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Date: Sun, 16 Feb 2020 23:47:05 +0100 (CET)
From: Michal Kubecek <mkubecek@...e.cz>
To: John Linville <linville@...driver.com>, netdev@...r.kernel.org
Cc: Andrew Lunn <andrew@...n.ch>,
Florian Fainelli <f.fainelli@...il.com>
Subject: [PATCH ethtool 07/19] netlink: message buffer and composition helpers
Add data structure for flexible message buffer and helpers for safe message
composition.
The nl_msg_buff structure is an abstraction for a message buffer used to
compose an outgoing netlink message. When the message exceeds currently
allocated length, buffer is reallocated. Only if the buffer size reaches
MAX_MSG_SIZE (4 MB), an error is issued.
Signed-off-by: Michal Kubecek <mkubecek@...e.cz>
---
Makefile.am | 1 +
netlink/msgbuff.c | 169 ++++++++++++++++++++++++++++++++++++++++++++++
netlink/msgbuff.h | 106 +++++++++++++++++++++++++++++
netlink/netlink.h | 1 +
4 files changed, 277 insertions(+)
create mode 100644 netlink/msgbuff.c
create mode 100644 netlink/msgbuff.h
diff --git a/Makefile.am b/Makefile.am
index 3748d0df5608..12412b433445 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -27,6 +27,7 @@ endif
if ETHTOOL_ENABLE_NETLINK
ethtool_SOURCES += \
netlink/netlink.c netlink/netlink.h netlink/extapi.h \
+ netlink/msgbuff.c netlink/msgbuff.h \
uapi/linux/ethtool_netlink.h \
uapi/linux/netlink.h uapi/linux/genetlink.h
ethtool_CFLAGS += @MNL_CFLAGS@
diff --git a/netlink/msgbuff.c b/netlink/msgbuff.c
new file mode 100644
index 000000000000..1e73354d194b
--- /dev/null
+++ b/netlink/msgbuff.c
@@ -0,0 +1,169 @@
+/*
+ * msgbuff.c - netlink message buffer
+ *
+ * Data structures and code for flexible message buffer abstraction.
+ */
+
+#include <string.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+#include "../internal.h"
+#include "netlink.h"
+#include "msgbuff.h"
+
+#define MAX_MSG_SIZE (4 << 20) /* 4 MB */
+
+int msgbuff_realloc(struct nl_msg_buff *msgbuff, unsigned int new_size)
+{
+ unsigned int nlhdr_off, genlhdr_off, payload_off;
+ unsigned int old_size = msgbuff->size;
+ char *nbuff;
+
+ nlhdr_off = (char *)msgbuff->nlhdr - msgbuff->buff;
+ genlhdr_off = (char *)msgbuff->genlhdr - msgbuff->buff;
+ payload_off = (char *)msgbuff->payload - msgbuff->buff;
+
+ if (!new_size)
+ new_size = old_size + MNL_SOCKET_BUFFER_SIZE;
+ if (new_size <= old_size)
+ return 0;
+ if (new_size > MAX_MSG_SIZE)
+ return -EMSGSIZE;
+ nbuff = realloc(msgbuff->buff, new_size);
+ if (!nbuff) {
+ msgbuff->buff = NULL;
+ msgbuff->size = 0;
+ msgbuff->left = 0;
+ return -ENOMEM;
+ }
+ if (nbuff != msgbuff->buff) {
+ if (new_size > old_size)
+ memset(nbuff + old_size, '\0', new_size - old_size);
+ msgbuff->nlhdr = (struct nlmsghdr *)(nbuff + nlhdr_off);
+ msgbuff->genlhdr = (struct genlmsghdr *)(nbuff + genlhdr_off);
+ msgbuff->payload = nbuff + payload_off;
+ msgbuff->buff = nbuff;
+ }
+ msgbuff->size = new_size;
+ msgbuff->left += (new_size - old_size);
+
+ return 0;
+}
+
+int msgbuff_append(struct nl_msg_buff *dest, struct nl_msg_buff *src)
+{
+ unsigned int src_len = mnl_nlmsg_get_payload_len(src->nlhdr);
+ unsigned int dest_len = MNL_ALIGN(msgbuff_len(dest));
+ int ret;
+
+ ret = msgbuff_realloc(dest, dest_len + src_len);
+ if (ret < 0)
+ return ret;
+ memcpy(mnl_nlmsg_get_payload_tail(dest->nlhdr), src->payload, src_len);
+ msgbuff_reset(dest, dest_len + src_len);
+
+ return 0;
+}
+
+bool ethnla_put(struct nl_msg_buff *msgbuff, uint16_t type, size_t len,
+ const void *data)
+{
+ struct nlmsghdr *nlhdr = msgbuff->nlhdr;
+
+ while (!mnl_attr_put_check(nlhdr, msgbuff->left, type, len, data)) {
+ int ret = msgbuff_realloc(msgbuff, 0);
+
+ if (ret < 0)
+ return true;
+ }
+
+ return false;
+}
+
+struct nlattr *ethnla_nest_start(struct nl_msg_buff *msgbuff, uint16_t type)
+{
+ struct nlmsghdr *nlhdr = msgbuff->nlhdr;
+ struct nlattr *attr;
+
+ do {
+ attr = mnl_attr_nest_start_check(nlhdr, msgbuff->left, type);
+ if (attr)
+ return attr;
+ } while (msgbuff_realloc(msgbuff, 0) == 0);
+
+ return NULL;
+}
+
+bool ethnla_fill_header(struct nl_msg_buff *msgbuff, uint16_t type,
+ const char *devname, uint32_t flags)
+{
+ struct nlattr *nest;
+
+ nest = ethnla_nest_start(msgbuff, type);
+ if (!nest)
+ return true;
+
+ if ((devname &&
+ ethnla_put_strz(msgbuff, ETHTOOL_A_HEADER_DEV_NAME, devname)) ||
+ (flags &&
+ ethnla_put_u32(msgbuff, ETHTOOL_A_HEADER_FLAGS, flags)))
+ goto err;
+
+ ethnla_nest_end(msgbuff, nest);
+ return false;
+
+err:
+ ethnla_nest_cancel(msgbuff, nest);
+ return true;
+}
+
+/* initialize a genetlink message and fill netlink and genetlink header */
+int __msg_init(struct nl_msg_buff *msgbuff, int family, int cmd,
+ unsigned int flags, int version)
+{
+ struct nlmsghdr *nlhdr;
+ struct genlmsghdr *genlhdr;
+ int ret;
+
+ ret = msgbuff_realloc(msgbuff, MNL_SOCKET_BUFFER_SIZE);
+ if (ret < 0)
+ return ret;
+ memset(msgbuff->buff, '\0', NLMSG_HDRLEN + GENL_HDRLEN);
+
+ nlhdr = mnl_nlmsg_put_header(msgbuff->buff);
+ nlhdr->nlmsg_type = family;
+ nlhdr->nlmsg_flags = flags;
+ msgbuff->nlhdr = nlhdr;
+
+ genlhdr = mnl_nlmsg_put_extra_header(nlhdr, sizeof(*genlhdr));
+ genlhdr->cmd = cmd;
+ genlhdr->version = version;
+ msgbuff->genlhdr = genlhdr;
+
+ msgbuff->payload = mnl_nlmsg_get_payload_offset(nlhdr, GENL_HDRLEN);
+
+ return 0;
+}
+
+/* simplified wrapper to initialize an ethtool netlink message */
+int msg_init(struct nl_context *nlctx, struct nl_msg_buff *msgbuff, int cmd,
+ unsigned int flags)
+{
+ return __msg_init(msgbuff, nlctx->ethnl_fam, cmd, flags,
+ ETHTOOL_GENL_VERSION);
+}
+
+void msgbuff_init(struct nl_msg_buff *msgbuff)
+{
+ memset(msgbuff, '\0', sizeof(*msgbuff));
+}
+
+void msgbuff_done(struct nl_msg_buff *msgbuff)
+{
+ free(msgbuff->buff);
+ msgbuff->buff = NULL;
+ msgbuff->size = 0;
+ msgbuff->left = 0;
+}
diff --git a/netlink/msgbuff.h b/netlink/msgbuff.h
new file mode 100644
index 000000000000..6f3baa9992fd
--- /dev/null
+++ b/netlink/msgbuff.h
@@ -0,0 +1,106 @@
+/*
+ * msgbuff.h - netlink message buffer
+ *
+ * Declarations of netlink message buffer and related functions.
+ */
+
+#ifndef ETHTOOL_NETLINK_MSGBUFF_H__
+#define ETHTOOL_NETLINK_MSGBUFF_H__
+
+#include <string.h>
+#include <libmnl/libmnl.h>
+#include <linux/netlink.h>
+#include <linux/genetlink.h>
+
+struct nl_context;
+
+struct nl_msg_buff {
+ char *buff;
+ unsigned int size;
+ unsigned int left;
+ struct nlmsghdr *nlhdr;
+ struct genlmsghdr *genlhdr;
+ void *payload;
+};
+
+void msgbuff_init(struct nl_msg_buff *msgbuff);
+void msgbuff_done(struct nl_msg_buff *msgbuff);
+int msgbuff_realloc(struct nl_msg_buff *msgbuff, unsigned int new_size);
+int msgbuff_append(struct nl_msg_buff *dest, struct nl_msg_buff *src);
+
+int __msg_init(struct nl_msg_buff *msgbuff, int family, int cmd,
+ unsigned int flags, int version);
+int msg_init(struct nl_context *nlctx, struct nl_msg_buff *msgbuff, int cmd,
+ unsigned int flags);
+
+bool ethnla_put(struct nl_msg_buff *msgbuff, uint16_t type, size_t len,
+ const void *data);
+struct nlattr *ethnla_nest_start(struct nl_msg_buff *msgbuff, uint16_t type);
+bool ethnla_fill_header(struct nl_msg_buff *msgbuff, uint16_t type,
+ const char *devname, uint32_t flags);
+
+static inline unsigned int msgbuff_len(const struct nl_msg_buff *msgbuff)
+{
+ return msgbuff->nlhdr->nlmsg_len;
+}
+
+static inline void msgbuff_reset(const struct nl_msg_buff *msgbuff,
+ unsigned int len)
+{
+ msgbuff->nlhdr->nlmsg_len = len;
+}
+
+/* put data wrappers */
+
+static inline void ethnla_nest_end(struct nl_msg_buff *msgbuff,
+ struct nlattr *nest)
+{
+ return mnl_attr_nest_end(msgbuff->nlhdr, nest);
+}
+
+static inline void ethnla_nest_cancel(struct nl_msg_buff *msgbuff,
+ struct nlattr *nest)
+{
+ return mnl_attr_nest_cancel(msgbuff->nlhdr, nest);
+}
+
+static inline bool ethnla_put_u32(struct nl_msg_buff *msgbuff, uint16_t type,
+ uint32_t data)
+{
+ return ethnla_put(msgbuff, type, sizeof(uint32_t), &data);
+}
+
+static inline bool ethnla_put_u8(struct nl_msg_buff *msgbuff, uint16_t type,
+ uint8_t data)
+{
+ return ethnla_put(msgbuff, type, sizeof(uint8_t), &data);
+}
+
+static inline bool ethnla_put_flag(struct nl_msg_buff *msgbuff, uint16_t type,
+ bool val)
+{
+ if (val)
+ return ethnla_put(msgbuff, type, 0, &val);
+ else
+ return false;
+}
+
+static inline bool ethnla_put_bitfield32(struct nl_msg_buff *msgbuff,
+ uint16_t type, uint32_t value,
+ uint32_t selector)
+{
+ struct nla_bitfield32 val = {
+ .value = value,
+ .selector = selector,
+ };
+
+ return ethnla_put(msgbuff, type, sizeof(val), &val);
+}
+
+static inline bool ethnla_put_strz(struct nl_msg_buff *msgbuff, uint16_t type,
+ const char *data)
+{
+ return ethnla_put(msgbuff, type, strlen(data) + 1, data);
+}
+
+#endif /* ETHTOOL_NETLINK_MSGBUFF_H__ */
diff --git a/netlink/netlink.h b/netlink/netlink.h
index 610beccbefda..48c4ebb3d7aa 100644
--- a/netlink/netlink.h
+++ b/netlink/netlink.h
@@ -21,6 +21,7 @@ struct nl_context {
bool is_dump;
int exit_code;
bool suppress_nlerr;
+ uint16_t ethnl_fam;
};
#endif /* ETHTOOL_NETLINK_INT_H__ */
--
2.25.0
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