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authorAlan Cox <alan@redhat.com>2008-10-13 05:41:03 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-13 12:51:42 -0400
commit15582d36a15978355d2168eaa018a3736db7281f (patch)
tree6ea2b94bb4504cf0d8dffdecbd85a60fe0d69c06 /drivers/char
parentdbda4c0b97b18fd59b3964548361b4f92357f730 (diff)
pty: If the administrator creates a device for a ptmx slave we should not error
The open path for ptmx slaves is via the ptmx device. Opening them any other way is not allowed. Vegard Nossum found that previously this was not the case and mknod foo c 128 42; cat foo would produce nasty diagnostics Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/tty_io.c18
1 files changed, 12 insertions, 6 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index f40298e9873a..2e96ce0fddc5 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1227,7 +1227,8 @@ static void tty_line_name(struct tty_driver *driver, int index, char *p)
1227 * init_dev - initialise a tty device 1227 * init_dev - initialise a tty device
1228 * @driver: tty driver we are opening a device on 1228 * @driver: tty driver we are opening a device on
1229 * @idx: device index 1229 * @idx: device index
1230 * @tty: returned tty structure 1230 * @ret_tty: returned tty structure
1231 * @first_ok: ok to open a new device (used by ptmx)
1231 * 1232 *
1232 * Prepare a tty device. This may not be a "new" clean device but 1233 * Prepare a tty device. This may not be a "new" clean device but
1233 * could also be an active device. The pty drivers require special 1234 * could also be an active device. The pty drivers require special
@@ -1248,7 +1249,7 @@ static void tty_line_name(struct tty_driver *driver, int index, char *p)
1248 */ 1249 */
1249 1250
1250static int init_dev(struct tty_driver *driver, int idx, 1251static int init_dev(struct tty_driver *driver, int idx,
1251 struct tty_struct **ret_tty) 1252 struct tty_struct **ret_tty, int first_ok)
1252{ 1253{
1253 struct tty_struct *tty, *o_tty; 1254 struct tty_struct *tty, *o_tty;
1254 struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc; 1255 struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc;
@@ -1279,6 +1280,11 @@ static int init_dev(struct tty_driver *driver, int idx,
1279 } 1280 }
1280 if (tty) goto fast_track; 1281 if (tty) goto fast_track;
1281 1282
1283 if (driver->subtype == PTY_TYPE_MASTER &&
1284 (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
1285 retval = -EIO;
1286 goto end_init;
1287 }
1282 /* 1288 /*
1283 * First time open is complex, especially for PTY devices. 1289 * First time open is complex, especially for PTY devices.
1284 * This code guarantees that either everything succeeds and the 1290 * This code guarantees that either everything succeeds and the
@@ -1413,7 +1419,7 @@ static int init_dev(struct tty_driver *driver, int idx,
1413 1419
1414 if (retval) 1420 if (retval)
1415 goto release_mem_out; 1421 goto release_mem_out;
1416 goto success; 1422 goto success;
1417 1423
1418 /* 1424 /*
1419 * This fast open can be used if the tty is already open. 1425 * This fast open can be used if the tty is already open.
@@ -1795,7 +1801,7 @@ static void release_dev(struct file *filp)
1795} 1801}
1796 1802
1797/** 1803/**
1798 * tty_open - open a tty device 1804 * __tty_open - open a tty device
1799 * @inode: inode of device file 1805 * @inode: inode of device file
1800 * @filp: file pointer to tty 1806 * @filp: file pointer to tty
1801 * 1807 *
@@ -1874,7 +1880,7 @@ retry_open:
1874 return -ENODEV; 1880 return -ENODEV;
1875 } 1881 }
1876got_driver: 1882got_driver:
1877 retval = init_dev(driver, index, &tty); 1883 retval = init_dev(driver, index, &tty, 0);
1878 mutex_unlock(&tty_mutex); 1884 mutex_unlock(&tty_mutex);
1879 if (retval) 1885 if (retval)
1880 return retval; 1886 return retval;
@@ -1971,7 +1977,7 @@ static int __ptmx_open(struct inode *inode, struct file *filp)
1971 return index; 1977 return index;
1972 1978
1973 mutex_lock(&tty_mutex); 1979 mutex_lock(&tty_mutex);
1974 retval = init_dev(ptm_driver, index, &tty); 1980 retval = init_dev(ptm_driver, index, &tty, 1);
1975 mutex_unlock(&tty_mutex); 1981 mutex_unlock(&tty_mutex);
1976 1982
1977 if (retval) 1983 if (retval)