Return-path: Received: from mail-yw0-f198.google.com ([209.85.211.198]:38530 "EHLO mail-yw0-f198.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754971Ab0C1SZZ (ORCPT ); Sun, 28 Mar 2010 14:25:25 -0400 Received: by ywh36 with SMTP id 36so2918459ywh.4 for ; Sun, 28 Mar 2010 11:25:24 -0700 (PDT) Message-ID: <4BAF9F11.6050802@lwfinger.net> Date: Sun, 28 Mar 2010 13:25:21 -0500 From: Larry Finger MIME-Version: 1.0 To: =?ISO-8859-1?Q?Nicolas_de_Peslo=FCan?= CC: Michael Buesch , Calvin Walton , linux-wireless@vger.kernel.org, b43-dev@lists.infradead.org Subject: Re: [PATCH V2] ssb: Implement virtual SPROM on disk References: <4ba6aa45.z5Wso1NMth9eMeFG%Larry.Finger@lwfinger.net> <1269377903.21181.8.camel@nayuki> <4BAA1EA3.9060803@lwfinger.net> <201003242021.39502.mb@bu3sch.de> <4BAC2E36.8000900@lwfinger.net> <4BAF8E62.4060902@free.fr> In-Reply-To: <4BAF8E62.4060902@free.fr> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 03/28/2010 12:14 PM, Nicolas de Peslo?an wrote: > Larry Finger wrote: >> On 03/24/2010 02:21 PM, Michael Buesch wrote: >>> On Wednesday 24 March 2010 15:16:03 Larry Finger wrote: >>>> I have modified ssb to supply a MAC address of 80:80:80:80:80:80, >>>> rather than >>> What about also setting the local-assignment bit for this temporary >>> address? >>> >>>> The one remaining problem is that the interface has already been >>>> renamed before >>>> 60-persistent-b43-mac.rules is processed. In my case, the interface >>>> is wlan13, >>>> not wlan0. After I manually modified 60-..., then the new address is >>>> applied. >>>> I'm still working on this problem. >>> Well, udev scripts are processed in alphabetical order. Can't you >>> simply run >>> the persistent mac rules before the persistent ifname rules? >> >> I finally figured out the problem I was having. The address attribute >> was not >> being changed by the "ifconfig" call that changed the hardware >> address. The fix >> is to create a new environment when the hardware address and lock out >> the rule >> generation process when that value is detected. The new code for >> /lib/udev/rules.d/65-persistent-b43-mac-generator.rules is as follows >> (Note: >> These files are line-wrapped here.): >> >> #======================================= >> # >> # Rules file to assign a unique, permanent address to BCM43XX devices >> without >> # an SPROM. >> # >> # Copyright (c) 2010 by Calvin Walton >> # Copyright (c) 2010 by Larry Finger >> >> # skip this code if action is not add, i.e. change or remove >> >> ACTION!="add", GOTO="persistent_b43_mac_generator_end" >> >> # Use the value of the MAC_CHANGED environment variable to see if the >> address >> # has already been changed. >> >> ENV{MAC_CHANGED}=="yes", GOTO="persistent_b43_mac_generator_end" >> >> # Call script to get a random address - if this device previously >> encountered, >> # the address will already have been changed. >> >> SUBSYSTEM=="net", ATTR{address}=="82:82:82:82:82:82", >> IMPORT{program}="write_persistent_b43_mac" >> >> # Apply the new hardware address returned by the script >> >> SUBSYSTEM=="net", ATTR{address}=="82:82:82:82:82:82", >> RUN+="/sbin/ifconfig >> $env{INTERFACE} hw ether $env{MACADDRESS_NEW}" > > Why do you use ifconfig hw ether instead of ip link set address ? > >> LABEL="persistent_b43_mac_generator_end" >> #======================================= >> >> The code for /lib/udev/write_persistent_b43_mac is as follows: >> >> #======================================= >> #!/bin/bash >> >> # Script to Generate a random MAC address for a BCM43XX device without >> # an SPROM. >> # >> # Copyright (c) 2010 by Calvin Walton >> # Copyright (c) 2010 by Larry Finger >> >> # Use /dev/urandom to generate the last 5 bytes of the address. >> # Make the first byte 2 to avoid generating a multicast address and to >> set >> # the locally administered address bit. >> >> MACADDRESS=$(/bin/dd if=/dev/urandom bs=1 count=5 2>/dev/null | >> /usr/bin/od -tx1 >> | /usr/bin/head -1 | \ >> /usr/bin/cut -d' ' -f2- | /usr/bin/awk '{ print >> "02:"$1":"$2":"$3":"$4":"$5 }') > > A suggest the following : > > - 6 bytes of randomness and force lower half of first byte to 2 if the > value does not have bit #2 set. > - sed, instead of head|cut|awk > > MACADDRESS=$(/bin/dd if=/dev/random bs=1 count=6 2>/dev/null | > /usr/bin/od -tx1 | > sed -ne '1{;s/0000000 //;s/^\(.\)[014589cd]/\12/;y/ /:/;p}' It also needs to be even as an odd value would be a broadcast address. Using only sed instead of head|cut|awk does have merit and the randomness is increased by 6 bits. It will take me a while to understand the sed here. Regular expressions are not my thing. >> # Define the output rules file >> RULES_FILE='/etc/udev/rules.d/60-persistent-b43-mac.rules' >> >> . /lib/udev/rule_generator.functions >> >> # Prevent concurrent processes from modifying the file at the same time. >> lock_rules_file >> >> # Check if the rules file is writeable. >> choose_rules_file >> >> # The rule should apply for all wlan devices -s some other wireless >> driver might >> # be loaded first - change wlanNN to wlan* >> GEN_PATH=$(echo $DEVPATH | /usr/bin/sed s/wlan[0-9]*/wlan*/) > > sed should be quoted here : /usr/bin/sed -e 's/wlan[0-9]*/wlan*/' > Else, it might be fun if you happen to have a file called s/wlan7/wlan15 > in current directory. OK - I see your point. As the current directory is /lib/udev, the presence of such a file is unlikely, but better to protect against the problem. >> # Output new rule >> echo "SUBSYSTEM==\"net\", DEVPATH==\"$GEN_PATH\", >> ATTR{address}==\"82:82:82:82:82:82\", ENV{MAC_CHANGED}=\"yes\", >> RUN+=\"/sbin/ifconfig \$env{INTERFACE} hw ether $MACADDRESS\"" >> >> $RULES_FILE > > If DEVPATH is "generic" (wlan*), how would you distinguish between two > broadcom NIC present in the system, both without an SPROM ? That is covered by the /devices/pci0000:00/0000:00:0d.0/0000:04:00.0/... part of DEVPATH. A second device on the same bridge would have ...04:01.0... and a device on a different bridge would change some other part of the string. The change to wlan* handles the case where the BCM43XX device is discovered first with some configuration, and second when another device is plugged in at discovery time. Larry