134 lines
2.7 KiB
C
134 lines
2.7 KiB
C
#include <errno.h>
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#include <poll.h>
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#include <pwd.h>
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#include <signal.h>
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <unistd.h>
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int main(int argc, char *argv[]) {
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(void)argc;
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char sockbuf[256];
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sprintf(sockbuf, "/tmp/seatd.%d.sock", getpid());
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unlink(sockbuf);
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int fds[2];
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if (pipe(fds) == -1) {
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perror("Could not create pipe");
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goto error;
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}
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pid_t seatd_child = fork();
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if (seatd_child == -1) {
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perror("Could not fork seatd process");
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goto error;
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} else if (seatd_child == 0) {
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close(fds[0]);
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char pipebuf[8];
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sprintf(pipebuf, "%d", fds[1]);
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struct passwd *user = getpwuid(getuid());
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if (!user) {
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perror("getpwuid failed");
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_exit(1);
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}
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// TODO: Make seatd accept the numeric UID
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execlp("seatd", "seatd", "-n", pipebuf, "-u", user->pw_name, "-s", sockbuf, NULL);
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perror("Could not start seatd");
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_exit(1);
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}
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close(fds[1]);
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// Drop privileges
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if (setgid(getgid()) == -1) {
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perror("Could not set gid to drop privileges");
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goto error_seatd;
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}
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if (setuid(getuid()) == -1) {
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perror("Could not set uid to drop privileges");
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goto error_seatd;
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}
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char buf[1] = {0};
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while (true) {
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pid_t p = waitpid(seatd_child, NULL, WNOHANG);
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if (p == seatd_child) {
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fprintf(stderr, "seatd exited prematurely\n");
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goto error_seatd;
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} else if (p == -1 && (errno != EINTR && errno != ECHILD)) {
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perror("Could not wait for seatd process");
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goto error_seatd;
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}
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struct pollfd fd = {
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.fd = fds[0],
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.events = POLLIN,
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};
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// We poll with timeout to avoid a racing on a blocking read
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if (poll(&fd, 1, 1000) == -1) {
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if (errno == EAGAIN || errno == EINTR) {
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continue;
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} else {
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perror("Could not poll notification fd");
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goto error_seatd;
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}
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}
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if (fd.revents & POLLIN) {
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ssize_t n = read(fds[0], buf, 1);
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if (n == -1 && errno != EINTR) {
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perror("Could not read from pipe");
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goto error_seatd;
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} else if (n > 0) {
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break;
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}
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}
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}
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close(fds[0]);
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pid_t child = fork();
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if (child == -1) {
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perror("Could not fork target process");
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goto error_seatd;
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} else if (child == 0) {
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setenv("SEATD_SOCK", sockbuf, 1);
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execv(argv[1], &argv[1]);
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perror("Could not start target");
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_exit(1);
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}
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int status = 0;
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while (true) {
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pid_t p = waitpid(child, &status, 0);
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if (p == child) {
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break;
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} else if (p == -1 && errno != EINTR) {
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perror("Could not wait for target process");
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goto error_seatd;
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}
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}
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unlink(sockbuf);
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kill(seatd_child, SIGTERM);
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if (WIFEXITED(status)) {
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return WEXITSTATUS(status);
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} else {
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return 1;
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}
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error_seatd:
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unlink(sockbuf);
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kill(seatd_child, SIGTERM);
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error:
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return 1;
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}
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