diff options
Diffstat (limited to 'lib/netlink.c')
| -rw-r--r-- | lib/netlink.c | 1077 |
1 files changed, 1077 insertions, 0 deletions
diff --git a/lib/netlink.c b/lib/netlink.c new file mode 100644 index 000000000..bc1956a66 --- /dev/null +++ b/lib/netlink.c @@ -0,0 +1,1077 @@ +/* + * Copyright (c) 2008, 2009 Nicira Networks. + * + * Permission to use, copy, modify, and/or distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +#include <config.h> +#include "netlink.h" +#include <assert.h> +#include <errno.h> +#include <inttypes.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <time.h> +#include <unistd.h> +#include "coverage.h" +#include "dynamic-string.h" +#include "netlink-protocol.h" +#include "ofpbuf.h" +#include "poll-loop.h" +#include "timeval.h" +#include "util.h" + +#include "vlog.h" +#define THIS_MODULE VLM_netlink + +/* Linux header file confusion causes this to be undefined. */ +#ifndef SOL_NETLINK +#define SOL_NETLINK 270 +#endif + +/* A single (bad) Netlink message can in theory dump out many, many log + * messages, so the burst size is set quite high here to avoid missing useful + * information. Also, at high logging levels we log *all* Netlink messages. */ +static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(60, 600); + +static void log_nlmsg(const char *function, int error, + const void *message, size_t size); + +/* Netlink sockets. */ + +struct nl_sock +{ + int fd; + uint32_t pid; +}; + +/* Next nlmsghdr sequence number. + * + * This implementation uses sequence numbers that are unique process-wide, to + * avoid a hypothetical race: send request, close socket, open new socket that + * reuses the old socket's PID value, send request on new socket, receive reply + * from kernel to old socket but with same PID and sequence number. (This race + * could be avoided other ways, e.g. by preventing PIDs from being quickly + * reused). */ +static uint32_t next_seq; + +static int alloc_pid(uint32_t *); +static void free_pid(uint32_t); + +/* Creates a new netlink socket for the given netlink 'protocol' + * (NETLINK_ROUTE, NETLINK_GENERIC, ...). Returns 0 and sets '*sockp' to the + * new socket if successful, otherwise returns a positive errno value. + * + * If 'multicast_group' is nonzero, the new socket subscribes to the specified + * netlink multicast group. (A netlink socket may listen to an arbitrary + * number of multicast groups, but so far we only need one at a time.) + * + * Nonzero 'so_sndbuf' or 'so_rcvbuf' override the kernel default send or + * receive buffer size, respectively. + */ +int +nl_sock_create(int protocol, int multicast_group, + size_t so_sndbuf, size_t so_rcvbuf, struct nl_sock **sockp) +{ + struct nl_sock *sock; + struct sockaddr_nl local, remote; + int retval = 0; + + if (next_seq == 0) { + /* Pick initial sequence number. */ + next_seq = getpid() ^ time_now(); + } + + *sockp = NULL; + sock = malloc(sizeof *sock); + if (sock == NULL) { + return ENOMEM; + } + + sock->fd = socket(AF_NETLINK, SOCK_RAW, protocol); + if (sock->fd < 0) { + VLOG_ERR("fcntl: %s", strerror(errno)); + goto error; + } + + retval = alloc_pid(&sock->pid); + if (retval) { + goto error; + } + + if (so_sndbuf != 0 + && setsockopt(sock->fd, SOL_SOCKET, SO_SNDBUF, + &so_sndbuf, sizeof so_sndbuf) < 0) { + VLOG_ERR("setsockopt(SO_SNDBUF,%zu): %s", so_sndbuf, strerror(errno)); + goto error_free_pid; + } + + if (so_rcvbuf != 0 + && setsockopt(sock->fd, SOL_SOCKET, SO_RCVBUF, + &so_rcvbuf, sizeof so_rcvbuf) < 0) { + VLOG_ERR("setsockopt(SO_RCVBUF,%zu): %s", so_rcvbuf, strerror(errno)); + goto error_free_pid; + } + + /* Bind local address as our selected pid. */ + memset(&local, 0, sizeof local); + local.nl_family = AF_NETLINK; + local.nl_pid = sock->pid; + if (multicast_group > 0 && multicast_group <= 32) { + /* This method of joining multicast groups is supported by old kernels, + * but it only allows 32 multicast groups per protocol. */ + local.nl_groups |= 1ul << (multicast_group - 1); + } + if (bind(sock->fd, (struct sockaddr *) &local, sizeof local) < 0) { + VLOG_ERR("bind(%"PRIu32"): %s", sock->pid, strerror(errno)); + goto error_free_pid; + } + + /* Bind remote address as the kernel (pid 0). */ + memset(&remote, 0, sizeof remote); + remote.nl_family = AF_NETLINK; + remote.nl_pid = 0; + if (connect(sock->fd, (struct sockaddr *) &remote, sizeof remote) < 0) { + VLOG_ERR("connect(0): %s", strerror(errno)); + goto error_free_pid; + } + + /* Older kernel headers failed to define this macro. We want our programs + * to support the newer kernel features even if compiled with older + * headers, so define it ourselves in such a case. */ +#ifndef NETLINK_ADD_MEMBERSHIP +#define NETLINK_ADD_MEMBERSHIP 1 +#endif + + /* This method of joining multicast groups is only supported by newish + * kernels, but it allows for an arbitrary number of multicast groups. */ + if (multicast_group > 32 + && setsockopt(sock->fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, + &multicast_group, sizeof multicast_group) < 0) { + VLOG_ERR("setsockopt(NETLINK_ADD_MEMBERSHIP,%d): %s", + multicast_group, strerror(errno)); + goto error_free_pid; + } + + *sockp = sock; + return 0; + +error_free_pid: + free_pid(sock->pid); +error: + if (retval == 0) { + retval = errno; + if (retval == 0) { + retval = EINVAL; + } + } + if (sock->fd >= 0) { + close(sock->fd); + } + free(sock); + return retval; +} + +/* Destroys netlink socket 'sock'. */ +void +nl_sock_destroy(struct nl_sock *sock) +{ + if (sock) { + close(sock->fd); + free_pid(sock->pid); + free(sock); + } +} + +/* Tries to send 'msg', which must contain a Netlink message, to the kernel on + * 'sock'. nlmsg_len in 'msg' will be finalized to match msg->size before the + * message is sent. + * + * Returns 0 if successful, otherwise a positive errno value. If + * 'wait' is true, then the send will wait until buffer space is ready; + * otherwise, returns EAGAIN if the 'sock' send buffer is full. */ +int +nl_sock_send(struct nl_sock *sock, const struct ofpbuf *msg, bool wait) +{ + int error; + + nl_msg_nlmsghdr(msg)->nlmsg_len = msg->size; + do { + int retval; + retval = send(sock->fd, msg->data, msg->size, wait ? 0 : MSG_DONTWAIT); + error = retval < 0 ? errno : 0; + } while (error == EINTR); + log_nlmsg(__func__, error, msg->data, msg->size); + if (!error) { + COVERAGE_INC(netlink_sent); + } + return error; +} + +/* Tries to send the 'n_iov' chunks of data in 'iov' to the kernel on 'sock' as + * a single Netlink message. (The message must be fully formed and not require + * finalization of its nlmsg_len field.) + * + * Returns 0 if successful, otherwise a positive errno value. If 'wait' is + * true, then the send will wait until buffer space is ready; otherwise, + * returns EAGAIN if the 'sock' send buffer is full. */ +int +nl_sock_sendv(struct nl_sock *sock, const struct iovec iov[], size_t n_iov, + bool wait) +{ + struct msghdr msg; + int error; + + COVERAGE_INC(netlink_send); + memset(&msg, 0, sizeof msg); + msg.msg_iov = (struct iovec *) iov; + msg.msg_iovlen = n_iov; + do { + int retval; + retval = sendmsg(sock->fd, &msg, wait ? 0 : MSG_DONTWAIT); + error = retval < 0 ? errno : 0; + } while (error == EINTR); + if (error != EAGAIN) { + log_nlmsg(__func__, error, iov[0].iov_base, iov[0].iov_len); + if (!error) { + COVERAGE_INC(netlink_sent); + } + } + return error; +} + +/* Tries to receive a netlink message from the kernel on 'sock'. If + * successful, stores the received message into '*bufp' and returns 0. The + * caller is responsible for destroying the message with ofpbuf_delete(). On + * failure, returns a positive errno value and stores a null pointer into + * '*bufp'. + * + * If 'wait' is true, nl_sock_recv waits for a message to be ready; otherwise, + * returns EAGAIN if the 'sock' receive buffer is empty. */ +int +nl_sock_recv(struct nl_sock *sock, struct ofpbuf **bufp, bool wait) +{ + uint8_t tmp; + ssize_t bufsize = 2048; + ssize_t nbytes, nbytes2; + struct ofpbuf *buf; + struct nlmsghdr *nlmsghdr; + struct iovec iov; + struct msghdr msg = { + .msg_name = NULL, + .msg_namelen = 0, + .msg_iov = &iov, + .msg_iovlen = 1, + .msg_control = NULL, + .msg_controllen = 0, + .msg_flags = 0 + }; + + buf = ofpbuf_new(bufsize); + *bufp = NULL; + +try_again: + /* Attempt to read the message. We don't know the size of the data + * yet, so we take a guess at 2048. If we're wrong, we keep trying + * and doubling the buffer size each time. + */ + nlmsghdr = ofpbuf_put_uninit(buf, bufsize); + iov.iov_base = nlmsghdr; + iov.iov_len = bufsize; + do { + nbytes = recvmsg(sock->fd, &msg, (wait ? 0 : MSG_DONTWAIT) | MSG_PEEK); + } while (nbytes < 0 && errno == EINTR); + if (nbytes < 0) { + ofpbuf_delete(buf); + return errno; + } + if (msg.msg_flags & MSG_TRUNC) { + COVERAGE_INC(netlink_recv_retry); + bufsize *= 2; + ofpbuf_reinit(buf, bufsize); + goto try_again; + } + buf->size = nbytes; + + /* We successfully read the message, so recv again to clear the queue */ + iov.iov_base = &tmp; + iov.iov_len = 1; + do { + nbytes2 = recvmsg(sock->fd, &msg, MSG_DONTWAIT); + } while (nbytes2 < 0 && errno == EINTR); + if (nbytes2 < 0) { + if (errno == ENOBUFS) { + /* The kernel is notifying us that a message it tried to send to us + * was dropped. We have to pass this along to the caller in case + * it wants to retry a request. So kill the buffer, which we can + * re-read next time. */ + COVERAGE_INC(netlink_overflow); + ofpbuf_delete(buf); + return ENOBUFS; + } else { + VLOG_ERR_RL(&rl, "failed to remove nlmsg from socket: %s\n", + strerror(errno)); + } + } + if (nbytes < sizeof *nlmsghdr + || nlmsghdr->nlmsg_len < sizeof *nlmsghdr + || nlmsghdr->nlmsg_len > nbytes) { + VLOG_ERR_RL(&rl, "received invalid nlmsg (%zd bytes < %d)", + bufsize, NLMSG_HDRLEN); + ofpbuf_delete(buf); + return EPROTO; + } + *bufp = buf; + log_nlmsg(__func__, 0, buf->data, buf->size); + COVERAGE_INC(netlink_received); + return 0; +} + +/* Sends 'request' to the kernel via 'sock' and waits for a response. If + * successful, stores the reply into '*replyp' and returns 0. The caller is + * responsible for destroying the reply with ofpbuf_delete(). On failure, + * returns a positive errno value and stores a null pointer into '*replyp'. + * + * The caller is responsible for destroying 'request'. + * + * Bare Netlink is an unreliable transport protocol. This function layers + * reliable delivery and reply semantics on top of bare Netlink. + * + * In Netlink, sending a request to the kernel is reliable enough, because the + * kernel will tell us if the message cannot be queued (and we will in that + * case put it on the transmit queue and wait until it can be delivered). + * + * Receiving the reply is the real problem: if the socket buffer is full when + * the kernel tries to send the reply, the reply will be dropped. However, the + * kernel sets a flag that a reply has been dropped. The next call to recv + * then returns ENOBUFS. We can then re-send the request. + * + * Caveats: + * + * 1. Netlink depends on sequence numbers to match up requests and + * replies. The sender of a request supplies a sequence number, and + * the reply echos back that sequence number. + * + * This is fine, but (1) some kernel netlink implementations are + * broken, in that they fail to echo sequence numbers and (2) this + * function will drop packets with non-matching sequence numbers, so + * that only a single request can be usefully transacted at a time. + * + * 2. Resending the request causes it to be re-executed, so the request + * needs to be idempotent. + */ +int +nl_sock_transact(struct nl_sock *sock, + const struct ofpbuf *request, struct ofpbuf **replyp) +{ + uint32_t seq = nl_msg_nlmsghdr(request)->nlmsg_seq; + struct nlmsghdr *nlmsghdr; + struct ofpbuf *reply; + int retval; + + *replyp = NULL; + + /* Ensure that we get a reply even if this message doesn't ordinarily call + * for one. */ + nl_msg_nlmsghdr(request)->nlmsg_flags |= NLM_F_ACK; + +send: + retval = nl_sock_send(sock, request, true); + if (retval) { + return retval; + } + +recv: + retval = nl_sock_recv(sock, &reply, true); + if (retval) { + if (retval == ENOBUFS) { + COVERAGE_INC(netlink_overflow); + VLOG_DBG_RL(&rl, "receive buffer overflow, resending request"); + goto send; + } else { + return retval; + } + } + nlmsghdr = nl_msg_nlmsghdr(reply); + if (seq != nlmsghdr->nlmsg_seq) { + VLOG_DBG_RL(&rl, "ignoring seq %"PRIu32" != expected %"PRIu32, + nl_msg_nlmsghdr(reply)->nlmsg_seq, seq); + ofpbuf_delete(reply); + goto recv; + } + if (nl_msg_nlmsgerr(reply, &retval)) { + ofpbuf_delete(reply); + if (retval) { + VLOG_DBG_RL(&rl, "received NAK error=%d (%s)", + retval, strerror(retval)); + } + return retval != EAGAIN ? retval : EPROTO; + } + + *replyp = reply; + return 0; +} + +/* Causes poll_block() to wake up when any of the specified 'events' (which is + * a OR'd combination of POLLIN, POLLOUT, etc.) occur on 'sock'. */ +void +nl_sock_wait(const struct nl_sock *sock, short int events) +{ + poll_fd_wait(sock->fd, events); +} + +/* Netlink messages. */ + +/* Returns the nlmsghdr at the head of 'msg'. + * + * 'msg' must be at least as large as a nlmsghdr. */ +struct nlmsghdr * +nl_msg_nlmsghdr(const struct ofpbuf *msg) +{ + return ofpbuf_at_assert(msg, 0, NLMSG_HDRLEN); +} + +/* Returns the genlmsghdr just past 'msg''s nlmsghdr. + * + * Returns a null pointer if 'msg' is not large enough to contain an nlmsghdr + * and a genlmsghdr. */ +struct genlmsghdr * +nl_msg_genlmsghdr(const struct ofpbuf *msg) +{ + return ofpbuf_at(msg, NLMSG_HDRLEN, GENL_HDRLEN); +} + +/* If 'buffer' is a NLMSG_ERROR message, stores 0 in '*errorp' if it is an ACK + * message, otherwise a positive errno value, and returns true. If 'buffer' is + * not an NLMSG_ERROR message, returns false. + * + * 'msg' must be at least as large as a nlmsghdr. */ +bool +nl_msg_nlmsgerr(const struct ofpbuf *msg, int *errorp) +{ + if (nl_msg_nlmsghdr(msg)->nlmsg_type == NLMSG_ERROR) { + struct nlmsgerr *err = ofpbuf_at(msg, NLMSG_HDRLEN, sizeof *err); + int code = EPROTO; + if (!err) { + VLOG_ERR_RL(&rl, "received invalid nlmsgerr (%zd bytes < %zd)", + msg->size, NLMSG_HDRLEN + sizeof *err); + } else if (err->error <= 0 && err->error > INT_MIN) { + code = -err->error; + } + if (errorp) { + *errorp = code; + } + return true; + } else { + return false; + } +} + +/* Ensures that 'b' has room for at least 'size' bytes plus netlink padding at + * its tail end, reallocating and copying its data if necessary. */ +void +nl_msg_reserve(struct ofpbuf *msg, size_t size) +{ + ofpbuf_prealloc_tailroom(msg, NLMSG_ALIGN(size)); +} + +/* Puts a nlmsghdr at the beginning of 'msg', which must be initially empty. + * Uses the given 'type' and 'flags'. 'sock' is used to obtain a PID and + * sequence number for proper routing of replies. 'expected_payload' should be + * an estimate of the number of payload bytes to be supplied; if the size of + * the payload is unknown a value of 0 is acceptable. + * + * 'type' is ordinarily an enumerated value specific to the Netlink protocol + * (e.g. RTM_NEWLINK, for NETLINK_ROUTE protocol). For Generic Netlink, 'type' + * is the family number obtained via nl_lookup_genl_family(). + * + * 'flags' is a bit-mask that indicates what kind of request is being made. It + * is often NLM_F_REQUEST indicating that a request is being made, commonly + * or'd with NLM_F_ACK to request an acknowledgement. + * + * nl_msg_put_genlmsghdr is more convenient for composing a Generic Netlink + * message. */ +void +nl_msg_put_nlmsghdr(struct ofpbuf *msg, struct nl_sock *sock, + size_t expected_payload, uint32_t type, uint32_t flags) +{ + struct nlmsghdr *nlmsghdr; + + assert(msg->size == 0); + + nl_msg_reserve(msg, NLMSG_HDRLEN + expected_payload); + nlmsghdr = nl_msg_put_uninit(msg, NLMSG_HDRLEN); + nlmsghdr->nlmsg_len = 0; + nlmsghdr->nlmsg_type = type; + nlmsghdr->nlmsg_flags = flags; + nlmsghdr->nlmsg_seq = ++next_seq; + nlmsghdr->nlmsg_pid = sock->pid; +} + +/* Puts a nlmsghdr and genlmsghdr at the beginning of 'msg', which must be + * initially empty. 'sock' is used to obtain a PID and sequence number for + * proper routing of replies. 'expected_payload' should be an estimate of the + * number of payload bytes to be supplied; if the size of the payload is + * unknown a value of 0 is acceptable. + * + * 'family' is the family number obtained via nl_lookup_genl_family(). + * + * 'flags' is a bit-mask that indicates what kind of request is being made. It + * is often NLM_F_REQUEST indicating that a request is being made, commonly + * or'd with NLM_F_ACK to request an acknowledgement. + * + * 'cmd' is an enumerated value specific to the Generic Netlink family + * (e.g. CTRL_CMD_NEWFAMILY for the GENL_ID_CTRL family). + * + * 'version' is a version number specific to the family and command (often 1). + * + * nl_msg_put_nlmsghdr should be used to compose Netlink messages that are not + * Generic Netlink messages. */ +void +nl_msg_put_genlmsghdr(struct ofpbuf *msg, struct nl_sock *sock, + size_t expected_payload, int family, uint32_t flags, + uint8_t cmd, uint8_t version) +{ + struct genlmsghdr *genlmsghdr; + + nl_msg_put_nlmsghdr(msg, sock, GENL_HDRLEN + expected_payload, + family, flags); + assert(msg->size == NLMSG_HDRLEN); + genlmsghdr = nl_msg_put_uninit(msg, GENL_HDRLEN); + genlmsghdr->cmd = cmd; + genlmsghdr->version = version; + genlmsghdr->reserved = 0; +} + +/* Appends the 'size' bytes of data in 'p', plus Netlink padding if needed, to + * the tail end of 'msg'. Data in 'msg' is reallocated and copied if + * necessary. */ +void +nl_msg_put(struct ofpbuf *msg, const void *data, size_t size) +{ + memcpy(nl_msg_put_uninit(msg, size), data, size); +} + +/* Appends 'size' bytes of data, plus Netlink padding if needed, to the tail + * end of 'msg', reallocating and copying its data if necessary. Returns a + * pointer to the first byte of the new data, which is left uninitialized. */ +void * +nl_msg_put_uninit(struct ofpbuf *msg, size_t size) +{ + size_t pad = NLMSG_ALIGN(size) - size; + char *p = ofpbuf_put_uninit(msg, size + pad); + if (pad) { + memset(p + size, 0, pad); + } + return p; +} + +/* Appends a Netlink attribute of the given 'type' and room for 'size' bytes of + * data as its payload, plus Netlink padding if needed, to the tail end of + * 'msg', reallocating and copying its data if necessary. Returns a pointer to + * the first byte of data in the attribute, which is left uninitialized. */ +void * +nl_msg_put_unspec_uninit(struct ofpbuf *msg, uint16_t type, size_t size) +{ + size_t total_size = NLA_HDRLEN + size; + struct nlattr* nla = nl_msg_put_uninit(msg, total_size); + assert(NLA_ALIGN(total_size) <= UINT16_MAX); + nla->nla_len = total_size; + nla->nla_type = type; + return nla + 1; +} + +/* Appends a Netlink attribute of the given 'type' and the 'size' bytes of + * 'data' as its payload, to the tail end of 'msg', reallocating and copying + * its data if necessary. Returns a pointer to the first byte of data in the + * attribute, which is left uninitialized. */ +void +nl_msg_put_unspec(struct ofpbuf *msg, uint16_t type, + const void *data, size_t size) +{ + memcpy(nl_msg_put_unspec_uninit(msg, type, size), data, size); +} + +/* Appends a Netlink attribute of the given 'type' and no payload to 'msg'. + * (Some Netlink protocols use the presence or absence of an attribute as a + * Boolean flag.) */ +void +nl_msg_put_flag(struct ofpbuf *msg, uint16_t type) +{ + nl_msg_put_unspec(msg, type, NULL, 0); +} + +/* Appends a Netlink attribute of the given 'type' and the given 8-bit 'value' + * to 'msg'. */ +void +nl_msg_put_u8(struct ofpbuf *msg, uint16_t type, uint8_t value) +{ + nl_msg_put_unspec(msg, type, &value, sizeof value); +} + +/* Appends a Netlink attribute of the given 'type' and the given 16-bit 'value' + * to 'msg'. */ +void +nl_msg_put_u16(struct ofpbuf *msg, uint16_t type, uint16_t value) +{ + nl_msg_put_unspec(msg, type, &value, sizeof value); +} + +/* Appends a Netlink attribute of the given 'type' and the given 32-bit 'value' + * to 'msg'. */ +void +nl_msg_put_u32(struct ofpbuf *msg, uint16_t type, uint32_t value) +{ + nl_msg_put_unspec(msg, type, &value, sizeof value); +} + +/* Appends a Netlink attribute of the given 'type' and the given 64-bit 'value' + * to 'msg'. */ +void +nl_msg_put_u64(struct ofpbuf *msg, uint16_t type, uint64_t value) +{ + nl_msg_put_unspec(msg, type, &value, sizeof value); +} + +/* Appends a Netlink attribute of the given 'type' and the given + * null-terminated string 'value' to 'msg'. */ +void +nl_msg_put_string(struct ofpbuf *msg, uint16_t type, const char *value) +{ + nl_msg_put_unspec(msg, type, value, strlen(value) + 1); +} + +/* Appends a Netlink attribute of the given 'type' and the given buffered + * netlink message in 'nested_msg' to 'msg'. The nlmsg_len field in + * 'nested_msg' is finalized to match 'nested_msg->size'. */ +void +nl_msg_put_nested(struct ofpbuf *msg, + uint16_t type, struct ofpbuf *nested_msg) +{ + nl_msg_nlmsghdr(nested_msg)->nlmsg_len = nested_msg->size; + nl_msg_put_unspec(msg, type, nested_msg->data, nested_msg->size); +} + +/* Returns the first byte in the payload of attribute 'nla'. */ +const void * +nl_attr_get(const struct nlattr *nla) +{ + assert(nla->nla_len >= NLA_HDRLEN); + return nla + 1; +} + +/* Returns the number of bytes in the payload of attribute 'nla'. */ +size_t +nl_attr_get_size(const struct nlattr *nla) +{ + assert(nla->nla_len >= NLA_HDRLEN); + return nla->nla_len - NLA_HDRLEN; +} + +/* Asserts that 'nla''s payload is at least 'size' bytes long, and returns the + * first byte of the payload. */ +const void * +nl_attr_get_unspec(const struct nlattr *nla, size_t size) +{ + assert(nla->nla_len >= NLA_HDRLEN + size); + return nla + 1; +} + +/* Returns true if 'nla' is nonnull. (Some Netlink protocols use the presence + * or absence of an attribute as a Boolean flag.) */ +bool +nl_attr_get_flag(const struct nlattr *nla) +{ + return nla != NULL; +} + +#define NL_ATTR_GET_AS(NLA, TYPE) \ + (*(TYPE*) nl_attr_get_unspec(nla, sizeof(TYPE))) + +/* Returns the 8-bit value in 'nla''s payload. + * + * Asserts that 'nla''s payload is at least 1 byte long. */ +uint8_t +nl_attr_get_u8(const struct nlattr *nla) +{ + return NL_ATTR_GET_AS(nla, uint8_t); +} + +/* Returns the 16-bit value in 'nla''s payload. + * + * Asserts that 'nla''s payload is at least 2 bytes long. */ +uint16_t +nl_attr_get_u16(const struct nlattr *nla) +{ + return NL_ATTR_GET_AS(nla, uint16_t); +} + +/* Returns the 32-bit value in 'nla''s payload. + * + * Asserts that 'nla''s payload is at least 4 bytes long. */ +uint32_t +nl_attr_get_u32(const struct nlattr *nla) +{ + return NL_ATTR_GET_AS(nla, uint32_t); +} + +/* Returns the 64-bit value in 'nla''s payload. + * + * Asserts that 'nla''s payload is at least 8 bytes long. */ +uint64_t +nl_attr_get_u64(const struct nlattr *nla) +{ + return NL_ATTR_GET_AS(nla, uint64_t); +} + +/* Returns the null-terminated string value in 'nla''s payload. + * + * Asserts that 'nla''s payload contains a null-terminated string. */ +const char * +nl_attr_get_string(const struct nlattr *nla) +{ + assert(nla->nla_len > NLA_HDRLEN); + assert(memchr(nl_attr_get(nla), '\0', nla->nla_len - NLA_HDRLEN) != NULL); + return nl_attr_get(nla); +} + +/* Default minimum and maximum payload sizes for each type of attribute. */ +static const size_t attr_len_range[][2] = { + [0 ... N_NL_ATTR_TYPES - 1] = { 0, SIZE_MAX }, + [NL_A_U8] = { 1, 1 }, + [NL_A_U16] = { 2, 2 }, + [NL_A_U32] = { 4, 4 }, + [NL_A_U64] = { 8, 8 }, + [NL_A_STRING] = { 1, SIZE_MAX }, + [NL_A_FLAG] = { 0, SIZE_MAX }, + [NL_A_NESTED] = { NLMSG_HDRLEN, SIZE_MAX }, +}; + +/* Parses the 'msg' starting at the given 'nla_offset' as a sequence of Netlink + * attributes. 'policy[i]', for 0 <= i < n_attrs, specifies how the attribute + * with nla_type == i is parsed; a pointer to attribute i is stored in + * attrs[i]. Returns true if successful, false on failure. + * + * If the Netlink attributes in 'msg' follow a Netlink header and a Generic + * Netlink header, then 'nla_offset' should be NLMSG_HDRLEN + GENL_HDRLEN. */ +bool +nl_policy_parse(const struct ofpbuf *msg, size_t nla_offset, + const struct nl_policy policy[], + struct nlattr *attrs[], size_t n_attrs) +{ + void *p, *tail; + size_t n_required; + size_t i; + + n_required = 0; + for (i = 0; i < n_attrs; i++) { + attrs[i] = NULL; + + assert(policy[i].type < N_NL_ATTR_TYPES); + if (policy[i].type != NL_A_NO_ATTR + && policy[i].type != NL_A_FLAG + && !policy[i].optional) { + n_required++; + } + } + + p = ofpbuf_at(msg, nla_offset, 0); + if (p == NULL) { + VLOG_DBG_RL(&rl, "missing headers in nl_policy_parse"); + return false; + } + tail = ofpbuf_tail(msg); + + while (p < tail) { + size_t offset = (char*)p - (char*)msg->data; + struct nlattr *nla = p; + size_t len, aligned_len; + uint16_t type; + + /* Make sure its claimed length is plausible. */ + if (nla->nla_len < NLA_HDRLEN) { + VLOG_DBG_RL(&rl, "%zu: attr shorter than NLA_HDRLEN (%"PRIu16")", + offset, nla->nla_len); + return false; + } + len = nla->nla_len - NLA_HDRLEN; + aligned_len = NLA_ALIGN(len); + if (aligned_len > (char*)tail - (char*)p) { + VLOG_DBG_RL(&rl, "%zu: attr %"PRIu16" aligned data len (%zu) " + "> bytes left (%tu)", + offset, nla->nla_type, aligned_len, + (char*)tail - (char*)p); + return false; + } + + type = nla->nla_type; + if (type < n_attrs && policy[type].type != NL_A_NO_ATTR) { + const struct nl_policy *p = &policy[type]; + size_t min_len, max_len; + + /* Validate length and content. */ + min_len = p->min_len ? p->min_len : attr_len_range[p->type][0]; + max_len = p->max_len ? p->max_len : attr_len_range[p->type][1]; + if (len < min_len || len > max_len) { + VLOG_DBG_RL(&rl, "%zu: attr %"PRIu16" length %zu not in " + "allowed range %zu...%zu", + offset, type, len, min_len, max_len); + return false; + } + if (p->type == NL_A_STRING) { + if (((char *) nla)[nla->nla_len - 1]) { + VLOG_DBG_RL(&rl, "%zu: attr %"PRIu16" lacks null at end", + offset, type); + return false; + } + if (memchr(nla + 1, '\0', len - 1) != NULL) { + VLOG_DBG_RL(&rl, "%zu: attr %"PRIu16" has bad length", + offset, type); + return false; + } + } + if (!p->optional && attrs[type] == NULL) { + assert(n_required > 0); + --n_required; + } + attrs[type] = nla; + } else { + /* Skip attribute type that we don't care about. */ + } + p = (char*)p + NLA_ALIGN(nla->nla_len); + } + if (n_required) { + VLOG_DBG_RL(&rl, "%zu required attrs missing", n_required); + return false; + } + return true; +} + +/* Miscellaneous. */ + +static const struct nl_policy family_policy[CTRL_ATTR_MAX + 1] = { + [CTRL_ATTR_FAMILY_ID] = {.type = NL_A_U16}, +}; + +static int do_lookup_genl_family(const char *name) +{ + struct nl_sock *sock; + struct ofpbuf request, *reply; + struct nlattr *attrs[ARRAY_SIZE(family_policy)]; + int retval; + + retval = nl_sock_create(NETLINK_GENERIC, 0, 0, 0, &sock); + if (retval) { + return -retval; + } + + ofpbuf_init(&request, 0); + nl_msg_put_genlmsghdr(&request, sock, 0, GENL_ID_CTRL, NLM_F_REQUEST, + CTRL_CMD_GETFAMILY, 1); + nl_msg_put_string(&request, CTRL_ATTR_FAMILY_NAME, name); + retval = nl_sock_transact(sock, &request, &reply); + ofpbuf_uninit(&request); + if (retval) { + nl_sock_destroy(sock); + return -retval; + } + + if (!nl_policy_parse(reply, NLMSG_HDRLEN + GENL_HDRLEN, + family_policy, attrs, ARRAY_SIZE(family_policy))) { + nl_sock_destroy(sock); + ofpbuf_delete(reply); + return -EPROTO; + } + + retval = nl_attr_get_u16(attrs[CTRL_ATTR_FAMILY_ID]); + if (retval == 0) { + retval = -EPROTO; + } + nl_sock_destroy(sock); + ofpbuf_delete(reply); + return retval; +} + +/* If '*number' is 0, translates the given Generic Netlink family 'name' to a + * number and stores it in '*number'. If successful, returns 0 and the caller + * may use '*number' as the family number. On failure, returns a positive + * errno value and '*number' caches the errno value. */ +int +nl_lookup_genl_family(const char *name, int *number) +{ + if (*number == 0) { + *number = do_lookup_genl_family(name); + assert(*number != 0); + } + return *number > 0 ? 0 : -*number; +} + +/* Netlink PID. + * + * Every Netlink socket must be bound to a unique 32-bit PID. By convention, + * programs that have a single Netlink socket use their Unix process ID as PID, + * and programs with multiple Netlink sockets add a unique per-socket + * identifier in the bits above the Unix process ID. + * + * The kernel has Netlink PID 0. + */ + +/* Parameters for how many bits in the PID should come from the Unix process ID + * and how many unique per-socket. */ +#define SOCKET_BITS 10 +#define MAX_SOCKETS (1u << SOCKET_BITS) + +#define PROCESS_BITS (32 - SOCKET_BITS) +#define MAX_PROCESSES (1u << PROCESS_BITS) +#define PROCESS_MASK ((uint32_t) (MAX_PROCESSES - 1)) + +/* Bit vector of unused socket identifiers. */ +static uint32_t avail_sockets[ROUND_UP(MAX_SOCKETS, 32)]; + +/* Allocates and returns a new Netlink PID. */ +static int +alloc_pid(uint32_t *pid) +{ + int i; + + for (i = 0; i < MAX_SOCKETS; i++) { + if ((avail_sockets[i / 32] & (1u << (i % 32))) == 0) { + avail_sockets[i / 32] |= 1u << (i % 32); + *pid = (getpid() & PROCESS_MASK) | (i << PROCESS_BITS); + return 0; + } + } + VLOG_ERR("netlink pid space exhausted"); + return ENOBUFS; +} + +/* Makes the specified 'pid' available for reuse. */ +static void +free_pid(uint32_t pid) +{ + int sock = pid >> PROCESS_BITS; + assert(avail_sockets[sock / 32] & (1u << (sock % 32))); + avail_sockets[sock / 32] &= ~(1u << (sock % 32)); +} + +static void +nlmsghdr_to_string(const struct nlmsghdr *h, struct ds *ds) +{ + struct nlmsg_flag { + unsigned int bits; + const char *name; + }; + static const struct nlmsg_flag flags[] = { + { NLM_F_REQUEST, "REQUEST" }, + { NLM_F_MULTI, "MULTI" }, + { NLM_F_ACK, "ACK" }, + { NLM_F_ECHO, "ECHO" }, + { NLM_F_DUMP, "DUMP" }, + { NLM_F_ROOT, "ROOT" }, + { NLM_F_MATCH, "MATCH" }, + { NLM_F_ATOMIC, "ATOMIC" }, + }; + const struct nlmsg_flag *flag; + uint16_t flags_left; + + ds_put_format(ds, "nl(len:%"PRIu32", type=%"PRIu16, + h->nlmsg_len, h->nlmsg_type); + if (h->nlmsg_type == NLMSG_NOOP) { + ds_put_cstr(ds, "(no-op)"); + } else if (h->nlmsg_type == NLMSG_ERROR) { + ds_put_cstr(ds, "(error)"); + } else if (h->nlmsg_type == NLMSG_DONE) { + ds_put_cstr(ds, "(done)"); + } else if (h->nlmsg_type == NLMSG_OVERRUN) { + ds_put_cstr(ds, "(overrun)"); + } else if (h->nlmsg_type < NLMSG_MIN_TYPE) { + ds_put_cstr(ds, "(reserved)"); + } else { + ds_put_cstr(ds, "(family-defined)"); + } + ds_put_format(ds, ", flags=%"PRIx16, h->nlmsg_flags); + flags_left = h->nlmsg_flags; + for (flag = flags; flag < &flags[ARRAY_SIZE(flags)]; flag++) { + if ((flags_left & flag->bits) == flag->bits) { + ds_put_format(ds, "[%s]", flag->name); + flags_left &= ~flag->bits; + } + } + if (flags_left) { + ds_put_format(ds, "[OTHER:%"PRIx16"]", flags_left); + } + ds_put_format(ds, ", seq=%"PRIx32", pid=%"PRIu32"(%d:%d))", + h->nlmsg_seq, h->nlmsg_pid, + (int) (h->nlmsg_pid & PROCESS_MASK), + (int) (h->nlmsg_pid >> PROCESS_BITS)); +} + +static char * +nlmsg_to_string(const struct ofpbuf *buffer) +{ + struct ds ds = DS_EMPTY_INITIALIZER; + const struct nlmsghdr *h = ofpbuf_at(buffer, 0, NLMSG_HDRLEN); + if (h) { + nlmsghdr_to_string(h, &ds); + if (h->nlmsg_type == NLMSG_ERROR) { + const struct nlmsgerr *e; + e = ofpbuf_at(buffer, NLMSG_HDRLEN, + NLMSG_ALIGN(sizeof(struct nlmsgerr))); + if (e) { + ds_put_format(&ds, " error(%d", e->error); + if (e->error < 0) { + ds_put_format(&ds, "(%s)", strerror(-e->error)); + } + ds_put_cstr(&ds, ", in-reply-to("); + nlmsghdr_to_string(&e->msg, &ds); + ds_put_cstr(&ds, "))"); + } else { + ds_put_cstr(&ds, " error(truncated)"); + } + } else if (h->nlmsg_type == NLMSG_DONE) { + int *error = ofpbuf_at(buffer, NLMSG_HDRLEN, sizeof *error); + if (error) { + ds_put_format(&ds, " done(%d", *error); + if (*error < 0) { + ds_put_format(&ds, "(%s)", strerror(-*error)); + } + ds_put_cstr(&ds, ")"); + } else { + ds_put_cstr(&ds, " done(truncated)"); + } + } + } else { + ds_put_cstr(&ds, "nl(truncated)"); + } + return ds.string; +} + +static void +log_nlmsg(const char *function, int error, + const void *message, size_t size) +{ + struct ofpbuf buffer; + char *nlmsg; + + if (!VLOG_IS_DBG_ENABLED()) { + return; + } + + buffer.data = (void *) message; + buffer.size = size; + nlmsg = nlmsg_to_string(&buffer); + VLOG_DBG_RL(&rl, "%s (%s): %s", function, strerror(error), nlmsg); + free(nlmsg); +} + |