Annotation of src/usr.bin/ssh/sshpty.c, Revision 1.13
1.1 djm 1: /*
2: * Author: Tatu Ylonen <ylo@cs.hut.fi>
3: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: * All rights reserved
5: * Allocating a pseudo-terminal, and making it the controlling tty.
6: *
7: * As far as I am concerned, the code I have written for this software
8: * can be used freely for any purpose. Any derived versions of this
9: * software must be clearly marked as such, and if the derived work is
10: * incompatible with the protocol description in the RFC file, it must be
11: * called by a name other than "ssh" or "Secure Shell".
12: */
13:
14: #include "includes.h"
1.13 ! stevesk 15: RCSID("$OpenBSD: sshpty.c,v 1.12 2004/06/21 17:36:31 avsm Exp $");
1.1 djm 16:
1.13 ! stevesk 17: #include <termios.h>
1.1 djm 18: #include <util.h>
1.13 ! stevesk 19:
1.1 djm 20: #include "sshpty.h"
21: #include "log.h"
22:
23: /* Pty allocated with _getpty gets broken if we do I_PUSH:es to it. */
24: #if defined(HAVE__GETPTY) || defined(HAVE_OPENPTY)
25: #undef HAVE_DEV_PTMX
26: #endif
27:
28: #ifndef O_NOCTTY
29: #define O_NOCTTY 0
30: #endif
31:
32: /*
33: * Allocates and opens a pty. Returns 0 if no pty could be allocated, or
34: * nonzero if a pty was successfully allocated. On success, open file
35: * descriptors for the pty and tty sides and the name of the tty side are
36: * returned (the buffer must be able to hold at least 64 characters).
37: */
38:
39: int
40: pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, int namebuflen)
41: {
42: char buf[64];
43: int i;
44:
45: i = openpty(ptyfd, ttyfd, buf, NULL, NULL);
46: if (i < 0) {
47: error("openpty: %.100s", strerror(errno));
48: return 0;
49: }
50: strlcpy(namebuf, buf, namebuflen); /* possible truncation */
51: return 1;
52: }
53:
54: /* Releases the tty. Its ownership is returned to root, and permissions to 0666. */
55:
56: void
1.12 avsm 57: pty_release(const char *tty)
1.1 djm 58: {
1.12 avsm 59: if (chown(tty, (uid_t) 0, (gid_t) 0) < 0)
60: error("chown %.100s 0 0 failed: %.100s", tty, strerror(errno));
61: if (chmod(tty, (mode_t) 0666) < 0)
62: error("chmod %.100s 0666 failed: %.100s", tty, strerror(errno));
1.1 djm 63: }
64:
1.10 markus 65: /* Makes the tty the process's controlling tty and sets it to sane modes. */
1.1 djm 66:
67: void
1.12 avsm 68: pty_make_controlling_tty(int *ttyfd, const char *tty)
1.1 djm 69: {
70: int fd;
71:
72: /* First disconnect from the old controlling tty. */
73: #ifdef TIOCNOTTY
74: fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
75: if (fd >= 0) {
76: (void) ioctl(fd, TIOCNOTTY, NULL);
77: close(fd);
78: }
79: #endif /* TIOCNOTTY */
80: if (setsid() < 0)
81: error("setsid: %.100s", strerror(errno));
82:
83: /*
84: * Verify that we are successfully disconnected from the controlling
85: * tty.
86: */
87: fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
88: if (fd >= 0) {
89: error("Failed to disconnect from controlling tty.");
90: close(fd);
91: }
92: /* Make it our controlling tty. */
93: #ifdef TIOCSCTTY
94: debug("Setting controlling tty using TIOCSCTTY.");
95: if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0)
96: error("ioctl(TIOCSCTTY): %.100s", strerror(errno));
97: #endif /* TIOCSCTTY */
1.12 avsm 98: fd = open(tty, O_RDWR);
1.1 djm 99: if (fd < 0)
1.12 avsm 100: error("%.100s: %.100s", tty, strerror(errno));
1.1 djm 101: else
102: close(fd);
103:
104: /* Verify that we now have a controlling tty. */
105: fd = open(_PATH_TTY, O_WRONLY);
106: if (fd < 0)
107: error("open /dev/tty failed - could not set controlling tty: %.100s",
1.4 deraadt 108: strerror(errno));
1.6 deraadt 109: else
1.1 djm 110: close(fd);
111: }
112:
113: /* Changes the window size associated with the pty. */
114:
115: void
116: pty_change_window_size(int ptyfd, int row, int col,
1.4 deraadt 117: int xpixel, int ypixel)
1.1 djm 118: {
119: struct winsize w;
1.6 deraadt 120:
1.1 djm 121: w.ws_row = row;
122: w.ws_col = col;
123: w.ws_xpixel = xpixel;
124: w.ws_ypixel = ypixel;
125: (void) ioctl(ptyfd, TIOCSWINSZ, &w);
126: }
127:
128: void
1.12 avsm 129: pty_setowner(struct passwd *pw, const char *tty)
1.1 djm 130: {
131: struct group *grp;
132: gid_t gid;
133: mode_t mode;
134: struct stat st;
135:
136: /* Determine the group to make the owner of the tty. */
137: grp = getgrnam("tty");
138: if (grp) {
139: gid = grp->gr_gid;
140: mode = S_IRUSR | S_IWUSR | S_IWGRP;
141: } else {
142: gid = pw->pw_gid;
143: mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH;
144: }
145:
146: /*
147: * Change owner and mode of the tty as required.
1.3 markus 148: * Warn but continue if filesystem is read-only and the uids match/
149: * tty is owned by root.
1.1 djm 150: */
1.12 avsm 151: if (stat(tty, &st))
152: fatal("stat(%.100s) failed: %.100s", tty,
1.1 djm 153: strerror(errno));
154:
155: if (st.st_uid != pw->pw_uid || st.st_gid != gid) {
1.12 avsm 156: if (chown(tty, pw->pw_uid, gid) < 0) {
1.4 deraadt 157: if (errno == EROFS &&
1.6 deraadt 158: (st.st_uid == pw->pw_uid || st.st_uid == 0))
1.8 markus 159: debug("chown(%.100s, %u, %u) failed: %.100s",
1.12 avsm 160: tty, (u_int)pw->pw_uid, (u_int)gid,
1.4 deraadt 161: strerror(errno));
1.1 djm 162: else
1.5 deraadt 163: fatal("chown(%.100s, %u, %u) failed: %.100s",
1.12 avsm 164: tty, (u_int)pw->pw_uid, (u_int)gid,
1.4 deraadt 165: strerror(errno));
1.1 djm 166: }
167: }
168:
169: if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) {
1.12 avsm 170: if (chmod(tty, mode) < 0) {
1.1 djm 171: if (errno == EROFS &&
172: (st.st_mode & (S_IRGRP | S_IROTH)) == 0)
1.8 markus 173: debug("chmod(%.100s, 0%o) failed: %.100s",
1.12 avsm 174: tty, (u_int)mode, strerror(errno));
1.1 djm 175: else
176: fatal("chmod(%.100s, 0%o) failed: %.100s",
1.12 avsm 177: tty, (u_int)mode, strerror(errno));
1.1 djm 178: }
179: }
180: }
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