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lwt: BPF support for LWT

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Adds support to configure BPF programs as nexthop actions via the LWT
framework.

Example:
   ip route add 192.168.253.2/32 \
     encap bpf out obj lwt_len_hist_kern.o section len_hist \
     dev veth0

Signed-off-by: Thomas Graf <tgraf@suug.ch>
This commit is contained in:
Thomas Graf 2016-12-12 01:14:35 +01:00 committed by Stephen Hemminger
parent ba2a2124ec
commit b15f440e78
4 changed files with 235 additions and 15 deletions
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5
include/bpf_api.h
View File

@ -87,6 +87,11 @@
__section(ELF_SECTION_ACTION)
#endif
#ifndef __section_lwt_entry
# define __section_lwt_entry \
__section(ELF_SECTION_PROG)
#endif
#ifndef __section_license
# define __section_license \
__section(ELF_SECTION_LICENSE)

186
ip/iproute_lwtunnel.c
View File

@ -24,20 +24,7 @@
#include "rt_names.h"
#include "utils.h"
#include "iproute_lwtunnel.h"
static int read_encap_type(const char *name)
{
if (strcmp(name, "mpls") == 0)
return LWTUNNEL_ENCAP_MPLS;
else if (strcmp(name, "ip") == 0)
return LWTUNNEL_ENCAP_IP;
else if (strcmp(name, "ip6") == 0)
return LWTUNNEL_ENCAP_IP6;
else if (strcmp(name, "ila") == 0)
return LWTUNNEL_ENCAP_ILA;
else
return LWTUNNEL_ENCAP_NONE;
}
#include "bpf_util.h"
static const char *format_encap_type(int type)
{
@ -50,11 +37,44 @@ static const char *format_encap_type(int type)
return "ip6";
case LWTUNNEL_ENCAP_ILA:
return "ila";
case LWTUNNEL_ENCAP_BPF:
return "bpf";
default:
return "unknown";
}
}
static void encap_type_usage(void)
{
int i;
fprintf(stderr, "Usage: ip route ... encap TYPE [ OPTIONS ] [...]\n");
for (i = 1; i <= LWTUNNEL_ENCAP_MAX; i++)
fprintf(stderr, "%s %s\n", format_encap_type(i),
i == 1 ? "TYPE := " : " ");
exit(-1);
}
static int read_encap_type(const char *name)
{
if (strcmp(name, "mpls") == 0)
return LWTUNNEL_ENCAP_MPLS;
else if (strcmp(name, "ip") == 0)
return LWTUNNEL_ENCAP_IP;
else if (strcmp(name, "ip6") == 0)
return LWTUNNEL_ENCAP_IP6;
else if (strcmp(name, "ila") == 0)
return LWTUNNEL_ENCAP_ILA;
else if (strcmp(name, "bpf") == 0)
return LWTUNNEL_ENCAP_BPF;
else if (strcmp(name, "help") == 0)
encap_type_usage();
return LWTUNNEL_ENCAP_NONE;
}
static void print_encap_mpls(FILE *fp, struct rtattr *encap)
{
struct rtattr *tb[MPLS_IPTUNNEL_MAX+1];
@ -159,6 +179,34 @@ static void print_encap_ip6(FILE *fp, struct rtattr *encap)
fprintf(fp, "tc %d ", rta_getattr_u8(tb[LWTUNNEL_IP6_TC]));
}
static void print_encap_bpf_prog(FILE *fp, struct rtattr *encap,
const char *str)
{
struct rtattr *tb[LWT_BPF_PROG_MAX+1];
parse_rtattr_nested(tb, LWT_BPF_PROG_MAX, encap);
fprintf(fp, "%s ", str);
if (tb[LWT_BPF_PROG_NAME])
fprintf(fp, "%s ", rta_getattr_str(tb[LWT_BPF_PROG_NAME]));
}
static void print_encap_bpf(FILE *fp, struct rtattr *encap)
{
struct rtattr *tb[LWT_BPF_MAX+1];
parse_rtattr_nested(tb, LWT_BPF_MAX, encap);
if (tb[LWT_BPF_IN])
print_encap_bpf_prog(fp, tb[LWT_BPF_IN], "in");
if (tb[LWT_BPF_OUT])
print_encap_bpf_prog(fp, tb[LWT_BPF_OUT], "out");
if (tb[LWT_BPF_XMIT])
print_encap_bpf_prog(fp, tb[LWT_BPF_XMIT], "xmit");
if (tb[LWT_BPF_XMIT_HEADROOM])
fprintf(fp, "%d ", rta_getattr_u32(tb[LWT_BPF_XMIT_HEADROOM]));
}
void lwt_print_encap(FILE *fp, struct rtattr *encap_type,
struct rtattr *encap)
{
@ -184,6 +232,9 @@ void lwt_print_encap(FILE *fp, struct rtattr *encap_type,
case LWTUNNEL_ENCAP_IP6:
print_encap_ip6(fp, encap);
break;
case LWTUNNEL_ENCAP_BPF:
print_encap_bpf(fp, encap);
break;
}
}
@ -365,6 +416,109 @@ static int parse_encap_ip6(struct rtattr *rta, size_t len, int *argcp, char ***a
return 0;
}
struct lwt_x {
struct rtattr *rta;
size_t len;
};
static void bpf_lwt_cb(void *lwt_ptr, int fd, const char *annotation)
{
struct lwt_x *x = lwt_ptr;
rta_addattr32(x->rta, x->len, LWT_BPF_PROG_FD, fd);
rta_addattr_l(x->rta, x->len, LWT_BPF_PROG_NAME, annotation,
strlen(annotation) + 1);
}
static const struct bpf_cfg_ops bpf_cb_ops = {
.ebpf_cb = bpf_lwt_cb,
};
static int lwt_parse_bpf(struct rtattr *rta, size_t len, int *argcp, char ***argvp,
int attr, const enum bpf_prog_type bpf_type)
{
struct bpf_cfg_in cfg = {
.argc = *argcp,
.argv = *argvp,
};
struct lwt_x x = {
.rta = rta,
.len = len,
};
struct rtattr *nest;
int err;
nest = rta_nest(rta, len, attr);
err = bpf_parse_common(bpf_type, &cfg, &bpf_cb_ops, &x);
if (err < 0) {
fprintf(stderr, "Failed to parse eBPF program: %s\n", strerror(err));
return -1;
}
rta_nest_end(rta, nest);
*argcp = cfg.argc;
*argvp = cfg.argv;
return 0;
}
static void lwt_bpf_usage(void)
{
fprintf(stderr, "Usage: ip route ... encap bpf [ in BPF ] [ out BPF ] [ xmit BPF ] [...]\n");
fprintf(stderr, "BPF := obj FILE [ section NAME ] [ verbose ]\n");
exit(-1);
}
static int parse_encap_bpf(struct rtattr *rta, size_t len, int *argcp,
char ***argvp)
{
char **argv = *argvp;
int argc = *argcp;
int headroom_set = 0;
while (argc > 0) {
if (strcmp(*argv, "in") == 0) {
NEXT_ARG();
if (lwt_parse_bpf(rta, len, &argc, &argv, LWT_BPF_IN,
BPF_PROG_TYPE_LWT_IN) < 0)
return -1;
} else if (strcmp(*argv, "out") == 0) {
NEXT_ARG();
if (lwt_parse_bpf(rta, len, &argc, &argv, LWT_BPF_OUT,
BPF_PROG_TYPE_LWT_OUT) < 0)
return -1;
} else if (strcmp(*argv, "xmit") == 0) {
NEXT_ARG();
if (lwt_parse_bpf(rta, len, &argc, &argv, LWT_BPF_XMIT,
BPF_PROG_TYPE_LWT_XMIT) < 0)
return -1;
} else if (strcmp(*argv, "headroom") == 0) {
unsigned int headroom;
NEXT_ARG();
if (get_unsigned(&headroom, *argv, 0) || headroom == 0)
invarg("headroom is invalid\n", *argv);
if (!headroom_set)
rta_addattr32(rta, 1024, LWT_BPF_XMIT_HEADROOM,
headroom);
headroom_set = 1;
} else if (strcmp(*argv, "help") == 0) {
lwt_bpf_usage();
} else {
break;
}
NEXT_ARG_FWD();
}
/* argv is currently the first unparsed argument,
* but the lwt_parse_encap() caller will move to the next,
* so step back */
*argcp = argc + 1;
*argvp = argv - 1;
return 0;
}
int lwt_parse_encap(struct rtattr *rta, size_t len, int *argcp, char ***argvp)
{
struct rtattr *nest;
@ -397,6 +551,10 @@ int lwt_parse_encap(struct rtattr *rta, size_t len, int *argcp, char ***argvp)
case LWTUNNEL_ENCAP_IP6:
parse_encap_ip6(rta, len, &argc, &argv);
break;
case LWTUNNEL_ENCAP_BPF:
if (parse_encap_bpf(rta, len, &argc, &argv) < 0)
exit(-1);
break;
default:
fprintf(stderr, "Error: unsupported encap type\n");
break;

18
lib/bpf.c
View File

@ -56,6 +56,9 @@ static const enum bpf_prog_type __bpf_types[] = {
BPF_PROG_TYPE_SCHED_CLS,
BPF_PROG_TYPE_SCHED_ACT,
BPF_PROG_TYPE_XDP,
BPF_PROG_TYPE_LWT_IN,
BPF_PROG_TYPE_LWT_OUT,
BPF_PROG_TYPE_LWT_XMIT,
};
static const struct bpf_prog_meta __bpf_prog_meta[] = {
@ -76,6 +79,21 @@ static const struct bpf_prog_meta __bpf_prog_meta[] = {
.subdir = "xdp",
.section = ELF_SECTION_PROG,
},
[BPF_PROG_TYPE_LWT_IN] = {
.type = "lwt_in",
.subdir = "ip",
.section = ELF_SECTION_PROG,
},
[BPF_PROG_TYPE_LWT_OUT] = {
.type = "lwt_out",
.subdir = "ip",
.section = ELF_SECTION_PROG,
},
[BPF_PROG_TYPE_LWT_XMIT] = {
.type = "lwt_xmit",
.subdir = "ip",
.section = ELF_SECTION_PROG,
},
};
static const char *bpf_prog_to_subdir(enum bpf_prog_type type)

41
man/man8/ip-route.8.in
View File

@ -174,7 +174,7 @@ throw " | " unreachable " | " prohibit " | " blackhole " | " nat " ]"
.ti -8
.IR ENCAP " := [ "
.IR MPLS " | " IP " ]"
.IR MPLS " | " IP | " BPF " ] "
.ti -8
.IR ENCAP_MPLS " := "
@ -193,6 +193,19 @@ throw " | " unreachable " | " prohibit " | " blackhole " | " nat " ]"
.B ttl
.IR TTL " ]"
.ti -8
.IR ENCAP_BPF " := "
.BR bpf " [ "
.B in
.IR PROG " ] ["
.B out
.IR PROG " ] ["
.B xmit
.IR PROG " ] ["
.B headroom
.IR SIZE " ]"
.SH DESCRIPTION
.B ip route
is used to manipulate entries in the kernel routing tables.
@ -636,6 +649,9 @@ is a string specifying the supported encapsulation type. Namely:
.BI ip
- IP encapsulation (Geneve, GRE, VXLAN, ...)
.sp
.BI bpf
- Execution of BPF program
.sp
.in -8
.I ENCAPHDR
@ -664,6 +680,29 @@ is a set of encapsulation attributes specific to the
.in -2
.sp
.B bpf
.in +2
.B in
.I PROG
- BPF program to execute for incoming packets
.sp
.B out
.I PROG
- BPF program to execute for outgoing packets
.sp
.B xmit
.I PROG
- BPF program to execute for transmitted packets
.sp
.B headroom
.I SIZE
- Size of header BPF program will attach (xmit)
.in -2
.sp
.in -8
.RE