Hi, I hope this is the right place to ask for a little bit of help as I'm currently beyond stuck on a challenge I'm trying to accomplish. I'm trying to write a "simple" LKM that properly uses a ieee80211 header to print information about the mac addresses (addr1->addr4) and later down the road try to send my own data. I only need to get L2 working, no need for TCP/IP, just a proper ieee80211 based on input from skb would be huge for me. So my issue: when placing the ieee80211 on my mac_header after I hook my skb from my wireless device (wlan0 on android - I9100) I get a huge amount of zero's and random(?) numbers when trying to print the addresses. This leads me to the first conclusion that mac_header is placed wrong when using 80211. After that I saw a lot of people just using the skb->data pointer. Now this gives even weirder issues for me and actually totally crashes my kernel. So I went back to starting with printing as much info as possible. This is a sample output after I hook my packet type: Skb->dev->name: wlan0 Skb->head: 0xe1d37040 Skb->mac_header: 0xe1d372a9 Skb->data: 0x510 (!!!) Skb->tail: 0xe1d37460 Skb->len: 617 Skb->hdr_len: 0 When trying to just capture this and only print a certain message when one of the addresses maches my dev->dev_addr I never get any data while the phone is connected and actively browsing the internet. I'm aware that before I throw my hook some data is being changed around already in net/core/dev.c and in net/mac80211/rx.c The weird part is that these seem to be putting on ethernet headers (skb->protocol = eth_type_trans(skb, dev); AND kb_pull_inline(skb, ETH_HLEN); eth = eth_hdr(skb); ) on items that should be ieee80211 headers. Any insights as to why my data header is in such a weird spot (nowhere between my head and my tail) or where I should call the ieee80211_header on? I have tried working my way back from tail with len and adding another ETH_HLEN but while I get data, it never really matches my own mac addr so I'm assuming the data is still pretty wrong. Added links: https://github.com/mathieudevos/kernelmodules/blob/master/ethernet_test.c (my own program) https://github.com/mathieudevos/linux_kernel_3.2.48 (used to get all the .c files from to acquire information) If possible I'd like to write a small guide after these issues have been fixes for people who like me would like to get started with a basic LKM in the ieee80211 part of linux. If this is not the place to ask these questions, please disregard me (hopefully it is) but all help would be welcome. Kind regards, Mathieu Devos -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
