[PATCH net-next v5 06/22] ethtool: helper functions for netlink interface

Michal Kubecek
2019-03-25T17:08:18Z

Various helpers used by ethtool netlink code.

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
---
include/uapi/linux/ethtool_netlink.h | 11 ++
net/ethtool/netlink.c | 144 +++++++++++++++++++++++++++
net/ethtool/netlink.h | 144 +++++++++++++++++++++++++++
3 files changed, 299 insertions(+)

diff --git a/include/uapi/linux/ethtool_netlink.h b/include/uapi/linux/ethtool_netlink.h
index 6aa267451542..59240a2cda56 100644
--- a/include/uapi/linux/ethtool_netlink.h
+++ b/include/uapi/linux/ethtool_netlink.h
@@ -18,6 +18,17 @@ enum {
ETHNL_CMD_MAX = (__ETHNL_CMD_CNT - 1)
};

+/* device specification */
+
+enum {
+ ETHA_DEV_UNSPEC,
+ ETHA_DEV_INDEX, /* u32 */
+ ETHA_DEV_NAME, /* string */
+
+ __ETHA_DEV_CNT,
+ ETHA_DEV_MAX = (__ETHA_DEV_CNT - 1)
+};
+
/* generic netlink info */
#define ETHTOOL_GENL_NAME "ethtool"
#define ETHTOOL_GENL_VERSION 1
diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
index 85dd6dac71a2..cc6829ba4331 100644
--- a/net/ethtool/netlink.c
+++ b/net/ethtool/netlink.c
@@ -1,8 +1,152 @@
// SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note

+#include <net/sock.h>
#include <linux/ethtool_netlink.h>
#include "netlink.h"

+static const struct nla_policy dev_policy[ETHA_DEV_MAX + 1] = {
+ [ETHA_DEV_UNSPEC] = { .type = NLA_REJECT },
+ [ETHA_DEV_INDEX] = { .type = NLA_U32 },
+ [ETHA_DEV_NAME] = { .type = NLA_NUL_STRING,
+ .len = IFNAMSIZ - 1 },
+};
+
+/**
+ * ethnl_dev_get() - get device identified by nested attribute
+ * @info: genetlink info (also used for extack error reporting)
+ * @nest: nest attribute with device identification
+ *
+ * Finds the network device identified by ETHA_DEV_INDEX (ifindex) or
+ * ETHA_DEV_NAME (name) attributes in a nested attribute @nest. If both
+ * are supplied, they must identify the same device. If successful, takes
+ * a reference to the device which is to be released by caller.
+ *
+ * Return: pointer to the device if successful, ERR_PTR(err) on error
+ */
+struct net_device *ethnl_dev_get(struct genl_info *info, struct nlattr *nest)
+{
+ struct net *net = genl_info_net(info);
+ struct nlattr *tb[ETHA_DEV_MAX + 1];
+ struct net_device *dev;
+ int ret;
+
+ if (!nest) {
+ ETHNL_SET_ERRMSG(info,
+ "mandatory device identification missing");
+ return ERR_PTR(-EINVAL);
+ }
+ ret = nla_parse_nested_strict(tb, ETHA_DEV_MAX, nest, dev_policy,
+ info->extack);
+ if (ret < 0)
+ return ERR_PTR(ret);
+
+ if (tb[ETHA_DEV_INDEX]) {
+ dev = dev_get_by_index(net, nla_get_u32(tb[ETHA_DEV_INDEX]));
+ if (!dev)
+ return ERR_PTR(-ENODEV);
+ /* if both ifindex and ifname are passed, they must match */
+ if (tb[ETHA_DEV_NAME]) {
+ const char *nl_name = nla_data(tb[ETHA_DEV_NAME]);
+
+ if (strncmp(dev->name, nl_name, IFNAMSIZ)) {
+ dev_put(dev);
+ ETHNL_SET_ERRMSG(info,
+ "ifindex and ifname do not match");
+ return ERR_PTR(-ENODEV);
+ }
+ }
+ return dev;
+ } else if (tb[ETHA_DEV_NAME]) {
+ dev = dev_get_by_name(net, nla_data(tb[ETHA_DEV_NAME]));
+ if (!dev)
+ return ERR_PTR(-ENODEV);
+ } else {
+ ETHNL_SET_ERRMSG(info, "either ifindex or ifname required");
+ return ERR_PTR(-EINVAL);
+ }
+
+ if (!netif_device_present(dev)) {
+ dev_put(dev);
+ ETHNL_SET_ERRMSG(info, "device not present");
+ return ERR_PTR(-ENODEV);
+ }
+ return dev;
+}
+
+/**
+ * ethnl_fill_dev() - Put device identification nest into a message
+ * @msg: skb with the message
+ * @dev: network device to describe
+ * @attrtype: attribute type to use for the nest
+ *
+ * Create a nested attribute with attributes describing given network device.
+ * Clean up on error.
+ *
+ * Return: 0 on success, error value (-EMSGSIZE only) on error
+ */
+int ethnl_fill_dev(struct sk_buff *msg, struct net_device *dev, u16 attrtype)
+{
+ struct nlattr *nest;
+ int ret = -EMSGSIZE;
+
+ nest = ethnl_nest_start(msg, attrtype);
+ if (!nest)
+ return -EMSGSIZE;
+
+ if (nla_put_u32(msg, ETHA_DEV_INDEX, (u32)dev->ifindex))
+ goto err;
+ if (nla_put_string(msg, ETHA_DEV_NAME, dev->name))
+ goto err;
+
+ nla_nest_end(msg, nest);
+ return 0;
+err:
+ nla_nest_cancel(msg, nest);
+ return ret;
+}
+
+/**
+ * ethnl_reply_init() - Create skb for a reply and fill device identification
+ * @payload: payload length (without netlink and genetlink header)
+ * @dev: device the reply is about (may be null)
+ * @cmd: ETHNL_CMD_* command for reply
+ * @info: genetlink info of the received packet we respond to
+ * @ehdrp: place to store payload pointer returned by genlmsg_new()
+ *
+ * Return: pointer to allocated skb on success, NULL on error
+ */
+struct sk_buff *ethnl_reply_init(size_t payload, struct net_device *dev, u8 cmd,
+ u16 dev_attrtype, struct genl_info *info,
+ void **ehdrp)
+{
+ struct sk_buff *rskb;
+ void *ehdr;
+
+ rskb = genlmsg_new(payload, GFP_KERNEL);
+ if (!rskb) {
+ ETHNL_SET_ERRMSG(info,
+ "failed to allocate reply message");
+ return NULL;
+ }
+
+ ehdr = genlmsg_put_reply(rskb, info, &ethtool_genl_family, 0, cmd);
+ if (!ehdr)
+ goto err;
+ if (ehdrp)
+ *ehdrp = ehdr;
+ if (dev) {
+ int ret = ethnl_fill_dev(rskb, dev, dev_attrtype);
+
+ if (ret < 0)
+ goto err;
+ }
+
+ return rskb;
+err:
+ nlmsg_free(rskb);
+ return NULL;
+}
+
/* genetlink setup */

static const struct genl_ops ethtool_genl_ops[] = {
diff --git a/net/ethtool/netlink.h b/net/ethtool/netlink.h
index 63063b582ca2..db90d95410b1 100644
--- a/net/ethtool/netlink.h
+++ b/net/ethtool/netlink.h
@@ -6,7 +6,151 @@
#include <linux/ethtool_netlink.h>
#include <linux/netdevice.h>
#include <net/genetlink.h>
+#include <net/sock.h>
+
+#define ETHNL_SET_ERRMSG(info, msg) \
+ do { if (info) GENL_SET_ERR_MSG(info, msg); } while (0)

extern struct genl_family ethtool_genl_family;

+struct net_device *ethnl_dev_get(struct genl_info *info, struct nlattr *nest);
+int ethnl_fill_dev(struct sk_buff *msg, struct net_device *dev, u16 attrtype);
+
+struct sk_buff *ethnl_reply_init(size_t payload, struct net_device *dev, u8 cmd,
+ u16 dev_attrtype, struct genl_info *info,
+ void **ehdrp);
+
+static inline int ethnl_str_size(const char *s)
+{
+ return nla_total_size(strlen(s) + 1);
+}
+
+static inline int ethnl_str_ifne_size(const char *s)
+{
+ return s[0] ? ethnl_str_size(s) : 0;
+}
+
+static inline int ethnl_put_str_ifne(struct sk_buff *skb, int attrtype,
+ const char *s)
+{
+ if (!s[0])
+ return 0;
+ return nla_put_string(skb, attrtype, s);
+}
+
+static inline struct nlattr *ethnl_nest_start(struct sk_buff *skb,
+ int attrtype)
+{
+ return nla_nest_start(skb, attrtype | NLA_F_NESTED);
+}
+
+static inline int ethnlmsg_parse(const struct nlmsghdr *nlh,
+ struct nlattr *tb[], int maxtype,
+ const struct nla_policy *policy,
+ struct genl_info *info)
+{
+ return nlmsg_parse_strict(nlh, GENL_HDRLEN, tb, maxtype, policy,
+ info ? info->extack : NULL);
+}
+
+/* ethnl_update_* return true if the value is changed */
+static inline bool ethnl_update_u32(u32 *dst, struct nlattr *attr)
+{
+ u32 val;
+
+ if (!attr)
+ return false;
+ val = nla_get_u32(attr);
+ if (*dst == val)
+ return false;
+
+ *dst = val;
+ return true;
+}
+
+static inline bool ethnl_update_u8(u8 *dst, struct nlattr *attr)
+{
+ u8 val;
+
+ if (!attr)
+ return false;
+ val = nla_get_u8(attr);
+ if (*dst == val)
+ return false;
+
+ *dst = val;
+ return true;
+}
+
+/* update u32 value used as bool from NLA_U8 */
+static inline bool ethnl_update_bool32(u32 *dst, struct nlattr *attr)
+{
+ u8 val;
+
+ if (!attr)
+ return false;
+ val = !!nla_get_u8(attr);
+ if (!!*dst == val)
+ return false;
+
+ *dst = val;
+ return true;
+}
+
+static inline bool ethnl_update_binary(u8 *dst, unsigned int len,
+ struct nlattr *attr)
+{
+ if (!attr)
+ return false;
+ if (nla_len(attr) < len)
+ len = nla_len(attr);
+ if (!memcmp(dst, nla_data(attr), len))
+ return false;
+
+ memcpy(dst, nla_data(attr), len);
+ return true;
+}
+
+static inline bool ethnl_update_bitfield32(u32 *dst, struct nlattr *attr)
+{
+ struct nla_bitfield32 change;
+ u32 newval;
+
+ if (!attr)
+ return false;
+ change = nla_get_bitfield32(attr);
+ newval = (*dst & ~change.selector) | (change.value & change.selector);
+ if (*dst == newval)
+ return false;
+
+ *dst = newval;
+ return true;
+}
+
+static inline void warn_partial_info(struct genl_info *info)
+{
+ ETHNL_SET_ERRMSG(info, "not all requested data could be retrieved");
+}
+
+/* Check user privileges explicitly to allow finer access control based on
+ * context of the request or hiding part of the information from unprivileged
+ * users
+ */
+static inline bool ethnl_is_privileged(struct sk_buff *skb)
+{
+ struct net *net = sock_net(skb->sk);
+
+ return netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN);
+}
+
+/* total size of ETHA_*_DEV nested attribute; this is an upper estimate so that
+ * we do not need to hold RTNL longer than necessary to prevent rename between
+ * estimating the size and composing the message
+ */
+static inline unsigned int dev_ident_size(void)
+{
+ return nla_total_size(nla_total_size(sizeof(u32)) +
+ nla_total_size(IFNAMSIZ));
+}
+
#endif /* _NET_ETHTOOL_NETLINK_H */
--
2.21.0