diff options
Diffstat (limited to 'netlink/nlsock.c')
| -rw-r--r-- | netlink/nlsock.c | 405 |
1 files changed, 405 insertions, 0 deletions
diff --git a/netlink/nlsock.c b/netlink/nlsock.c new file mode 100644 index 0000000..0ec2738 --- /dev/null +++ b/netlink/nlsock.c @@ -0,0 +1,405 @@ +/* + * nlsock.c - netlink socket + * + * Data structure and code for netlink socket abstraction. + */ + +#include <stdint.h> +#include <errno.h> + +#include "../internal.h" +#include "nlsock.h" +#include "netlink.h" +#include "prettymsg.h" + +#define NLSOCK_RECV_BUFFSIZE 65536 + +static void ctrl_msg_summary(const struct nlmsghdr *nlhdr) +{ + const struct nlmsgerr *nlerr; + + switch (nlhdr->nlmsg_type) { + case NLMSG_NOOP: + printf(" noop\n"); + break; + case NLMSG_ERROR: + printf(" error"); + if (nlhdr->nlmsg_len < NLMSG_HDRLEN + sizeof(*nlerr)) { + printf(" malformed\n"); + break; + } + nlerr = mnl_nlmsg_get_payload(nlhdr); + printf(" errno=%d\n", nlerr->error); + break; + case NLMSG_DONE: + printf(" done\n"); + break; + case NLMSG_OVERRUN: + printf(" overrun\n"); + break; + default: + printf(" type %u\n", nlhdr->nlmsg_type); + break; + } +} + +static void genl_msg_summary(const struct nlmsghdr *nlhdr, int ethnl_fam, + bool outgoing, bool pretty) +{ + if (nlhdr->nlmsg_type == ethnl_fam) { + const struct pretty_nlmsg_desc *msg_desc; + const struct genlmsghdr *ghdr; + unsigned int n_desc; + + printf(" ethool"); + if (nlhdr->nlmsg_len < NLMSG_HDRLEN + GENL_HDRLEN) { + printf(" malformed\n"); + return; + } + ghdr = mnl_nlmsg_get_payload(nlhdr); + + msg_desc = outgoing ? ethnl_umsg_desc : ethnl_kmsg_desc; + n_desc = outgoing ? ethnl_umsg_n_desc : ethnl_kmsg_n_desc; + if (ghdr->cmd < n_desc && msg_desc[ghdr->cmd].name) + printf(" %s", msg_desc[ghdr->cmd].name); + else + printf(" cmd %u", ghdr->cmd); + fputc('\n', stdout); + + if (pretty) + pretty_print_genlmsg(nlhdr, msg_desc, n_desc, 0); + return; + } + + if (nlhdr->nlmsg_type == GENL_ID_CTRL) { + printf(" genl-ctrl\n"); + if (pretty) + pretty_print_genlmsg(nlhdr, genlctrl_msg_desc, + genlctrl_msg_n_desc, 0); + } else { + fputc('\n', stdout); + if (pretty) + pretty_print_genlmsg(nlhdr, NULL, 0, 0); + } +} + +static void rtnl_msg_summary(const struct nlmsghdr *nlhdr, bool pretty) +{ + unsigned int type = nlhdr->nlmsg_type; + + if (type < rtnl_msg_n_desc && rtnl_msg_desc[type].name) + printf(" %s\n", rtnl_msg_desc[type].name); + else + printf(" type %u\n", type); + + if (pretty) + pretty_print_rtnlmsg(nlhdr, 0); +} + +static void debug_msg_summary(const struct nlmsghdr *nlhdr, int ethnl_fam, + int nl_fam, bool outgoing, bool pretty) +{ + printf(" msg length %u", nlhdr->nlmsg_len); + + if (nlhdr->nlmsg_type < NLMSG_MIN_TYPE) { + ctrl_msg_summary(nlhdr); + return; + } + + switch(nl_fam) { + case NETLINK_GENERIC: + genl_msg_summary(nlhdr, ethnl_fam, outgoing, pretty); + break; + case NETLINK_ROUTE: + rtnl_msg_summary(nlhdr, pretty); + break; + default: + fputc('\n', stdout); + break; + } +} + +static void debug_msg(struct nl_socket *nlsk, const void *msg, unsigned int len, + bool outgoing) +{ + const char *dirlabel = outgoing ? "sending" : "received"; + uint32_t debug = nlsk->nlctx->ctx->debug; + const struct nlmsghdr *nlhdr = msg; + bool summary, dump, pretty; + const char *nl_fam_label; + int left = len; + + summary = debug_on(debug, DEBUG_NL_MSGS); + dump = debug_on(debug, + outgoing ? DEBUG_NL_DUMP_SND : DEBUG_NL_DUMP_RCV); + pretty = debug_on(debug, DEBUG_NL_PRETTY_MSG); + if (!summary && !dump) + return; + switch(nlsk->nl_fam) { + case NETLINK_GENERIC: + nl_fam_label = "genetlink"; + break; + case NETLINK_ROUTE: + nl_fam_label = "rtnetlink"; + break; + default: + nl_fam_label = "netlink"; + break; + } + printf("%s %s packet (%u bytes):\n", dirlabel, nl_fam_label, len); + + while (nlhdr && left > 0 && mnl_nlmsg_ok(nlhdr, left)) { + if (summary) + debug_msg_summary(nlhdr, nlsk->nlctx->ethnl_fam, + nlsk->nl_fam, outgoing, pretty); + if (dump) + mnl_nlmsg_fprintf(stdout, nlhdr, nlhdr->nlmsg_len, + GENL_HDRLEN); + + nlhdr = mnl_nlmsg_next(nlhdr, &left); + } +} + +/** + * nlsock_process_ack() - process NLMSG_ERROR message from kernel + * @nlhdr: pointer to netlink header + * @len: length of received data (from nlhdr to end of buffer) + * @suppress_nlerr: 0 show all errors, 1 silence -EOPNOTSUPP, 2 silence all + * + * Return: error code extracted from the message + */ +static int nlsock_process_ack(struct nlmsghdr *nlhdr, unsigned long len, + unsigned int suppress_nlerr, bool pretty) +{ + const struct nlattr *tb[NLMSGERR_ATTR_MAX + 1] = {}; + DECLARE_ATTR_TB_INFO(tb); + unsigned int err_offset = 0; + unsigned int tlv_offset; + struct nlmsgerr *nlerr; + bool silent; + + if ((len < NLMSG_HDRLEN + sizeof(*nlerr)) || (len < nlhdr->nlmsg_len)) + return -EFAULT; + nlerr = mnl_nlmsg_get_payload(nlhdr); + silent = suppress_nlerr >= 2 || + (suppress_nlerr && nlerr->error == -EOPNOTSUPP); + if (silent || !(nlhdr->nlmsg_flags & NLM_F_ACK_TLVS)) + goto tlv_done; + + tlv_offset = sizeof(*nlerr); + if (!(nlhdr->nlmsg_flags & NLM_F_CAPPED)) + tlv_offset += MNL_ALIGN(mnl_nlmsg_get_payload_len(&nlerr->msg)); + if (mnl_attr_parse(nlhdr, tlv_offset, attr_cb, &tb_info) < 0) + goto tlv_done; + + if (tb[NLMSGERR_ATTR_MSG]) { + const char *msg = mnl_attr_get_str(tb[NLMSGERR_ATTR_MSG]); + + fprintf(stderr, "netlink %s: %s", + nlerr->error ? "error" : "warning", msg); + if (!pretty && tb[NLMSGERR_ATTR_OFFS]) + fprintf(stderr, " (offset %u)", + mnl_attr_get_u32(tb[NLMSGERR_ATTR_OFFS])); + fputc('\n', stderr); + } + if (tb[NLMSGERR_ATTR_OFFS]) + err_offset = mnl_attr_get_u32(tb[NLMSGERR_ATTR_OFFS]); + +tlv_done: + if (nlerr->error && !silent) { + errno = -nlerr->error; + perror("netlink error"); + } + if (pretty && !(nlhdr->nlmsg_flags & NLM_F_CAPPED) && + nlhdr->nlmsg_len >= NLMSG_HDRLEN + nlerr->msg.nlmsg_len) { + fprintf(stderr, "offending message%s:\n", + err_offset ? " and attribute" : ""); + pretty_print_genlmsg(&nlerr->msg, ethnl_umsg_desc, + ethnl_umsg_n_desc, err_offset); + } + return nlerr->error; +} + +/** + * nlsock_process_reply() - process reply packet(s) from kernel + * @nlsk: netlink socket to read from + * @reply_cb: callback to process each message + * @data: pointer passed as argument to @reply_cb callback + * + * Read packets from kernel and pass reply messages to @reply_cb callback + * until an error is encountered or NLMSG_ERR message is received. In the + * latter case, return value is the error code extracted from it. + * + * Return: 0 on success or negative error code + */ +int nlsock_process_reply(struct nl_socket *nlsk, mnl_cb_t reply_cb, void *data) +{ + struct nl_msg_buff *msgbuff = &nlsk->msgbuff; + struct nlmsghdr *nlhdr; + ssize_t len; + char *buff; + int ret; + + ret = msgbuff_realloc(msgbuff, NLSOCK_RECV_BUFFSIZE); + if (ret < 0) + return ret; + buff = msgbuff->buff; + + do { + len = mnl_socket_recvfrom(nlsk->sk, buff, msgbuff->size); + if (len <= 0) + return (len ? -EFAULT : 0); + debug_msg(nlsk, buff, len, false); + if (len < NLMSG_HDRLEN) + return -EFAULT; + + nlhdr = (struct nlmsghdr *)buff; + if (nlhdr->nlmsg_type == NLMSG_ERROR) { + unsigned int suppress = nlsk->nlctx->suppress_nlerr; + bool pretty; + + pretty = debug_on(nlsk->nlctx->ctx->debug, + DEBUG_NL_PRETTY_MSG); + return nlsock_process_ack(nlhdr, len, suppress, pretty); + } + + msgbuff->nlhdr = nlhdr; + msgbuff->genlhdr = mnl_nlmsg_get_payload(nlhdr); + msgbuff->payload = + mnl_nlmsg_get_payload_offset(nlhdr, GENL_HDRLEN); + ret = mnl_cb_run(buff, len, nlsk->seq, nlsk->port, reply_cb, + data); + } while (ret > 0); + + return ret; +} + +int nlsock_prep_get_request(struct nl_socket *nlsk, unsigned int nlcmd, + uint16_t hdr_attrtype, u32 flags) +{ + unsigned int nlm_flags = NLM_F_REQUEST | NLM_F_ACK; + struct nl_context *nlctx = nlsk->nlctx; + const char *devname = nlctx->ctx->devname; + int ret; + + if (devname && !strcmp(devname, WILDCARD_DEVNAME)) { + devname = NULL; + nlm_flags |= NLM_F_DUMP; + } + nlctx->is_dump = !devname; + + ret = msg_init(nlctx, &nlsk->msgbuff, nlcmd, nlm_flags); + if (ret < 0) + return ret; + if (ethnla_fill_header(&nlsk->msgbuff, hdr_attrtype, devname, flags)) + return -EMSGSIZE; + + return 0; +} + +#ifndef TEST_ETHTOOL +/** + * nlsock_sendmsg() - send a netlink message to kernel + * @nlsk: netlink socket + * @altbuff: alternative message buffer; if null, use buffer embedded in @nlsk + * + * Return: sent size or negative error code + */ +ssize_t nlsock_sendmsg(struct nl_socket *nlsk, struct nl_msg_buff *altbuff) +{ + struct nl_msg_buff *msgbuff = altbuff ?: &nlsk->msgbuff; + struct nlmsghdr *nlhdr = msgbuff->nlhdr; + + nlhdr->nlmsg_seq = ++nlsk->seq; + debug_msg(nlsk, msgbuff->buff, nlhdr->nlmsg_len, true); + return mnl_socket_sendto(nlsk->sk, nlhdr, nlhdr->nlmsg_len); +} +#endif + +/** + * nlsock_send_get_request() - send request and process reply + * @nlsk: netlink socket + * @cb: callback to process reply message(s) + * + * This simple helper only handles the most common case when the embedded + * message buffer is sent and @cb takes netlink context (struct nl_context) + * as last argument. + */ +int nlsock_send_get_request(struct nl_socket *nlsk, mnl_cb_t cb) +{ + int ret; + + ret = nlsock_sendmsg(nlsk, NULL); + if (ret < 0) + goto err; + ret = nlsock_process_reply(nlsk, cb, nlsk->nlctx); + if (ret == 0) + return 0; +err: + return nlsk->nlctx->exit_code ?: 1; +} + +/** + * nlsock_init() - allocate and initialize netlink socket + * @nlctx: netlink context + * @__nlsk: store pointer to the allocated socket here + * @nl_fam: netlink family (e.g. NETLINK_GENERIC or NETLINK_ROUTE) + * + * Allocate and initialize netlink socket and its embedded message buffer. + * Cleans up on error, caller is responsible for destroying the socket with + * nlsock_done() on success. + * + * Return: 0 on success or negative error code + */ +int nlsock_init(struct nl_context *nlctx, struct nl_socket **__nlsk, int nl_fam) +{ + struct nl_socket *nlsk; + int val; + int ret; + + nlsk = calloc(1, sizeof(*nlsk)); + if (!nlsk) + return -ENOMEM; + nlsk->nlctx = nlctx; + msgbuff_init(&nlsk->msgbuff); + + ret = -ECONNREFUSED; + nlsk->sk = mnl_socket_open(nl_fam); + if (!nlsk->sk) + goto out_msgbuff; + val = 1; + mnl_socket_setsockopt(nlsk->sk, NETLINK_EXT_ACK, &val, sizeof(val)); + ret = mnl_socket_bind(nlsk->sk, 0, MNL_SOCKET_AUTOPID); + if (ret < 0) + goto out_close; + nlsk->port = mnl_socket_get_portid(nlsk->sk); + nlsk->nl_fam = nl_fam; + + *__nlsk = nlsk; + return 0; + +out_close: + if (nlsk->sk) + mnl_socket_close(nlsk->sk); +out_msgbuff: + msgbuff_done(&nlsk->msgbuff); + free(nlsk); + return ret; +} + +/** + * nlsock_done() - destroy a netlink socket + * @nlsk: netlink socket + * + * Close the socket and free the structure and related data. + */ +void nlsock_done(struct nl_socket *nlsk) +{ + if (!nlsk) + return; + if (nlsk->sk) + mnl_socket_close(nlsk->sk); + msgbuff_done(&nlsk->msgbuff); + memset(nlsk, '\0', sizeof(*nlsk)); + free(nlsk); +} |