mirror of
https://github.com/opencontainers/runc.git
synced 2026-07-11 06:03:57 +08:00
Cory Snider
85 lines
2.2 KiB
C
85 lines
2.2 KiB
C
#define _GNU_SOURCE
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#include <alloca.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/socket.h>
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#include "ipc.h"
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#include "log.h"
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int receive_fd(int sockfd)
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{
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int bytes_read;
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struct msghdr msg = { };
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struct cmsghdr *cmsg;
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struct iovec iov = { };
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char null_byte = '\0';
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int ret;
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int fd_count;
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iov.iov_base = &null_byte;
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iov.iov_len = 1;
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msg.msg_iov = &iov;
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msg.msg_iovlen = 1;
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msg.msg_controllen = CMSG_SPACE(sizeof(int));
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msg.msg_control = malloc(msg.msg_controllen);
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if (msg.msg_control == NULL) {
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bail("Can't allocate memory to receive fd.");
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}
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memset(msg.msg_control, 0, msg.msg_controllen);
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bytes_read = recvmsg(sockfd, &msg, MSG_CMSG_CLOEXEC);
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if (bytes_read != 1)
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bail("failed to receive fd from unix socket %d", sockfd);
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if (msg.msg_flags & MSG_CTRUNC)
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bail("received truncated control message from unix socket %d", sockfd);
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cmsg = CMSG_FIRSTHDR(&msg);
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if (!cmsg)
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bail("received message from unix socket %d without control message", sockfd);
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if (cmsg->cmsg_level != SOL_SOCKET)
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bail("received unknown control message from unix socket %d: cmsg_level=%d", sockfd, cmsg->cmsg_level);
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if (cmsg->cmsg_type != SCM_RIGHTS)
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bail("received unknown control message from unix socket %d: cmsg_type=%d", sockfd, cmsg->cmsg_type);
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fd_count = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
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if (fd_count != 1)
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bail("received control message from unix socket %d with too many fds: %d", sockfd, fd_count);
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ret = *(int *)CMSG_DATA(cmsg);
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free(msg.msg_control);
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return ret;
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}
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int send_fd(int sockfd, int fd)
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{
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struct msghdr msg = { };
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struct cmsghdr *cmsg;
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struct iovec iov[1] = { };
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char null_byte = '\0';
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iov[0].iov_base = &null_byte;
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iov[0].iov_len = 1;
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msg.msg_iov = iov;
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msg.msg_iovlen = 1;
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/* We send only one fd as specified by cmsg->cmsg_len below, even
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* though msg.msg_controllen might have more space due to alignment. */
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msg.msg_controllen = CMSG_SPACE(sizeof(int));
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msg.msg_control = alloca(msg.msg_controllen);
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memset(msg.msg_control, 0, msg.msg_controllen);
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cmsg = CMSG_FIRSTHDR(&msg);
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cmsg->cmsg_level = SOL_SOCKET;
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cmsg->cmsg_type = SCM_RIGHTS;
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cmsg->cmsg_len = CMSG_LEN(sizeof(int));
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memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));
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return sendmsg(sockfd, &msg, 0);
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}
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