106 lines
2.4 KiB
C
106 lines
2.4 KiB
C
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/*
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* Copyright (C) 2010 IBM Corporation
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*
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* Authors:
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* Mimi Zohar <zohar@us.ibm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 2 of the License.
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*
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* File: evm_secfs.c
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* - Used to signal when key is on keyring
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* - Get the key and enable EVM
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/uaccess.h>
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#include <linux/module.h>
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#include "evm.h"
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static struct dentry *evm_init_tpm;
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/**
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* evm_read_key - read() for <securityfs>/evm
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*
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* @filp: file pointer, not actually used
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* @buf: where to put the result
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* @count: maximum to send along
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* @ppos: where to start
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*
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* Returns number of bytes read or error code, as appropriate
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*/
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static ssize_t evm_read_key(struct file *filp, char __user *buf,
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size_t count, loff_t *ppos)
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{
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char temp[80];
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ssize_t rc;
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if (*ppos != 0)
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return 0;
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sprintf(temp, "%d", (evm_initialized & ~EVM_SETUP));
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rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
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return rc;
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}
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/**
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* evm_write_key - write() for <securityfs>/evm
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* @file: file pointer, not actually used
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* @buf: where to get the data from
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* @count: bytes sent
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* @ppos: where to start
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*
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* Used to signal that key is on the kernel key ring.
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* - get the integrity hmac key from the kernel key ring
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* - create list of hmac protected extended attributes
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* Returns number of bytes written or error code, as appropriate
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*/
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static ssize_t evm_write_key(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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int i, ret;
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if (!capable(CAP_SYS_ADMIN) || (evm_initialized & EVM_SETUP))
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return -EPERM;
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ret = kstrtoint_from_user(buf, count, 0, &i);
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if (ret)
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return ret;
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/* Reject invalid values */
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if (!i || (i & ~EVM_INIT_MASK) != 0)
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return -EINVAL;
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if (i & EVM_INIT_HMAC) {
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ret = evm_init_key();
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if (ret != 0)
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return ret;
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/* Forbid further writes after the symmetric key is loaded */
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i |= EVM_SETUP;
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}
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evm_initialized |= i;
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return count;
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}
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static const struct file_operations evm_key_ops = {
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.read = evm_read_key,
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.write = evm_write_key,
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};
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int __init evm_init_secfs(void)
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{
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int error = 0;
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evm_init_tpm = securityfs_create_file("evm", S_IRUSR | S_IRGRP,
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NULL, NULL, &evm_key_ops);
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if (!evm_init_tpm || IS_ERR(evm_init_tpm))
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error = -EFAULT;
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return error;
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}
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