我正在寻找一个在 C 中使用 OpenSSL API(可能是 DH.H)来实现 DH 上的密钥交换的示例。谁能分享一个紧凑的 C-shnik,以极其苦行的方式展示这个过程?
主页
/
user-215608
Ruslan R. Laishev's questions
我正在制作一个块设备驱动程序,在处理 READ 请求时,我在 bio.bi_end_io 字段中设置了我的处理程序(I/O 完成例程)。正在调用我的处理程序,但 bio 中没有 biovec,我需要在块 I/O 子系统将数据返回给应用程序之前处理数据。这里有一些代码片段来说明。*
static void __iob_enc_dec (
struct bio * iob
)
{
struct bio_vec bvec = {0};
struct bvec_iter iter = {0};
sector_t lbn, nlbn;
$TRACE("Start %scrypting ...", bio_data_dir(iob) == WRITE ? "En" : "De");
$SHOW_PTR(bio_data(iob));
/* Do each segment independently. */
**bio_for_each_segment**(bvec, iob, iter)
{
char * iobuf;
iobuf = __bio_kmap_atomic(iob, iter);
$TRACE("#%02d: page=%p, off=%u, len=%u, iobuf=%p, lbn=%lu",
iter.bi_idx, bvec.bv_page, bvec.bv_offset, bvec.bv_len, iobuf, iter.bi_sector);
iobuf += bvec.bv_offset;
lbn = iter.bi_sector;
nlbn = iter.bi_size/DUDRV$K_BLKSZ;
for ( ;nlbn; nlbn--, lbn++ , iobuf += DUDRV$K_BLKSZ)
{
**...**
}
__bio_kunmap_atomic(iob);
}
}
static void dua_bio_end_io (
struct bio * iob
)
{
IOB_ARGS * iob_args;
$TRACE("Entering to %s completion I/O, bio=%p ...", bio_data_dir(iob) == WRITE ? "WRITE" : "READ", iob);
$SHOW_UNSIGNED(iob->bi_flags);
$SHOW_INT(iob->bi_vcnt);
$SHOW_BOOL(bio_has_data(iob));
iob_args = iob->bi_private;
iob->bi_end_io = iob_args->bi_end_io;
iob->bi_private = iob_args->bi_private;
bio_put(iob);
__ret_iob_args (iob_args);
/* In case of READ request - we should decrypt data buffer right now */
if ( bio_data_dir(iob) == READ )
**__iob_enc_dec(iob)**;
bio_endio (iob);
}
static blk_qc_t dua_make_request_fn (
struct request_queue * ioq,
struct bio * iob
)
{
int status = 0;
$TRACE("Starting (%s), bio=%p, op=%d ...", bio_data_dir(iob) == WRITE ? "WRITE" : "READ", iob, bio_op(iob));
$SHOW_UNSIGNED(iob->bi_flags);
$SHOW_INT(iob->bi_vcnt);
$SHOW_BOOL(bio_has_data(iob));
/* In case of WRITE request - we can encrypt data buffer right now */
if ( bio_data_dir(iob) == WRITE )
__iob_enc_dec(iob);
/*
* A handling of the READ request is require 'enqueue read request' & 'wait for read completion' paradigm,
* so we need to allocate IOB_ARGS block to carry data to the "Read Completion I/O" routine.
*/
else if ( bio_data_dir(iob) == READ )
{
IOB_ARGS *iob_args = NULL;
if ( __get_iob_args (&iob_args) )
{
printk(KERN_ERR __MODULE__ ": Buffered I/O quota limit has been exhausted\n");
iob->bi_error = -EBUSY;
bio_endio(iob);
}
iob_args->bi_end_io = iob->bi_end_io;
iob_args->bi_private = iob->bi_private;
/*
* Replace an address of the Completion I/O routine for 'read' operation,
* save original address.
*/
iob->bi_private = iob_args;
iob->bi_end_io = dua_bio_end_io;
bio_get(iob);
}
/* Just for sanity check ... */
else {
printk(KERN_WARNING __MODULE__ ": Unhandled I/O request %d\n", bio_data_dir(iob) );
}
/* Call original make_reques_fn() to performs a main work ... */
status = backend_make_request_fn(ioq, iob);
return status;
}
[6463.418222] [DUDRIVER\dua_make_request_fn:479] Starting (READ), bio=ffff95c5f9552100, op=0 ...
[ 6463.418222] [DUDRIVER\dua_make_request_fn:482] : iob->bi_flags = 0x00000000
[ 6463.418223] [DUDRIVER\dua_make_request_fn:483] : iob->bi_vcnt = 1
[ 6463.418223] [DUDRIVER\dua_make_request_fn:485] : bio_has_data(iob) = ENABLED(TRUE)
[ 6463.418266] [DUDRIVER\dua_bio_end_io:445] Entering to READ completion I/O, bio=ffff95c5f9552100 ...
[ 6463.418266] [DUDRIVER\dua_bio_end_io:447] : iob->bi_flags = 0x00000102
[ 6463.418267] [DUDRIVER\dua_bio_end_io:448] : iob->bi_vcnt = 1
[ 6463.418267] [DUDRIVER\dua_bio_end_io:450] : bio_has_data(iob) = DISABLED(FALSE)
我需要做什么才能访问 bio_end_io() 中的数据缓冲区?这发生在 Ubuntu 16.x、Linux 内核 4.10.y 中。
更新1:设置了 BIO_CLONED 标志的 bio_for_each_segment 宏可能不允许您运行缓冲区段,但那该怎么办?