1// SPDX-License-Identifier: GPL-2.0
2/*
3 * ELF loader for kexec_file_load system call.
4 *
5 * Copyright IBM Corp. 2018
6 *
7 * Author(s): Philipp Rudo <prudo@linux.vnet.ibm.com>
8 */
9
10#include <linux/errno.h>
11#include <linux/kernel.h>
12#include <linux/kexec.h>
13#include <asm/ipl.h>
14#include <asm/setup.h>
15
16static int kexec_file_add_kernel_elf(struct kimage *image,
17				     struct s390_load_data *data)
18{
19	struct kexec_buf buf;
20	const Elf_Ehdr *ehdr;
21	const Elf_Phdr *phdr;
22	Elf_Addr entry;
23	void *kernel;
24	int i, ret;
25
26	kernel = image->kernel_buf;
27	ehdr = (Elf_Ehdr *)kernel;
28	buf.image = image;
29	if (image->type == KEXEC_TYPE_CRASH)
30		entry = STARTUP_KDUMP_OFFSET;
31	else
32		entry = ehdr->e_entry;
33
34	phdr = (void *)ehdr + ehdr->e_phoff;
35	for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
36		if (phdr->p_type != PT_LOAD)
37			continue;
38
39		buf.buffer = kernel + phdr->p_offset;
40		buf.bufsz = phdr->p_filesz;
41
42		buf.mem = ALIGN(phdr->p_paddr, phdr->p_align);
43#ifdef CONFIG_CRASH_DUMP
44		if (image->type == KEXEC_TYPE_CRASH)
45			buf.mem += crashk_res.start;
46#endif
47		buf.memsz = phdr->p_memsz;
48		data->memsz = ALIGN(data->memsz, phdr->p_align) + buf.memsz;
49
50		if (entry - phdr->p_paddr < phdr->p_memsz) {
51			data->kernel_buf = buf.buffer;
52			data->kernel_mem = buf.mem;
53			data->parm = buf.buffer + PARMAREA;
54		}
55
56		ipl_report_add_component(data->report, &buf,
57					 IPL_RB_COMPONENT_FLAG_SIGNED |
58					 IPL_RB_COMPONENT_FLAG_VERIFIED,
59					 IPL_RB_CERT_UNKNOWN);
60		ret = kexec_add_buffer(&buf);
61		if (ret)
62			return ret;
63	}
64
65	return data->memsz ? 0 : -EINVAL;
66}
67
68static void *s390_elf_load(struct kimage *image,
69			   char *kernel, unsigned long kernel_len,
70			   char *initrd, unsigned long initrd_len,
71			   char *cmdline, unsigned long cmdline_len)
72{
73	const Elf_Ehdr *ehdr;
74	const Elf_Phdr *phdr;
75	size_t size;
76	int i;
77
78	/* image->fobs->probe already checked for valid ELF magic number. */
79	ehdr = (Elf_Ehdr *)kernel;
80
81	if (ehdr->e_type != ET_EXEC ||
82	    ehdr->e_ident[EI_CLASS] != ELFCLASS64 ||
83	    !elf_check_arch(ehdr))
84		return ERR_PTR(-EINVAL);
85
86	if (!ehdr->e_phnum || ehdr->e_phentsize != sizeof(Elf_Phdr))
87		return ERR_PTR(-EINVAL);
88
89	size = ehdr->e_ehsize + ehdr->e_phoff;
90	size += ehdr->e_phentsize * ehdr->e_phnum;
91	if (size > kernel_len)
92		return ERR_PTR(-EINVAL);
93
94	phdr = (void *)ehdr + ehdr->e_phoff;
95	size = ALIGN(size, phdr->p_align);
96	for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
97		if (phdr->p_type == PT_INTERP)
98			return ERR_PTR(-EINVAL);
99
100		if (phdr->p_offset > kernel_len)
101			return ERR_PTR(-EINVAL);
102
103		size += ALIGN(phdr->p_filesz, phdr->p_align);
104	}
105
106	if (size > kernel_len)
107		return ERR_PTR(-EINVAL);
108
109	return kexec_file_add_components(image, kexec_file_add_kernel_elf);
110}
111
112static int s390_elf_probe(const char *buf, unsigned long len)
113{
114	const Elf_Ehdr *ehdr;
115
116	if (len < sizeof(Elf_Ehdr))
117		return -ENOEXEC;
118
119	ehdr = (Elf_Ehdr *)buf;
120
121	/* Only check the ELF magic number here and do proper validity check
122	 * in the loader. Any check here that fails would send the erroneous
123	 * ELF file to the image loader that does not care what it gets.
124	 * (Most likely) causing behavior not intended by the user.
125	 */
126	if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0)
127		return -ENOEXEC;
128
129	return 0;
130}
131
132const struct kexec_file_ops s390_kexec_elf_ops = {
133	.probe = s390_elf_probe,
134	.load = s390_elf_load,
135#ifdef CONFIG_KEXEC_SIG
136	.verify_sig = s390_verify_sig,
137#endif /* CONFIG_KEXEC_SIG */
138};
139