[RFC PATCH 2/8] KEYS: Provide keyctls to drive the new key type ops for asymmetric keys [ver 3]

From: David Howells
Date: Wed May 11 2016 - 10:22:24 EST

Provide five keyctl functions that permit userspace to make use of the new
key type ops for accessing and driving asymmetric keys.

(*) Query an asymmetric key.

long keyctl(KEYCTL_PKEY_QUERY,
key_serial_t key, key_serial_t password,
struct keyctl_pkey_query *info);

Get information about an asymmetric key. The information is returned
in the keyctl_pkey_query struct:

__u32 supported_ops;

A bit mask of flags indicating which ops are supported. This is
constructed from a bitwise-OR of:

KEYCTL_SUPPORTS_{ENCRYPT,DECRYPT,SIGN,VERIFY}

__u32 key_size;

The size in bits of the key.

__u16 max_data_size;
__u16 max_sig_size;
__u16 max_enc_size;
__u16 max_dec_size;

The maximum sizes in bytes of a blob of data to be signed, a signature
blob, a blob to be encrypted and a blob to be decypted.

If the key needs to be unlocked with a password, a logon-type key that
holds the password may be given as the password argument

If successful, 0 is returned. If the key is not an asymmetric key,
EOPNOTSUPP is returned.


(*) Encrypt, decrypt, sign or verify a blob using an asymmetric key.

long keyctl(KEYCTL_PKEY_ENCRYPT,
const struct keyctl_pkey_params *params,
const char *info,
const void *in,
void *out);

long keyctl(KEYCTL_PKEY_DECRYPT,
const struct keyctl_pkey_params *params,
const char *info,
const void *in,
void *out);

long keyctl(KEYCTL_PKEY_SIGN,
const struct keyctl_pkey_params *params,
const char *info,
const void *in,
void *out);

long keyctl(KEYCTL_PKEY_VERIFY,
const struct keyctl_pkey_params *params,
const char *info,
const void *in,
const void *in2);

Use an asymmetric key to perform a public-key cryptographic operation
a blob of data.

The parameter block pointed to by params contains a number of integer
values:

__s32 key_id;
__s32 password_id;
__u32 in_len;
__u32 out_len;
__u32 in2_len;

For a given operation, the in and out buffers are used as follows:

Operation ID in,in_len out,out_len in2,in2_len
======================= =============== =============== ===============
KEYCTL_PKEY_ENCRYPT Raw data Encrypted data -
KEYCTL_PKEY_DECRYPT Encrypted data Raw data -
KEYCTL_PKEY_SIGN Raw data Signature -
KEYCTL_PKEY_VERIFY Raw data - Signature

If the key must be unlocked with a password before it can be used,
password_id should point to a logon-type key that holds this.

info is a string of key=value pairs that supply supplementary
information.

If successful, encrypt, decrypt and sign all return the amount of data
written into the output buffer. Verification returns 0 on success.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

Documentation/security/keys.txt | 111 +++++++++++++
include/uapi/linux/keyctl.h | 26 +++
security/keys/Makefile | 1
security/keys/compat.c | 15 ++
security/keys/internal.h | 39 +++++
security/keys/keyctl.c | 23 +++
security/keys/keyctl_pkey.c | 335 +++++++++++++++++++++++++++++++++++++++
7 files changed, 550 insertions(+)
create mode 100644 security/keys/keyctl_pkey.c

diff --git a/Documentation/security/keys.txt b/Documentation/security/keys.txt
index ca72b70a24b9..01c2ae28a8c0 100644
--- a/Documentation/security/keys.txt
+++ b/Documentation/security/keys.txt
@@ -854,6 +854,117 @@ The keyctl syscall functions are:
supported, error ENOKEY if the key could not be found, or error
EACCES if the key is not readable by the caller.

+
+ (*) Query an asymmetric key.
+
+ long keyctl(KEYCTL_PKEY_QUERY,
+ key_serial_t key, key_serial_t password,
+ struct keyctl_pkey_query *info);
+
+ Get information about an asymmetric key. The information is returned in
+ the keyctl_pkey_query struct:
+
+ __u32 supported_ops;
+
+ A bit mask of flags indicating which ops are supported. This is
+ constructed from a bitwise-OR of:
+
+ KEYCTL_SUPPORTS_{ENCRYPT,DECRYPT,SIGN,VERIFY}
+
+ __u32 key_size;
+
+ The size in bits of the key.
+
+ __u16 max_data_size;
+ __u16 max_sig_size;
+ __u16 max_enc_size;
+ __u16 max_dec_size;
+
+ The maximum sizes in bytes of a blob of data to be signed, a signature
+ blob, a blob to be encrypted and a blob to be decypted.
+
+ If the key needs to be unlocked with a password, a logon-type key that
+ holds the password may be given as the password argument
+
+ If successful, 0 is returned. If the key is not an asymmetric key,
+ EOPNOTSUPP is returned.
+
+
+ (*) Encrypt, decrypt, sign or verify a blob using an asymmetric key.
+
+ long keyctl(KEYCTL_PKEY_ENCRYPT,
+ const struct keyctl_pkey_params *params,
+ const char *info,
+ const void *in,
+ void *out);
+
+ long keyctl(KEYCTL_PKEY_DECRYPT,
+ const struct keyctl_pkey_params *params,
+ const char *info,
+ const void *in,
+ void *out);
+
+ long keyctl(KEYCTL_PKEY_SIGN,
+ const struct keyctl_pkey_params *params,
+ const char *info,
+ const void *in,
+ void *out);
+
+ long keyctl(KEYCTL_PKEY_VERIFY,
+ const struct keyctl_pkey_params *params,
+ const char *info,
+ const void *in,
+ const void *in2);
+
+ Use an asymmetric key to perform a public-key cryptographic operation a
+ blob of data. For encryption and verification, the asymmetric key may
+ only need the public parts to be available, but for decryption and signing
+ the private parts are required also.
+
+ The parameter block pointed to by params contains a number of integer
+ values:
+
+ __s32 key_id;
+ __s32 password_id;
+ __u32 in_len;
+ __u32 out_len;
+ __u32 in2_len;
+
+ key_id is the ID of the asymmetric key to be used. in_len and in2_len
+ indicate the amount of data in the in and in2 buffers and out_len
+ indicates the size of the out buffer as appropriate for the above
+ operations.
+
+ For a given operation, the in and out buffers are used as follows:
+
+ Operation ID in,in_len out,out_len in2,in2_len
+ ======================= =============== =============== ===============
+ KEYCTL_PKEY_ENCRYPT Raw data Encrypted data -
+ KEYCTL_PKEY_DECRYPT Encrypted data Raw data -
+ KEYCTL_PKEY_SIGN Raw data Signature -
+ KEYCTL_PKEY_VERIFY Raw data - Signature
+
+ If the key must be unlocked with a password before it can be used,
+ password_id should point to a logon-type key that holds this.
+
+ info is a string of key=value pairs that supply supplementary information.
+ These include:
+
+ enc=<encoding> The encoding of the encrypted/signature blob. This can
+ be "pkcs1" for RSASSA-PKCS1-v1.5 or RSAES-PKCS1-v1.5;
+ "pss" for "RSASSA-PSS"; "oaep" for "RSAES-OAEP". If
+ omitted or is "raw", the raw output of the encryption
+ function is specified.
+
+ hash=<algo> If the data buffer contains the output of a hash
+ function and the encoding includes some indication of
+ which hash function was used, the hash function can be
+ specified with this, eg. "hash=sha256".
+
+ If successful, encrypt, decrypt and sign all return the amount of data
+ written into the output buffer. Verification returns 0 on success.
+
+
===============
KERNEL SERVICES
===============
diff --git a/include/uapi/linux/keyctl.h b/include/uapi/linux/keyctl.h
index 8ac2c5fbc8fc..05f4f6ffbad2 100644
--- a/include/uapi/linux/keyctl.h
+++ b/include/uapi/linux/keyctl.h
@@ -60,6 +60,11 @@
#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 */
+#define KEYCTL_PKEY_QUERY 24 /* Query public key parameters */
+#define KEYCTL_PKEY_ENCRYPT 25 /* Encrypt a blob using a public key */
+#define KEYCTL_PKEY_DECRYPT 26 /* Decrypt a blob using a public key */
+#define KEYCTL_PKEY_SIGN 27 /* Create a public key signature */
+#define KEYCTL_PKEY_VERIFY 28 /* Verify a public key signature */

/* keyctl structures */
struct keyctl_dh_params {
@@ -73,4 +78,25 @@ struct keyctl_dh_params {
#define KEYCTL_SUPPORTS_SIGN 0x04
#define KEYCTL_SUPPORTS_VERIFY 0x08

+struct keyctl_pkey_query {
+ __u32 supported_ops; /* Which ops are supported */
+ __u32 key_size; /* Size of the key in bits */
+ __u16 max_data_size; /* Maximum size of raw data to sign in bytes */
+ __u16 max_sig_size; /* Maximum size of signature in bytes */
+ __u16 max_enc_size; /* Maximum size of encrypted blob in bytes */
+ __u16 max_dec_size; /* Maximum size of decrypted blob in bytes */
+ __u32 __spare[10];
+};
+
+struct keyctl_pkey_params {
+ __s32 key_id; /* Serial no. of public key to use */
+ __s32 password_id; /* Serial no. of password-containing key to use (or 0) */
+ __u32 in_len; /* Input data size */
+ union {
+ __u32 out_len; /* Output buffer size (encrypt/decrypt/sign) */
+ __u32 in2_len; /* 2nd input data size (verify) */
+ };
+ __u32 __spare[4];
+};
+
#endif /* _LINUX_KEYCTL_H */
diff --git a/security/keys/Makefile b/security/keys/Makefile
index 1fd4a16e6daf..981be73e938f 100644
--- a/security/keys/Makefile
+++ b/security/keys/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_PROC_FS) += proc.o
obj-$(CONFIG_SYSCTL) += sysctl.o
obj-$(CONFIG_PERSISTENT_KEYRINGS) += persistent.o
obj-$(CONFIG_KEY_DH_OPERATIONS) += dh.o
+obj-$(CONFIG_ASYMMETRIC_KEY_TYPE) += keyctl_pkey.o

#
# Key types
diff --git a/security/keys/compat.c b/security/keys/compat.c
index c8783b3b628c..6298b651e522 100644
--- a/security/keys/compat.c
+++ b/security/keys/compat.c
@@ -136,6 +136,21 @@ COMPAT_SYSCALL_DEFINE5(keyctl, u32, option,
return keyctl_dh_compute(compat_ptr(arg2), compat_ptr(arg3),
arg4);

+ case KEYCTL_PKEY_QUERY:
+ return keyctl_pkey_query(arg2, arg3, compat_ptr(arg4),
+ compat_ptr(arg5));
+
+ case KEYCTL_PKEY_ENCRYPT:
+ case KEYCTL_PKEY_DECRYPT:
+ case KEYCTL_PKEY_SIGN:
+ return keyctl_pkey_e_d_s(option,
+ compat_ptr(arg2), compat_ptr(arg3),
+ compat_ptr(arg4), compat_ptr(arg5));
+
+ case KEYCTL_PKEY_VERIFY:
+ return keyctl_pkey_verify(compat_ptr(arg2), compat_ptr(arg3),
+ compat_ptr(arg4), compat_ptr(arg5));
+
default:
return -EOPNOTSUPP;
}
diff --git a/security/keys/internal.h b/security/keys/internal.h
index 8ec7a528365d..7da61fb8c6b4 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -269,6 +269,45 @@ static inline long keyctl_dh_compute(struct keyctl_dh_params __user *params,
}
#endif

+#ifdef CONFIG_ASYMMETRIC_KEY_TYPE
+extern long keyctl_pkey_query(key_serial_t, key_serial_t,
+ const char __user *,
+ struct keyctl_pkey_query __user *);
+
+extern long keyctl_pkey_verify(const struct keyctl_pkey_params __user *,
+ const char __user *,
+ const void __user *, const void __user *);
+
+extern long keyctl_pkey_e_d_s(int,
+ const struct keyctl_pkey_params __user *,
+ const char __user *,
+ const void __user *, void __user *);
+#else
+static inline long keyctl_pkey_query(key_serial_t id, key_serial_t password,
+ const char __user *_info,
+ struct keyctl_pkey_query __user *_res)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline long keyctl_pkey_verify(const struct keyctl_pkey_params __user *params,
+ const char __user *_info,
+ const void __user *_in,
+ const void __user *_in2)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline long keyctl_pkey_e_d_s(int op,
+ const struct keyctl_pkey_params __user *params,
+ const char __user *_info,
+ const void __user *_in,
+ void __user *_out)
+{
+ return -EOPNOTSUPP;
+}
+#endif
+
/*
* Debugging key validation
*/
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 3b135a0af344..4414c959fad3 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -1691,6 +1691,29 @@ SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
(char __user *) arg3,
(size_t) arg4);

+ case KEYCTL_PKEY_QUERY:
+ return keyctl_pkey_query((key_serial_t)arg2,
+ (key_serial_t)arg3,
+ (const char __user *)arg4,
+ (struct keyctl_pkey_query *)arg5);
+
+ case KEYCTL_PKEY_ENCRYPT:
+ case KEYCTL_PKEY_DECRYPT:
+ case KEYCTL_PKEY_SIGN:
+ return keyctl_pkey_e_d_s(
+ option,
+ (const struct keyctl_pkey_params __user *)arg2,
+ (const char __user *)arg3,
+ (const void __user *)arg4,
+ (void __user *)arg5);
+
+ case KEYCTL_PKEY_VERIFY:
+ return keyctl_pkey_verify(
+ (const struct keyctl_pkey_params __user *)arg2,
+ (const char __user *)arg3,
+ (const void __user *)arg4,
+ (const void __user *)arg5);
+
default:
return -EOPNOTSUPP;
}
diff --git a/security/keys/keyctl_pkey.c b/security/keys/keyctl_pkey.c
new file mode 100644
index 000000000000..7f51db984aaa
--- /dev/null
+++ b/security/keys/keyctl_pkey.c
@@ -0,0 +1,335 @@
+/* Public-key operation keyctls
+ *
+ * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@xxxxxxxxxx)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/key.h>
+#include <linux/keyctl.h>
+#include <linux/parser.h>
+#include <linux/uaccess.h>
+#include <keys/user-type.h>
+#include "internal.h"
+
+static void keyctl_pkey_params_free(struct kernel_pkey_params *params)
+{
+ kfree(params->info);
+ key_put(params->key);
+ key_put(params->password);
+}
+
+enum {
+ Opt_err = -1,
+ Opt_enc, /* "enc=<encoding>" eg. "enc=oaep" */
+ Opt_hash, /* "hash=<digest-name>" eg. "hash=sha1" */
+};
+
+static const match_table_t param_keys = {
+ { Opt_enc, "enc=%s" },
+ { Opt_hash, "hash=%s" },
+ { Opt_err, NULL }
+};
+
+/*
+ * Parse the information string which consists of key=val pairs.
+ */
+static int keyctl_pkey_params_parse(struct kernel_pkey_params *params)
+{
+ unsigned long token_mask = 0;
+ substring_t args[MAX_OPT_ARGS];
+ char *c = params->info, *p, *q;
+ int token;
+
+ while ((p = strsep(&c, " \t"))) {
+ if (*p == '\0' || *p == ' ' || *p == '\t')
+ continue;
+ token = match_token(p, param_keys, args);
+ if (__test_and_set_bit(token, &token_mask))
+ return -EINVAL;
+ q = args[0].from;
+ if (!q[0])
+ return -EINVAL;
+
+ switch (token) {
+ case Opt_enc:
+ params->encoding = q;
+ break;
+
+ case Opt_hash:
+ params->hash_algo = q;
+ break;
+
+ default:
+ return -EINVAL;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * Interpret parameters. Callers must always call the free function
+ * on params, even if an error is returned.
+ */
+static int keyctl_pkey_params_get(key_serial_t id,
+ key_serial_t password_id,
+ const char __user *_info,
+ struct kernel_pkey_params *params)
+{
+ key_ref_t key_ref;
+ void *p;
+ int ret;
+
+ memset(params, 0, sizeof(*params));
+ params->encoding = "raw";
+
+ p = strndup_user(_info, PAGE_SIZE);
+ if (IS_ERR(p))
+ return PTR_ERR(p);
+ params->info = p;
+
+ ret = keyctl_pkey_params_parse(params);
+ if (ret < 0)
+ return ret;
+
+ key_ref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
+ if (IS_ERR(key_ref))
+ return PTR_ERR(key_ref);
+ params->key = key_ref_to_ptr(key_ref);
+
+ if (!params->key->type->asym_query)
+ return -EOPNOTSUPP;
+
+ if (password_id) {
+ key_ref = lookup_user_key(password_id, 0, KEY_NEED_SEARCH);
+ if (IS_ERR(key_ref))
+ return PTR_ERR(key_ref);
+
+ params->password = key_ref_to_ptr(key_ref);
+ if (params->password->type != &key_type_logon)
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/*
+ * Get parameters from userspace. Callers must always call the free function
+ * on params, even if an error is returned.
+ */
+static int keyctl_pkey_params_get_2(const struct keyctl_pkey_params __user *_params,
+ const char __user *_info,
+ int op,
+ struct kernel_pkey_params *params)
+{
+ struct keyctl_pkey_params uparams;
+ struct kernel_pkey_query info;
+ int ret;
+
+ memset(params, 0, sizeof(*params));
+ params->encoding = "raw";
+
+ if (copy_from_user(&uparams, _params, sizeof(uparams)) != 0)
+ return -EFAULT;
+
+ ret = keyctl_pkey_params_get(uparams.key_id, uparams.password_id,
+ _info, params);
+ if (ret < 0)
+ return ret;
+
+ ret = params->key->type->asym_query(params, &info);
+ if (ret < 0)
+ return ret;
+
+ switch (op) {
+ case KEYCTL_PKEY_ENCRYPT:
+ case KEYCTL_PKEY_DECRYPT:
+ if (uparams.in_len > info.max_enc_size ||
+ uparams.out_len > info.max_dec_size)
+ return -EINVAL;
+ break;
+ case KEYCTL_PKEY_SIGN:
+ case KEYCTL_PKEY_VERIFY:
+ if (uparams.in_len > info.max_sig_size ||
+ uparams.out_len > info.max_data_size)
+ return -EINVAL;
+ break;
+ default:
+ BUG();
+ }
+
+ params->in_len = uparams.in_len;
+ params->out_len = uparams.out_len;
+ return 0;
+}
+
+/*
+ * Query information about an asymmetric key.
+ */
+long keyctl_pkey_query(key_serial_t id, key_serial_t password_id,
+ const char __user *_info,
+ struct keyctl_pkey_query __user *_res)
+{
+ struct kernel_pkey_params params;
+ struct kernel_pkey_query res;
+ long ret;
+
+ memset(&params, 0, sizeof(params));
+
+ ret = keyctl_pkey_params_get(id, password_id, _info, &params);
+ if (ret < 0)
+ goto error;
+
+ ret = params.key->type->asym_query(&params, &res);
+ if (ret < 0)
+ goto error;
+
+ ret = -EFAULT;
+ if (copy_to_user(_res, &res, sizeof(res)) == 0 &&
+ clear_user(_res->__spare, sizeof(_res->__spare)) == 0)
+ ret = 0;
+
+error:
+ keyctl_pkey_params_free(&params);
+ return ret;
+}
+
+/*
+ * Encrypt/decrypt/sign
+ *
+ * Encrypt data, decrypt data or sign data using a public key.
+ *
+ * _info is a string of supplementary information in key=val format. For
+ * instance, it might contain:
+ *
+ * "enc=pkcs1 hash=sha256"
+ *
+ * where enc= specifies the encoding and hash= selects the OID to go in that
+ * particular encoding if required. If enc= isn't supplied, it's assumed that
+ * the caller is supplying raw values.
+ *
+ * If needed, a password may be provided to unlock the private key in a logon
+ * key whose serial number is in _params->password_id.
+ *
+ * If successful, the amount of data written into the output buffer is
+ * returned.
+ */
+long keyctl_pkey_e_d_s(int op,
+ const struct keyctl_pkey_params __user *_params,
+ const char __user *_info,
+ const void __user *_in,
+ void __user *_out)
+{
+ struct kernel_pkey_params params;
+ void *in, *out;
+ long ret;
+
+ ret = keyctl_pkey_params_get_2(_params, _info, op, &params);
+ if (ret < 0)
+ goto error_params;
+
+ switch (op) {
+ case KEYCTL_PKEY_ENCRYPT:
+ params.op = kernel_pkey_encrypt;
+ break;
+ case KEYCTL_PKEY_DECRYPT:
+ params.op = kernel_pkey_decrypt;
+ break;
+ case KEYCTL_PKEY_SIGN:
+ params.op = kernel_pkey_sign;
+ break;
+ default:
+ BUG();
+ }
+
+ in = memdup_user(_in, params.in_len);
+ if (IS_ERR(in)) {
+ ret = PTR_ERR(in);
+ goto error_params;
+ }
+
+ ret = -ENOMEM;
+ out = kzalloc(params.out_len, GFP_KERNEL);
+ if (!out)
+ goto error_in;
+
+ ret = params.key->type->asym_eds_op(&params, in, out);
+ if (ret < 0)
+ goto error_out;
+
+ if (copy_to_user(_out, out, ret) != 0)
+ ret = -EFAULT;
+
+error_out:
+ kfree(out);
+error_in:
+ kfree(in);
+error_params:
+ keyctl_pkey_params_free(&params);
+ return ret;
+}
+
+/*
+ * Verify a signature.
+ *
+ * Verify a public key signature using the given key, or if not given, search
+ * for a matching key.
+ *
+ * _info is a string of supplementary information in key=val format. For
+ * instance, it might contain:
+ *
+ * "enc=pkcs1 hash=sha256"
+ *
+ * where enc= specifies the signature blob encoding and hash= selects the OID
+ * to go in that particular encoding. If enc= isn't supplied, it's assumed
+ * that the caller is supplying raw values.
+ *
+ * If successful, 0 is returned.
+ */
+long keyctl_pkey_verify(const struct keyctl_pkey_params __user *_params,
+ const char __user *_info,
+ const void __user *_in,
+ const void __user *_in2)
+{
+ struct kernel_pkey_params params;
+ void *in, *in2;
+ long ret;
+
+ ret = keyctl_pkey_params_get_2(_params, _info, KEYCTL_PKEY_VERIFY,
+ &params);
+ if (ret < 0)
+ goto error_params;
+
+ ret = -EOPNOTSUPP;
+ if (!params.key->type->asym_verify_signature)
+ goto error_params;
+
+ in = memdup_user(_in, params.in_len);
+ if (IS_ERR(in)) {
+ ret = PTR_ERR(in);
+ goto error_params;
+ }
+
+ in2 = memdup_user(_in2, params.in2_len);
+ if (IS_ERR(in2)) {
+ ret = PTR_ERR(in2);
+ goto error_in;
+ }
+
+ params.op = kernel_pkey_verify;
+ ret = params.key->type->asym_verify_signature(&params, in, in2);
+
+ kfree(in2);
+error_in:
+ kfree(in);
+error_params:
+ keyctl_pkey_params_free(&params);
+ return ret;
+}