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/setup.h>
14
kexec_file_add_elf_kernel(struct kimage * image,struct s390_load_data * data,char * kernel,unsigned long kernel_len)15 static int kexec_file_add_elf_kernel(struct kimage *image,
16 struct s390_load_data *data,
17 char *kernel, unsigned long kernel_len)
18 {
19 struct kexec_buf buf;
20 const Elf_Ehdr *ehdr;
21 const Elf_Phdr *phdr;
22 int i, ret;
23
24 ehdr = (Elf_Ehdr *)kernel;
25 buf.image = image;
26
27 phdr = (void *)ehdr + ehdr->e_phoff;
28 for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
29 if (phdr->p_type != PT_LOAD)
30 continue;
31
32 buf.buffer = kernel + phdr->p_offset;
33 buf.bufsz = phdr->p_filesz;
34
35 buf.mem = ALIGN(phdr->p_paddr, phdr->p_align);
36 buf.memsz = phdr->p_memsz;
37
38 if (phdr->p_paddr == 0) {
39 data->kernel_buf = buf.buffer;
40 data->memsz += STARTUP_NORMAL_OFFSET;
41
42 buf.buffer += STARTUP_NORMAL_OFFSET;
43 buf.bufsz -= STARTUP_NORMAL_OFFSET;
44
45 buf.mem += STARTUP_NORMAL_OFFSET;
46 buf.memsz -= STARTUP_NORMAL_OFFSET;
47 }
48
49 if (image->type == KEXEC_TYPE_CRASH)
50 buf.mem += crashk_res.start;
51
52 ret = kexec_add_buffer(&buf);
53 if (ret)
54 return ret;
55
56 data->memsz += buf.memsz;
57 }
58
59 return 0;
60 }
61
s390_elf_load(struct kimage * image,char * kernel,unsigned long kernel_len,char * initrd,unsigned long initrd_len,char * cmdline,unsigned long cmdline_len)62 static void *s390_elf_load(struct kimage *image,
63 char *kernel, unsigned long kernel_len,
64 char *initrd, unsigned long initrd_len,
65 char *cmdline, unsigned long cmdline_len)
66 {
67 struct s390_load_data data = {0};
68 const Elf_Ehdr *ehdr;
69 const Elf_Phdr *phdr;
70 size_t size;
71 int i, ret;
72
73 /* image->fobs->probe already checked for valid ELF magic number. */
74 ehdr = (Elf_Ehdr *)kernel;
75
76 if (ehdr->e_type != ET_EXEC ||
77 ehdr->e_ident[EI_CLASS] != ELFCLASS64 ||
78 !elf_check_arch(ehdr))
79 return ERR_PTR(-EINVAL);
80
81 if (!ehdr->e_phnum || ehdr->e_phentsize != sizeof(Elf_Phdr))
82 return ERR_PTR(-EINVAL);
83
84 size = ehdr->e_ehsize + ehdr->e_phoff;
85 size += ehdr->e_phentsize * ehdr->e_phnum;
86 if (size > kernel_len)
87 return ERR_PTR(-EINVAL);
88
89 phdr = (void *)ehdr + ehdr->e_phoff;
90 size = ALIGN(size, phdr->p_align);
91 for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
92 if (phdr->p_type == PT_INTERP)
93 return ERR_PTR(-EINVAL);
94
95 if (phdr->p_offset > kernel_len)
96 return ERR_PTR(-EINVAL);
97
98 size += ALIGN(phdr->p_filesz, phdr->p_align);
99 }
100
101 if (size > kernel_len)
102 return ERR_PTR(-EINVAL);
103
104 ret = kexec_file_add_elf_kernel(image, &data, kernel, kernel_len);
105 if (ret)
106 return ERR_PTR(ret);
107
108 if (!data.memsz)
109 return ERR_PTR(-EINVAL);
110
111 if (initrd) {
112 ret = kexec_file_add_initrd(image, &data, initrd, initrd_len);
113 if (ret)
114 return ERR_PTR(ret);
115 }
116
117 ret = kexec_file_add_purgatory(image, &data);
118 if (ret)
119 return ERR_PTR(ret);
120
121 return kexec_file_update_kernel(image, &data);
122 }
123
s390_elf_probe(const char * buf,unsigned long len)124 static int s390_elf_probe(const char *buf, unsigned long len)
125 {
126 const Elf_Ehdr *ehdr;
127
128 if (len < sizeof(Elf_Ehdr))
129 return -ENOEXEC;
130
131 ehdr = (Elf_Ehdr *)buf;
132
133 /* Only check the ELF magic number here and do proper validity check
134 * in the loader. Any check here that fails would send the erroneous
135 * ELF file to the image loader that does not care what it gets.
136 * (Most likely) causing behavior not intended by the user.
137 */
138 if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0)
139 return -ENOEXEC;
140
141 return 0;
142 }
143
144 const struct kexec_file_ops s390_kexec_elf_ops = {
145 .probe = s390_elf_probe,
146 .load = s390_elf_load,
147 };
148
