Hey guys I am having trouble with a module I am working on. I want to
grab packets coming in and going out and encrypt going out and decrypt
coming in. For right now I am simply testing this by loading the module
and saying: ping 127.0.0.1
I am using Netfilter hooks to "capture" the packets. I keep getting a
NULL pointer reference (if I remember correctly) when I try to encrypt
the packet. Here is the code I have right now (it fails at
crypto_cipher_encrypt). I am using Debian Kernel 2.4.26-1.
int encrypt_w_master(struct sk_buff *packet, char *key) {
struct scatterlist sg[8];
unsigned int fp;
unsigned char *dat;
int start_point = sizeof(struct iphdr); //icmp
printk("<1>ENCRYPT: Initializing encryption\n");
if(crypt == NULL)
return 0;
printk("<1>ENCRYPT: Start at %d bytes\n",start_point);
sg[0].page = virt_to_page(packet->data[start_point]);
sg[0].offset = offset_in_page(packet->data[start_point]);
sg[0].length = packet->len - start_point;
fp = crypto_cipher_setkey(crypt,key,strlen(key));
crypto_cipher_set_iv(crypt, IV, crypto_tfm_alg_ivsize(crypt));
printk("<1>ENCRYPT: Encrypt the data\n");
fp = crypto_cipher_encrypt(crypt,sg,sg,strlen(key));
if(!fp)
return -1;
packet->data[start_point] = (unsigned char*)(kmap(sg[0].page) +
sg[0].offset);
packet->len = start_point + sizeof(packet->data[start_point]);
printk("<1>ENCRYPT: Return");
return 1;
}
Just wondering if anyone sees anything right off. I am using AES for
the algorithm. I am shure there is a better way to do all of this, but
I am pretty new a kernel hacking so don't bash me to bad. ;-)
BTW Kernel Newbies mailing list page comes up blank, and has been like
that for at least a week or so:
http://www.kernelnewbies.org/mailinglist.php3 (<--- Comes up blank)
Thx!
--
Clayton Bluhm bluhmcc@xxxxxxxxxx
Computer Engineering Student http://www.auburn.edu/~bluhmcc/
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