libbpf: add API to get XDP/XSK supported features

Extend bpf_xdp_query routine in order to get XDP/XSK supported features
of netdev over route netlink interface.
Extend libbpf netlink implementation in order to support netlink_generic
protocol.

Co-developed-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Co-developed-by: Marek Majtyka <alardam@gmail.com>
Signed-off-by: Marek Majtyka <alardam@gmail.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/a72609ef4f0de7fee5376c40dbf54ad7f13bfb8d.1675245258.git.lorenzo@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 8777ff21ea1d417db24f31aa114825366025734d..b18581277eb27d6b262b81e234c53265296e0768 100644 (file)
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -1048,9 +1048,10 @@ struct bpf_xdp_query_opts {
        __u32 hw_prog_id;       /* output */
        __u32 skb_prog_id;      /* output */
        __u8 attach_mode;       /* output */
+       __u64 feature_flags;    /* output */
        size_t :0;
 };
-#define bpf_xdp_query_opts__last_field attach_mode
+#define bpf_xdp_query_opts__last_field feature_flags
 
 LIBBPF_API int bpf_xdp_attach(int ifindex, int prog_fd, __u32 flags,
                              const struct bpf_xdp_attach_opts *opts);

diff --git a/tools/lib/bpf/netlink.c b/tools/lib/bpf/netlink.c
index d2468a04a6c38844bb73edc2af458aa4648201bc..32b13b7a11b0d126cd5609d8fc459b529525aa02 100644 (file)
--- a/tools/lib/bpf/netlink.c
+++ b/tools/lib/bpf/netlink.c
@@ -9,6 +9,7 @@
 #include <linux/if_ether.h>
 #include <linux/pkt_cls.h>
 #include <linux/rtnetlink.h>
+#include <linux/netdev.h>
 #include <sys/socket.h>
 #include <errno.h>
 #include <time.h>
@@ -39,6 +40,12 @@ struct xdp_id_md {
        int ifindex;
        __u32 flags;
        struct xdp_link_info info;
+       __u64 feature_flags;
+};
+
+struct xdp_features_md {
+       int ifindex;
+       __u64 flags;
 };
 
 static int libbpf_netlink_open(__u32 *nl_pid, int proto)
@@ -238,6 +245,43 @@ out:
        return ret;
 }
 
+static int parse_genl_family_id(struct nlmsghdr *nh, libbpf_dump_nlmsg_t fn,
+                               void *cookie)
+{
+       struct genlmsghdr *gnl = NLMSG_DATA(nh);
+       struct nlattr *na = (struct nlattr *)((void *)gnl + GENL_HDRLEN);
+       struct nlattr *tb[CTRL_ATTR_FAMILY_ID + 1];
+       __u16 *id = cookie;
+
+       libbpf_nla_parse(tb, CTRL_ATTR_FAMILY_ID, na,
+                        NLMSG_PAYLOAD(nh, sizeof(*gnl)), NULL);
+       if (!tb[CTRL_ATTR_FAMILY_ID])
+               return NL_CONT;
+
+       *id = libbpf_nla_getattr_u16(tb[CTRL_ATTR_FAMILY_ID]);
+       return NL_DONE;
+}
+
+static int libbpf_netlink_resolve_genl_family_id(const char *name,
+                                                __u16 len, __u16 *id)
+{
+       struct libbpf_nla_req req = {
+               .nh.nlmsg_len   = NLMSG_LENGTH(GENL_HDRLEN),
+               .nh.nlmsg_type  = GENL_ID_CTRL,
+               .nh.nlmsg_flags = NLM_F_REQUEST,
+               .gnl.cmd        = CTRL_CMD_GETFAMILY,
+               .gnl.version    = 2,
+       };
+       int err;
+
+       err = nlattr_add(&req, CTRL_ATTR_FAMILY_NAME, name, len);
+       if (err < 0)
+               return err;
+
+       return libbpf_netlink_send_recv(&req, NETLINK_GENERIC,
+                                       parse_genl_family_id, NULL, id);
+}
+
 static int __bpf_set_link_xdp_fd_replace(int ifindex, int fd, int old_fd,
                                         __u32 flags)
 {
@@ -357,6 +401,29 @@ static int get_xdp_info(void *cookie, void *msg, struct nlattr **tb)
        return 0;
 }
 
+static int parse_xdp_features(struct nlmsghdr *nh, libbpf_dump_nlmsg_t fn,
+                             void *cookie)
+{
+       struct genlmsghdr *gnl = NLMSG_DATA(nh);
+       struct nlattr *na = (struct nlattr *)((void *)gnl + GENL_HDRLEN);
+       struct nlattr *tb[NETDEV_CMD_MAX + 1];
+       struct xdp_features_md *md = cookie;
+       __u32 ifindex;
+
+       libbpf_nla_parse(tb, NETDEV_CMD_MAX, na,
+                        NLMSG_PAYLOAD(nh, sizeof(*gnl)), NULL);
+
+       if (!tb[NETDEV_A_DEV_IFINDEX] || !tb[NETDEV_A_DEV_XDP_FEATURES])
+               return NL_CONT;
+
+       ifindex = libbpf_nla_getattr_u32(tb[NETDEV_A_DEV_IFINDEX]);
+       if (ifindex != md->ifindex)
+               return NL_CONT;
+
+       md->flags = libbpf_nla_getattr_u64(tb[NETDEV_A_DEV_XDP_FEATURES]);
+       return NL_DONE;
+}
+
 int bpf_xdp_query(int ifindex, int xdp_flags, struct bpf_xdp_query_opts *opts)
 {
        struct libbpf_nla_req req = {
@@ -366,6 +433,10 @@ int bpf_xdp_query(int ifindex, int xdp_flags, struct bpf_xdp_query_opts *opts)
                .ifinfo.ifi_family = AF_PACKET,
        };
        struct xdp_id_md xdp_id = {};
+       struct xdp_features_md md = {
+               .ifindex = ifindex,
+       };
+       __u16 id;
        int err;
 
        if (!OPTS_VALID(opts, bpf_xdp_query_opts))
@@ -393,6 +464,31 @@ int bpf_xdp_query(int ifindex, int xdp_flags, struct bpf_xdp_query_opts *opts)
        OPTS_SET(opts, skb_prog_id, xdp_id.info.skb_prog_id);
        OPTS_SET(opts, attach_mode, xdp_id.info.attach_mode);
 
+       if (!OPTS_HAS(opts, feature_flags))
+               return 0;
+
+       err = libbpf_netlink_resolve_genl_family_id("netdev", sizeof("netdev"), &id);
+       if (err < 0)
+               return libbpf_err(err);
+
+       memset(&req, 0, sizeof(req));
+       req.nh.nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN);
+       req.nh.nlmsg_flags = NLM_F_REQUEST;
+       req.nh.nlmsg_type = id;
+       req.gnl.cmd = NETDEV_CMD_DEV_GET;
+       req.gnl.version = 2;
+
+       err = nlattr_add(&req, NETDEV_A_DEV_IFINDEX, &ifindex, sizeof(ifindex));
+       if (err < 0)
+               return err;
+
+       err = libbpf_netlink_send_recv(&req, NETLINK_GENERIC,
+                                      parse_xdp_features, NULL, &md);
+       if (err)
+               return libbpf_err(err);
+
+       opts->feature_flags = md.flags;
+
        return 0;
 }
 

diff --git a/tools/lib/bpf/nlattr.h b/tools/lib/bpf/nlattr.h
index 4d15ae2ff812cdcf19ff44586ae254ada03fca44..d92d1c1de700ee6d39f1960b7b0577f76b40ddd6 100644 (file)
--- a/tools/lib/bpf/nlattr.h
+++ b/tools/lib/bpf/nlattr.h
@@ -14,6 +14,7 @@
 #include <errno.h>
 #include <linux/netlink.h>
 #include <linux/rtnetlink.h>
+#include <linux/genetlink.h>
 
 /* avoid multiple definition of netlink features */
 #define __LINUX_NETLINK_H
@@ -58,6 +59,7 @@ struct libbpf_nla_req {
        union {
                struct ifinfomsg ifinfo;
                struct tcmsg tc;
+               struct genlmsghdr gnl;
        };
        char buf[128];
 };
@@ -89,11 +91,21 @@ static inline uint8_t libbpf_nla_getattr_u8(const struct nlattr *nla)
        return *(uint8_t *)libbpf_nla_data(nla);
 }
 
+static inline uint16_t libbpf_nla_getattr_u16(const struct nlattr *nla)
+{
+       return *(uint16_t *)libbpf_nla_data(nla);
+}
+
 static inline uint32_t libbpf_nla_getattr_u32(const struct nlattr *nla)
 {
        return *(uint32_t *)libbpf_nla_data(nla);
 }
 
+static inline uint64_t libbpf_nla_getattr_u64(const struct nlattr *nla)
+{
+       return *(uint64_t *)libbpf_nla_data(nla);
+}
+
 static inline const char *libbpf_nla_getattr_str(const struct nlattr *nla)
 {
        return (const char *)libbpf_nla_data(nla);