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netns: improve netnsid allocation

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Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
This commit is contained in:
Christian Brauner
2018-08-11 02:21:34 +02:00
parent 4e3ed0d196
commit 0ce60f0d5f
1 changed files with 104 additions and 22 deletions
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126
src/lxc/network.c
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@@ -3192,16 +3192,102 @@ enum {
__LXC_NETNSA_MAX, __LXC_NETNSA_MAX,
}; };
static int nl_send(struct nl_handler *handler, struct nlmsghdr *nlmsghdr)
{
struct sockaddr_nl nladdr;
struct iovec iov = {
.iov_base = nlmsghdr,
.iov_len = nlmsghdr->nlmsg_len,
};
struct msghdr msg = {
.msg_name = &nladdr,
.msg_namelen = sizeof(nladdr),
.msg_iov = &iov,
.msg_iovlen = 1,
};
int ret;
memset(&nladdr, 0, sizeof(nladdr));
nladdr.nl_family = AF_NETLINK;
nladdr.nl_pid = 0;
nladdr.nl_groups = 0;
ret = sendmsg(handler->fd, &msg, MSG_NOSIGNAL);
if (ret < 0)
return -errno;
return ret;
}
static int nl_recv(struct nl_handler *handler, struct nlmsghdr *nlmsghdr)
{
int ret;
struct sockaddr_nl nladdr;
struct iovec iov = {
.iov_base = nlmsghdr,
.iov_len = nlmsghdr->nlmsg_len,
};
struct msghdr msg = {
.msg_name = &nladdr,
.msg_namelen = sizeof(nladdr),
.msg_iov = &iov,
.msg_iovlen = 1,
};
memset(&nladdr, 0, sizeof(nladdr));
nladdr.nl_family = AF_NETLINK;
nladdr.nl_pid = 0;
nladdr.nl_groups = 0;
again:
ret = recvmsg(handler->fd, &msg, 0);
if (ret < 0) {
if (errno == EINTR)
goto again;
return -1;
}
if (!ret)
return 0;
if (msg.msg_flags & MSG_TRUNC && (ret == nlmsghdr->nlmsg_len))
return -EMSGSIZE;
return ret;
}
extern int nl_transaction(struct nl_handler *handler, struct nlmsghdr *request,
struct nlmsghdr *answer)
{
int ret;
ret = nl_send(handler, request);
if (ret < 0)
return ret;
ret = nl_recv(handler, answer);
if (ret < 0)
return ret;
if (answer->nlmsg_type == NLMSG_ERROR) {
struct nlmsgerr *err = (struct nlmsgerr *)NLMSG_DATA(answer);
return err->error;
}
return 0;
}
int lxc_netns_set_nsid(int fd) int lxc_netns_set_nsid(int fd)
{ {
ssize_t ret; ssize_t ret;
char l_buffer[NLMSG_ALIGN(sizeof(struct nlmsghdr)) + char buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
NLMSG_ALIGN(sizeof(struct rtgenmsg)) + NLMSG_ALIGN(sizeof(struct rtgenmsg)) +
NLMSG_ALIGN(1024)]; NLMSG_ALIGN(1024)];
struct nl_handler nlh; struct nl_handler nlh;
struct nlmsghdr *l_hdr; struct nlmsghdr *hdr;
struct rtgenmsg *l_msg; struct rtgenmsg *msg;
struct sockaddr_nl l_addr;
__s32 ns_id = -1; __s32 ns_id = -1;
__u32 netns_fd = fd; __u32 netns_fd = fd;
@@ -3209,25 +3295,21 @@ int lxc_netns_set_nsid(int fd)
if (ret < 0) if (ret < 0)
return ret; return ret;
memset(l_buffer, 0, sizeof(l_buffer)); memset(buf, 0, sizeof(buf));
l_hdr = (struct nlmsghdr *)l_buffer; hdr = (struct nlmsghdr *)buf;
l_msg = (struct rtgenmsg *)NLMSG_DATA(l_hdr); msg = (struct rtgenmsg *)NLMSG_DATA(hdr);
l_hdr->nlmsg_len = NLMSG_LENGTH(sizeof(*l_msg)); hdr->nlmsg_len = NLMSG_LENGTH(sizeof(*msg));
l_hdr->nlmsg_type = RTM_NEWNSID; hdr->nlmsg_type = RTM_NEWNSID;
l_hdr->nlmsg_flags = NLM_F_REQUEST; hdr->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
l_hdr->nlmsg_pid = 0; hdr->nlmsg_pid = 0;
l_hdr->nlmsg_seq = RTM_NEWNSID; hdr->nlmsg_seq = RTM_NEWNSID;
l_msg->rtgen_family = AF_UNSPEC; msg->rtgen_family = AF_UNSPEC;
addattr(l_hdr, 1024, __LXC_NETNSA_FD, &netns_fd, sizeof(netns_fd)); addattr(hdr, 1024, __LXC_NETNSA_FD, &netns_fd, sizeof(netns_fd));
addattr(l_hdr, 1024, __LXC_NETNSA_NSID, &ns_id, sizeof(ns_id)); addattr(hdr, 1024, __LXC_NETNSA_NSID, &ns_id, sizeof(ns_id));
memset(&l_addr, 0, sizeof(l_addr)); ret = nl_transaction(&nlh, hdr, hdr);
l_addr.nl_family = AF_NETLINK;
ret = sendto(nlh.fd, l_hdr, l_hdr->nlmsg_len, 0,
(struct sockaddr *)&l_addr, sizeof(l_addr));
netlink_close(&nlh); netlink_close(&nlh);
if (ret < 0) if (ret < 0)
return -1; return -1;