df8b4fd4f84c8d0)
    (cherry picked from commit c750055382f73db964c20f8eba855a9ac9e19591)
---
 sys/net/if_ethersubr.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/sys/net/if_ethersubr.c b/sys/net/if_ethersubr.c
index d8043f0551ff..a3466c94d312 100644
--- a/sys/net/if_ethersubr.c
+++ b/sys/net/if_ethersubr.c
@@ -118,6 +118,8 @@ static	int ether_resolvemulti(struct ifnet *, struct sockaddr **,
 		struct sockaddr *);
 static	int ether_requestencap(struct ifnet *, struct if_encap_req *);
 
+static inline bool ether_do_pcp(struct ifnet *, struct mbuf *);
+
 #define senderr(e) do { error = (e); goto bad;} while (0)
 
 static void
@@ -466,11 +468,7 @@ ether_set_pcp(struct mbuf **mp, struct ifnet *ifp, uint8_t pcp)
 int
 ether_output_frame(struct ifnet *ifp, struct mbuf *m)
 {
-	uint8_t pcp;
-
-	pcp = ifp->if_pcp;
-	if (pcp != IFNET_PCP_NONE && ifp->if_type != IFT_L2VLAN &&
-	    !ether_set_pcp(&m, ifp, pcp))
+	if (ether_do_pcp(ifp, m) && !ether_set_pcp(&m, ifp, ifp->if_pcp))
 		return (0);
 
 	if (PFIL_HOOKED_OUT(V_link_pfil_head))
@@ -1355,6 +1353,19 @@ SYSCTL_INT(_net_link_vlan, OID_AUTO, mtag_pcp, CTLFLAG_RW,
     &vlan_mtag_pcp, 0,
     "Retain VLAN PCP information as packets are passed up the stack");
 
+static inline bool
+ether_do_pcp(struct ifnet *ifp, struct mbuf *m)
+{
+	if (ifp->if_type == IFT_L2VLAN)
+		return (false);
+	if (ifp->if_pcp != IFNET_PCP_NONE || (m->m_flags & M_VLANTAG) != 0)
+		return (true);
+	if (vlan_mtag_pcp &&
+	    m_tag_locate(m, MTAG_8021Q, MTAG_8021Q_PCP_OUT, NULL) != NULL)
+		return (true);
+	return (false);
+}
+
 bool
 ether_8021q_frame(struct mbuf **mp, struct ifnet *ife, struct ifnet *p,
     const struct ether_8021q_tag *qtag)