Folks, John Walker reported an issue with 3.10 kernels not having the max EIRP not set properly when CFG80211_INTERNAL_REGDB is used [0]. Krishna Chaitanya later confirmed this and annotated that an RFC I had posted a while back, shortly after the change the created this issue, is being carried over on OpenWrt as a fix for this [1]. The RFC was for new kernels and it seems we just never got around to following up and moving this upstream, so this change is certainly needed however upon review on issues with older kernels I found an issue with CFG80211_INTERNAL_REGDB which we hadn't considered before which we should review in terms of strategy for newer kernels to avoid these issues. Usage of CFG80211_INTERNAL_REGDB is popular for mobile and AP devices. I'm Cc'ing the netfilter folks in case they might have some ideas. By design we have ensured that we make wireless-regdb backward compatible with older versions of CRDA. We have done this well for a while now by not requiring a binary format file change, but realizing that at one point though we might have to upgrade the format and at which point we may require two file formats on wireless-regdb for different kernels. There's been some recent talks though over a new strategy however which could always enable backward compatibility. While those talks are underway we should consider that CFG80211_INTERNAL_REGDB actually has a bit more different implications on what we support on wireless-regdb for older kernels. The issue is that CFG80211_INTERNAL_REGDB makes use of an awk script for parsing the ASCII db.txt file, not the binary format. Commit e56cd9618e3e5 removed the antenna gain on wireless-regdb, upstream was not affected for kernels using CRDA even when using older CRDA as the binary format was not changed but since CFG80211_INTERNAL_REGDB relies on its own ASCII parser older kernels are affected if this option is used. The impact is that without an awk script update the max EIRP will be 0 when CFG80211_INTERNAL_REGDB is used with new wireless-regdb so devices can't transmit. What this also means is that when CFG80211_INTERNAL_REGDB is used you cannot use older versions of wireless-regdb unless we update the awk script, this however gets tricky and the awk script can become complicated quickly. The change below is an example change to make the the awk script backward compatible upstream but for stable kernels we'd have port this a bit -- we'd have to remove usage of the new dfs_cac as that wasn't available on older kernels. We need to decide what we want to do for older kernels, right now, and in the future in consideration for the parser requirements on the ASCII file by CFG80211_INTERNAL_REGDB then. For the current kernel we could intake the patch below, and I can port the change to no use dfs_cac, that would enable older kernels to use new and older versions of the ASCII database file. For future kernels I started looking at ditching the awk script completely and instead using the new C parser already on CRDA. Another option is to have a something that reads the regulatory binary file in the kernel, that is, a built-in CRDA. We can use the C parser but that would require the making it also backward compatible, today it is not, and #ifdef'ing some upstream code with __KERNEL if we wanted to share some headers. I started mucking with this as an option but it does require a bit of change. Having an internal CRDA is a rather bigger change but one at this point worth considering. I saw that for example recently we moved firmware uploading into the kernel and that udev will soon remove the firmware loader option. This a bit different change but a bit similar -- the only difference here is that we do rely on RSA digital signatures on the binary file, and we allow usage of either gcrypt or openssl for verifying the signature on the file. When CFG80211_INTERNAL_REGDB is used though we don't rely on any signatures though given that the file is read and parsed at build time once so there is no chance to corrupt the file. We could upkeep that behavior but the reading of the file then would be binary to txt transformation, and it'd be a one time thing at build time. If we wanted instead to have CFG80211_INTERNAL_REGDB to mean that CRDA is then built-in to read files from the filesystem at run time we'd have to decide if we wanted to upkeep parsing the RSA digitial signature at read time. I should note that CRDA is licensed under the copyleft-next license, I have checked with Richard on license compatibility and he's verified that copyleft-next is GPLv2 compatible and would not implicate any new things if we're to share copyleft-next code on the kernel. It'd be no different than for example how we have ISC licensed code upstream. This would enable us to share code between userspace and kernel however we wish. We need a fix strategy, and also a path forward. What are folks thoughts? [0] http://marc.info/?t=140093492500001&r=1&w=3 [1] https://dev.openwrt.org/browser/trunk/package/kernel/mac80211/patches/005-make-genregdb.awk-skip-antenna-gain.patch?rev=40296 Luis diff --git a/net/wireless/genregdb.awk b/net/wireless/genregdb.awk index 40c37fc..8aa73b1 100644 --- a/net/wireless/genregdb.awI +++ b/net/wireless/genregdb.awk @@ -51,32 +51,48 @@ function parse_country_head() { function parse_reg_rule() { + flag_starts_at = 8 + start = $1 sub(/\(/, "", start) end = $3 bw = $5 sub(/\),/, "", bw) + + # We have two ASCII formats, one without the antenna gain gain = $6 - sub(/\(/, "", gain) - sub(/,/, "", gain) power = $7 - sub(/\)/, "", power) + units = $8 + dfs_cac = 0 + + if (gain ~ /)/) { + flag_starts_at = 7 + + gain = 0 + power = $6 + units = $7 + dfs_cac = $9 + if (units != "mW") + dfs_cac = $8 + } else { + sub(/\(/, "", gain) + sub(/,/, "", gain) + } + + sub(/\(/, "", power) sub(/,/, "", power) + sub(/\)/, "", power) # power might be in mW... - units = $8 sub(/\)/, "", units) sub(/,/, "", units) - dfs_cac = $9 if (units == "mW") { power = 10 * log(power)/log(10) - } else { - dfs_cac = $8 } sub(/,/, "", dfs_cac) sub(/\(/, "", dfs_cac) sub(/\)/, "", dfs_cac) flagstr = "" - for (i=8; i<=NF; i++) + for (i=flag_starts_at; i<=NF; i++) flagstr = flagstr $i split(flagstr, flagarray, ",") flags = "" -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
