On Tue, Mar 19, 2019 at 01:09:12PM -0700, Sean Christopherson wrote:

On Sun, Mar 17, 2019 at 11:14:46PM +0200, Jarkko Sakkinen wrote:

quoted

In order to provide a mechanism for devilering provisoning rights:

1. Add a new file to the securityfs file called sgx/provision that works
   as a token for allowing an enclave to have the provisioning privileges.
2. Add a new ioctl called SGX_IOC_ENCLAVE_SET_ATTRIBUTE that accepts the
   following data structure:

   struct sgx_enclave_set_attribute {
           __u64 addr;
           __u64 token_fd;
   };

A daemon could sit on top of sgx/provision and send a file descriptor of
this file to a process that needs to be able to provision enclaves.

The way this API is used is more or less straight-forward. Lets assume that
dev_fd is a handle to /dev/sgx and prov_fd is a handle to sgx/provision.
You would allow SGX_IOC_ENCLAVE_CREATE to initialize an enclave with the
PROVISIONKEY attribute by

params.addr = <enclave address>;
params.token_fd = prov_fd;

ioctl(dev_fd, SGX_IOC_ENCLAVE_SET_ATTRIBUTE, &params);

Cc: James Morris <jmorris@namei.org>
Cc: Serge E. Hallyn <serge@hallyn.com>
Cc: linux-security-module@vger.kernel.org
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Jarkko Sakkinen <redacted>
---
 arch/x86/include/uapi/asm/sgx.h        | 13 +++++++
 arch/x86/kernel/cpu/sgx/driver/ioctl.c | 43 +++++++++++++++++++++++
 arch/x86/kernel/cpu/sgx/driver/main.c  | 47 ++++++++++++++++++++++++++
 3 files changed, 103 insertions(+)

diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h
index aadf9c76e360..150a784db395 100644
--- a/arch/x86/include/uapi/asm/sgx.h
+++ b/arch/x86/include/uapi/asm/sgx.h

@@ -16,6 +16,8 @@
 	_IOW(SGX_MAGIC, 0x01, struct sgx_enclave_add_page)
 #define SGX_IOC_ENCLAVE_INIT \
 	_IOW(SGX_MAGIC, 0x02, struct sgx_enclave_init)
+#define SGX_IOC_ENCLAVE_SET_ATTRIBUTE \
+	_IOW(SGX_MAGIC, 0x03, struct sgx_enclave_set_attribute)
 
 /* IOCTL return values */
 #define SGX_POWER_LOST_ENCLAVE		0x40000000

@@ -56,4 +58,15 @@ struct sgx_enclave_init {
 	__u64	sigstruct;
 };
 
+/**
+ * struct sgx_enclave_set_attribute - parameter structure for the
+ *				      %SGX_IOC_ENCLAVE_INIT ioctl
+ * @addr:		address within the ELRANGE
+ * @attribute_fd:	file handle of the attribute file in the securityfs
+ */
+struct sgx_enclave_set_attribute {
+	__u64	addr;
+	__u64	attribute_fd;
+};
+
 #endif /* _UAPI_ASM_X86_SGX_H */

diff --git a/arch/x86/kernel/cpu/sgx/driver/ioctl.c b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
index 4b9a91b53b50..5d85bd3f7876 100644
--- a/arch/x86/kernel/cpu/sgx/driver/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/driver/ioctl.c

@@ -759,6 +759,46 @@ static long sgx_ioc_enclave_init(struct file *filep, unsigned int cmd,
 	return ret;
 }
 
+/**
+ * sgx_ioc_enclave_set_attribute - handler for %SGX_IOC_ENCLAVE_SET_ATTRIBUTE
+ * @filep:	open file to /dev/sgx
+ * @cmd:	the command value
+ * @arg:	pointer to a struct sgx_enclave_set_attribute instance
+ *
+ * Sets an attribute matching the attribute file that is pointed by the
+ * parameter structure field attribute_fd.

With the @data change (see below), this becomes something like:

 * Allow the enclave to request the attribute managed by the SGX security file
 * pointed at by the parameter structure field attribute_fd.

I see your point but the current implementation is just a tiny bit
simpler and right now we have one single file.

But I would do to fix this patch right now is to rename
sgx_fs_provision_ops as sgx_fs_ops to point out that only single fops
are required.

The current implementation is "good enough" for handling the
provisioning key.

/Jarkko