path: root/net/rfkill
diff options
authorJohannes Berg <johannes@sipsolutions.net>2009-07-05 14:51:06 +0200
committerJohn W. Linville <linville@tuxdriver.com>2009-07-10 15:02:29 -0400
commit1be491fca12ff599c37ceaf7e9042ebee9f0068e (patch)
tree96033bde1ed8561201c42574ec716f7cfd033697 /net/rfkill
parent3355443ad7601991affa5992b0d53870335af765 (diff)
rfkill: prep for rfkill API changes
We've designed the /dev/rfkill API in a way that we can increase the event struct by adding members at the end, should it become necessary. To validate the events, userspace and the kernel need to have the proper event size to check for -- when reading from the other end they need to verify that it's at least version 1 of the event API, with the current struct size, so define a constant for that and make the code a little more 'future proof'. Not that I expect that we'll have to change the event size any time soon, but it's better to write the code in a way that lends itself to extending. Due to the current size of the event struct, the code is currently equivalent, but should the event struct ever need to be increased the new code might not need changing. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'net/rfkill')
1 files changed, 8 insertions, 2 deletions
diff --git a/net/rfkill/core.c b/net/rfkill/core.c
index 79693fe2001..47497c97c8d 100644
--- a/net/rfkill/core.c
+++ b/net/rfkill/core.c
@@ -1076,10 +1076,16 @@ static ssize_t rfkill_fop_write(struct file *file, const char __user *buf,
struct rfkill_event ev;
/* we don't need the 'hard' variable but accept it */
- if (count < sizeof(ev) - 1)
+ if (count < RFKILL_EVENT_SIZE_V1 - 1)
return -EINVAL;
- if (copy_from_user(&ev, buf, sizeof(ev) - 1))
+ /*
+ * Copy as much data as we can accept into our 'ev' buffer,
+ * but tell userspace how much we've copied so it can determine
+ * our API version even in a write() call, if it cares.
+ */
+ count = min(count, sizeof(ev));
+ if (copy_from_user(&ev, buf, count))
return -EFAULT;
if (ev.op != RFKILL_OP_CHANGE && ev.op != RFKILL_OP_CHANGE_ALL)