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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/err.h>#include <linux/module.h>#include <linux/slab.h>#include <linux/key.h>#include <crypto/sha1.h>#include <keys/user-type.h>#include <linux/mpi.h>#include <linux/digsig.h>
static const char *pkcs_1_v1_5_decode_emsa(const unsigned char *msg, unsigned long msglen, unsigned long modulus_bitlen, unsigned long *outlen){ unsigned long modulus_len, ps_len, i;
modulus_len = (modulus_bitlen >> 3) + (modulus_bitlen & 7 ? 1 : 0);
/* test message size */ if ((msglen > modulus_len) || (modulus_len < 11)) return NULL;
/* separate encoded message */ if (msg[0] != 0x00 || msg[1] != 0x01) return NULL;
for (i = 2; i < modulus_len - 1; i++) if (msg[i] != 0xFF) break;
/* separator check */ if (msg[i] != 0) /* There was no octet with hexadecimal value 0x00 to separate ps from m. */ return NULL;
ps_len = i - 2;
*outlen = (msglen - (2 + ps_len + 1));
return msg + 2 + ps_len + 1;}
/* * RSA Signature verification with public key */static int digsig_verify_rsa(struct key *key, const char *sig, int siglen, const char *h, int hlen){ int err = -EINVAL; unsigned long len; unsigned long mlen, mblen; unsigned nret, l; int head, i; unsigned char *out1 = NULL; const char *m; MPI in = NULL, res = NULL, pkey[2]; uint8_t *p, *datap; const uint8_t *endp; const struct user_key_payload *ukp; struct pubkey_hdr *pkh;
down_read(&key->sem); ukp = user_key_payload_locked(key);
if (!ukp) { /* key was revoked before we acquired its semaphore */ err = -EKEYREVOKED; goto err1; }
if (ukp->datalen < sizeof(*pkh)) goto err1;
pkh = (struct pubkey_hdr *)ukp->data;
if (pkh->version != 1) goto err1;
if (pkh->algo != PUBKEY_ALGO_RSA) goto err1;
if (pkh->nmpi != 2) goto err1;
datap = pkh->mpi; endp = ukp->data + ukp->datalen;
for (i = 0; i < pkh->nmpi; i++) { unsigned int remaining = endp - datap; pkey[i] = mpi_read_from_buffer(datap, &remaining); if (IS_ERR(pkey[i])) { err = PTR_ERR(pkey[i]); goto err; } datap += remaining; }
mblen = mpi_get_nbits(pkey[0]); mlen = DIV_ROUND_UP(mblen, 8);
if (mlen == 0) { err = -EINVAL; goto err; }
err = -ENOMEM;
out1 = kzalloc(mlen, GFP_KERNEL); if (!out1) goto err;
nret = siglen; in = mpi_read_from_buffer(sig, &nret); if (IS_ERR(in)) { err = PTR_ERR(in); goto err; }
res = mpi_alloc(mpi_get_nlimbs(in) * 2); if (!res) goto err;
err = mpi_powm(res, in, pkey[1], pkey[0]); if (err) goto err;
if (mpi_get_nlimbs(res) * BYTES_PER_MPI_LIMB > mlen) { err = -EINVAL; goto err; }
p = mpi_get_buffer(res, &l, NULL); if (!p) { err = -EINVAL; goto err; }
len = mlen; head = len - l; memcpy(out1 + head, p, l);
kfree(p);
m = pkcs_1_v1_5_decode_emsa(out1, len, mblen, &len);
if (!m || len != hlen || memcmp(m, h, hlen)) err = -EINVAL;
err: mpi_free(in); mpi_free(res); kfree(out1); while (--i >= 0) mpi_free(pkey[i]);err1: up_read(&key->sem);
return err;}
/** * digsig_verify() - digital signature verification with public key * @keyring: keyring to search key in * @sig: digital signature * @siglen: length of the signature * @data: data * @datalen: length of the data * * Returns 0 on success, -EINVAL otherwise * * Verifies data integrity against digital signature. * Currently only RSA is supported. * Normally hash of the content is used as a data for this function. * */int digsig_verify(struct key *keyring, const char *sig, int siglen, const char *data, int datalen){ struct signature_hdr *sh = (struct signature_hdr *)sig; struct sha1_ctx ctx; unsigned char hash[SHA1_DIGEST_SIZE]; struct key *key; char name[20]; int err;
if (siglen < sizeof(*sh) + 2) return -EINVAL;
if (sh->algo != PUBKEY_ALGO_RSA) return -ENOTSUPP;
sprintf(name, "%llX", __be64_to_cpup((uint64_t *)sh->keyid));
if (keyring) { /* search in specific keyring */ key_ref_t kref; kref = keyring_search(make_key_ref(keyring, 1UL), &key_type_user, name, true); if (IS_ERR(kref)) key = ERR_CAST(kref); else key = key_ref_to_ptr(kref); } else { key = request_key(&key_type_user, name, NULL); } if (IS_ERR(key)) { pr_err("key not found, id: %s\n", name); return PTR_ERR(key); }
sha1_init(&ctx); sha1_update(&ctx, data, datalen); sha1_update(&ctx, sig, sizeof(*sh)); sha1_final(&ctx, hash);
/* pass signature mpis address */ err = digsig_verify_rsa(key, sig + sizeof(*sh), siglen - sizeof(*sh), hash, sizeof(hash));
key_put(key);
return err ? -EINVAL : 0;}EXPORT_SYMBOL_GPL(digsig_verify);
MODULE_LICENSE("GPL");