1 | /* |
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2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
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3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
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4 | * All rights reserved |
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5 | * Allocating a pseudo-terminal, and making it the controlling tty. |
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6 | * |
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7 | * As far as I am concerned, the code I have written for this software |
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8 | * can be used freely for any purpose. Any derived versions of this |
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9 | * software must be clearly marked as such, and if the derived work is |
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10 | * incompatible with the protocol description in the RFC file, it must be |
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11 | * called by a name other than "ssh" or "Secure Shell". |
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12 | */ |
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13 | |
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14 | #include "includes.h" |
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15 | RCSID("$OpenBSD: sshpty.c,v 1.12 2004/06/21 17:36:31 avsm Exp $"); |
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16 | |
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17 | #ifdef HAVE_UTIL_H |
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18 | # include <util.h> |
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19 | #endif /* HAVE_UTIL_H */ |
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20 | |
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21 | #include "sshpty.h" |
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22 | #include "log.h" |
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23 | #include "misc.h" |
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24 | |
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25 | #ifdef HAVE_PTY_H |
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26 | # include <pty.h> |
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27 | #endif |
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28 | |
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29 | #ifndef O_NOCTTY |
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30 | #define O_NOCTTY 0 |
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31 | #endif |
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32 | |
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33 | /* |
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34 | * Allocates and opens a pty. Returns 0 if no pty could be allocated, or |
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35 | * nonzero if a pty was successfully allocated. On success, open file |
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36 | * descriptors for the pty and tty sides and the name of the tty side are |
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37 | * returned (the buffer must be able to hold at least 64 characters). |
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38 | */ |
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39 | |
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40 | int |
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41 | pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, int namebuflen) |
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42 | { |
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43 | /* openpty(3) exists in OSF/1 and some other os'es */ |
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44 | char *name; |
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45 | int i; |
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46 | |
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47 | i = openpty(ptyfd, ttyfd, NULL, NULL, NULL); |
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48 | if (i < 0) { |
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49 | error("openpty: %.100s", strerror(errno)); |
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50 | return 0; |
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51 | } |
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52 | name = ttyname(*ttyfd); |
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53 | if (!name) |
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54 | fatal("openpty returns device for which ttyname fails."); |
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55 | |
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56 | strlcpy(namebuf, name, namebuflen); /* possible truncation */ |
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57 | return 1; |
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58 | } |
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59 | |
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60 | /* Releases the tty. Its ownership is returned to root, and permissions to 0666. */ |
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61 | |
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62 | void |
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63 | pty_release(const char *tty) |
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64 | { |
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65 | if (chown(tty, (uid_t) 0, (gid_t) 0) < 0) |
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66 | error("chown %.100s 0 0 failed: %.100s", tty, strerror(errno)); |
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67 | if (chmod(tty, (mode_t) 0666) < 0) |
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68 | error("chmod %.100s 0666 failed: %.100s", tty, strerror(errno)); |
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69 | } |
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70 | |
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71 | /* Makes the tty the process's controlling tty and sets it to sane modes. */ |
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72 | |
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73 | void |
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74 | pty_make_controlling_tty(int *ttyfd, const char *tty) |
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75 | { |
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76 | int fd; |
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77 | #ifdef USE_VHANGUP |
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78 | void *old; |
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79 | #endif /* USE_VHANGUP */ |
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80 | |
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81 | #ifdef _UNICOS |
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82 | if (setsid() < 0) |
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83 | error("setsid: %.100s", strerror(errno)); |
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84 | |
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85 | fd = open(tty, O_RDWR|O_NOCTTY); |
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86 | if (fd != -1) { |
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87 | signal(SIGHUP, SIG_IGN); |
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88 | ioctl(fd, TCVHUP, (char *)NULL); |
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89 | signal(SIGHUP, SIG_DFL); |
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90 | setpgid(0, 0); |
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91 | close(fd); |
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92 | } else { |
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93 | error("Failed to disconnect from controlling tty."); |
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94 | } |
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95 | |
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96 | debug("Setting controlling tty using TCSETCTTY."); |
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97 | ioctl(*ttyfd, TCSETCTTY, NULL); |
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98 | fd = open("/dev/tty", O_RDWR); |
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99 | if (fd < 0) |
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100 | error("%.100s: %.100s", tty, strerror(errno)); |
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101 | close(*ttyfd); |
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102 | *ttyfd = fd; |
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103 | #else /* _UNICOS */ |
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104 | |
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105 | /* First disconnect from the old controlling tty. */ |
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106 | #ifdef TIOCNOTTY |
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107 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); |
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108 | if (fd >= 0) { |
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109 | (void) ioctl(fd, TIOCNOTTY, NULL); |
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110 | close(fd); |
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111 | } |
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112 | #endif /* TIOCNOTTY */ |
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113 | if (setsid() < 0) |
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114 | error("setsid: %.100s", strerror(errno)); |
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115 | |
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116 | /* |
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117 | * Verify that we are successfully disconnected from the controlling |
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118 | * tty. |
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119 | */ |
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120 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); |
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121 | if (fd >= 0) { |
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122 | error("Failed to disconnect from controlling tty."); |
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123 | close(fd); |
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124 | } |
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125 | /* Make it our controlling tty. */ |
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126 | #ifdef TIOCSCTTY |
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127 | debug("Setting controlling tty using TIOCSCTTY."); |
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128 | if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0) |
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129 | error("ioctl(TIOCSCTTY): %.100s", strerror(errno)); |
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130 | #endif /* TIOCSCTTY */ |
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131 | #ifdef NEED_SETPGRP |
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132 | if (setpgrp(0,0) < 0) |
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133 | error("SETPGRP %s",strerror(errno)); |
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134 | #endif /* NEED_SETPGRP */ |
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135 | #ifdef USE_VHANGUP |
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136 | old = signal(SIGHUP, SIG_IGN); |
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137 | vhangup(); |
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138 | signal(SIGHUP, old); |
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139 | #endif /* USE_VHANGUP */ |
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140 | fd = open(tty, O_RDWR); |
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141 | if (fd < 0) { |
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142 | error("%.100s: %.100s", tty, strerror(errno)); |
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143 | } else { |
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144 | #ifdef USE_VHANGUP |
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145 | close(*ttyfd); |
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146 | *ttyfd = fd; |
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147 | #else /* USE_VHANGUP */ |
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148 | close(fd); |
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149 | #endif /* USE_VHANGUP */ |
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150 | } |
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151 | /* Verify that we now have a controlling tty. */ |
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152 | fd = open(_PATH_TTY, O_WRONLY); |
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153 | if (fd < 0) |
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154 | error("open /dev/tty failed - could not set controlling tty: %.100s", |
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155 | strerror(errno)); |
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156 | else |
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157 | close(fd); |
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158 | #endif /* _UNICOS */ |
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159 | } |
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160 | |
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161 | /* Changes the window size associated with the pty. */ |
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162 | |
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163 | void |
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164 | pty_change_window_size(int ptyfd, int row, int col, |
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165 | int xpixel, int ypixel) |
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166 | { |
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167 | struct winsize w; |
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168 | |
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169 | w.ws_row = row; |
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170 | w.ws_col = col; |
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171 | w.ws_xpixel = xpixel; |
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172 | w.ws_ypixel = ypixel; |
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173 | (void) ioctl(ptyfd, TIOCSWINSZ, &w); |
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174 | } |
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175 | |
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176 | void |
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177 | pty_setowner(struct passwd *pw, const char *tty) |
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178 | { |
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179 | struct group *grp; |
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180 | gid_t gid; |
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181 | mode_t mode; |
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182 | struct stat st; |
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183 | |
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184 | /* Determine the group to make the owner of the tty. */ |
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185 | grp = getgrnam("tty"); |
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186 | if (grp) { |
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187 | gid = grp->gr_gid; |
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188 | mode = S_IRUSR | S_IWUSR | S_IWGRP; |
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189 | } else { |
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190 | gid = pw->pw_gid; |
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191 | mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH; |
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192 | } |
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193 | |
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194 | /* |
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195 | * Change owner and mode of the tty as required. |
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196 | * Warn but continue if filesystem is read-only and the uids match/ |
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197 | * tty is owned by root. |
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198 | */ |
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199 | if (stat(tty, &st)) |
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200 | fatal("stat(%.100s) failed: %.100s", tty, |
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201 | strerror(errno)); |
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202 | |
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203 | if (st.st_uid != pw->pw_uid || st.st_gid != gid) { |
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204 | if (chown(tty, pw->pw_uid, gid) < 0) { |
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205 | if (errno == EROFS && |
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206 | (st.st_uid == pw->pw_uid || st.st_uid == 0)) |
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207 | debug("chown(%.100s, %u, %u) failed: %.100s", |
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208 | tty, (u_int)pw->pw_uid, (u_int)gid, |
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209 | strerror(errno)); |
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210 | else |
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211 | fatal("chown(%.100s, %u, %u) failed: %.100s", |
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212 | tty, (u_int)pw->pw_uid, (u_int)gid, |
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213 | strerror(errno)); |
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214 | } |
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215 | } |
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216 | |
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217 | if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) { |
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218 | if (chmod(tty, mode) < 0) { |
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219 | if (errno == EROFS && |
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220 | (st.st_mode & (S_IRGRP | S_IROTH)) == 0) |
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221 | debug("chmod(%.100s, 0%o) failed: %.100s", |
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222 | tty, (u_int)mode, strerror(errno)); |
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223 | else |
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224 | fatal("chmod(%.100s, 0%o) failed: %.100s", |
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225 | tty, (u_int)mode, strerror(errno)); |
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226 | } |
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227 | } |
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228 | } |
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