using /dev/crypto

["J. Bruce Fields" <bfields@umich.edu>]

I'm trying to write code that uses the /dev/crypto pseudo-device.  I've
read crypto(4) and /usr/src/sys/cryptodev.h, and tried the following:

#########################
#include <sys/types.h>
#include <crypto/crypto.h>
#include <crypto/cryptodev.h>
#include <sys/ioctl.h>
#include <stdio.h>
#include <fcntl.h>

int cryptodev_fd;
struct session_op session;

int main() {
  if ((cryptodev_fd = open("/dev/crypto",O_RDWR,0)) < 0) {
    perror("failed to open /dev/crypto");
    exit(1);
  }
  session.cipher=CRYPTO_3DES_CBC;
  session.mac=0;
  session.keylen=24;
  session.key=(caddr_t)"123456781234567812345678";
  if (ioctl(cryptodev_fd, CIOCGSESSION, &session) == -1) {
    perror("ioctl failed");
    exit(1);
  }
}
############################

The result is "ioctl failed: invalid argument"

By putting some printf statements in /usr/src/sys/crypto/cryptodev.c, I've
found that the function that's getting called there when I do the ioctl
isn't the one I expected; instead of cryptof_ioctl(), which contains code
to handle CIOCGSESSION, the function that's called is cryptoioctl().  The
latter function only understands a CRIOGET command.  I've tried
ioctl(cryptodev_fd,CRIOGET), but that gives a "Bad address" error.  I
believe this error comes from the falloc call in cryptoioctl(), but I
can't understand why.

Thanks in advance for any pointers to help.  It's likely there's an
obvious error on my part here that I'm overlooking.... If so,
apologies.

---Bruce Fields