Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 24 Mar 2010 14:24:00 +0100 | Subject | Re: [rt2x00-users] [PATCH RFC] rt2500usb: disable broken HW encryption by default | From | Ivo Van Doorn <> |
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On Wed, Mar 24, 2010 at 2:12 PM, Ondrej Zary <linux@rainbow-software.org> wrote: > On Tuesday 23 March 2010, Ivo Van Doorn wrote: >> On Tue, Mar 23, 2010 at 4:09 PM, Ondrej Zary <linux@rainbow-software.org> > wrote: >> > On Tuesday 23 March 2010, Ivo Van Doorn wrote: >> >> On Tue, Mar 23, 2010 at 10:27 AM, Ondrej Zary >> >> >> >> <linux@rainbow-software.org> wrote: >> >> > On Monday 22 March 2010, Ivo Van Doorn wrote: >> >> >> >> But I though it was mentioned that disabling HW crypto didn't >> >> >> >> solve the issue due to a second bug in a later kernel? >> >> >> > >> >> >> > That was a false positive. Probably because the device was not >> >> >> > unplugged between the tests (and looks like the driver does not >> >> >> > initialize the chip completely). It's not reliable, it sometimes >> >> >> > stops working after reboot. >> >> >> >> >> >> Ah well that at least simplifies the problem. I'll have to retest >> >> >> rt2500usb soon to see why the HW crypto failed. I am sure I had it >> >> >> working for WEP, WPA and WPA2 >> >> >> before I submitted the patch. >> >> > >> >> > So let's try to fix it instead of disabling. >> >> > >> >> > First, the unrealiability (keeping HW encryption disabled). With the >> >> > driver loaded but not doing anything more, the register dumps are same >> >> > for both working and non-working case (dump-init.txt). >> >> > >> >> > dump-good-connected.txt is a dump after successful association and >> >> > DHCP dump-bad-attempt.txt is a dump after successful association >> >> > during non-working DHCP attempt >> >> > dump-bad-after.txt is a dump after DHCP timed out >> >> >> >> With association working, but DHCP failing it most likely means that >> >> somehow the frame was malformatted. >> >> The code for HW crypto alters the frame (alters IV/EIV/ICV data etc). >> >> And that is commonly the source of >> >> problems, because what has to be done depends heavily on the encryption >> >> type. >> >> >> >> So could you verify which of the encryption types (WEP,WPA,WPA2) is >> >> failing or working? That would give a starting >> >> position on which bytes might be corrupted. >> > >> > I was testing only with WPA2 before. I did some more testing today. The >> > results: >> > >> > No encryption - works always >> > WEP - sometimes works, sometimes not - same with and without HW >> > encryption WPA - sometimes works, sometimes not - same with and without >> > HW encryption WPA2 - never works with HW encryption >> > - sometimes works, sometimes not without HW encryptionn >> > >> > So it seems that there are two problems: >> > 1. random problems with any encryption >> > 2. WPA2 is broken with HW encryption >> > >> > When the "random" problem appears, this appears in dmesg: >> > wlan1: authenticate with 00:13:d4:0f:f3:17 (try 1) >> > wlan1: authenticated >> > wlan1: associate with 00:13:d4:0f:f3:17 (try 1) >> > wlan1: RX AssocResp from 00:13:d4:0f:f3:17 (capab=0x411 status=0 aid=2) >> > wlan1: associated >> > phy0 -> rt2500usb_set_device_state: Error - Device failed to enter state >> > 3 (-16). phy0 -> rt2500usb_set_device_state: Error - Device failed to >> > enter state 3 (-16). No probe response from AP 00:13:d4:0f:f3:17 after >> > 500ms, disconnecting. >> > >> > Disabling call to rt2500usb_set_state() in rt2500usb_set_device_state() >> > seems to fix problem 1. After this change, WEP and WPA work always >> > regardless of HW encryption (and WPA2 works always without it). >> >> Ok, lets focus on the HW crypto for now. >> >> If WPA2 fails, then the WPA2 specific code for IV/EIV/ICV isn't >> working. Most likely >> the device either doesn't send all data back to the driver (while the >> driver does expect it) >> or it adds additional data which the driver doesn't expect. (See >> rt2x00crypto.c for the frame >> manipulation during HW crypto). >> >> Could you check the full packet data of a DHCP request with and >> without HW crypto? >> That might give a clue about what the hardware is sending for extra data. > > How do I access the full packets? I tried using another machine with "iwconfig > wlan0 mode monitor" and tcpdump. It captured many packets and I'm unable to > identify the interesting ones.
You won't get the useful stuff from monitor mode. You have to enable rt2x00 debugfs support, to find a framedump file in the rt2x00 debugfs folder.
You should use the framedump tool from: http://kernel.org/pub/linux/kernel/people/ivd/tools/
To get the frame dumps in nicely formatted lines for analysis.
Ivo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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