4feb8d4126
- TUNSETIFF works, the interface is indeed created.
- An fd is indeed passed over the unix socket,
- and is a valid (enough) fd because it can fed into `dup2`.
- `nix run -f . --offline pkgs.taps -- pass sleep 5` works, the
interface exists for 5 seconds and disappears
- `nix run -f . --offline pkgs.taps -- pass ch-remote --api-socket=$HOME/uvms/nixos/vmm.sock add-net fd=3`
obscurely fails, killing the VMM with:
```console
[root@nixos:~]# cloud-hypervisor: 12.388270s: <_net1_qp0> ERROR:/build/source/net_util/src/queue_pair.rs:112 -- net: tx: failed writing to tap: Input/output error (os er
ror 5)
cloud-hypervisor: 12.388459s: <_net1_qp0> ERROR:virtio-devices/src/thread_helper.rs:54 -- Error running worker: HandleEvent(Error processing TX queue: NetQueuePair(Write
Tap(Os { code: 5, kind: Uncategorized, message: "Input/output error" })))
```
74 lines
1.8 KiB
C
74 lines
1.8 KiB
C
#include "sendfd.h"
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#include "sys/socket.h" /* cmsghdr */
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#include "stdio.h" /* perror */
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ssize_t send_fd(int dst_fd, int fd, const struct iovec *iov) {
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struct msghdr msg = { 0 };
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/* openssh expects to receive a dummy length=1 iovec? */
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char ch = 0;
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struct iovec vecDefault = { 0 };
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vecDefault.iov_base = &ch;
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vecDefault.iov_len = 1;
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msg.msg_iov = iov == NULL ? &vecDefault : iov;
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msg.msg_iovlen = 1;
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union {
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struct cmsghdr align;
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char buf[CMSG_SPACE(sizeof(int))];
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} u;
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msg.msg_control = u.buf;
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msg.msg_controllen = sizeof(u.buf);
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struct cmsghdr *cmptr;
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cmptr = CMSG_FIRSTHDR(&msg);
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if (cmptr == NULL) {
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perror("ch-proxy/send_fd/CMSG_FIRSTHDR: failed to initialize msg_control\n");
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}
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cmptr->cmsg_len = CMSG_LEN(sizeof(int));
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cmptr->cmsg_level = SOL_SOCKET;
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cmptr->cmsg_type = SCM_RIGHTS;
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*((int*) CMSG_DATA(cmptr)) = fd;
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return (sendmsg(dst_fd, &msg, 0));
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}
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int recv_fd(int sock, int flags) {
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int out = -1;
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struct msghdr msg = { 0 };
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struct cmsghdr *cmsg = NULL;
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struct iovec iov = { 0 };
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char dummy = 0;
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msg.msg_iov = &iov;
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msg.msg_iovlen = 1;
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iov.iov_base = &dummy;
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iov.iov_len = sizeof(dummy);
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union {
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struct cmsghdr align;
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char buf[CMSG_SPACE(sizeof(int))];
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} u;
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msg.msg_control = u.buf;
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msg.msg_controllen = sizeof(u.buf);
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int bytes = 0;
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if ((bytes = recvmsg(sock, &msg, flags)) < 0) {
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perror("recv_fd: recvmsg");
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return -1;
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}
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for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
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if (cmsg->cmsg_level != SOL_SOCKET) { continue; }
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if (cmsg->cmsg_type != SCM_RIGHTS) { continue; }
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if (CMSG_LEN(cmsg) < sizeof(out)) { continue; }
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out = *(int*)CMSG_DATA(cmsg);
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}
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return out;
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}
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