/*
* Copyright (C) 2016 IBM Corporation
*
* Authors:
* Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
*
* 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/slab.h>
#include <linux/kexec.h>
#include <linux/of.h>
#include <linux/memblock.h>
#include <linux/libfdt.h>
static int get_addr_size_cells(int *addr_cells, int *size_cells)
{
struct device_node *root;
root = of_find_node_by_path("/");
if (!root)
return -EINVAL;
*addr_cells = of_n_addr_cells(root);
*size_cells = of_n_size_cells(root);
of_node_put(root);
return 0;
}
static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
size_t *size)
{
int ret, addr_cells, size_cells;
ret = get_addr_size_cells(&addr_cells, &size_cells);
if (ret)
return ret;
if (len < 4 * (addr_cells + size_cells))
return -ENOENT;
*addr = of_read_number(prop, addr_cells);
*size = of_read_number(prop + 4 * addr_cells, size_cells);
return 0;
}
/**
* ima_get_kexec_buffer - get IMA buffer from the previous kernel
* @addr: On successful return, set to point to the buffer contents.
* @size: On successful return, set to the buffer size.
*
* Return: 0 on success, negative errno on error.
*/
int ima_get_kexec_buffer(void **addr, size_t *size)
{
int ret, len;
unsigned long tmp_addr;
size_t tmp_size;
const void *prop;
prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len);
if (!prop)
return -ENOENT;
ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size);
if (ret)
return ret;
*addr = __va(tmp_addr);
*size = tmp_size;
return 0;
}
/**
* ima_free_kexec_buffer - free memory used by the IMA buffer
*/
int ima_free_kexec_buffer(void)
{
int ret;
unsigned long addr;
size_t size;
struct property *prop;
prop = of_find_property(of_chosen, "linux,ima-kexec-buffer", NULL);
if (!prop)
return -ENOENT;
ret = do_get_kexec_buffer(prop->value, prop->length, &addr, &size);
if (ret)
return ret;
ret = of_remove_property(of_chosen, prop);
if (ret)
return ret;
return memblock_free(addr, size);
}
/**
* remove_ima_buffer - remove the IMA buffer property and reservation from @fdt
*
* The IMA measurement buffer is of no use to a subsequent kernel, so we always
* remove it from the device tree.
*/
void remove_ima_buffer(void *fdt, int chosen_node)
{
int ret, len;
unsigned long addr;
size_t size;
const void *prop;
prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len);
if (!prop)
return;
ret = do_get_kexec_buffer(prop, len, &addr, &size);
fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
if (ret)
return;
ret = delete_fdt_mem_rsv(fdt, addr, size);
if (!ret)
pr_debug("Removed old IMA buffer reservation.\n");
}
#ifdef CONFIG_IMA_KEXEC
/**
* arch_ima_add_kexec_buffer - do arch-specific steps to add the IMA buffer
*
* Architectures should use this function to pass on the IMA buffer
* information to the next kernel.
*
* Return: 0 on success, negative errno on error.
*/
int arch_ima_add_kexec_buffer(struct kimage *image, unsigned long load_addr,
size_t size)
{
image->arch.ima_buffer_addr = load_addr;
image->arch.ima_buffer_size = size;
return 0;
}
static int write_number(void *p, u64 value, int cells)
{
if (cells == 1) {
u32 tmp;
if (value > U32_MAX)
return -EINVAL;
tmp = cpu_to_be32(value);
memcpy(p, &tmp, sizeof(tmp));
} else if (cells == 2) {
u64 tmp;
tmp = cpu_to_be64(value);
memcpy(p, &tmp, sizeof(tmp));
} else
return -EINVAL;
return 0;
}
/**
* setup_ima_buffer - add IMA buffer information to the fdt
* @image: kexec image being loaded.
* @fdt: Flattened device tree for the next kernel.
* @chosen_node: Offset to the chosen node.
*
* Return: 0 on success, or negative errno on error.
*/
int setup_ima_buffer(const struct kimage *image, void *fdt, int chosen_node)
{
int ret, addr_cells, size_cells, entry_size;
u8 value[16];
remove_ima_buffer(fdt, chosen_node);
if (!image->arch.ima_buffer_size)
return 0;
ret = get_addr_size_cells(&addr_cells, &size_cells);
if (ret)
return ret;
entry_size = 4 * (addr_cells + size_cells);
if (entry_size > sizeof(value))
return -EINVAL;
ret = write_number(value, image->arch.ima_buffer_addr, addr_cells);
if (ret)
return ret;
ret = write_number(value + 4 * addr_cells, image->arch.ima_buffer_size,
size_cells);
if (ret)
return ret;
ret = fdt_setprop(fdt, chosen_node, "linux,ima-kexec-buffer", value,
entry_size);
if (ret < 0)
return -EINVAL;
ret = fdt_add_mem_rsv(fdt, image->arch.ima_buffer_addr,
image->arch.ima_buffer_size);
if (ret)
return -EINVAL;
pr_debug("IMA buffer at 0x%llx, size = 0x%zx\n",
image->arch.ima_buffer_addr, image->arch.ima_buffer_size);
return 0;
}
#endif /* CONFIG_IMA_KEXEC */
