[linux-block.git] / kernel / kexec_elf.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Load ELF vmlinux file for the kexec_file_load syscall.
 *
 * Copyright (C) 2004  Adam Litke (agl@us.ibm.com)
 * Copyright (C) 2004  IBM Corp.
 * Copyright (C) 2005  R Sharada (sharada@in.ibm.com)
 * Copyright (C) 2006  Mohan Kumar M (mohan@in.ibm.com)
 * Copyright (C) 2016  IBM Corporation
 *
 * Based on kexec-tools' kexec-elf-exec.c and kexec-elf-ppc64.c.
 * Heavily modified for the kernel by
 * Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>.
 */

#define pr_fmt(fmt)	"kexec_elf: " fmt

#include <linux/elf.h>
#include <linux/kexec.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>

#define elf_addr_to_cpu	elf64_to_cpu

static inline bool elf_is_elf_file(const struct elfhdr *ehdr)
{
	return memcmp(ehdr->e_ident, ELFMAG, SELFMAG) == 0;
}

static uint64_t elf64_to_cpu(const struct elfhdr *ehdr, uint64_t value)
{
	if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
		value = le64_to_cpu(value);
	else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
		value = be64_to_cpu(value);

	return value;
}

static uint32_t elf32_to_cpu(const struct elfhdr *ehdr, uint32_t value)
{
	if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
		value = le32_to_cpu(value);
	else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
		value = be32_to_cpu(value);

	return value;
}

static uint16_t elf16_to_cpu(const struct elfhdr *ehdr, uint16_t value)
{
	if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
		value = le16_to_cpu(value);
	else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
		value = be16_to_cpu(value);

	return value;
}

/**
 * elf_is_ehdr_sane - check that it is safe to use the ELF header
 * @buf_len:	size of the buffer in which the ELF file is loaded.
 */
static bool elf_is_ehdr_sane(const struct elfhdr *ehdr, size_t buf_len)
{
	if (ehdr->e_phnum > 0 && ehdr->e_phentsize != sizeof(struct elf_phdr)) {
		pr_debug("Bad program header size.\n");
		return false;
	} else if (ehdr->e_shnum > 0 &&
		   ehdr->e_shentsize != sizeof(struct elf_shdr)) {
		pr_debug("Bad section header size.\n");
		return false;
	} else if (ehdr->e_ident[EI_VERSION] != EV_CURRENT ||
		   ehdr->e_version != EV_CURRENT) {
		pr_debug("Unknown ELF version.\n");
		return false;
	}

	if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
		size_t phdr_size;

		/*
		 * e_phnum is at most 65535 so calculating the size of the
		 * program header cannot overflow.
		 */
		phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;

		/* Sanity check the program header table location. */
		if (ehdr->e_phoff + phdr_size < ehdr->e_phoff) {
			pr_debug("Program headers at invalid location.\n");
			return false;
		} else if (ehdr->e_phoff + phdr_size > buf_len) {
			pr_debug("Program headers truncated.\n");
			return false;
		}
	}

	if (ehdr->e_shoff > 0 && ehdr->e_shnum > 0) {
		size_t shdr_size;

		/*
		 * e_shnum is at most 65536 so calculating
		 * the size of the section header cannot overflow.
		 */
		shdr_size = sizeof(struct elf_shdr) * ehdr->e_shnum;

		/* Sanity check the section header table location. */
		if (ehdr->e_shoff + shdr_size < ehdr->e_shoff) {
			pr_debug("Section headers at invalid location.\n");
			return false;
		} else if (ehdr->e_shoff + shdr_size > buf_len) {
			pr_debug("Section headers truncated.\n");
			return false;
		}
	}

	return true;
}

static int elf_read_ehdr(const char *buf, size_t len, struct elfhdr *ehdr)
{
	struct elfhdr *buf_ehdr;

	if (len < sizeof(*buf_ehdr)) {
		pr_debug("Buffer is too small to hold ELF header.\n");
		return -ENOEXEC;
	}

	memset(ehdr, 0, sizeof(*ehdr));
	memcpy(ehdr->e_ident, buf, sizeof(ehdr->e_ident));
	if (!elf_is_elf_file(ehdr)) {
		pr_debug("No ELF header magic.\n");
		return -ENOEXEC;
	}

	if (ehdr->e_ident[EI_CLASS] != ELF_CLASS) {
		pr_debug("Not a supported ELF class.\n");
		return -ENOEXEC;
	} else  if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB &&
		ehdr->e_ident[EI_DATA] != ELFDATA2MSB) {
		pr_debug("Not a supported ELF data format.\n");
		return -ENOEXEC;
	}

	buf_ehdr = (struct elfhdr *) buf;
	if (elf16_to_cpu(ehdr, buf_ehdr->e_ehsize) != sizeof(*buf_ehdr)) {
		pr_debug("Bad ELF header size.\n");
		return -ENOEXEC;
	}

	ehdr->e_type      = elf16_to_cpu(ehdr, buf_ehdr->e_type);
	ehdr->e_machine   = elf16_to_cpu(ehdr, buf_ehdr->e_machine);
	ehdr->e_version   = elf32_to_cpu(ehdr, buf_ehdr->e_version);
	ehdr->e_entry     = elf_addr_to_cpu(ehdr, buf_ehdr->e_entry);
	ehdr->e_phoff     = elf_addr_to_cpu(ehdr, buf_ehdr->e_phoff);
	ehdr->e_shoff     = elf_addr_to_cpu(ehdr, buf_ehdr->e_shoff);
	ehdr->e_flags     = elf32_to_cpu(ehdr, buf_ehdr->e_flags);
	ehdr->e_phentsize = elf16_to_cpu(ehdr, buf_ehdr->e_phentsize);
	ehdr->e_phnum     = elf16_to_cpu(ehdr, buf_ehdr->e_phnum);
	ehdr->e_shentsize = elf16_to_cpu(ehdr, buf_ehdr->e_shentsize);
	ehdr->e_shnum     = elf16_to_cpu(ehdr, buf_ehdr->e_shnum);
	ehdr->e_shstrndx  = elf16_to_cpu(ehdr, buf_ehdr->e_shstrndx);

	return elf_is_ehdr_sane(ehdr, len) ? 0 : -ENOEXEC;
}

/**
 * elf_is_phdr_sane - check that it is safe to use the program header
 * @buf_len:	size of the buffer in which the ELF file is loaded.
 */
static bool elf_is_phdr_sane(const struct elf_phdr *phdr, size_t buf_len)
{

	if (phdr->p_offset + phdr->p_filesz < phdr->p_offset) {
		pr_debug("ELF segment location wraps around.\n");
		return false;
	} else if (phdr->p_offset + phdr->p_filesz > buf_len) {
		pr_debug("ELF segment not in file.\n");
		return false;
	} else if (phdr->p_paddr + phdr->p_memsz < phdr->p_paddr) {
		pr_debug("ELF segment address wraps around.\n");
		return false;
	}

	return true;
}

static int elf_read_phdr(const char *buf, size_t len,
			 struct kexec_elf_info *elf_info,
			 int idx)
{
	/* Override the const in proghdrs, we are the ones doing the loading. */
	struct elf_phdr *phdr = (struct elf_phdr *) &elf_info->proghdrs[idx];
	const char *pbuf;
	struct elf_phdr *buf_phdr;

	pbuf = buf + elf_info->ehdr->e_phoff + (idx * sizeof(*buf_phdr));
	buf_phdr = (struct elf_phdr *) pbuf;

	phdr->p_type   = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_type);
	phdr->p_offset = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_offset);
	phdr->p_paddr  = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_paddr);
	phdr->p_vaddr  = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_vaddr);
	phdr->p_flags  = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_flags);

	/*
	 * The following fields have a type equivalent to Elf_Addr
	 * both in 32 bit and 64 bit ELF.
	 */
	phdr->p_filesz = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_filesz);
	phdr->p_memsz  = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_memsz);
	phdr->p_align  = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_align);

	return elf_is_phdr_sane(phdr, len) ? 0 : -ENOEXEC;
}

/**
 * elf_read_phdrs - read the program headers from the buffer
 *
 * This function assumes that the program header table was checked for sanity.
 * Use elf_is_ehdr_sane() if it wasn't.
 */
static int elf_read_phdrs(const char *buf, size_t len,
			  struct kexec_elf_info *elf_info)
{
	size_t phdr_size, i;
	const struct elfhdr *ehdr = elf_info->ehdr;

	/*
	 * e_phnum is at most 65535 so calculating the size of the
	 * program header cannot overflow.
	 */
	phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;

	elf_info->proghdrs = kzalloc(phdr_size, GFP_KERNEL);
	if (!elf_info->proghdrs)
		return -ENOMEM;

	for (i = 0; i < ehdr->e_phnum; i++) {
		int ret;

		ret = elf_read_phdr(buf, len, elf_info, i);
		if (ret) {
			kfree(elf_info->proghdrs);
			elf_info->proghdrs = NULL;
			return ret;
		}
	}

	return 0;
}

/**
 * elf_read_from_buffer - read ELF file and sets up ELF header and ELF info
 * @buf:	Buffer to read ELF file from.
 * @len:	Size of @buf.
 * @ehdr:	Pointer to existing struct which will be populated.
 * @elf_info:	Pointer to existing struct which will be populated.
 *
 * This function allows reading ELF files with different byte order than
 * the kernel, byte-swapping the fields as needed.
 *
 * Return:
 * On success returns 0, and the caller should call
 * kexec_free_elf_info(elf_info) to free the memory allocated for the section
 * and program headers.
 */
static int elf_read_from_buffer(const char *buf, size_t len,
				struct elfhdr *ehdr,
				struct kexec_elf_info *elf_info)
{
	int ret;

	ret = elf_read_ehdr(buf, len, ehdr);
	if (ret)
		return ret;

	elf_info->buffer = buf;
	elf_info->ehdr = ehdr;
	if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
		ret = elf_read_phdrs(buf, len, elf_info);
		if (ret)
			return ret;
	}
	return 0;
}

/**
 * kexec_free_elf_info - free memory allocated by elf_read_from_buffer
 */
void kexec_free_elf_info(struct kexec_elf_info *elf_info)
{
	kfree(elf_info->proghdrs);
	memset(elf_info, 0, sizeof(*elf_info));
}
/**
 * kexec_build_elf_info - read ELF executable and check that we can use it
 */
int kexec_build_elf_info(const char *buf, size_t len, struct elfhdr *ehdr,
			       struct kexec_elf_info *elf_info)
{
	int i;
	int ret;

	ret = elf_read_from_buffer(buf, len, ehdr, elf_info);
	if (ret)
		return ret;

	/* Big endian vmlinux has type ET_DYN. */
	if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) {
		pr_err("Not an ELF executable.\n");
		goto error;
	} else if (!elf_info->proghdrs) {
		pr_err("No ELF program header.\n");
		goto error;
	}

	for (i = 0; i < ehdr->e_phnum; i++) {
		/*
		 * Kexec does not support loading interpreters.
		 * In addition this check keeps us from attempting
		 * to kexec ordinay executables.
		 */
		if (elf_info->proghdrs[i].p_type == PT_INTERP) {
			pr_err("Requires an ELF interpreter.\n");
			goto error;
		}
	}

	return 0;
error:
	kexec_free_elf_info(elf_info);
	return -ENOEXEC;
}


int kexec_elf_probe(const char *buf, unsigned long len)
{
	struct elfhdr ehdr;
	struct kexec_elf_info elf_info;
	int ret;

	ret = kexec_build_elf_info(buf, len, &ehdr, &elf_info);
	if (ret)
		return ret;

	kexec_free_elf_info(&elf_info);

	return elf_check_arch(&ehdr) ? 0 : -ENOEXEC;
}

/**
 * kexec_elf_load - load ELF executable image
 * @lowest_load_addr:	On return, will be the address where the first PT_LOAD
 *			section will be loaded in memory.
 *
 * Return:
 * 0 on success, negative value on failure.
 */
int kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
			 struct kexec_elf_info *elf_info,
			 struct kexec_buf *kbuf,
			 unsigned long *lowest_load_addr)
{
	unsigned long base = 0, lowest_addr = UINT_MAX;
	int ret;
	size_t i;

	/* Read in the PT_LOAD segments. */
	for (i = 0; i < ehdr->e_phnum; i++) {
		unsigned long load_addr;
		size_t size;
		const struct elf_phdr *phdr;

		phdr = &elf_info->proghdrs[i];
		if (phdr->p_type != PT_LOAD)
			continue;

		size = phdr->p_filesz;
		if (size > phdr->p_memsz)
			size = phdr->p_memsz;

		kbuf->buffer = (void *) elf_info->buffer + phdr->p_offset;
		kbuf->bufsz = size;
		kbuf->memsz = phdr->p_memsz;
		kbuf->buf_align = phdr->p_align;
		kbuf->buf_min = phdr->p_paddr + base;
		kbuf->mem = KEXEC_BUF_MEM_UNKNOWN;
		ret = kexec_add_buffer(kbuf);
		if (ret)
			goto out;
		load_addr = kbuf->mem;

		if (load_addr < lowest_addr)
			lowest_addr = load_addr;
	}

	/* Update entry point to reflect new load address. */
	ehdr->e_entry += base;

	*lowest_load_addr = lowest_addr;
	ret = 0;
 out:
	return ret;
}
Commit	Line	Data
175fca3b SS	1	// SPDX-License-Identifier: GPL-2.0-only
	2	/*
	3	* Load ELF vmlinux file for the kexec_file_load syscall.
	4	*
	5	* Copyright (C) 2004 Adam Litke (agl@us.ibm.com)
	6	* Copyright (C) 2004 IBM Corp.
	7	* Copyright (C) 2005 R Sharada (sharada@in.ibm.com)
	8	* Copyright (C) 2006 Mohan Kumar M (mohan@in.ibm.com)
	9	* Copyright (C) 2016 IBM Corporation
	10	*
	11	* Based on kexec-tools' kexec-elf-exec.c and kexec-elf-ppc64.c.
	12	* Heavily modified for the kernel by
	13	* Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>.
	14	*/
	15
	16	#define pr_fmt(fmt) "kexec_elf: " fmt
	17
	18	#include <linux/elf.h>
	19	#include <linux/kexec.h>
	20	#include <linux/module.h>
	21	#include <linux/slab.h>
	22	#include <linux/types.h>
	23
175fca3b SS	24	#define elf_addr_to_cpu elf64_to_cpu
175fca3b SS	25
175fca3b SS	26	static inline bool elf_is_elf_file(const struct elfhdr *ehdr)
	27	{
	28	return memcmp(ehdr->e_ident, ELFMAG, SELFMAG) == 0;
	29	}
	30
	31	static uint64_t elf64_to_cpu(const struct elfhdr *ehdr, uint64_t value)
	32	{
	33	if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
	34	value = le64_to_cpu(value);
	35	else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
	36	value = be64_to_cpu(value);
	37
	38	return value;
	39	}
	40
d34e0ad3	41	static uint32_t elf32_to_cpu(const struct elfhdr *ehdr, uint32_t value)
175fca3b SS	42	{
175fca3b SS	43	if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
d34e0ad3	44	value = le32_to_cpu(value);
175fca3b	45	else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
d34e0ad3	46	value = be32_to_cpu(value);
175fca3b SS	47
	48	return value;
	49	}
	50
d34e0ad3	51	static uint16_t elf16_to_cpu(const struct elfhdr *ehdr, uint16_t value)
175fca3b SS	52	{
175fca3b SS	53	if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
d34e0ad3	54	value = le16_to_cpu(value);
175fca3b	55	else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
d34e0ad3	56	value = be16_to_cpu(value);
175fca3b SS	57
	58	return value;
	59	}
	60
	61	/**
	62	* elf_is_ehdr_sane - check that it is safe to use the ELF header
	63	* @buf_len: size of the buffer in which the ELF file is loaded.
	64	*/
	65	static bool elf_is_ehdr_sane(const struct elfhdr *ehdr, size_t buf_len)
	66	{
	67	if (ehdr->e_phnum > 0 && ehdr->e_phentsize != sizeof(struct elf_phdr)) {
	68	pr_debug("Bad program header size.\n");
	69	return false;
	70	} else if (ehdr->e_shnum > 0 &&
	71	ehdr->e_shentsize != sizeof(struct elf_shdr)) {
	72	pr_debug("Bad section header size.\n");
	73	return false;
	74	} else if (ehdr->e_ident[EI_VERSION] != EV_CURRENT \|\|
	75	ehdr->e_version != EV_CURRENT) {
	76	pr_debug("Unknown ELF version.\n");
	77	return false;
	78	}
	79
	80	if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
	81	size_t phdr_size;
	82
	83	/*
	84	* e_phnum is at most 65535 so calculating the size of the
	85	* program header cannot overflow.
	86	*/
	87	phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;
	88
	89	/* Sanity check the program header table location. */
	90	if (ehdr->e_phoff + phdr_size < ehdr->e_phoff) {
	91	pr_debug("Program headers at invalid location.\n");
	92	return false;
	93	} else if (ehdr->e_phoff + phdr_size > buf_len) {
	94	pr_debug("Program headers truncated.\n");
	95	return false;
	96	}
	97	}
	98
	99	if (ehdr->e_shoff > 0 && ehdr->e_shnum > 0) {
	100	size_t shdr_size;
	101
	102	/*
	103	* e_shnum is at most 65536 so calculating
	104	* the size of the section header cannot overflow.
	105	*/
	106	shdr_size = sizeof(struct elf_shdr) * ehdr->e_shnum;
	107
	108	/* Sanity check the section header table location. */
	109	if (ehdr->e_shoff + shdr_size < ehdr->e_shoff) {
	110	pr_debug("Section headers at invalid location.\n");
	111	return false;
	112	} else if (ehdr->e_shoff + shdr_size > buf_len) {
	113	pr_debug("Section headers truncated.\n");
	114	return false;
	115	}
	116	}
	117
	118	return true;
	119	}
	120
121	static int elf_read_ehdr(const char buf, size_t len, struct elfhdr ehdr)
122	{
123	struct elfhdr *buf_ehdr;
124
125	if (len < sizeof(*buf_ehdr)) {
126	pr_debug("Buffer is too small to hold ELF header.\n");
127	return -ENOEXEC;
128	}
129
130	memset(ehdr, 0, sizeof(*ehdr));
131	memcpy(ehdr->e_ident, buf, sizeof(ehdr->e_ident));
132	if (!elf_is_elf_file(ehdr)) {
133	pr_debug("No ELF header magic.\n");
134	return -ENOEXEC;
135	}
136
137	if (ehdr->e_ident[EI_CLASS] != ELF_CLASS) {
138	pr_debug("Not a supported ELF class.\n");
139	return -ENOEXEC;
140	} else if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB &&
141	ehdr->e_ident[EI_DATA] != ELFDATA2MSB) {
142	pr_debug("Not a supported ELF data format.\n");
143	return -ENOEXEC;
144	}
145
146	buf_ehdr = (struct elfhdr *) buf;
147	if (elf16_to_cpu(ehdr, buf_ehdr->e_ehsize) != sizeof(*buf_ehdr)) {
148	pr_debug("Bad ELF header size.\n");
149	return -ENOEXEC;
150	}
151
152	ehdr->e_type = elf16_to_cpu(ehdr, buf_ehdr->e_type);
153	ehdr->e_machine = elf16_to_cpu(ehdr, buf_ehdr->e_machine);
154	ehdr->e_version = elf32_to_cpu(ehdr, buf_ehdr->e_version);
155	ehdr->e_entry = elf_addr_to_cpu(ehdr, buf_ehdr->e_entry);
156	ehdr->e_phoff = elf_addr_to_cpu(ehdr, buf_ehdr->e_phoff);
157	ehdr->e_shoff = elf_addr_to_cpu(ehdr, buf_ehdr->e_shoff);
158	ehdr->e_flags = elf32_to_cpu(ehdr, buf_ehdr->e_flags);
159	ehdr->e_phentsize = elf16_to_cpu(ehdr, buf_ehdr->e_phentsize);
160	ehdr->e_phnum = elf16_to_cpu(ehdr, buf_ehdr->e_phnum);
161	ehdr->e_shentsize = elf16_to_cpu(ehdr, buf_ehdr->e_shentsize);
162	ehdr->e_shnum = elf16_to_cpu(ehdr, buf_ehdr->e_shnum);
163	ehdr->e_shstrndx = elf16_to_cpu(ehdr, buf_ehdr->e_shstrndx);
164
165	return elf_is_ehdr_sane(ehdr, len) ? 0 : -ENOEXEC;
166	}
167
168	/**
169	* elf_is_phdr_sane - check that it is safe to use the program header
170	* @buf_len: size of the buffer in which the ELF file is loaded.
171	*/
172	static bool elf_is_phdr_sane(const struct elf_phdr *phdr, size_t buf_len)
173	{
174
175	if (phdr->p_offset + phdr->p_filesz < phdr->p_offset) {
176	pr_debug("ELF segment location wraps around.\n");
177	return false;
178	} else if (phdr->p_offset + phdr->p_filesz > buf_len) {
179	pr_debug("ELF segment not in file.\n");
180	return false;
181	} else if (phdr->p_paddr + phdr->p_memsz < phdr->p_paddr) {
182	pr_debug("ELF segment address wraps around.\n");
183	return false;
184	}
185
186	return true;
187	}
188
189	static int elf_read_phdr(const char *buf, size_t len,
190	struct kexec_elf_info *elf_info,
191	int idx)
192	{
193	/* Override the const in proghdrs, we are the ones doing the loading. */
194	struct elf_phdr phdr = (struct elf_phdr ) &elf_info->proghdrs[idx];
195	const char *pbuf;
196	struct elf_phdr *buf_phdr;
197
198	pbuf = buf + elf_info->ehdr->e_phoff + (idx * sizeof(*buf_phdr));
199	buf_phdr = (struct elf_phdr *) pbuf;
200
201	phdr->p_type = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_type);
202	phdr->p_offset = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_offset);
203	phdr->p_paddr = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_paddr);
204	phdr->p_vaddr = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_vaddr);
205	phdr->p_flags = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_flags);
206
207	/*
208	* The following fields have a type equivalent to Elf_Addr
209	* both in 32 bit and 64 bit ELF.
210	*/
211	phdr->p_filesz = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_filesz);
212	phdr->p_memsz = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_memsz);
213	phdr->p_align = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_align);
214
215	return elf_is_phdr_sane(phdr, len) ? 0 : -ENOEXEC;
216	}
217
218	/**
219	* elf_read_phdrs - read the program headers from the buffer
220	*
221	* This function assumes that the program header table was checked for sanity.
222	* Use elf_is_ehdr_sane() if it wasn't.
223	*/
224	static int elf_read_phdrs(const char *buf, size_t len,
225	struct kexec_elf_info *elf_info)
226	{
227	size_t phdr_size, i;
228	const struct elfhdr *ehdr = elf_info->ehdr;
229
230	/*
231	* e_phnum is at most 65535 so calculating the size of the
232	* program header cannot overflow.
233	*/
234	phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;
235
236	elf_info->proghdrs = kzalloc(phdr_size, GFP_KERNEL);
237	if (!elf_info->proghdrs)
238	return -ENOMEM;
239
240	for (i = 0; i < ehdr->e_phnum; i++) {
241	int ret;
242
243	ret = elf_read_phdr(buf, len, elf_info, i);
244	if (ret) {
245	kfree(elf_info->proghdrs);
246	elf_info->proghdrs = NULL;
247	return ret;
248	}
249	}
250
251	return 0;
252	}
253
175fca3b SS	254	/**
	255	* elf_read_from_buffer - read ELF file and sets up ELF header and ELF info
	256	* @buf: Buffer to read ELF file from.
	257	* @len: Size of @buf.
	258	* @ehdr: Pointer to existing struct which will be populated.
	259	* @elf_info: Pointer to existing struct which will be populated.
	260	*
	261	* This function allows reading ELF files with different byte order than
	262	* the kernel, byte-swapping the fields as needed.
	263	*
	264	* Return:
	265	* On success returns 0, and the caller should call
	266	* kexec_free_elf_info(elf_info) to free the memory allocated for the section
	267	* and program headers.
	268	*/
	269	static int elf_read_from_buffer(const char *buf, size_t len,
	270	struct elfhdr *ehdr,
	271	struct kexec_elf_info *elf_info)
	272	{
	273	int ret;
	274
	275	ret = elf_read_ehdr(buf, len, ehdr);
	276	if (ret)
	277	return ret;
	278
	279	elf_info->buffer = buf;
	280	elf_info->ehdr = ehdr;
	281	if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
	282	ret = elf_read_phdrs(buf, len, elf_info);
	283	if (ret)
	284	return ret;
	285	}
175fca3b SS	286	return 0;
	287	}
	288
	289	/**
	290	* kexec_free_elf_info - free memory allocated by elf_read_from_buffer
	291	*/
	292	void kexec_free_elf_info(struct kexec_elf_info *elf_info)
	293	{
	294	kfree(elf_info->proghdrs);
175fca3b SS	295	memset(elf_info, 0, sizeof(*elf_info));
	296	}
	297	/**
	298	* kexec_build_elf_info - read ELF executable and check that we can use it
	299	*/
	300	int kexec_build_elf_info(const char buf, size_t len, struct elfhdr ehdr,
	301	struct kexec_elf_info *elf_info)
	302	{
	303	int i;
	304	int ret;
	305
	306	ret = elf_read_from_buffer(buf, len, ehdr, elf_info);
	307	if (ret)
	308	return ret;
	309
	310	/* Big endian vmlinux has type ET_DYN. */
	311	if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) {
	312	pr_err("Not an ELF executable.\n");
	313	goto error;
	314	} else if (!elf_info->proghdrs) {
	315	pr_err("No ELF program header.\n");
	316	goto error;
	317	}
	318
	319	for (i = 0; i < ehdr->e_phnum; i++) {
	320	/*
	321	* Kexec does not support loading interpreters.
	322	* In addition this check keeps us from attempting
	323	* to kexec ordinay executables.
	324	*/
	325	if (elf_info->proghdrs[i].p_type == PT_INTERP) {
	326	pr_err("Requires an ELF interpreter.\n");
	327	goto error;
	328	}
	329	}
	330
	331	return 0;
	332	error:
	333	kexec_free_elf_info(elf_info);
	334	return -ENOEXEC;
	335	}
	336
	337
	338	int kexec_elf_probe(const char *buf, unsigned long len)
	339	{
	340	struct elfhdr ehdr;
	341	struct kexec_elf_info elf_info;
	342	int ret;
	343
	344	ret = kexec_build_elf_info(buf, len, &ehdr, &elf_info);
	345	if (ret)
	346	return ret;
	347
	348	kexec_free_elf_info(&elf_info);
	349
	350	return elf_check_arch(&ehdr) ? 0 : -ENOEXEC;
	351	}
	352
	353	/**
	354	* kexec_elf_load - load ELF executable image
	355	* @lowest_load_addr: On return, will be the address where the first PT_LOAD
	356	* section will be loaded in memory.
	357	*
	358	* Return:
359	* 0 on success, negative value on failure.
360	*/
361	int kexec_elf_load(struct kimage image, struct elfhdr ehdr,
362	struct kexec_elf_info *elf_info,
363	struct kexec_buf *kbuf,
364	unsigned long *lowest_load_addr)
365	{
366	unsigned long base = 0, lowest_addr = UINT_MAX;
367	int ret;
368	size_t i;
369
370	/* Read in the PT_LOAD segments. */
371	for (i = 0; i < ehdr->e_phnum; i++) {
372	unsigned long load_addr;
373	size_t size;
374	const struct elf_phdr *phdr;
375
376	phdr = &elf_info->proghdrs[i];
377	if (phdr->p_type != PT_LOAD)
378	continue;
379
380	size = phdr->p_filesz;
381	if (size > phdr->p_memsz)
382	size = phdr->p_memsz;
383
384	kbuf->buffer = (void *) elf_info->buffer + phdr->p_offset;
385	kbuf->bufsz = size;
386	kbuf->memsz = phdr->p_memsz;
387	kbuf->buf_align = phdr->p_align;
388	kbuf->buf_min = phdr->p_paddr + base;
389	kbuf->mem = KEXEC_BUF_MEM_UNKNOWN;
390	ret = kexec_add_buffer(kbuf);
391	if (ret)
392	goto out;
393	load_addr = kbuf->mem;
394
395	if (load_addr < lowest_addr)
396	lowest_addr = load_addr;
397	}
398
399	/* Update entry point to reflect new load address. */
400	ehdr->e_entry += base;
401
402	*lowest_load_addr = lowest_addr;
403	ret = 0;
404	out:
405	return ret;
406	}