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 
kexec_file_add_kernel_elf(struct kimage * image,struct s390_load_data * data)16 static 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 		if (image->type == KEXEC_TYPE_CRASH)
44 			buf.mem += crashk_res.start;
45 		buf.memsz = phdr->p_memsz;
46 		data->memsz = ALIGN(data->memsz, phdr->p_align) + buf.memsz;
47 
48 		if (entry - phdr->p_paddr < phdr->p_memsz) {
49 			data->kernel_buf = buf.buffer;
50 			data->kernel_mem = buf.mem;
51 			data->parm = buf.buffer + PARMAREA;
52 		}
53 
54 		ipl_report_add_component(data->report, &buf,
55 					 IPL_RB_COMPONENT_FLAG_SIGNED |
56 					 IPL_RB_COMPONENT_FLAG_VERIFIED,
57 					 IPL_RB_CERT_UNKNOWN);
58 		ret = kexec_add_buffer(&buf);
59 		if (ret)
60 			return ret;
61 	}
62 
63 	return data->memsz ? 0 : -EINVAL;
64 }
65 
s390_elf_load(struct kimage * image,char * kernel,unsigned long kernel_len,char * initrd,unsigned long initrd_len,char * cmdline,unsigned long cmdline_len)66 static void *s390_elf_load(struct kimage *image,
67 			   char *kernel, unsigned long kernel_len,
68 			   char *initrd, unsigned long initrd_len,
69 			   char *cmdline, unsigned long cmdline_len)
70 {
71 	const Elf_Ehdr *ehdr;
72 	const Elf_Phdr *phdr;
73 	size_t size;
74 	int i;
75 
76 	/* image->fobs->probe already checked for valid ELF magic number. */
77 	ehdr = (Elf_Ehdr *)kernel;
78 
79 	if (ehdr->e_type != ET_EXEC ||
80 	    ehdr->e_ident[EI_CLASS] != ELFCLASS64 ||
81 	    !elf_check_arch(ehdr))
82 		return ERR_PTR(-EINVAL);
83 
84 	if (!ehdr->e_phnum || ehdr->e_phentsize != sizeof(Elf_Phdr))
85 		return ERR_PTR(-EINVAL);
86 
87 	size = ehdr->e_ehsize + ehdr->e_phoff;
88 	size += ehdr->e_phentsize * ehdr->e_phnum;
89 	if (size > kernel_len)
90 		return ERR_PTR(-EINVAL);
91 
92 	phdr = (void *)ehdr + ehdr->e_phoff;
93 	size = ALIGN(size, phdr->p_align);
94 	for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
95 		if (phdr->p_type == PT_INTERP)
96 			return ERR_PTR(-EINVAL);
97 
98 		if (phdr->p_offset > kernel_len)
99 			return ERR_PTR(-EINVAL);
100 
101 		size += ALIGN(phdr->p_filesz, phdr->p_align);
102 	}
103 
104 	if (size > kernel_len)
105 		return ERR_PTR(-EINVAL);
106 
107 	return kexec_file_add_components(image, kexec_file_add_kernel_elf);
108 }
109 
s390_elf_probe(const char * buf,unsigned long len)110 static int s390_elf_probe(const char *buf, unsigned long len)
111 {
112 	const Elf_Ehdr *ehdr;
113 
114 	if (len < sizeof(Elf_Ehdr))
115 		return -ENOEXEC;
116 
117 	ehdr = (Elf_Ehdr *)buf;
118 
119 	/* Only check the ELF magic number here and do proper validity check
120 	 * in the loader. Any check here that fails would send the erroneous
121 	 * ELF file to the image loader that does not care what it gets.
122 	 * (Most likely) causing behavior not intended by the user.
123 	 */
124 	if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0)
125 		return -ENOEXEC;
126 
127 	return 0;
128 }
129 
130 const struct kexec_file_ops s390_kexec_elf_ops = {
131 	.probe = s390_elf_probe,
132 	.load = s390_elf_load,
133 #ifdef CONFIG_KEXEC_SIG
134 	.verify_sig = s390_verify_sig,
135 #endif /* CONFIG_KEXEC_SIG */
136 };
137