From 93da17b18539cb021f1075f8620ee8f6da9b42aa Mon Sep 17 00:00:00 2001 From: Andreas Ziegler Date: Tue, 12 Apr 2016 19:54:58 +0100 Subject: [PATCH 1/4] security: integrity: Remove select to deleted option PUBLIC_KEY_ALGO_RSA Commit d43de6c780a8 ("akcipher: Move the RSA DER encoding check to the crypto layer") removed the Kconfig option PUBLIC_KEY_ALGO_RSA, but forgot to remove a 'select' to this option in the definition of INTEGRITY_ASYMMETRIC_KEYS. Let's remove the select, as it's ineffective now. Signed-off-by: Andreas Ziegler Signed-off-by: David Howells --- security/integrity/Kconfig | 1 - 1 file changed, 1 deletion(-) diff --git a/security/integrity/Kconfig b/security/integrity/Kconfig index 979be65d22c4..da9565891738 100644 --- a/security/integrity/Kconfig +++ b/security/integrity/Kconfig @@ -35,7 +35,6 @@ config INTEGRITY_ASYMMETRIC_KEYS default n select ASYMMETRIC_KEY_TYPE select ASYMMETRIC_PUBLIC_KEY_SUBTYPE - select PUBLIC_KEY_ALGO_RSA select CRYPTO_RSA select X509_CERTIFICATE_PARSER help From 898de7d0f298e53568891f0ec3547b14fe8bb5d5 Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 12 Apr 2016 19:54:58 +0100 Subject: [PATCH 2/4] KEYS: user_update should use copy of payload made during preparsing The payload preparsing routine for user keys makes a copy of the payload provided by the caller and stashes it in the key_preparsed_payload struct for ->instantiate() or ->update() to use. However, ->update() takes another copy of this to attach to the keyring. ->update() should be using this directly and clearing the pointer in the preparse data. Signed-off-by: David Howells --- security/keys/user_defined.c | 40 +++++++++--------------------------- 1 file changed, 10 insertions(+), 30 deletions(-) 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, prep->datalen); + if (ret < 0) + return ret; - 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; - } + /* 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); /* From 13100a72f40f5748a04017e0ab3df4cf27c809ef Mon Sep 17 00:00:00 2001 From: Kirill Marinushkin Date: Tue, 12 Apr 2016 19:54:58 +0100 Subject: [PATCH 3/4] Security: Keys: Big keys stored encrypted Solved TODO task: big keys saved to shmem file are now stored encrypted. The encryption key is randomly generated and saved to payload[big_key_data]. Signed-off-by: Kirill Marinushkin Signed-off-by: David Howells --- security/keys/Kconfig | 4 + security/keys/big_key.c | 200 ++++++++++++++++++++++++++++++++++++---- 2 files changed, 185 insertions(+), 19 deletions(-) diff --git a/security/keys/Kconfig b/security/keys/Kconfig index fe4d74e126a7..45828095080d 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 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 #include #include +#include #include #include +#include /* * Layout of key payload words. @@ -27,6 +29,14 @@ enum { big_key_len, }; +/* + * 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 @@ -34,6 +44,11 @@ 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 @@ -49,6 +64,54 @@ struct key_type key_type_big_key = { .read = big_key_read, }; +/* + * 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 */ @@ -56,6 +119,8 @@ 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); - if (IS_ERR(file)) { - ret = PTR_ERR(file); + 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; } - written = kernel_write(file, prep->data, prep->datalen, 0); - if (written != datalen) { + 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 err_enckey; + } + + 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); From ddbb41148724367394d0880c516bfaeed127b52e Mon Sep 17 00:00:00 2001 From: Mat Martineau Date: Tue, 12 Apr 2016 19:54:58 +0100 Subject: [PATCH 4/4] KEYS: Add KEYCTL_DH_COMPUTE command This adds userspace access to Diffie-Hellman computations through a new keyctl() syscall command to calculate shared secrets or public keys using input parameters stored in the keyring. Input key ids are provided in a struct due to the current 5-arg limit for the keyctl syscall. Only user keys are supported in order to avoid exposing the content of logon or encrypted keys. The output is written to the provided buffer, based on the assumption that the values are only needed in userspace. Future support for other types of key derivation would involve a new command, like KEYCTL_ECDH_COMPUTE. Once Diffie-Hellman support is included in the crypto API, this code can be converted to use the crypto API to take advantage of possible hardware acceleration and reduce redundant code. Signed-off-by: Mat Martineau Signed-off-by: David Howells --- Documentation/security/keys.txt | 30 ++++++ include/uapi/linux/keyctl.h | 10 ++ security/keys/Kconfig | 11 +++ security/keys/Makefile | 1 + security/keys/compat.c | 4 + security/keys/dh.c | 160 ++++++++++++++++++++++++++++++++ security/keys/internal.h | 12 +++ security/keys/keyctl.c | 5 + 8 files changed, 233 insertions(+) create mode 100644 security/keys/dh.c diff --git a/Documentation/security/keys.txt b/Documentation/security/keys.txt index 8c183873b2b7..a2f70cf6763a 100644 --- a/Documentation/security/keys.txt +++ b/Documentation/security/keys.txt @@ -823,6 +823,36 @@ The keyctl syscall functions are: A process must have search permission on the key for this function to be successful. + (*) Compute a Diffie-Hellman shared secret or public key + + long keyctl(KEYCTL_DH_COMPUTE, struct keyctl_dh_params *params, + char *buffer, size_t buflen); + + The params struct contains serial numbers for three keys: + + - The prime, p, known to both parties + - The local private key + - The base integer, which is either a shared generator or the + remote public key + + The value computed is: + + result = base ^ private (mod prime) + + If the base is the shared generator, the result is the local + public key. If the base is the remote public key, the result is + the shared secret. + + The buffer length must be at least the length of the prime, or zero. + + If the buffer length is nonzero, the length of the result is + returned when it is successfully calculated and copied in to the + buffer. When the buffer length is zero, the minimum required + buffer length is returned. + + This function will return error EOPNOTSUPP if the key type is not + supported, error ENOKEY if the key could not be found, or error + EACCES if the key is not readable by the caller. =============== KERNEL SERVICES diff --git a/include/uapi/linux/keyctl.h b/include/uapi/linux/keyctl.h index 840cb990abe2..86eddd6241f3 100644 --- a/include/uapi/linux/keyctl.h +++ b/include/uapi/linux/keyctl.h @@ -12,6 +12,8 @@ #ifndef _LINUX_KEYCTL_H #define _LINUX_KEYCTL_H +#include + /* special process keyring shortcut IDs */ #define KEY_SPEC_THREAD_KEYRING -1 /* - key ID for thread-specific keyring */ #define KEY_SPEC_PROCESS_KEYRING -2 /* - key ID for process-specific keyring */ @@ -57,5 +59,13 @@ #define KEYCTL_INSTANTIATE_IOV 20 /* instantiate a partially constructed key */ #define KEYCTL_INVALIDATE 21 /* invalidate a key */ #define KEYCTL_GET_PERSISTENT 22 /* get a user's persistent keyring */ +#define KEYCTL_DH_COMPUTE 23 /* Compute Diffie-Hellman values */ + +/* keyctl structures */ +struct keyctl_dh_params { + __s32 private; + __s32 prime; + __s32 base; +}; #endif /* _LINUX_KEYCTL_H */ diff --git a/security/keys/Kconfig b/security/keys/Kconfig index 45828095080d..f826e8739023 100644 --- a/security/keys/Kconfig +++ b/security/keys/Kconfig @@ -85,3 +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/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 +#include +#include +#include +#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 #include #include +#include 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; }