linux/drivers/of/kexec.c
Lakshmi Ramasubramanian 28db15d49c kexec: Use fdt_appendprop_addrrange() to add ima buffer to FDT
fdt_appendprop_addrrange() function adds a property, with the given name,
to the device tree at the given node offset, and also sets the address
and size of the property.  This function should be used to add
"linux,ima-kexec-buffer" property to the device tree and set the address
and size of the IMA measurement buffer, instead of using custom function.

Use fdt_appendprop_addrrange() to add  "linux,ima-kexec-buffer" property
to the device tree.  This property holds the address and size of
the IMA measurement buffer that needs to be passed from the current
kernel to the next kernel across kexec system call.

Remove custom code that is used in setup_ima_buffer() to add
"linux,ima-kexec-buffer" property to the device tree.

Co-developed-by: Prakhar Srivastava <prsriva@linux.microsoft.com>
Signed-off-by: Prakhar Srivastava <prsriva@linux.microsoft.com>
Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210221174930.27324-12-nramas@linux.microsoft.com
2021-03-08 12:06:30 -07:00

459 lines
11 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2020 Arm Limited
*
* Based on arch/arm64/kernel/machine_kexec_file.c:
* Copyright (C) 2018 Linaro Limited
*
* And arch/powerpc/kexec/file_load.c:
* Copyright (C) 2016 IBM Corporation
*/
#include <linux/kernel.h>
#include <linux/kexec.h>
#include <linux/memblock.h>
#include <linux/libfdt.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/random.h>
#include <linux/types.h>
/* relevant device tree properties */
#define FDT_PROP_KEXEC_ELFHDR "linux,elfcorehdr"
#define FDT_PROP_MEM_RANGE "linux,usable-memory-range"
#define FDT_PROP_INITRD_START "linux,initrd-start"
#define FDT_PROP_INITRD_END "linux,initrd-end"
#define FDT_PROP_BOOTARGS "bootargs"
#define FDT_PROP_KASLR_SEED "kaslr-seed"
#define FDT_PROP_RNG_SEED "rng-seed"
#define RNG_SEED_SIZE 128
/*
* Additional space needed for the FDT buffer so that we can add initrd,
* bootargs, kaslr-seed, rng-seed, useable-memory-range and elfcorehdr.
*/
#define FDT_EXTRA_SPACE 0x1000
/**
* fdt_find_and_del_mem_rsv - delete memory reservation with given address and size
*
* @fdt: Flattened device tree for the current kernel.
* @start: Starting address of the reserved memory.
* @size: Size of the reserved memory.
*
* Return: 0 on success, or negative errno on error.
*/
static int fdt_find_and_del_mem_rsv(void *fdt, unsigned long start, unsigned long size)
{
int i, ret, num_rsvs = fdt_num_mem_rsv(fdt);
for (i = 0; i < num_rsvs; i++) {
u64 rsv_start, rsv_size;
ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
if (ret) {
pr_err("Malformed device tree.\n");
return -EINVAL;
}
if (rsv_start == start && rsv_size == size) {
ret = fdt_del_mem_rsv(fdt, i);
if (ret) {
pr_err("Error deleting device tree reservation.\n");
return -EINVAL;
}
return 0;
}
}
return -ENOENT;
}
/**
* get_addr_size_cells - Get address and size of root node
*
* @addr_cells: Return address of the root node
* @size_cells: Return size of the root node
*
* Return: 0 on success, or negative errno on error.
*/
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;
}
/**
* do_get_kexec_buffer - Get address and size of device tree property
*
* @prop: Device tree property
* @len: Size of @prop
* @addr: Return address of the node
* @size: Return size of the node
*
* Return: 0 on success, or negative errno on error.
*/
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;
if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
return -ENOTSUPP;
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;
if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
return -ENOTSUPP;
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
*
* @fdt: Flattened Device Tree to update
* @chosen_node: Offset to the chosen node in the device tree
*
* The IMA measurement buffer is of no use to a subsequent kernel, so we always
* remove it from the device tree.
*/
static void remove_ima_buffer(void *fdt, int chosen_node)
{
int ret, len;
unsigned long addr;
size_t size;
const void *prop;
if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
return;
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 = fdt_find_and_del_mem_rsv(fdt, addr, size);
if (!ret)
pr_debug("Removed old IMA buffer reservation.\n");
}
#ifdef CONFIG_IMA_KEXEC
/**
* 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.
*/
static int setup_ima_buffer(const struct kimage *image, void *fdt,
int chosen_node)
{
int ret;
if (!image->ima_buffer_size)
return 0;
ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
"linux,ima-kexec-buffer",
image->ima_buffer_addr,
image->ima_buffer_size);
if (ret < 0)
return -EINVAL;
ret = fdt_add_mem_rsv(fdt, image->ima_buffer_addr,
image->ima_buffer_size);
if (ret)
return -EINVAL;
pr_debug("IMA buffer at 0x%llx, size = 0x%zx\n",
image->ima_buffer_addr, image->ima_buffer_size);
return 0;
}
#else /* CONFIG_IMA_KEXEC */
static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
int chosen_node)
{
return 0;
}
#endif /* CONFIG_IMA_KEXEC */
/*
* of_kexec_alloc_and_setup_fdt - Alloc and setup a new Flattened Device Tree
*
* @image: kexec image being loaded.
* @initrd_load_addr: Address where the next initrd will be loaded.
* @initrd_len: Size of the next initrd, or 0 if there will be none.
* @cmdline: Command line for the next kernel, or NULL if there will
* be none.
* @extra_fdt_size: Additional size for the new FDT buffer.
*
* Return: fdt on success, or NULL errno on error.
*/
void *of_kexec_alloc_and_setup_fdt(const struct kimage *image,
unsigned long initrd_load_addr,
unsigned long initrd_len,
const char *cmdline, size_t extra_fdt_size)
{
void *fdt;
int ret, chosen_node;
const void *prop;
size_t fdt_size;
fdt_size = fdt_totalsize(initial_boot_params) +
(cmdline ? strlen(cmdline) : 0) +
FDT_EXTRA_SPACE +
extra_fdt_size;
fdt = kvmalloc(fdt_size, GFP_KERNEL);
if (!fdt)
return NULL;
ret = fdt_open_into(initial_boot_params, fdt, fdt_size);
if (ret < 0) {
pr_err("Error %d setting up the new device tree.\n", ret);
goto out;
}
/* Remove memory reservation for the current device tree. */
ret = fdt_find_and_del_mem_rsv(fdt, __pa(initial_boot_params),
fdt_totalsize(initial_boot_params));
if (ret == -EINVAL) {
pr_err("Error removing memory reservation.\n");
goto out;
}
chosen_node = fdt_path_offset(fdt, "/chosen");
if (chosen_node == -FDT_ERR_NOTFOUND)
chosen_node = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"),
"chosen");
if (chosen_node < 0) {
ret = chosen_node;
goto out;
}
ret = fdt_delprop(fdt, chosen_node, FDT_PROP_KEXEC_ELFHDR);
if (ret && ret != -FDT_ERR_NOTFOUND)
goto out;
ret = fdt_delprop(fdt, chosen_node, FDT_PROP_MEM_RANGE);
if (ret && ret != -FDT_ERR_NOTFOUND)
goto out;
/* Did we boot using an initrd? */
prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", NULL);
if (prop) {
u64 tmp_start, tmp_end, tmp_size;
tmp_start = fdt64_to_cpu(*((const fdt64_t *) prop));
prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", NULL);
if (!prop) {
ret = -EINVAL;
goto out;
}
tmp_end = fdt64_to_cpu(*((const fdt64_t *) prop));
/*
* kexec reserves exact initrd size, while firmware may
* reserve a multiple of PAGE_SIZE, so check for both.
*/
tmp_size = tmp_end - tmp_start;
ret = fdt_find_and_del_mem_rsv(fdt, tmp_start, tmp_size);
if (ret == -ENOENT)
ret = fdt_find_and_del_mem_rsv(fdt, tmp_start,
round_up(tmp_size, PAGE_SIZE));
if (ret == -EINVAL)
goto out;
}
/* add initrd-* */
if (initrd_load_addr) {
ret = fdt_setprop_u64(fdt, chosen_node, FDT_PROP_INITRD_START,
initrd_load_addr);
if (ret)
goto out;
ret = fdt_setprop_u64(fdt, chosen_node, FDT_PROP_INITRD_END,
initrd_load_addr + initrd_len);
if (ret)
goto out;
ret = fdt_add_mem_rsv(fdt, initrd_load_addr, initrd_len);
if (ret)
goto out;
} else {
ret = fdt_delprop(fdt, chosen_node, FDT_PROP_INITRD_START);
if (ret && (ret != -FDT_ERR_NOTFOUND))
goto out;
ret = fdt_delprop(fdt, chosen_node, FDT_PROP_INITRD_END);
if (ret && (ret != -FDT_ERR_NOTFOUND))
goto out;
}
if (image->type == KEXEC_TYPE_CRASH) {
/* add linux,elfcorehdr */
ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
FDT_PROP_KEXEC_ELFHDR,
image->elf_load_addr,
image->elf_headers_sz);
if (ret)
goto out;
/*
* Avoid elfcorehdr from being stomped on in kdump kernel by
* setting up memory reserve map.
*/
ret = fdt_add_mem_rsv(fdt, image->elf_load_addr,
image->elf_headers_sz);
if (ret)
goto out;
/* add linux,usable-memory-range */
ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
FDT_PROP_MEM_RANGE,
crashk_res.start,
crashk_res.end - crashk_res.start + 1);
if (ret)
goto out;
}
/* add bootargs */
if (cmdline) {
ret = fdt_setprop_string(fdt, chosen_node, FDT_PROP_BOOTARGS, cmdline);
if (ret)
goto out;
} else {
ret = fdt_delprop(fdt, chosen_node, FDT_PROP_BOOTARGS);
if (ret && (ret != -FDT_ERR_NOTFOUND))
goto out;
}
/* add kaslr-seed */
ret = fdt_delprop(fdt, chosen_node, FDT_PROP_KASLR_SEED);
if (ret == -FDT_ERR_NOTFOUND)
ret = 0;
else if (ret)
goto out;
if (rng_is_initialized()) {
u64 seed = get_random_u64();
ret = fdt_setprop_u64(fdt, chosen_node, FDT_PROP_KASLR_SEED, seed);
if (ret)
goto out;
} else {
pr_notice("RNG is not initialised: omitting \"%s\" property\n",
FDT_PROP_KASLR_SEED);
}
/* add rng-seed */
if (rng_is_initialized()) {
void *rng_seed;
ret = fdt_setprop_placeholder(fdt, chosen_node, FDT_PROP_RNG_SEED,
RNG_SEED_SIZE, &rng_seed);
if (ret)
goto out;
get_random_bytes(rng_seed, RNG_SEED_SIZE);
} else {
pr_notice("RNG is not initialised: omitting \"%s\" property\n",
FDT_PROP_RNG_SEED);
}
ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0);
if (ret)
goto out;
remove_ima_buffer(fdt, chosen_node);
ret = setup_ima_buffer(image, fdt, fdt_path_offset(fdt, "/chosen"));
out:
if (ret) {
kvfree(fdt);
fdt = NULL;
}
return fdt;
}