diff options
| -rw-r--r-- | Documentation/security/keys.txt | 30 | ||||
| -rw-r--r-- | include/uapi/linux/keyctl.h | 10 | ||||
| -rw-r--r-- | security/keys/Kconfig | 11 | ||||
| -rw-r--r-- | security/keys/Makefile | 1 | ||||
| -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 |
8 files changed, 233 insertions, 0 deletions
diff --git a/Documentation/security/keys.txt b/Documentation/security/keys.txt index 8c18387..a2f70cf 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 840cb99..86eddd6 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 <linux/types.h> + /* 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 4582809..f826e87 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 dfb3a7b..1fd4a16 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 25430a3..c8783b3 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 0000000..880505a --- /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 5105c2c..8ec7a52 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 ed73c6c..3b135a0 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; } |
