[alfred] master: alfred: Translate mac addresses via netlink (7a31e43) - commits - lists.open-mesh.org

26 Jul 2016

Repository : ssh://git@open-mesh.org/alfred
On branch  : master
...

commit 7a31e43fd5447a16beb46f96ee4bcb850d3cc959
Author: Sven Eckelmann sven@narfation.org
Date:   Sun Jun 5 20:47:04 2016 +0200
alfred: Translate mac addresses via netlink
The debugfs entries are only available on the main network namespace. All
    other network namespaces have to fall back to netlink to read the global
    translation table.
alfred has therefore try to access the translation table via netlink and
    try to fall back to the debugfs table in case the batman-adv module doesn't
    support BATADV_CMD_GET_TRANSTABLE_GLOBAL.
Signed-off-by: Sven Eckelmann sven@narfation.org
    Signed-off-by: Simon Wunderlich sw@simonwunderlich.de
...

7a31e43fd5447a16beb46f96ee4bcb850d3cc959
 batadv_query.c |  49 +++++++++++++-
 netlink.c      | 198 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 netlink.h      |  23 +++++++
 3 files changed, 269 insertions(+), 1 deletion(-)

diff --git a/batadv_query.c b/batadv_query.c
index b0679fc..9082576 100644
--- a/batadv_query.c
+++ b/batadv_query.c
@@ -33,12 +33,53 @@
 #include <sys/capability.h>
 #endif
 #include <sys/types.h>
+
+#include "netlink.h"
 #include "debugfs.h"
#define DEBUG_BATIF_PATH_FMT "%s/batman_adv/%s"
 #define DEBUG_TRANSTABLE_GLOBAL "transtable_global"
 #define DEBUG_ORIGINATORS "originators"
+static int enable_net_admin_capability(int enable)
+{
+	int ret = 0;
+
+#ifdef CONFIG_ALFRED_CAPABILITIES
+	cap_t cap_cur;
+	cap_flag_value_t cap_flag;
+	cap_value_t cap_net_admin = CAP_NET_ADMIN;
+
+	if (enable)
+		cap_flag = CAP_SET;
+	else
+		cap_flag = CAP_CLEAR;
+
+	cap_cur = cap_get_proc();
+	if (!cap_cur) {
+		perror("cap_get_proc");
+		return -1;
+	}
+
+	ret = cap_set_flag(cap_cur, CAP_EFFECTIVE, 1, &cap_net_admin, cap_flag);
+	if (ret < 0) {
+		perror("cap_set_flag");
+		goto out;
+	}
+
+	ret = cap_set_proc(cap_cur);
+	if (ret < 0) {
+		perror("cap_set_proc");
+		goto out;
+	}
+
+out:
+	cap_free(cap_cur);
+#endif
+
+	return ret;
+}
+
 int mac_to_ipv6(const struct ether_addr *mac, struct in6_addr *addr)
 {
    memset(addr, 0, sizeof(*addr));
@@ -212,6 +253,7 @@ struct ether_addr *translate_mac(const char *mesh_iface,
    struct ether_addr in_mac;
    static struct ether_addr out_mac;
    struct ether_addr *mac_result;
+	int ret;
/* input mac has to be copied because it could be in the shared
     * ether_aton buffer
@@ -220,7 +262,12 @@ struct ether_addr *translate_mac(const char *mesh_iface,
    memcpy(&out_mac, mac, sizeof(out_mac));
    mac_result = &out_mac;
-	translate_mac_debugfs(mesh_iface, &in_mac, mac_result);
+	enable_net_admin_capability(1);
+	ret = translate_mac_netlink(mesh_iface, &in_mac, mac_result);
+	enable_net_admin_capability(0);
+
+	if (ret == -EOPNOTSUPP)
+		translate_mac_debugfs(mesh_iface, &in_mac, mac_result);
return mac_result;
 }
diff --git a/netlink.c b/netlink.c
index d9c1f55..e1ebc07 100644
--- a/netlink.c
+++ b/netlink.c
@@ -21,6 +21,14 @@
#include "netlink.h"
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <net/ethernet.h>
+#include <net/if.h>
 #include <netlink/netlink.h>
 #include <netlink/genl/genl.h>
 #include <netlink/genl/ctrl.h>
@@ -28,6 +36,10 @@
#include "batman_adv.h"
+#ifndef __unused
+#define __unused __attribute__((unused))
+#endif
+
 struct nla_policy batadv_netlink_policy[NUM_BATADV_ATTR] = {
    [BATADV_ATTR_VERSION]		= { .type = NLA_STRING },
    [BATADV_ATTR_ALGO_NAME]		= { .type = NLA_STRING },
@@ -82,3 +94,189 @@ struct nla_policy batadv_netlink_policy[NUM_BATADV_ATTR] = {
    				    .maxlen = ETH_ALEN },
    [BATADV_ATTR_BLA_CRC]		= { .type = NLA_U16 },
 };
+
+int missing_mandatory_attrs(struct nlattr *attrs[],  const int mandatory[],
+			    size_t num)
+{
+	size_t i;
+
+	for (i = 0; i < num; i++)
+		if (!attrs[mandatory[i]])
+			return -EINVAL;
+
+	return 0;
+}
+
+static int nlquery_error_cb(struct sockaddr_nl *nla __unused,
+			    struct nlmsgerr *nlerr, void *arg)
+{
+	struct nlquery_opts *query_opts = arg;
+
+	query_opts->err = nlerr->error;
+
+	return NL_STOP;
+}
+
+static int nlquery_stop_cb(struct nl_msg *msg, void *arg)
+{
+	struct nlmsghdr *nlh = nlmsg_hdr(msg);
+	struct nlquery_opts *query_opts = arg;
+	int *error = nlmsg_data(nlh);
+
+	if (*error)
+		query_opts->err = *error;
+
+	return NL_STOP;
+}
+
+int netlink_query_common(const char *mesh_iface, uint8_t nl_cmd,
+			 nl_recvmsg_msg_cb_t callback,
+			 struct nlquery_opts *query_opts)
+{
+	struct nl_sock *sock;
+	struct nl_msg *msg;
+	struct nl_cb *cb;
+	int ifindex;
+	int family;
+	int ret;
+
+	query_opts->err = 0;
+
+	sock = nl_socket_alloc();
+	if (!sock)
+		return -ENOMEM;
+
+	ret = genl_connect(sock);
+	if (ret < 0) {
+		query_opts->err = ret;
+		goto err_free_sock;
+	}
+
+	family = genl_ctrl_resolve(sock, BATADV_NL_NAME);
+	if (family < 0) {
+		query_opts->err = -EOPNOTSUPP;
+		goto err_free_sock;
+	}
+
+	ifindex = if_nametoindex(mesh_iface);
+	if (!ifindex) {
+		query_opts->err = -ENODEV;
+		goto err_free_sock;
+	}
+
+	cb = nl_cb_alloc(NL_CB_DEFAULT);
+	if (!cb) {
+		query_opts->err = -ENOMEM;
+		goto err_free_sock;
+	}
+
+	nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, callback, query_opts);
+	nl_cb_set(cb, NL_CB_FINISH, NL_CB_CUSTOM, nlquery_stop_cb, query_opts);
+	nl_cb_err(cb, NL_CB_CUSTOM, nlquery_error_cb, query_opts);
+
+	msg = nlmsg_alloc();
+	if (!msg) {
+		query_opts->err = -ENOMEM;
+		goto err_free_cb;
+	}
+
+	genlmsg_put(msg, NL_AUTO_PID, NL_AUTO_SEQ, family, 0, NLM_F_DUMP,
+		    nl_cmd, 1);
+
+	nla_put_u32(msg, BATADV_ATTR_MESH_IFINDEX, ifindex);
+	nl_send_auto_complete(sock, msg);
+	nlmsg_free(msg);
+
+	nl_recvmsgs(sock, cb);
+
+err_free_cb:
+	nl_cb_put(cb);
+err_free_sock:
+	nl_socket_free(sock);
+
+	return query_opts->err;
+}
+
+static const int translate_mac_netlink_mandatory[] = {
+	BATADV_ATTR_TT_ADDRESS,
+	BATADV_ATTR_ORIG_ADDRESS,
+};
+
+struct translate_mac_netlink_opts {
+	struct ether_addr mac;
+	bool found;
+	struct nlquery_opts query_opts;
+};
+
+static int translate_mac_netlink_cb(struct nl_msg *msg, void *arg)
+{
+	struct nlattr *attrs[BATADV_ATTR_MAX+1];
+	struct nlmsghdr *nlh = nlmsg_hdr(msg);
+	struct nlquery_opts *query_opts = arg;
+	struct translate_mac_netlink_opts *opts;
+	struct genlmsghdr *ghdr;
+	uint8_t *addr;
+	uint8_t *orig;
+
+	opts = container_of(query_opts, struct translate_mac_netlink_opts,
+			    query_opts);
+
+	if (!genlmsg_valid_hdr(nlh, 0))
+		return NL_OK;
+
+	ghdr = nlmsg_data(nlh);
+
+	if (ghdr->cmd != BATADV_CMD_GET_TRANSTABLE_GLOBAL)
+		return NL_OK;
+
+	if (nla_parse(attrs, BATADV_ATTR_MAX, genlmsg_attrdata(ghdr, 0),
+		      genlmsg_len(ghdr), batadv_netlink_policy)) {
+		return NL_OK;
+	}
+
+	if (missing_mandatory_attrs(attrs, translate_mac_netlink_mandatory,
+				    ARRAY_SIZE(translate_mac_netlink_mandatory)))
+		return NL_OK;
+
+	addr = nla_data(attrs[BATADV_ATTR_TT_ADDRESS]);
+	orig = nla_data(attrs[BATADV_ATTR_ORIG_ADDRESS]);
+
+	if (!attrs[BATADV_ATTR_FLAG_BEST])
+		return NL_OK;
+
+	if (memcmp(&opts->mac, addr, ETH_ALEN) != 0)
+		return NL_OK;
+
+	memcpy(&opts->mac, orig, ETH_ALEN);
+	opts->found = true;
+	opts->query_opts.err = 0;
+
+	return NL_STOP;
+}
+
+int translate_mac_netlink(const char *mesh_iface, const struct ether_addr *mac,
+			  struct ether_addr *mac_out)
+{
+	struct translate_mac_netlink_opts opts = {
+		.found = false,
+		.query_opts = {
+			.err = 0,
+		},
+	};
+	int ret;
+
+	memcpy(&opts.mac, mac, ETH_ALEN);
+
+	ret = netlink_query_common(mesh_iface,
+				   BATADV_CMD_GET_TRANSTABLE_GLOBAL,
+			           translate_mac_netlink_cb, &opts.query_opts);
+	if (ret < 0)
+		return ret;
+
+	if (!opts.found)
+		return -ENOENT;
+
+	memcpy(mac_out, &opts.mac, ETH_ALEN);
+
+	return 0;
+}
diff --git a/netlink.h b/netlink.h
index f903563..8e54235 100644
--- a/netlink.h
+++ b/netlink.h
@@ -24,6 +24,29 @@
#include <netlink/genl/genl.h>
 #include <netlink/genl/ctrl.h>
+#include <stddef.h>
+
+struct ether_addr;
+
+struct nlquery_opts {
+	int err;
+};
+
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
+
+#ifndef container_of
+#define container_of(ptr, type, member) __extension__ ({ \
+	const __typeof__(((type *)0)->member) *__pmember = (ptr); \
+	(type *)((char *)__pmember - offsetof(type, member)); })
+#endif
+
+int netlink_query_common(const char *mesh_iface, uint8_t nl_cmd,
+			 nl_recvmsg_msg_cb_t callback,
+			 struct nlquery_opts *query_opts);
+int missing_mandatory_attrs(struct nlattr *attrs[],  const int mandatory[],
+			    size_t num);
+int translate_mac_netlink(const char *mesh_iface, const struct ether_addr *mac,
+			  struct ether_addr *mac_out);
extern struct nla_policy batadv_netlink_policy[];

    