Linux Kernel Crypto API : skcipher algorithm name not found by "crypto_alloc_skcipher" - c

Question

I'm trying to make a Linux kernel driver using crypto API.
So first I have my own skcipher algorithm that I developed successfully registered on the crypto API and I can see it in the list of cryptos that is well registered.
.base = {
/* Name used by the framework to find who is implementing what. */
.cra_name = "cbc(aes)stackOverFlow",
/* Driver name. Can be used to request a specific implementation of an algorithm. */
.cra_driver_name = "stackOverFlow-cbc-aes",
/* Priority is used when implementation auto-selection takes place:
* if there are several implementers, the one with the highest priority is chosen.
* By convention: HW engine > ASM/arch-optimized > plain C
* */
.cra_priority = 300,
/* Driver module */
.cra_module = THIS_MODULE,
/* Size of the data blocks this algo operates on. */
.cra_blocksize = AES_BLOCK_SIZE,
.cra_flags = CRYPTO_ALG_INTERNAL | CRYPTO_ALG_TYPE_SKCIPHER,
/* Size of the context attached to an algorithm instance.
* This value informs the kernel crypto API about the memory size
* needed to be allocated for the transformation context.
*/
.cra_ctxsize = sizeof(struct crypto_aes_ctx),
/* Alignment mask for the input and output data buffer. */
.cra_alignmask = 15,
},
/* constructor/destructor methods called every time an alg instance is created/destroyed. */
.min_keysize = AES_MIN_KEY_SIZE,
.max_keysize = AES_MAX_KEY_SIZE,
.ivsize = AES_BLOCK_SIZE,
.init = test_skcipher_cra_init,
.exit = test_skcipher_cra_exit,
.setkey = test_aes_setkey,
.encrypt = test_cbc_aes_encrypt,
.decrypt = test_cbc_aes_decrypt,
};
And this is my init function module :
static int __init test_skcipher_cra_init(struct crypto_skcipher *tfm){
int ret;
ret = crypto_register_skcipher(&test_cbc_aes_alg);
if (ret < 0){
printk(KERN_ALERT "register failed %d", ret);
}
else{
printk(KERN_INFO "SUCCESS crypto_register\n");
}
return ret;
}
So to ensure that my driver works fine, I'm using the implementation user code (that I got from link) to encrypt some data : https://www.kernel.org/doc/html/v4.17/crypto/api-samples.html
But when I compile everything and move to see the kernel log messages I receive an error message "could not allocate skcipher handle" that comes from a part of the implementation code :
skcipher = crypto_alloc_skcipher("stackOverFlow-cbc-aes", 0, 0);
if (IS_ERR(skcipher)) {
pr_info("could not allocate skcipher handle\n");
return PTR_ERR(skcipher);
}
But in the crypto API, I can see the driver :
name : cbc(aes)stackOverFlow
driver : stackOverFlow-cbc-aes
module : kernel
priority : 300
refcnt : 1
selftest : passed
internal : yes
type : skcipher
async : no
blocksize : 16
min keysize : 16
max keysize : 32
ivsize : 16
chunksize : 16
walksize : 16
I really tried many times to modify the flag and other things in my algorithm but I don't understund it keeps showing me this message. So my question is why it gives me this error and my crypto driver is already registred on the crypto API ?
Notice that when I change the name to crypto_alloc_skcipher("cbc-aes-aesni", 0, 0) which is one of the already exist ones in the API, everything works fine.

Answer 1

I managed to resolve the problem, it was stupid mistake because of the Init algorithm function that I confused with Init function module.