diff options
Diffstat (limited to 'security/keys/dh.c')
| -rw-r--r-- | security/keys/dh.c | 220 |
1 files changed, 208 insertions, 12 deletions
diff --git a/security/keys/dh.c b/security/keys/dh.c index 893af4c45038..e603bd912e4c 100644 --- a/security/keys/dh.c +++ b/security/keys/dh.c @@ -11,6 +11,8 @@ #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" @@ -77,9 +79,146 @@ error: 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; + + /* 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); + } + + size = sizeof(struct shash_desc) + crypto_shash_descsize(tfm); + sdesc = kmalloc(size, GFP_KERNEL); + if (!sdesc) + return -ENOMEM; + sdesc->shash.tfm = tfm; + sdesc->shash.flags = 0x0; + + *sdesc_ret = sdesc; + + return 0; +} + +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; @@ -88,6 +227,7 @@ long keyctl_dh_compute(struct keyctl_dh_params __user *params, uint8_t *kbuf; ssize_t keylen; size_t resultlen; + struct kdf_sdesc *sdesc = NULL; if (!params || (!buffer && buflen)) { ret = -EINVAL; @@ -98,12 +238,34 @@ long keyctl_dh_compute(struct keyctl_dh_params __user *params, 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. @@ -133,12 +295,25 @@ long keyctl_dh_compute(struct keyctl_dh_params __user *params, 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; @@ -147,12 +322,17 @@ long keyctl_dh_compute(struct keyctl_dh_params __user *params, 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: @@ -162,5 +342,21 @@ error2: 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); +} |