[1108] | 1 | |
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| 2 | #include <errno.h> |
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| 3 | #include <fcntl.h> |
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| 4 | #include <signal.h> |
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| 5 | #include <stdio.h> |
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| 6 | #include <stdlib.h> |
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| 7 | #include <string.h> |
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| 8 | #include <syslog.h> |
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| 9 | #include <unistd.h> |
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| 10 | |
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| 11 | #include <sys/types.h> |
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| 12 | #include <sys/stat.h> |
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| 13 | |
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| 14 | void alarm_handler(int num) { |
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| 15 | return; |
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| 16 | } |
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| 17 | |
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| 18 | int open_and_lock_securetty() { |
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| 19 | int fd; |
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| 20 | struct flock lock; |
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| 21 | struct sigaction act, oldact; |
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| 22 | |
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| 23 | lock.l_type = F_WRLCK; |
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| 24 | lock.l_whence = SEEK_SET; |
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| 25 | lock.l_start = 0; |
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| 26 | lock.l_len = 0; |
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| 27 | |
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| 28 | fd = open("/etc/securetty", O_RDWR); |
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| 29 | if (fd == -1) { |
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| 30 | syslog(LOG_ERR, "Couldn't open /etc/securetty: %s",strerror(errno)); |
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| 31 | return -1; |
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| 32 | } |
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| 33 | act.sa_handler = alarm_handler; |
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| 34 | act.sa_flags = 0; |
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| 35 | sigaction(SIGALRM, &act, &oldact); |
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| 36 | alarm(2); |
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| 37 | while (fcntl(fd, F_SETLKW, &lock) == -1) { |
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| 38 | if (errno == EINTR) { |
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| 39 | syslog(LOG_ERR, "Couldn't lock /etc/securetty: Timeout exceeded"); |
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| 40 | } else { |
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| 41 | syslog(LOG_ERR, "Couldn't lock /etc/securetty: %s",strerror(errno)); |
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| 42 | } |
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| 43 | return -1; |
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| 44 | } |
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| 45 | alarm(0); |
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| 46 | sigaction(SIGALRM, &oldact, NULL); |
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| 47 | return fd; |
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| 48 | } |
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| 49 | |
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| 50 | int rewrite_securetty(char *terminal) { |
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| 51 | int fd; |
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| 52 | char *buf, *pos; |
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| 53 | struct stat sbuf; |
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| 54 | |
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| 55 | fd = open_and_lock_securetty(); |
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| 56 | if (fd == -1) |
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| 57 | return 1; |
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| 58 | if (fstat(fd, &sbuf) == -1) { |
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| 59 | close(fd); |
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| 60 | syslog(LOG_ERR, "Couldn't stat /etc/securetty: %s",strerror(errno)); |
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| 61 | return 1; |
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| 62 | } |
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| 63 | buf = malloc(sbuf.st_size + 1); |
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| 64 | if (read(fd, buf, sbuf.st_size) != sbuf.st_size) { |
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| 65 | close(fd); |
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| 66 | syslog(LOG_ERR, "Couldn't read /etc/securetty: %s",strerror(errno)); |
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| 67 | return 1; |
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| 68 | } |
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| 69 | if (!strncmp(buf,terminal,strlen(terminal)) && buf[strlen(terminal)] == '\n') |
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| 70 | goto out_ok; |
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| 71 | if ((pos = strstr(buf, terminal))) { |
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| 72 | if (pos[strlen(terminal)] == '\n' && *(pos-1) == '\n') |
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| 73 | goto out_ok; |
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| 74 | } |
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| 75 | if (lseek(fd, 0, SEEK_END) == -1) { |
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| 76 | close(fd); |
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| 77 | syslog(LOG_ERR, "Couldn't seek to end of /etc/securetty: %s",strerror(errno)); |
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| 78 | return 1; |
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| 79 | } |
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| 80 | write(fd, terminal, strlen(terminal)); |
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| 81 | write(fd, "\n", 1); |
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| 82 | out_ok: |
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| 83 | close(fd); |
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| 84 | return 0; |
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| 85 | } |
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| 86 | |
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| 87 | int main(int argc, char **argv) { |
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| 88 | if (argc < 2 ) { |
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| 89 | fprintf(stderr, "Usage: securetty <device>\n"); |
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| 90 | exit(1); |
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| 91 | } |
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| 92 | openlog("securetty", LOG_CONS, LOG_DAEMON); |
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| 93 | return rewrite_securetty(argv[1]); |
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| 94 | } |
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