On 6/2/05, rjf <itripn@private> wrote:
> Dang, I sent this a little too early... I meant to point out that the
> read() call is returning -14, which I believe is EFAULT. I think the
And just to go ahead and wrap the thread up... grin... After about 90
minutes of googling, I came up with the right set of terms to find
this page:
http://www.daimi.au.dk/~kasperd/comp.os.linux.development.faq.html#filp_open
Which led to the following, operational, version of my kernel module
file hashing function:
static void hashFile(char *filename, char *algo, struct file *file) {
struct scatterlist sg[1];
char result[64];
struct crypto_tfm *tfm;
// alloc a buffer
unsigned long page = __get_free_page(GFP_KERNEL);
if ( !page ) {
printk("failed to alloc buffer...\n");
return;
}
char *m = (char*)page;
// init crypto
tfm = crypto_alloc_tfm(algo, 0);
if (tfm == NULL) {
printk("failed to load transform for %s\n", algo);
return;
}
crypto_digest_init (tfm);
// init scatterlist -- the first two fields shouldn't change
// since we read into the same buffer each time.
sg[0].page = virt_to_page (m);
sg[0].offset = offset_in_page (m);
sg[0].length = 0;
mm_segment_t orgfs = get_fs();
set_fs( KERNEL_DS );
// loop reading the file a buffer at a time, updating the hash.
int bytesRead = 0;
int ret = file->f_op->open( file->f_mapping->host, file );
if ( ret == 0 ) {
do {
bytesRead = file->f_op->read(file, m, PAGE_SIZE, &file->f_pos);
if ( bytesRead > 0 ) {
sg[0].length = bytesRead;
crypto_digest_update (tfm, sg, 1);
}
else
printk("failed to read: %d\n", bytesRead);
} while (bytesRead == PAGE_SIZE);
// cleanup
file->f_op->release(file->f_mapping->host, file);
crypto_digest_final(tfm, result);
// log the hash to the syslog
hexdump(filename, result, crypto_tfm_alg_digestsize (tfm));
}
else
printk("failed to open file: %s (%d)\n", filename, ret);
free_page(page);
set_fs(orgfs);
}
--
rjf&
This archive was generated by hypermail 2.1.3 : Thu Jun 02 2005 - 23:35:34 PDT