#include <linux/mpi.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
+#include <linux/crypto.h>
+#include <crypto/hash.h>
#include <keys/user-type.h>
#include "internal.h"
return ret;
}
-long keyctl_dh_compute(struct keyctl_dh_params __user *params,
- char __user *buffer, size_t buflen,
- void __user *reserved)
+struct kdf_sdesc {
+ struct shash_desc shash;
+ char ctx[];
+};
+
+static int kdf_alloc(struct kdf_sdesc **sdesc_ret, char *hashname)
+{
+ struct crypto_shash *tfm;
+ struct kdf_sdesc *sdesc;
+ int size;
+ int err;
+
+ /* allocate synchronous hash */
+ tfm = crypto_alloc_shash(hashname, 0, 0);
+ if (IS_ERR(tfm)) {
+ pr_info("could not allocate digest TFM handle %s\n", hashname);
+ return PTR_ERR(tfm);
+ }
+
+ err = -EINVAL;
+ if (crypto_shash_digestsize(tfm) == 0)
+ goto out_free_tfm;
+
+ err = -ENOMEM;
+ size = sizeof(struct shash_desc) + crypto_shash_descsize(tfm);
+ sdesc = kmalloc(size, GFP_KERNEL);
+ if (!sdesc)
+ goto out_free_tfm;
+ sdesc->shash.tfm = tfm;
+ sdesc->shash.flags = 0x0;
+
+ *sdesc_ret = sdesc;
+
+ return 0;
+
+out_free_tfm:
+ crypto_free_shash(tfm);
+ return err;
+}
+
+static void kdf_dealloc(struct kdf_sdesc *sdesc)
+{
+ if (!sdesc)
+ return;
+
+ if (sdesc->shash.tfm)
+ crypto_free_shash(sdesc->shash.tfm);
+
+ kzfree(sdesc);
+}
+
+/* convert 32 bit integer into its string representation */
+static inline void crypto_kw_cpu_to_be32(u32 val, u8 *buf)
+{
+ __be32 *a = (__be32 *)buf;
+
+ *a = cpu_to_be32(val);
+}
+
+/*
+ * Implementation of the KDF in counter mode according to SP800-108 section 5.1
+ * as well as SP800-56A section 5.8.1 (Single-step KDF).
+ *
+ * SP800-56A:
+ * The src pointer is defined as Z || other info where Z is the shared secret
+ * from DH and other info is an arbitrary string (see SP800-56A section
+ * 5.8.1.2).
+ */
+static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen,
+ u8 *dst, unsigned int dlen)
+{
+ struct shash_desc *desc = &sdesc->shash;
+ unsigned int h = crypto_shash_digestsize(desc->tfm);
+ int err = 0;
+ u8 *dst_orig = dst;
+ u32 i = 1;
+ u8 iteration[sizeof(u32)];
+
+ while (dlen) {
+ err = crypto_shash_init(desc);
+ if (err)
+ goto err;
+
+ crypto_kw_cpu_to_be32(i, iteration);
+ err = crypto_shash_update(desc, iteration, sizeof(u32));
+ if (err)
+ goto err;
+
+ if (src && slen) {
+ err = crypto_shash_update(desc, src, slen);
+ if (err)
+ goto err;
+ }
+
+ if (dlen < h) {
+ u8 tmpbuffer[h];
+
+ err = crypto_shash_final(desc, tmpbuffer);
+ if (err)
+ goto err;
+ memcpy(dst, tmpbuffer, dlen);
+ memzero_explicit(tmpbuffer, h);
+ return 0;
+ } else {
+ err = crypto_shash_final(desc, dst);
+ if (err)
+ goto err;
+
+ dlen -= h;
+ dst += h;
+ i++;
+ }
+ }
+
+ return 0;
+
+err:
+ memzero_explicit(dst_orig, dlen);
+ return err;
+}
+
+static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc,
+ char __user *buffer, size_t buflen,
+ uint8_t *kbuf, size_t kbuflen)
+{
+ uint8_t *outbuf = NULL;
+ int ret;
+
+ outbuf = kmalloc(buflen, GFP_KERNEL);
+ if (!outbuf) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ ret = kdf_ctr(sdesc, kbuf, kbuflen, outbuf, buflen);
+ if (ret)
+ goto err;
+
+ ret = buflen;
+ if (copy_to_user(buffer, outbuf, buflen) != 0)
+ ret = -EFAULT;
+
+err:
+ kzfree(outbuf);
+ return ret;
+}
+
+long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
+ char __user *buffer, size_t buflen,
+ struct keyctl_kdf_params *kdfcopy)
{
long ret;
MPI base, private, prime, result;
uint8_t *kbuf;
ssize_t keylen;
size_t resultlen;
+ struct kdf_sdesc *sdesc = NULL;
if (!params || (!buffer && buflen)) {
ret = -EINVAL;
goto out;
}
- if (reserved) {
- ret = -EINVAL;
- goto out;
+ if (kdfcopy) {
+ char *hashname;
+
+ if (buflen > KEYCTL_KDF_MAX_OUTPUT_LEN ||
+ kdfcopy->otherinfolen > KEYCTL_KDF_MAX_OI_LEN) {
+ ret = -EMSGSIZE;
+ goto out;
+ }
+
+ /* get KDF name string */
+ hashname = strndup_user(kdfcopy->hashname, CRYPTO_MAX_ALG_NAME);
+ if (IS_ERR(hashname)) {
+ ret = PTR_ERR(hashname);
+ goto out;
+ }
+
+ /* allocate KDF from the kernel crypto API */
+ ret = kdf_alloc(&sdesc, hashname);
+ kfree(hashname);
+ if (ret)
+ goto out;
}
- keylen = mpi_from_key(pcopy.prime, buflen, &prime);
+ /*
+ * If the caller requests postprocessing with a KDF, allow an
+ * arbitrary output buffer size since the KDF ensures proper truncation.
+ */
+ keylen = mpi_from_key(pcopy.prime, kdfcopy ? SIZE_MAX : buflen, &prime);
if (keylen < 0 || !prime) {
/* buflen == 0 may be used to query the required buffer size,
* which is the prime key length.
goto error3;
}
- kbuf = kmalloc(resultlen, GFP_KERNEL);
+ /* allocate space for DH shared secret and SP800-56A otherinfo */
+ kbuf = kmalloc(kdfcopy ? (resultlen + kdfcopy->otherinfolen) : resultlen,
+ GFP_KERNEL);
if (!kbuf) {
ret = -ENOMEM;
goto error4;
}
+ /*
+ * Concatenate SP800-56A otherinfo past DH shared secret -- the
+ * input to the KDF is (DH shared secret || otherinfo)
+ */
+ if (kdfcopy && kdfcopy->otherinfo &&
+ copy_from_user(kbuf + resultlen, kdfcopy->otherinfo,
+ kdfcopy->otherinfolen) != 0) {
+ ret = -EFAULT;
+ goto error5;
+ }
+
ret = do_dh(result, base, private, prime);
if (ret)
goto error5;
if (ret != 0)
goto error5;
- ret = nbytes;
- if (copy_to_user(buffer, kbuf, nbytes) != 0)
- ret = -EFAULT;
+ if (kdfcopy) {
+ ret = keyctl_dh_compute_kdf(sdesc, buffer, buflen, kbuf,
+ resultlen + kdfcopy->otherinfolen);
+ } else {
+ ret = nbytes;
+ if (copy_to_user(buffer, kbuf, nbytes) != 0)
+ ret = -EFAULT;
+ }
error5:
- kfree(kbuf);
+ kzfree(kbuf);
error4:
mpi_free(result);
error3:
error1:
mpi_free(prime);
out:
+ kdf_dealloc(sdesc);
return ret;
}
+
+long keyctl_dh_compute(struct keyctl_dh_params __user *params,
+ char __user *buffer, size_t buflen,
+ struct keyctl_kdf_params __user *kdf)
+{
+ struct keyctl_kdf_params kdfcopy;
+
+ if (!kdf)
+ return __keyctl_dh_compute(params, buffer, buflen, NULL);
+
+ if (copy_from_user(&kdfcopy, kdf, sizeof(kdfcopy)) != 0)
+ return -EFAULT;
+
+ return __keyctl_dh_compute(params, buffer, buflen, &kdfcopy);
+}
projects / karo-tx-linux.git / blobdiff