bpf: Add an ioctl to set the VLAN Priority on packets sent by bpf

This allows the use of VLAN PCP in dhclient, which is required for
certain ISPs (such as Orange.fr).

Reviewed by:	bcr (man page)
MFC after:	1 week
Sponsored by:	Rubicon Communications, LLC ("Netgate")
Differential Revision:	https://reviews.freebsd.org/D31263

Author: loos-br

sbin/dhclient/bpf.c

@@ -90,6 +90,14 @@ if_register_bpf(struct interface_info *info, int flags)
 		error("Can't attach interface %s to bpf device %s: %m",
 		    info->name, filename);
 
+	/* Tag the packets with the proper VLAN PCP setting. */
+	if (info->client->config->vlan_pcp != 0) {
+		if (ioctl(sock, BIOCSETVLANPCP,
+		    &info->client->config->vlan_pcp) < 0)
+			error( "Can't set the VLAN PCP tag on interface %s: %m",
+			    info->name);
+	}
+
 	return (sock);
 }
 

sbin/dhclient/clparse.c

@@ -76,6 +76,7 @@ read_client_conf(void)
 	memset(&top_level_config, 0, sizeof(top_level_config));
 
 	/* Set some defaults... */
+	top_level_config.vlan_pcp = 0;
 	top_level_config.timeout = 60;
 	top_level_config.select_interval = 0;
 	top_level_config.reboot_timeout = 10;
@@ -201,6 +202,7 @@ parse_client_statement(FILE *cfile, struct interface_info *ip,
 	int		 token;
 	char		*val;
 	struct option	*option;
+	time_t		 tmp;
 
 	switch (next_token(&val, cfile)) {
 	case SEND:
@@ -260,6 +262,10 @@ parse_client_statement(FILE *cfile, struct interface_info *ip,
 	case REBOOT:
 		parse_lease_time(cfile, &config->reboot_timeout);
 		return;
+	case VLAN_PCP:
+		parse_lease_time(cfile, &tmp);
+		config->vlan_pcp = (u_int)tmp;
+		return;
 	case BACKOFF_CUTOFF:
 		parse_lease_time(cfile, &config->backoff_cutoff);
 		return;

sbin/dhclient/conflex.c

@@ -524,6 +524,8 @@ intern(char *atom, int dfv)
 	case 'v':
 		if (!strcasecmp(atom + 1, "endor-class"))
 			return (VENDOR_CLASS);
+		if (!strcasecmp(atom + 1, "lan-pcp"))
+			return (VLAN_PCP);
 		break;
 	case 'y':
 		if (!strcasecmp(atom + 1, "iaddr"))

sbin/dhclient/dhclient.conf.5

@@ -38,7 +38,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd May 31, 2018
+.Dd July 21, 2021
 .Dt DHCLIENT.CONF 5
 .Os
 .Sh NAME
@@ -484,6 +484,13 @@ lease database and will record the media type used to acquire the address.
 Whenever the client tries to renew the lease, it will use that same media type.
 The lease must expire before the client will go back to cycling through media
 types.
+.It Ic vlan-pcp Ar code ;
+The
+.Ic vlan-pcp
+statement sets the PCP (Priority Code Point) value for the VLAN header.
+This requires the
+.Va net.link.vlan.mtag_pcp
+sysctl to be set to 1.
 .El
 .Sh EXAMPLES
 The following configuration file is used on a laptop

sbin/dhclient/dhcpd.h

@@ -159,6 +159,7 @@ struct client_config {
 	u_int8_t		 required_options[256];
 	u_int8_t		 requested_options[256];
 	int			 requested_option_count;
+	u_int			 vlan_pcp;
 	time_t			 timeout;
 	time_t			 initial_interval;
 	time_t			 retry_interval;

sbin/dhclient/dhctoken.h

@@ -133,6 +133,7 @@
 #define AUTHORITATIVE	333
 #define TOKEN_NOT	334
 #define ALWAYS_REPLY_RFC1048 335
+#define VLAN_PCP	336
 
 #define is_identifier(x)	((x) >= FIRST_TOKEN &&	\
 				 (x) != STRING &&	\

share/man/man4/bpf.4

@@ -49,7 +49,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd October 9, 2020
+.Dd July 22, 2021
 .Dt BPF 4
 .Os
 .Sh NAME
@@ -659,6 +659,8 @@ therefore ownership is not assigned, the user process must check
 .Vt bzh_kernel_gen
 against
 .Vt bzh_user_gen .
+.It Dv BIOCSETVLANPCP
+Set the VLAN PCP bits to the supplied value.
 .El
 .Sh STANDARD IOCTLS
 .Nm

sys/net/bpf.c

@@ -78,6 +78,7 @@ __FBSDID("$FreeBSD$");
 
 #include <net/if.h>
 #include <net/if_var.h>
+#include <net/if_vlan_var.h>
 #include <net/if_dl.h>
 #include <net/bpf.h>
 #include <net/bpf_buffer.h>
@@ -130,6 +131,7 @@ struct bpf_program_buffer {
 #if defined(DEV_BPF) || defined(NETGRAPH_BPF)
 
 #define PRINET  26			/* interruptible */
+#define BPF_PRIO_MAX	7
 
 #define	SIZEOF_BPF_HDR(type)	\
     (offsetof(type, bh_hdrlen) + sizeof(((type *)0)->bh_hdrlen))
@@ -977,6 +979,9 @@ bpfopen(struct cdev *dev, int flags, int fmt, struct thread *td)
 	callout_init_mtx(&d->bd_callout, &d->bd_lock, 0);
 	knlist_init_mtx(&d->bd_sel.si_note, &d->bd_lock);
 
+	/* Disable VLAN pcp tagging. */
+	d->bd_pcp = 0;
+
 	return (0);
 }
 
@@ -1167,6 +1172,27 @@ bpf_ready(struct bpf_d *d)
 	return (0);
 }
 
+static int
+bpf_setpcp(struct mbuf *m, u_int8_t prio)
+{
+	struct m_tag *mtag;
+
+	KASSERT(prio <= BPF_PRIO_MAX,
+	    ("%s with invalid pcp", __func__));
+
+	mtag = m_tag_locate(m, MTAG_8021Q, MTAG_8021Q_PCP_OUT, NULL);
+	if (mtag == NULL) {
+		mtag = m_tag_alloc(MTAG_8021Q, MTAG_8021Q_PCP_OUT,
+		    sizeof(uint8_t), M_NOWAIT);
+		if (mtag == NULL)
+			return (ENOMEM);
+		m_tag_prepend(m, mtag);
+	}
+
+	*(uint8_t *)(mtag + 1) = prio;
+	return (0);
+}
+
 static int
 bpfwrite(struct cdev *dev, struct uio *uio, int ioflag)
 {
@@ -1267,6 +1293,9 @@ bpfwrite(struct cdev *dev, struct uio *uio, int ioflag)
 		ro.ro_flags = RT_HAS_HEADER;
 	}
 
+	if (d->bd_pcp != 0)
+		bpf_setpcp(m, d->bd_pcp);
+
 	/* Avoid possible recursion on BPFD_LOCK(). */
 	NET_EPOCH_ENTER(et);
 	BPFD_UNLOCK(d);
@@ -1356,6 +1385,7 @@ reset_d(struct bpf_d *d)
  *  BIOCROTZBUF		Force rotation of zero-copy buffer
  *  BIOCSETBUFMODE	Set buffer mode.
  *  BIOCGETBUFMODE	Get current buffer mode.
+ *  BIOCSETVLANPCP	Set VLAN PCP tag.
  */
 /* ARGSUSED */
 static	int
@@ -1906,6 +1936,19 @@ bpfioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags,
 	case BIOCROTZBUF:
 		error = bpf_ioctl_rotzbuf(td, d, (struct bpf_zbuf *)addr);
 		break;
+
+	case BIOCSETVLANPCP:
+		{
+			u_int pcp;
+
+			pcp = *(u_int *)addr;
+			if (pcp > BPF_PRIO_MAX || pcp < 0) {
+				error = EINVAL;
+				break;
+			}
+			d->bd_pcp = pcp;
+			break;
+		}
 	}
 	CURVNET_RESTORE();
 	return (error);

sys/net/bpf.h

@@ -153,6 +153,7 @@ struct bpf_zbuf {
 #define	BIOCSETFNR	_IOW('B', 130, struct bpf_program)
 #define	BIOCGTSTAMP	_IOR('B', 131, u_int)
 #define	BIOCSTSTAMP	_IOW('B', 132, u_int)
+#define	BIOCSETVLANPCP	_IOW('B', 133, u_int)
 
 /* Obsolete */
 #define	BIOCGSEESENT	BIOCGDIRECTION

sys/net/bpfdesc.h

@@ -91,6 +91,7 @@ struct bpf_d {
 	int		bd_feedback;	/* true to feed back sent packets */
 	int		bd_async;	/* non-zero if packet reception should generate signal */
 	int		bd_sig;		/* signal to send upon packet reception */
+	int		bd_pcp;		/* VLAN pcp tag */
 	struct sigio *	bd_sigio;	/* information for async I/O */
 	struct selinfo	bd_sel;		/* bsd select info */
 	struct mtx	bd_lock;	/* per-descriptor lock */