libbpf: add function to setup XDP

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>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 5128677..bf27725 100644 (file)
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -25,6 +25,12 @@
 #include <asm/unistd.h>
 #include <linux/bpf.h>
 #include "bpf.h"
+#include "libbpf.h"
+#include "nlattr.h"
+#include <linux/rtnetlink.h>
+#include <linux/if_link.h>
+#include <sys/socket.h>
+#include <errno.h>
 
 /*
  * When building perf, unistd.h is overridden. __NR_bpf is
@@ -46,7 +52,9 @@
 # endif
 #endif
 
+#ifndef min
 #define min(x, y) ((x) < (y) ? (x) : (y))
+#endif
 
 static inline __u64 ptr_to_u64(const void *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 = -LIBBPF_ERRNO__INTERNAL;
+               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 30c7763..c60122d 100644 (file)
--- 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 6e20003..e42f969 100644 (file)
--- 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