tun/tun.patch@0ba300bdf30a (annotated)
tun/tun.patch
Mon, 20 Apr 2009 19:22:00 +0200
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Mon, 20 Apr 2009 19:22:00 +0200
- changeset 178
- 0ba300bdf30a
- child 667
- 9dacbd1d1aa2
- permissions
- -rw-r--r--
Change unfortunate but partly useful overreaching security tradeoff.
The principle of allocating each running process an individual system
user and group can have security benefits, however maintining a plethora
of users, groups, processes, file modes, file permissions, and even
nonportable file ACLs on a host serving from a hundred processes has
some security disadvantages. This tradeoff is even worse for systems
like OpenPKG which benefit from administration transparency through the
use of minimal system intrusion and only three usage privilege levels.
| michael@75 | 1 | Index: linux/2.2/tun.c |
| michael@75 | 2 | --- linux/2.2/tun.c.orig 2006-10-10 14:45:00.338589000 +0200 |
| michael@75 | 3 | +++ linux/2.2/tun.c 2006-10-10 14:44:05.695404000 +0200 |
| michael@75 | 4 | @@ -178,10 +178,22 @@ |
| michael@75 | 5 | |
| michael@75 | 6 | DBG( KERN_INFO "%s: tun_chr_poll\n", tun->name); |
| michael@75 | 7 | |
| michael@75 | 8 | + /* Data written to the /dev/tunX device is immediately placed into a socket buffer, making it |
| michael@75 | 9 | + * available to networking code at the tunX interface. Writes never block. |
| michael@75 | 10 | + * Likewise, data flows from the network stack, through the tunX interface and into the /dev/tun* device, |
| michael@75 | 11 | + * where it is queued, making it available for read(). |
| michael@75 | 12 | + * Thus the character device /dev/tunX is: |
| michael@75 | 13 | + * - readable if data was "transmitted" to the tunX interface and is now queued at the /dev/tunX device. |
| michael@75 | 14 | + * - always writable. |
| michael@75 | 15 | + * Everything written here is equally true of taps. |
| michael@75 | 16 | + * The author made a mistake when implementing this routine; he forgot that the device is always writable. |
| michael@75 | 17 | + * -jeff stearns 22-Dec-2005 |
| michael@75 | 18 | + */ |
| michael@75 | 19 | + |
| michael@75 | 20 | poll_wait(file, &tun->read_wait, wait); |
| michael@75 | 21 | |
| michael@75 | 22 | if( skb_queue_len(&tun->txq) ) |
| michael@75 | 23 | - return POLLIN | POLLRDNORM; |
| michael@75 | 24 | + return POLLIN | POLLRDNORM | POLLOUT | POLLWRNORM; |
| michael@75 | 25 | |
| michael@75 | 26 | return POLLOUT | POLLWRNORM; |
| michael@75 | 27 | } |
| michael@75 | 28 | Index: linux/2.4/tun.c |
| michael@75 | 29 | --- linux/2.4/tun.c.orig 2006-10-10 14:41:57.910408000 +0200 |
| michael@75 | 30 | +++ linux/2.4/tun.c 2006-10-10 14:43:40.067700000 +0200 |
| michael@75 | 31 | @@ -176,9 +176,21 @@ |
| michael@75 | 32 | DBG(KERN_INFO "%s: tun_chr_poll\n", tun->name); |
| michael@75 | 33 | |
| michael@75 | 34 | poll_wait(file, &tun->read_wait, wait); |
| michael@75 | 35 | + |
| michael@75 | 36 | + /* Data written to the /dev/tunX device is immediately placed into a socket buffer, making it |
| michael@75 | 37 | + * available to networking code at the tunX interface. Writes never block. |
| michael@75 | 38 | + * Likewise, data flows from the network stack, through the tunX interface and into the /dev/tun* device, |
| michael@75 | 39 | + * where it is queued, making it available for read(). |
| michael@75 | 40 | + * Thus the character device /dev/tunX is: |
| michael@75 | 41 | + * - readable if data was "transmitted" to the tunX interface and is now queued at the /dev/tunX device. |
| michael@75 | 42 | + * - always writable. |
| michael@75 | 43 | + * Everything written here is equally true of taps. |
| michael@75 | 44 | + * The author made a mistake when implementing this routine; he forgot that the device is always writable. |
| michael@75 | 45 | + * -jeff stearns 22-Dec-2005 |
| michael@75 | 46 | + */ |
| michael@75 | 47 | |
| michael@75 | 48 | if (skb_queue_len(&tun->txq)) |
| michael@75 | 49 | - return POLLIN | POLLRDNORM; |
| michael@75 | 50 | + return POLLIN | POLLRDNORM | POLLOUT | POLLWRNORM; |
| michael@75 | 51 | |
| michael@75 | 52 | return POLLOUT | POLLWRNORM; |
| michael@75 | 53 | } |
