KEYS: Provide keyctls to drive the new key type ops for asymmetric keys [ver #2]

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, unsigned long reserved,
		    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 decrypted.

     reserved must be set to 0.  This is intended for future use to hand
     over one or more passphrases needed unlock a key.

     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;
	__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

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

     The __spare space in the parameter block must be set to 0.  This is
     intended, amongst other things, to allow the passing of passphrases
     required to unlock a key.

     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@redhat.com>
Tested-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Denis Kenzior <denkenz@gmail.com>
Tested-by: Denis Kenzior <denkenz@gmail.com>
Signed-off-by: James Morris <james.morris@microsoft.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/include/uapi/linux/keyctl.h b/include/uapi/linux/keyctl.h
index 1d1e9f2877af..f45ee0f69c0c 100644
--- a/include/uapi/linux/keyctl.h
+++ b/include/uapi/linux/keyctl.h
@@ -61,6 +61,11 @@
 #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 */
 #define KEYCTL_RESTRICT_KEYRING		29	/* Restrict keys allowed to link to a keyring */
 
 /* keyctl structures */
@@ -87,4 +92,24 @@ struct keyctl_kdf_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 */
+	__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[7];
+};
+
 #endif /*  _LINUX_KEYCTL_H */