diff options
Diffstat (limited to 'zebra/zebra_netns_id.c')
| -rw-r--r-- | zebra/zebra_netns_id.c | 351 |
1 files changed, 351 insertions, 0 deletions
diff --git a/zebra/zebra_netns_id.c b/zebra/zebra_netns_id.c new file mode 100644 index 0000000..0531ab9 --- /dev/null +++ b/zebra/zebra_netns_id.c @@ -0,0 +1,351 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* zebra NETNS ID handling routines + * those routines are implemented locally to avoid having external dependencies. + * Copyright (C) 2018 6WIND + */ + +#include <zebra.h> + +#include "ns.h" +#include "vrf.h" +#include "log.h" +#include "lib_errors.h" +#include "network.h" + +#include "zebra/rib.h" +#include "zebra/zebra_dplane.h" +#if defined(HAVE_NETLINK) + +#include <linux/net_namespace.h> +#include <linux/netlink.h> +#include <linux/rtnetlink.h> + +#include "zebra_ns.h" +#include "kernel_netlink.h" +#endif /* defined(HAVE_NETLINK) */ + +#include "zebra/zebra_netns_id.h" +#include "zebra/zebra_errors.h" + +/* in case NEWNSID not available, the NSID will be locally obtained + */ +#define NS_BASE_NSID 0 + +#if defined(HAVE_NETLINK) + +#define NETLINK_SOCKET_BUFFER_SIZE 512 +#define NETLINK_ALIGNTO 4 +#define NETLINK_ALIGN(len) \ + (((len) + NETLINK_ALIGNTO - 1) & ~(NETLINK_ALIGNTO - 1)) +#define NETLINK_NLATTR_LEN(_a, _b) (unsigned int)((char *)_a - (char *)_b) + +#endif /* defined(HAVE_NETLINK) */ + +static ns_id_t zebra_ns_id_get_fallback(const char *netnspath) +{ + static int zebra_ns_id_local; + + return zebra_ns_id_local++; +} + +#if defined(HAVE_NETLINK) + +static struct nlmsghdr *initiate_nlh(char *buf, unsigned int *seq, int type) +{ + struct nlmsghdr *nlh; + + nlh = (struct nlmsghdr *)buf; + nlh->nlmsg_len = NETLINK_ALIGN(sizeof(struct nlmsghdr)); + + nlh->nlmsg_type = type; + nlh->nlmsg_flags = NLM_F_REQUEST; + if (type == RTM_NEWNSID) + nlh->nlmsg_flags |= NLM_F_ACK; + nlh->nlmsg_seq = *seq = frr_sequence32_next(); + return nlh; +} + +static int send_receive(int sock, struct nlmsghdr *nlh, unsigned int seq, + char *buf) +{ + int ret; + static const struct sockaddr_nl snl = {.nl_family = AF_NETLINK}; + + ret = sendto(sock, (const void *)nlh, (size_t)nlh->nlmsg_len, 0, + (struct sockaddr *)&snl, (socklen_t)sizeof(snl)); + if (ret < 0) { + flog_err_sys(EC_LIB_SOCKET, "netlink( %u) sendmsg() error: %s", + sock, safe_strerror(errno)); + return -1; + } + + /* reception */ + struct sockaddr_nl addr; + struct iovec iov = { + .iov_base = buf, .iov_len = NETLINK_SOCKET_BUFFER_SIZE, + }; + struct msghdr msg = { + .msg_name = &addr, + .msg_namelen = sizeof(struct sockaddr_nl), + .msg_iov = &iov, + .msg_iovlen = 1, + .msg_control = NULL, + .msg_controllen = 0, + .msg_flags = 0, + }; + ret = recvmsg(sock, &msg, 0); + if (ret < 0) { + flog_err_sys(EC_LIB_SOCKET, + "netlink recvmsg: error %d (errno %u)", ret, + errno); + return -1; + } + if (msg.msg_flags & MSG_TRUNC) { + flog_err(EC_ZEBRA_NETLINK_LENGTH_ERROR, + "netlink recvmsg : error message truncated"); + return -1; + } + /* nlh already points to buf */ + if (nlh->nlmsg_seq != seq) { + flog_err( + EC_ZEBRA_NETLINK_BAD_SEQUENCE, + "netlink recvmsg: bad sequence number %x (expected %x)", + seq, nlh->nlmsg_seq); + return -1; + } + return ret; +} + +/* extract on a valid nlmsg the nsid + * valid nlmsghdr - not a nlmsgerr + */ +static ns_id_t extract_nsid(struct nlmsghdr *nlh, char *buf) +{ + ns_id_t ns_id = NS_UNKNOWN; + int offset = NETLINK_ALIGN(sizeof(struct nlmsghdr)) + + NETLINK_ALIGN(sizeof(struct rtgenmsg)); + void *tail = (void *)((char *)nlh + NETLINK_ALIGN(nlh->nlmsg_len)); + struct nlattr *attr; + + for (attr = (struct nlattr *)(buf + offset); + NETLINK_NLATTR_LEN(tail, attr) >= sizeof(struct nlattr) + && attr->nla_len >= sizeof(struct nlattr) + && attr->nla_len <= NETLINK_NLATTR_LEN(tail, attr); + attr += NETLINK_ALIGN(attr->nla_len)) { + if ((attr->nla_type & NLA_TYPE_MASK) == NETNSA_NSID) { + uint32_t *ptr = (uint32_t *)(attr); + + ns_id = ptr[1]; + break; + } + } + return ns_id; +} + +/* fd_param = -1 is ignored. + * netnspath set to null is ignored. + * one of the 2 params is mandatory. netnspath is looked in priority + */ +ns_id_t zebra_ns_id_get(const char *netnspath, int fd_param) +{ + int ns_id = -1; + struct sockaddr_nl snl; + int fd = -1, sock, ret; + unsigned int seq; + ns_id_t return_nsid = NS_UNKNOWN; + + /* netns path check */ + if (!netnspath && fd_param == -1) + return NS_UNKNOWN; + if (netnspath) { + fd = open(netnspath, O_RDONLY); + if (fd == -1) + return NS_UNKNOWN; + } else if (fd_param != -1) + fd = fd_param; + /* netlink socket */ + sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE); + if (sock < 0) { + flog_err_sys(EC_LIB_SOCKET, "netlink( %u) socket() error: %s", + sock, safe_strerror(errno)); + if (netnspath) + close(fd); + return NS_UNKNOWN; + } + memset(&snl, 0, sizeof(snl)); + snl.nl_family = AF_NETLINK; + snl.nl_groups = RTNLGRP_NSID; + snl.nl_pid = 0; /* AUTO PID */ + ret = bind(sock, (struct sockaddr *)&snl, sizeof(snl)); + if (ret < 0) { + flog_err_sys(EC_LIB_SOCKET, + "netlink( %u) socket() bind error: %s", sock, + safe_strerror(errno)); + close(sock); + if (netnspath) + close(fd); + return NS_UNKNOWN; + } + + /* message to send to netlink,and response : NEWNSID */ + char buf[NETLINK_SOCKET_BUFFER_SIZE]; + struct nlmsghdr *nlh; + struct rtgenmsg *rt; + int len; + + memset(buf, 0, NETLINK_SOCKET_BUFFER_SIZE); + nlh = initiate_nlh(buf, &seq, RTM_NEWNSID); + rt = (struct rtgenmsg *)(buf + nlh->nlmsg_len); + nlh->nlmsg_len += NETLINK_ALIGN(sizeof(struct rtgenmsg)); + rt->rtgen_family = AF_UNSPEC; + + nl_attr_put32(nlh, NETLINK_SOCKET_BUFFER_SIZE, NETNSA_FD, fd); + nl_attr_put32(nlh, NETLINK_SOCKET_BUFFER_SIZE, NETNSA_NSID, ns_id); + + ret = send_receive(sock, nlh, seq, buf); + if (ret < 0) { + close(sock); + if (netnspath) + close(fd); + return NS_UNKNOWN; + } + nlh = (struct nlmsghdr *)buf; + + /* message to analyse : NEWNSID response */ + ret = 0; + if (nlh->nlmsg_type >= NLMSG_MIN_TYPE) { + return_nsid = extract_nsid(nlh, buf); + } else { + if (nlh->nlmsg_type == NLMSG_ERROR) { + struct nlmsgerr *err = + (struct nlmsgerr + *)((char *)nlh + + NETLINK_ALIGN( + sizeof(struct nlmsghdr))); + + ret = -1; + if (err->error < 0) + errno = -err->error; + else + errno = err->error; + if (errno == 0) { + /* request NEWNSID was successfull + * return EEXIST error to get GETNSID + */ + errno = EEXIST; + } + } else { + /* other errors ignored + * attempt to get nsid + */ + ret = -1; + errno = EEXIST; + } + } + + if (errno != EEXIST && ret != 0) { + flog_err(EC_LIB_SOCKET, + "netlink( %u) recvfrom() error 2 when reading: %s", fd, + safe_strerror(errno)); + close(sock); + if (netnspath) + close(fd); + if (errno == ENOTSUP) { + zlog_debug("NEWNSID locally generated"); + return zebra_ns_id_get_fallback(netnspath); + } + return NS_UNKNOWN; + } + /* message to send to netlink : GETNSID */ + memset(buf, 0, NETLINK_SOCKET_BUFFER_SIZE); + nlh = initiate_nlh(buf, &seq, RTM_GETNSID); + rt = (struct rtgenmsg *)(buf + nlh->nlmsg_len); + nlh->nlmsg_len += NETLINK_ALIGN(sizeof(struct rtgenmsg)); + rt->rtgen_family = AF_UNSPEC; + + nl_attr_put32(nlh, NETLINK_SOCKET_BUFFER_SIZE, NETNSA_FD, fd); + nl_attr_put32(nlh, NETLINK_SOCKET_BUFFER_SIZE, NETNSA_NSID, ns_id); + + ret = send_receive(sock, nlh, seq, buf); + if (ret < 0) { + close(sock); + if (netnspath) + close(fd); + return NS_UNKNOWN; + } + nlh = (struct nlmsghdr *)buf; + len = ret; + ret = 0; + do { + if (nlh->nlmsg_type >= NLMSG_MIN_TYPE) { + return_nsid = extract_nsid(nlh, buf); + if (return_nsid != NS_UNKNOWN) + break; + } else if (nlh->nlmsg_type == NLMSG_ERROR) { + struct nlmsgerr *err = + (struct nlmsgerr *)((char *)nlh + + NETLINK_ALIGN(sizeof( + struct nlmsghdr))); + if (err->error < 0) + errno = -err->error; + else + errno = err->error; + break; + } + len = len - NETLINK_ALIGN(nlh->nlmsg_len); + nlh = (struct nlmsghdr *)((char *)nlh + + NETLINK_ALIGN(nlh->nlmsg_len)); + } while (len != 0 && ret == 0); + + if (netnspath) + close(fd); + close(sock); + return return_nsid; +} + +#else +ns_id_t zebra_ns_id_get(const char *netnspath, int fd __attribute__ ((unused))) +{ + return zebra_ns_id_get_fallback(netnspath); +} + +#endif /* ! defined(HAVE_NETLINK) */ + +#ifdef HAVE_NETNS +static void zebra_ns_create_netns_directory(void) +{ + /* check that /var/run/netns is created */ + /* S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH */ + if (mkdir(NS_RUN_DIR, 0755)) { + if (errno != EEXIST) { + flog_warn(EC_ZEBRA_NAMESPACE_DIR_INACCESSIBLE, + "NS check: failed to access %s", NS_RUN_DIR); + return; + } + } +} +#endif + +ns_id_t zebra_ns_id_get_default(void) +{ +#ifdef HAVE_NETNS + int fd; +#endif /* !HAVE_NETNS */ + +#ifdef HAVE_NETNS + if (vrf_is_backend_netns()) + zebra_ns_create_netns_directory(); + fd = open(NS_DEFAULT_NAME, O_RDONLY); + + if (fd == -1) + return NS_DEFAULT; + if (!vrf_is_backend_netns()) { + close(fd); + return NS_DEFAULT; + } + close(fd); + return zebra_ns_id_get((char *)NS_DEFAULT_NAME, -1); +#else /* HAVE_NETNS */ + return NS_DEFAULT; +#endif /* !HAVE_NETNS */ +} |