This change refactors the Unix socket / pipe backend to have a ring buffer containing segments, where each segment has an optional leading ancillary buffer containing control messages followed by a normal data buffer. The SCM_RIGHTS control message has been implemented which transfers file descriptors to the receiving process. File descriptors are reference counted and cycles are prevented using the following restrictions: 1) Unix sockets cannot be sent on themselves (on either end). 2) Unix sockets themselves being sent cannot be sent on. 3) Unix sockets cannot send a Unix socket being sent on. This is a compatible ABI change.
67 lines
1.8 KiB
C
67 lines
1.8 KiB
C
/*
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* Copyright (c) 2021 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* test-unix-socket-fd-leak.c
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* Tests whether leaking file descriptors over a Unix socket works.
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*/
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#include <sys/stat.h>
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#include <sys/socket.h>
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#include <sys/wait.h>
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#include <stdalign.h>
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#include <stdio.h>
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#include <unistd.h>
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#include "test.h"
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int main(void)
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{
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int fds[2];
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test_assert(socketpair(AF_UNIX, SOCK_STREAM, 0, fds) == 0);
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FILE* file;
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test_assert((file = tmpfile()));
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struct msghdr mhdr;
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char buf[1] = { 0 };
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struct iovec iov;
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iov.iov_base = buf;
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iov.iov_len = sizeof(buf);
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alignas(struct cmsghdr) char cmsgdata[CMSG_SPACE(sizeof(int))];
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buf[0] = 'X';
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memset(&mhdr, 0, sizeof(mhdr));
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mhdr.msg_iov = &iov;
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mhdr.msg_iovlen = 1;
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mhdr.msg_control = cmsgdata;
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mhdr.msg_controllen = sizeof(cmsgdata);
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struct cmsghdr* cmsg = CMSG_FIRSTHDR(&mhdr);
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cmsg->cmsg_len = CMSG_LEN(sizeof(int));
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cmsg->cmsg_level = SOL_SOCKET;
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cmsg->cmsg_type = SCM_RIGHTS;
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int* cdata = (int*) CMSG_DATA(cmsg);
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*cdata = fileno(file);
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ssize_t amount = sendmsg(fds[1], &mhdr, 0);
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test_assert(0 <= amount);
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test_assertx(amount == 1);
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fclose(file);
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close(fds[0]);
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close(fds[1]);
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return 0;
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}
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