diff options
Diffstat (limited to 'security/keys')
| -rw-r--r-- | security/keys/Kconfig | 15 | ||||
| -rw-r--r-- | security/keys/Makefile | 1 | ||||
| -rw-r--r-- | security/keys/big_key.c | 198 | ||||
| -rw-r--r-- | security/keys/compat.c | 4 | ||||
| -rw-r--r-- | security/keys/dh.c | 160 | ||||
| -rw-r--r-- | security/keys/internal.h | 12 | ||||
| -rw-r--r-- | security/keys/keyctl.c | 5 | ||||
| -rw-r--r-- | security/keys/user_defined.c | 42 |
8 files changed, 388 insertions, 49 deletions
diff --git a/security/keys/Kconfig b/security/keys/Kconfig index fe4d74e126a7..f826e8739023 100644 --- a/security/keys/Kconfig +++ b/security/keys/Kconfig @@ -41,6 +41,10 @@ config BIG_KEYS bool "Large payload keys" depends on KEYS depends on TMPFS + select CRYPTO + select CRYPTO_AES + select CRYPTO_ECB + select CRYPTO_RNG help This option provides support for holding large keys within the kernel (for example Kerberos ticket caches). The data may be stored out to @@ -81,3 +85,14 @@ config ENCRYPTED_KEYS Userspace only ever sees/stores encrypted blobs. If you are unsure as to whether this is required, answer N. + +config KEY_DH_OPERATIONS + bool "Diffie-Hellman operations on retained keys" + depends on KEYS + select MPILIB + help + This option provides support for calculating Diffie-Hellman + public keys and shared secrets using values stored as keys + in the kernel. + + If you are unsure as to whether this is required, answer N. diff --git a/security/keys/Makefile b/security/keys/Makefile index dfb3a7bededf..1fd4a16e6daf 100644 --- a/security/keys/Makefile +++ b/security/keys/Makefile @@ -19,6 +19,7 @@ obj-$(CONFIG_KEYS_COMPAT) += compat.o obj-$(CONFIG_PROC_FS) += proc.o obj-$(CONFIG_SYSCTL) += sysctl.o obj-$(CONFIG_PERSISTENT_KEYRINGS) += persistent.o +obj-$(CONFIG_KEY_DH_OPERATIONS) += dh.o # # Key types diff --git a/security/keys/big_key.c b/security/keys/big_key.c index c721e398893a..9e443fccad4c 100644 --- a/security/keys/big_key.c +++ b/security/keys/big_key.c @@ -14,8 +14,10 @@ #include <linux/file.h> #include <linux/shmem_fs.h> #include <linux/err.h> +#include <linux/scatterlist.h> #include <keys/user-type.h> #include <keys/big_key-type.h> +#include <crypto/rng.h> /* * Layout of key payload words. @@ -28,6 +30,14 @@ enum { }; /* + * Crypto operation with big_key data + */ +enum big_key_op { + BIG_KEY_ENC, + BIG_KEY_DEC, +}; + +/* * If the data is under this limit, there's no point creating a shm file to * hold it as the permanently resident metadata for the shmem fs will be at * least as large as the data. @@ -35,6 +45,11 @@ enum { #define BIG_KEY_FILE_THRESHOLD (sizeof(struct inode) + sizeof(struct dentry)) /* + * Key size for big_key data encryption + */ +#define ENC_KEY_SIZE 16 + +/* * big_key defined keys take an arbitrary string as the description and an * arbitrary blob of data as the payload */ @@ -50,12 +65,62 @@ struct key_type key_type_big_key = { }; /* + * Crypto names for big_key data encryption + */ +static const char big_key_rng_name[] = "stdrng"; +static const char big_key_alg_name[] = "ecb(aes)"; + +/* + * Crypto algorithms for big_key data encryption + */ +static struct crypto_rng *big_key_rng; +static struct crypto_blkcipher *big_key_blkcipher; + +/* + * Generate random key to encrypt big_key data + */ +static inline int big_key_gen_enckey(u8 *key) +{ + return crypto_rng_get_bytes(big_key_rng, key, ENC_KEY_SIZE); +} + +/* + * Encrypt/decrypt big_key data + */ +static int big_key_crypt(enum big_key_op op, u8 *data, size_t datalen, u8 *key) +{ + int ret = -EINVAL; + struct scatterlist sgio; + struct blkcipher_desc desc; + + if (crypto_blkcipher_setkey(big_key_blkcipher, key, ENC_KEY_SIZE)) { + ret = -EAGAIN; + goto error; + } + + desc.flags = 0; + desc.tfm = big_key_blkcipher; + + sg_init_one(&sgio, data, datalen); + + if (op == BIG_KEY_ENC) + ret = crypto_blkcipher_encrypt(&desc, &sgio, &sgio, datalen); + else + ret = crypto_blkcipher_decrypt(&desc, &sgio, &sgio, datalen); + +error: + return ret; +} + +/* * Preparse a big key */ int big_key_preparse(struct key_preparsed_payload *prep) { struct path *path = (struct path *)&prep->payload.data[big_key_path]; struct file *file; + u8 *enckey; + u8 *data = NULL; ssize_t written; size_t datalen = prep->datalen; int ret; @@ -73,16 +138,43 @@ int big_key_preparse(struct key_preparsed_payload *prep) /* Create a shmem file to store the data in. This will permit the data * to be swapped out if needed. * - * TODO: Encrypt the stored data with a temporary key. + * File content is stored encrypted with randomly generated key. */ - file = shmem_kernel_file_setup("", datalen, 0); + size_t enclen = ALIGN(datalen, crypto_blkcipher_blocksize(big_key_blkcipher)); + + /* prepare aligned data to encrypt */ + data = kmalloc(enclen, GFP_KERNEL); + if (!data) + return -ENOMEM; + + memcpy(data, prep->data, datalen); + memset(data + datalen, 0x00, enclen - datalen); + + /* generate random key */ + enckey = kmalloc(ENC_KEY_SIZE, GFP_KERNEL); + if (!enckey) { + ret = -ENOMEM; + goto error; + } + + ret = big_key_gen_enckey(enckey); + if (ret) + goto err_enckey; + + /* encrypt aligned data */ + ret = big_key_crypt(BIG_KEY_ENC, data, enclen, enckey); + if (ret) + goto err_enckey; + + /* save aligned data to file */ + file = shmem_kernel_file_setup("", enclen, 0); if (IS_ERR(file)) { ret = PTR_ERR(file); - goto error; + goto err_enckey; } - written = kernel_write(file, prep->data, prep->datalen, 0); - if (written != datalen) { + written = kernel_write(file, data, enclen, 0); + if (written != enclen) { ret = written; if (written >= 0) ret = -ENOMEM; @@ -92,12 +184,15 @@ int big_key_preparse(struct key_preparsed_payload *prep) /* Pin the mount and dentry to the key so that we can open it again * later */ + prep->payload.data[big_key_data] = enckey; *path = file->f_path; path_get(path); fput(file); + kfree(data); } else { /* Just store the data in a buffer */ void *data = kmalloc(datalen, GFP_KERNEL); + if (!data) return -ENOMEM; @@ -108,7 +203,10 @@ int big_key_preparse(struct key_preparsed_payload *prep) err_fput: fput(file); +err_enckey: + kfree(enckey); error: + kfree(data); return ret; } @@ -119,10 +217,10 @@ void big_key_free_preparse(struct key_preparsed_payload *prep) { if (prep->datalen > BIG_KEY_FILE_THRESHOLD) { struct path *path = (struct path *)&prep->payload.data[big_key_path]; + path_put(path); - } else { - kfree(prep->payload.data[big_key_data]); } + kfree(prep->payload.data[big_key_data]); } /* @@ -147,15 +245,15 @@ void big_key_destroy(struct key *key) { size_t datalen = (size_t)key->payload.data[big_key_len]; - if (datalen) { + if (datalen > BIG_KEY_FILE_THRESHOLD) { struct path *path = (struct path *)&key->payload.data[big_key_path]; + path_put(path); path->mnt = NULL; path->dentry = NULL; - } else { - kfree(key->payload.data[big_key_data]); - key->payload.data[big_key_data] = NULL; } + kfree(key->payload.data[big_key_data]); + key->payload.data[big_key_data] = NULL; } /* @@ -188,17 +286,41 @@ long big_key_read(const struct key *key, char __user *buffer, size_t buflen) if (datalen > BIG_KEY_FILE_THRESHOLD) { struct path *path = (struct path *)&key->payload.data[big_key_path]; struct file *file; - loff_t pos; + u8 *data; + u8 *enckey = (u8 *)key->payload.data[big_key_data]; + size_t enclen = ALIGN(datalen, crypto_blkcipher_blocksize(big_key_blkcipher)); + + data = kmalloc(enclen, GFP_KERNEL); + if (!data) + return -ENOMEM; file = dentry_open(path, O_RDONLY, current_cred()); - if (IS_ERR(file)) - return PTR_ERR(file); + if (IS_ERR(file)) { + ret = PTR_ERR(file); + goto error; + } - pos = 0; - ret = vfs_read(file, buffer, datalen, &pos); - fput(file); - if (ret >= 0 && ret != datalen) + /* read file to kernel and decrypt */ + ret = kernel_read(file, 0, data, enclen); + if (ret >= 0 && ret != enclen) { ret = -EIO; + goto err_fput; + } + + ret = big_key_crypt(BIG_KEY_DEC, data, enclen, enckey); + if (ret) + goto err_fput; + + ret = datalen; + + /* copy decrypted data to user */ + if (copy_to_user(buffer, data, datalen) != 0) + ret = -EFAULT; + +err_fput: + fput(file); +error: + kfree(data); } else { ret = datalen; if (copy_to_user(buffer, key->payload.data[big_key_data], @@ -209,8 +331,48 @@ long big_key_read(const struct key *key, char __user *buffer, size_t buflen) return ret; } +/* + * Register key type + */ static int __init big_key_init(void) { return register_key_type(&key_type_big_key); } + +/* + * Initialize big_key crypto and RNG algorithms + */ +static int __init big_key_crypto_init(void) +{ + int ret = -EINVAL; + + /* init RNG */ + big_key_rng = crypto_alloc_rng(big_key_rng_name, 0, 0); + if (IS_ERR(big_key_rng)) { + big_key_rng = NULL; + return -EFAULT; + } + + /* seed RNG */ + ret = crypto_rng_reset(big_key_rng, NULL, crypto_rng_seedsize(big_key_rng)); + if (ret) + goto error; + + /* init block cipher */ + big_key_blkcipher = crypto_alloc_blkcipher(big_key_alg_name, 0, 0); + if (IS_ERR(big_key_blkcipher)) { + big_key_blkcipher = NULL; + ret = -EFAULT; + goto error; + } + + return 0; + +error: + crypto_free_rng(big_key_rng); + big_key_rng = NULL; + return ret; +} + device_initcall(big_key_init); +late_initcall(big_key_crypto_init); diff --git a/security/keys/compat.c b/security/keys/compat.c index 25430a3aa7f7..c8783b3b628c 100644 --- a/security/keys/compat.c +++ b/security/keys/compat.c @@ -132,6 +132,10 @@ COMPAT_SYSCALL_DEFINE5(keyctl, u32, option, case KEYCTL_GET_PERSISTENT: return keyctl_get_persistent(arg2, arg3); + case KEYCTL_DH_COMPUTE: + return keyctl_dh_compute(compat_ptr(arg2), compat_ptr(arg3), + arg4); + default: return -EOPNOTSUPP; } diff --git a/security/keys/dh.c b/security/keys/dh.c new file mode 100644 index 000000000000..880505a4b9f1 --- /dev/null +++ b/security/keys/dh.c @@ -0,0 +1,160 @@ +/* Crypto operations using stored keys + * + * Copyright (c) 2016, Intel Corporation + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include <linux/mpi.h> +#include <linux/slab.h> +#include <linux/uaccess.h> +#include <keys/user-type.h> +#include "internal.h" + +/* + * Public key or shared secret generation function [RFC2631 sec 2.1.1] + * + * ya = g^xa mod p; + * or + * ZZ = yb^xa mod p; + * + * where xa is the local private key, ya is the local public key, g is + * the generator, p is the prime, yb is the remote public key, and ZZ + * is the shared secret. + * + * Both are the same calculation, so g or yb are the "base" and ya or + * ZZ are the "result". + */ +static int do_dh(MPI result, MPI base, MPI xa, MPI p) +{ + return mpi_powm(result, base, xa, p); +} + +static ssize_t mpi_from_key(key_serial_t keyid, size_t maxlen, MPI *mpi) +{ + struct key *key; + key_ref_t key_ref; + long status; + ssize_t ret; + + key_ref = lookup_user_key(keyid, 0, KEY_NEED_READ); + if (IS_ERR(key_ref)) { + ret = -ENOKEY; + goto error; + } + + key = key_ref_to_ptr(key_ref); + + ret = -EOPNOTSUPP; + if (key->type == &key_type_user) { + down_read(&key->sem); + status = key_validate(key); + if (status == 0) { + const struct user_key_payload *payload; + + payload = user_key_payload(key); + + if (maxlen == 0) { + *mpi = NULL; + ret = payload->datalen; + } else if (payload->datalen <= maxlen) { + *mpi = mpi_read_raw_data(payload->data, + payload->datalen); + if (*mpi) + ret = payload->datalen; + } else { + ret = -EINVAL; + } + } + up_read(&key->sem); + } + + key_put(key); +error: + return ret; +} + +long keyctl_dh_compute(struct keyctl_dh_params __user *params, + char __user *buffer, size_t buflen) +{ + long ret; + MPI base, private, prime, result; + unsigned nbytes; + struct keyctl_dh_params pcopy; + uint8_t *kbuf; + ssize_t keylen; + size_t resultlen; + + if (!params || (!buffer && buflen)) { + ret = -EINVAL; + goto out; + } + if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) { + ret = -EFAULT; + goto out; + } + + keylen = mpi_from_key(pcopy.prime, buflen, &prime); + if (keylen < 0 || !prime) { + /* buflen == 0 may be used to query the required buffer size, + * which is the prime key length. + */ + ret = keylen; + goto out; + } + + /* The result is never longer than the prime */ + resultlen = keylen; + + keylen = mpi_from_key(pcopy.base, SIZE_MAX, &base); + if (keylen < 0 || !base) { + ret = keylen; + goto error1; + } + + keylen = mpi_from_key(pcopy.private, SIZE_MAX, &private); + if (keylen < 0 || !private) { + ret = keylen; + goto error2; + } + + result = mpi_alloc(0); + if (!result) { + ret = -ENOMEM; + goto error3; + } + + kbuf = kmalloc(resultlen, GFP_KERNEL); + if (!kbuf) { + ret = -ENOMEM; + goto error4; + } + + ret = do_dh(result, base, private, prime); + if (ret) + goto error5; + + ret = mpi_read_buffer(result, kbuf, resultlen, &nbytes, NULL); + if (ret != 0) + goto error5; + + ret = nbytes; + if (copy_to_user(buffer, kbuf, nbytes) != 0) + ret = -EFAULT; + +error5: + kfree(kbuf); +error4: + mpi_free(result); +error3: + mpi_free(private); +error2: + mpi_free(base); +error1: + mpi_free(prime); +out: + return ret; +} diff --git a/security/keys/internal.h b/security/keys/internal.h index 5105c2c2da75..8ec7a528365d 100644 --- a/security/keys/internal.h +++ b/security/keys/internal.h @@ -15,6 +15,7 @@ #include <linux/sched.h> #include <linux/key-type.h> #include <linux/task_work.h> +#include <linux/keyctl.h> struct iovec; @@ -257,6 +258,17 @@ static inline long keyctl_get_persistent(uid_t uid, key_serial_t destring) } #endif +#ifdef CONFIG_KEY_DH_OPERATIONS +extern long keyctl_dh_compute(struct keyctl_dh_params __user *, char __user *, + size_t); +#else +static inline long keyctl_dh_compute(struct keyctl_dh_params __user *params, + char __user *buffer, size_t buflen) +{ + return -EOPNOTSUPP; +} +#endif + /* * Debugging key validation */ diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index ed73c6c1c326..3b135a0af344 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -1686,6 +1686,11 @@ SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3, case KEYCTL_GET_PERSISTENT: return keyctl_get_persistent((uid_t)arg2, (key_serial_t)arg3); + case KEYCTL_DH_COMPUTE: + return keyctl_dh_compute((struct keyctl_dh_params __user *) arg2, + (char __user *) arg3, + (size_t) arg4); + default: return -EOPNOTSUPP; } diff --git a/security/keys/user_defined.c b/security/keys/user_defined.c index 8705d79b2c6f..66b1840b4110 100644 --- a/security/keys/user_defined.c +++ b/security/keys/user_defined.c @@ -96,45 +96,25 @@ EXPORT_SYMBOL_GPL(user_free_preparse); */ int user_update(struct key *key, struct key_preparsed_payload *prep) { - struct user_key_payload *upayload, *zap; - size_t datalen = prep->datalen; + struct user_key_payload *zap = NULL; int ret; - ret = -EINVAL; - if (datalen <= 0 || datalen > 32767 || !prep->data) - goto error; - - /* construct a replacement payload */ - ret = -ENOMEM; - upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); - if (!upayload) - goto error; - - upayload->datalen = datalen; - memcpy(upayload->data, prep->data, datalen); - /* check the quota and attach the new data */ - zap = upayload; - - ret = key_payload_reserve(key, datalen); - - if (ret == 0) { - /* attach the new data, displacing the old */ - if (!test_bit(KEY_FLAG_NEGATIVE, &key->flags)) - zap = key->payload.data[0]; - else - zap = NULL; - rcu_assign_keypointer(key, upayload); - key->expiry = 0; - } + ret = key_payload_reserve(key, prep->datalen); + if (ret < 0) + return ret; + + /* attach the new data, displacing the old */ + key->expiry = prep->expiry; + if (!test_bit(KEY_FLAG_NEGATIVE, &key->flags)) + zap = rcu_dereference_key(key); + rcu_assign_keypointer(key, prep->payload.data[0]); + prep->payload.data[0] = NULL; if (zap) kfree_rcu(zap, rcu); - -error: return ret; } - EXPORT_SYMBOL_GPL(user_update); /* |