cleanup hack added in v2.6.27-3203-g15582d3 comment from that patch: : 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> devpts_get_tty() returns non-null only for inodes on devpts, but there is no inodes for master-devices, /dev/ptmx (/dev/pts/ptmx) is the only way to open them. Thus we can completely forbid lookup for master-devices and eliminate that hack in tty_init_dev() because tty_open() will get EIO from tty_driver_lookup_tty().
Unified · Split
| @@ -515,10 +515,8 @@ static int pty_unix98_ioctl(struct tty_struct *tty, · 514 unmodified lines | ||
| 515 | 515 | static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver, |
| 516 | 516 | struct inode *ptm_inode, int idx) |
| 517 | 517 | { |
| 518 | − struct tty_struct *tty = devpts_get_tty(ptm_inode, idx); | |
| 519 | − if (tty) | |
| 520 | − tty = tty->link; | |
| 521 | − return tty; | |
| 518 | + /* Master must be open via /dev/ptmx */ | |
| 519 | + return ERR_PTR(-EIO); | |
| 522 | 520 | } |
| 523 | 521 | |
| 524 | 522 | /** |
| @@ -677,7 +675,7 @@ static int ptmx_open(struct inode *inode, struct file *filp) · 152 unmodified lines | ||
| 677 | 675 | |
| 678 | 676 | mutex_lock(&tty_mutex); |
| 679 | 677 | tty_lock(); |
| 680 | − tty = tty_init_dev(ptm_driver, index, 1); | |
| 678 | + tty = tty_init_dev(ptm_driver, index); | |
| 681 | 679 | mutex_unlock(&tty_mutex); |
| 682 | 680 | |
| 683 | 681 | if (IS_ERR(tty)) { |
| @@ -1365,7 +1365,6 @@ static int tty_reopen(struct tty_struct *tty) · 1364 unmodified lines | ||
| 1365 | 1365 | * @driver: tty driver we are opening a device on |
| 1366 | 1366 | * @idx: device index |
| 1367 | 1367 | * @ret_tty: returned tty structure |
| 1368 | − * @first_ok: ok to open a new device (used by ptmx) | |
| 1369 | 1368 | * |
| 1370 | 1369 | * Prepare a tty device. This may not be a "new" clean device but |
| 1371 | 1370 | * could also be an active device. The pty drivers require special |
| @@ -1385,18 +1384,11 @@ static int tty_reopen(struct tty_struct *tty) · 13 unmodified lines | ||
| 1385 | 1384 | * relaxed for the (most common) case of reopening a tty. |
| 1386 | 1385 | */ |
| 1387 | 1386 | |
| 1388 | −struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx, | |
| 1389 | − int first_ok) | |
| 1387 | +struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx) | |
| 1390 | 1388 | { |
| 1391 | 1389 | struct tty_struct *tty; |
| 1392 | 1390 | int retval; |
| 1393 | 1391 | |
| 1394 | − /* Check if pty master is being opened multiple times */ | |
| 1395 | − if (driver->subtype == PTY_TYPE_MASTER && | |
| 1396 | − (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) { | |
| 1397 | − return ERR_PTR(-EIO); | |
| 1398 | − } | |
| 1399 | − | |
| 1400 | 1392 | /* |
| 1401 | 1393 | * First time open is complex, especially for PTY devices. |
| 1402 | 1394 | * This code guarantees that either everything succeeds and the |
| @@ -1950,7 +1942,7 @@ retry_open: · 547 unmodified lines | ||
| 1950 | 1942 | if (retval) |
| 1951 | 1943 | tty = ERR_PTR(retval); |
| 1952 | 1944 | } else |
| 1953 | − tty = tty_init_dev(driver, index, 0); | |
| 1945 | + tty = tty_init_dev(driver, index); | |
| 1954 | 1946 | |
| 1955 | 1947 | mutex_unlock(&tty_mutex); |
| 1956 | 1948 | if (driver) |
| @@ -480,8 +480,7 @@ extern void free_tty_struct(struct tty_struct *tty); · 479 unmodified lines | ||
| 480 | 480 | extern void initialize_tty_struct(struct tty_struct *tty, |
| 481 | 481 | struct tty_driver *driver, int idx); |
| 482 | 482 | extern void deinitialize_tty_struct(struct tty_struct *tty); |
| 483 | −extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx, | |
| 484 | − int first_ok); | |
| 483 | +extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx); | |
| 485 | 484 | extern int tty_release(struct inode *inode, struct file *filp); |
| 486 | 485 | extern int tty_init_termios(struct tty_struct *tty); |
| 487 | 486 | |