125 lines
3.9 KiB
C
125 lines
3.9 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-cycle.c
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* Tests whether Unix socket file descriptor passing cycles are rejected.
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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 a_fds[2];
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test_assert(socketpair(AF_UNIX, SOCK_STREAM, 0, a_fds) == 0);
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int b_fds[2];
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test_assert(socketpair(AF_UNIX, SOCK_STREAM, 0, b_fds) == 0);
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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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ssize_t amount;
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struct cmsghdr* cmsg;
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// Passing a Unix socket on itself isn't permitted.
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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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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 = a_fds[1];
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amount = sendmsg(a_fds[1], &mhdr, 0);
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test_assertx(amount < 0);
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test_assert(errno == EPERM);
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// Passing a Unix socket on its other end isn't permitted.
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*cdata = a_fds[0];
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amount = sendmsg(a_fds[1], &mhdr, 0);
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test_assertx(amount < 0);
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test_assert(errno == EPERM);
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// Passing a Unix socket (with no fds passed) on another Unix socket (which
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// itself isn't being passed) is allowed.
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*cdata = b_fds[1];
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amount = sendmsg(a_fds[1], &mhdr, 0);
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test_assert(0 <= amount);
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test_assertx(amount == 1);
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// A Unix socket (itself being passed) is not permitted to pass fds.
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// b_fds[1] is already being sent on a_fds[1] (to a_fds[0]).
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FILE* file;
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test_assert((file = tmpfile()));
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*cdata = fileno(file);
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amount = sendmsg(b_fds[1], &mhdr, 0);
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test_assertx(amount < 0);
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test_assert(errno == EPERM);
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fclose(file);
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// A Unix socket is not permitted to send a socket with fds being sent.
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// b_fds[1] is already being sent on a_fds[1] (to a_fds[0]).
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*cdata = a_fds[1];
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amount = sendmsg(b_fds[0], &mhdr, 0);
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test_assertx(amount < 0);
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test_assert(errno == EPERM);
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// Receive b_fds[1] being sent on a_fds[1] to a_fds[0].
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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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amount = recvmsg(a_fds[0], &mhdr, 0);
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test_assert(0 <= amount);
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test_assertx(amount == 1);
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test_assertx(buf[0] == 'X');
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test_assertx(!(mhdr.msg_flags & MSG_CTRUNC));
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test_assertx(!mhdr.msg_flags);
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test_assertx(mhdr.msg_controllen);
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cmsg = CMSG_FIRSTHDR(&mhdr);
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test_assertx(cmsg);
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test_assertx(cmsg->cmsg_level == SOL_SOCKET);
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test_assertx(cmsg->cmsg_type == SCM_RIGHTS);
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test_assertx(cmsg->cmsg_len == CMSG_LEN(sizeof(int)));
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cdata = (int*) CMSG_DATA(cmsg);
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int file_fd = *cdata;
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test_assertx(0 <= file_fd);
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struct stat gotten_st;
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test_assert(fstat(file_fd, &gotten_st) == 0);
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struct stat expected_st;
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test_assert(fstat(b_fds[1], &expected_st) == 0);
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test_assertx(gotten_st.st_ino == expected_st.st_ino);
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test_assertx(gotten_st.st_dev == expected_st.st_dev);
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test_assertx(!CMSG_NXTHDR(&mhdr, cmsg));
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close(file_fd);
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return 0;
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}
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