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https://github.com/checkpoint-restore/criu
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30224abcb6
The flags are only one bit in the kernel (close-on-exec, all the rest are not per-fd, but per-file), but for simplicity I save it in a char field. Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
128 lines
3.1 KiB
C
128 lines
3.1 KiB
C
#include <sys/socket.h>
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#include <sys/un.h>
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#include <errno.h>
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#include "compiler.h"
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#include "memcpy_64.h"
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#include "types.h"
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#include "syscall.h"
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#include "util-net.h"
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static void scm_fdset_init_chunk(struct scm_fdset *fdset, int nr_fds)
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{
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struct cmsghdr *cmsg;
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fdset->hdr.msg_controllen = CMSG_LEN(sizeof(int) * nr_fds);
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cmsg = CMSG_FIRSTHDR(&fdset->hdr);
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cmsg->cmsg_len = fdset->hdr.msg_controllen;
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}
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static int *scm_fdset_init(struct scm_fdset *fdset, struct sockaddr_un *saddr,
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int saddr_len, bool with_flags)
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{
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struct cmsghdr *cmsg;
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BUILD_BUG_ON(CR_SCM_MAX_FD > SCM_MAX_FD);
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BUILD_BUG_ON(sizeof(fdset->msg_buf) < (CMSG_SPACE(sizeof(int) * CR_SCM_MAX_FD)));
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fdset->iov.iov_base = &fdset->msg;
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fdset->iov.iov_len = with_flags ? sizeof(fdset->msg) : 1;
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fdset->hdr.msg_iov = &fdset->iov;
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fdset->hdr.msg_iovlen = 1;
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fdset->hdr.msg_name = (struct sockaddr *)saddr;
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fdset->hdr.msg_namelen = saddr_len;
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fdset->hdr.msg_control = &fdset->msg_buf;
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fdset->hdr.msg_controllen = CMSG_LEN(sizeof(int) * CR_SCM_MAX_FD);
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cmsg = CMSG_FIRSTHDR(&fdset->hdr);
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cmsg->cmsg_len = fdset->hdr.msg_controllen;
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cmsg->cmsg_level = SOL_SOCKET;
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cmsg->cmsg_type = SCM_RIGHTS;
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return (int *)CMSG_DATA(cmsg);
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}
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int send_fds(int sock, struct sockaddr_un *saddr, int len,
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int *fds, int nr_fds, bool with_flags)
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{
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struct scm_fdset fdset;
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int *cmsg_data;
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int i, min_fd, ret;
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cmsg_data = scm_fdset_init(&fdset, saddr, len, with_flags);
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for (i = 0; i < nr_fds; i += min_fd) {
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min_fd = min(CR_SCM_MAX_FD, nr_fds - i);
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scm_fdset_init_chunk(&fdset, min_fd);
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builtin_memcpy(cmsg_data, &fds[i], sizeof(int) * min_fd);
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if (with_flags) {
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int j;
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for (j = 0; j < min_fd; j++) {
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int flags;
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flags = sys_fcntl(fds[i + j], F_GETFD, 0);
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if (flags < 0)
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return -1;
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fdset.msg[j] = (char)flags;
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}
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}
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ret = sys_sendmsg(sock, &fdset.hdr, 0);
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if (ret <= 0)
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return ret ? : -1;
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}
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return 0;
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}
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int recv_fds(int sock, int *fds, int nr_fds, char *flags)
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{
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struct scm_fdset fdset;
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struct cmsghdr *cmsg;
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int *cmsg_data;
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int ret;
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int i, min_fd;
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cmsg_data = scm_fdset_init(&fdset, NULL, 0, flags != NULL);
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for (i = 0; i < nr_fds; i += min_fd) {
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min_fd = min(CR_SCM_MAX_FD, nr_fds - i);
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scm_fdset_init_chunk(&fdset, min_fd);
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ret = sys_recvmsg(sock, &fdset.hdr, 0);
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if (ret <= 0)
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return ret ? : -1;
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cmsg = CMSG_FIRSTHDR(&fdset.hdr);
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if (!cmsg || cmsg->cmsg_type != SCM_RIGHTS)
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return -EINVAL;
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min_fd = (cmsg->cmsg_len - sizeof(struct cmsghdr)) / sizeof(int);
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/*
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* In case if kernel screwed the recepient, most probably
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* the caller stack frame will be overwriten, just scream
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* and exit.
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*
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* FIXME Need to sanitize util.h to be able to include it
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* into files which do not have glibc and a couple of
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* sys_write_ helpers. Meawhile opencoded BUG_ON here.
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*/
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if (unlikely(min_fd > CR_SCM_MAX_FD))
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*(volatile unsigned long *)NULL = 0xdead0000 + __LINE__;
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if (unlikely(min_fd <= 0))
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return -1;
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builtin_memcpy(&fds[i], cmsg_data, sizeof(int) * min_fd);
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if (flags)
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builtin_memcpy(flags, fdset.msg, sizeof(char) * min_fd);
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}
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return 0;
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}
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