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Subject[PATCH 1/4] libbpf: add function to setup XDP
Date
Most of the code is taken from set_link_xdp_fd() in bpf_load.c and
slightly modified to be library compliant.

Signed-off-by: Eric Leblond <eric@regit.org>
---
tools/lib/bpf/bpf.c | 126 ++++++++++++++++++++++++++++++++++++++++++++++++-
tools/lib/bpf/libbpf.c | 2 +
tools/lib/bpf/libbpf.h | 4 ++
3 files changed, 130 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 5128677e4117..1e3cfe6b9fce 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -25,6 +25,16 @@
#include <asm/unistd.h>
#include <linux/bpf.h>
#include "bpf.h"
+#include "libbpf.h"
+#include <linux/rtnetlink.h>
+#include <sys/socket.h>
+#include <errno.h>
+
+#ifndef IFLA_XDP_MAX
+#define IFLA_XDP 43
+#define IFLA_XDP_FD 1
+#define IFLA_XDP_FLAGS 3
+#endif

/*
* When building perf, unistd.h is overridden. __NR_bpf is
@@ -46,8 +56,6 @@
# endif
#endif

-#define min(x, y) ((x) < (y) ? (x) : (y))
-
static inline __u64 ptr_to_u64(const void *ptr)
{
return (__u64) (unsigned long) ptr;
@@ -413,3 +421,117 @@ int bpf_obj_get_info_by_fd(int prog_fd, void *info, __u32 *info_len)

return err;
}
+
+int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags)
+{
+ struct sockaddr_nl sa;
+ int sock, seq = 0, len, ret = -1;
+ char buf[4096];
+ struct nlattr *nla, *nla_xdp;
+ struct {
+ struct nlmsghdr nh;
+ struct ifinfomsg ifinfo;
+ char attrbuf[64];
+ } req;
+ struct nlmsghdr *nh;
+ struct nlmsgerr *err;
+ socklen_t addrlen;
+
+ memset(&sa, 0, sizeof(sa));
+ sa.nl_family = AF_NETLINK;
+
+ sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+ if (sock < 0) {
+ return -errno;
+ }
+
+ if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
+ ret = -errno;
+ goto cleanup;
+ }
+
+ addrlen = sizeof(sa);
+ if (getsockname(sock, (struct sockaddr *)&sa, &addrlen) < 0) {
+ ret = errno;
+ goto cleanup;
+ }
+
+ if (addrlen != sizeof(sa)) {
+ ret = errno;
+ goto cleanup;
+ }
+
+ memset(&req, 0, sizeof(req));
+ req.nh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
+ req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
+ req.nh.nlmsg_type = RTM_SETLINK;
+ req.nh.nlmsg_pid = 0;
+ req.nh.nlmsg_seq = ++seq;
+ req.ifinfo.ifi_family = AF_UNSPEC;
+ req.ifinfo.ifi_index = ifindex;
+
+ /* started nested attribute for XDP */
+ nla = (struct nlattr *)(((char *)&req)
+ + NLMSG_ALIGN(req.nh.nlmsg_len));
+ nla->nla_type = NLA_F_NESTED | IFLA_XDP;
+ nla->nla_len = NLA_HDRLEN;
+
+ /* add XDP fd */
+ nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len);
+ nla_xdp->nla_type = IFLA_XDP_FD;
+ nla_xdp->nla_len = NLA_HDRLEN + sizeof(int);
+ memcpy((char *)nla_xdp + NLA_HDRLEN, &fd, sizeof(fd));
+ nla->nla_len += nla_xdp->nla_len;
+
+ /* if user passed in any flags, add those too */
+ if (flags) {
+ nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len);
+ nla_xdp->nla_type = IFLA_XDP_FLAGS;
+ nla_xdp->nla_len = NLA_HDRLEN + sizeof(flags);
+ memcpy((char *)nla_xdp + NLA_HDRLEN, &flags, sizeof(flags));
+ nla->nla_len += nla_xdp->nla_len;
+ }
+
+ req.nh.nlmsg_len += NLA_ALIGN(nla->nla_len);
+
+ if (send(sock, &req, req.nh.nlmsg_len, 0) < 0) {
+ ret = -errno;
+ goto cleanup;
+ }
+
+ len = recv(sock, buf, sizeof(buf), 0);
+ if (len < 0) {
+ ret = -errno;
+ goto cleanup;
+ }
+
+ for (nh = (struct nlmsghdr *)buf; NLMSG_OK(nh, len);
+ nh = NLMSG_NEXT(nh, len)) {
+ if (nh->nlmsg_pid != sa.nl_pid) {
+ ret = -LIBBPF_ERRNO__WRNGPID;
+ goto cleanup;
+ }
+ if (nh->nlmsg_seq != seq) {
+ ret = -LIBBPF_ERRNO__INVSEQ;
+ goto cleanup;
+ }
+ switch (nh->nlmsg_type) {
+ case NLMSG_ERROR:
+ err = (struct nlmsgerr *)NLMSG_DATA(nh);
+ if (!err->error)
+ continue;
+ ret = err->error;
+ goto cleanup;
+ case NLMSG_DONE:
+ break;
+ default:
+ break;
+ }
+ }
+
+ ret = 0;
+
+cleanup:
+ close(sock);
+ return ret;
+}
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e9c4b7cabcf2..5fe8aaa2123e 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -106,6 +106,8 @@ static const char *libbpf_strerror_table[NR_ERRNO] = {
[ERRCODE_OFFSET(PROG2BIG)] = "Program too big",
[ERRCODE_OFFSET(KVER)] = "Incorrect kernel version",
[ERRCODE_OFFSET(PROGTYPE)] = "Kernel doesn't support this program type",
+ [ERRCODE_OFFSET(WRNGPID)] = "Wrong pid in netlink message",
+ [ERRCODE_OFFSET(INVSEQ)] = "Invalid netlink sequence",
};

int libbpf_strerror(int err, char *buf, size_t size)
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 6e20003109e0..e42f96900318 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -42,6 +42,8 @@ enum libbpf_errno {
LIBBPF_ERRNO__PROG2BIG, /* Program too big */
LIBBPF_ERRNO__KVER, /* Incorrect kernel version */
LIBBPF_ERRNO__PROGTYPE, /* Kernel doesn't support this program type */
+ LIBBPF_ERRNO__WRNGPID, /* Wrong pid in netlink message */
+ LIBBPF_ERRNO__INVSEQ, /* Invalid netlink sequence */
__LIBBPF_ERRNO__END,
};

@@ -246,4 +248,6 @@ long libbpf_get_error(const void *ptr);

int bpf_prog_load(const char *file, enum bpf_prog_type type,
struct bpf_object **pobj, int *prog_fd);
+
+int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags);
#endif
--
2.15.1
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