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 Elf_Addr entry;
23 int i, ret;
24
25 ehdr = (Elf_Ehdr *)kernel;
26 buf.image = image;
27 if (image->type == KEXEC_TYPE_CRASH)
28 entry = STARTUP_KDUMP_OFFSET;
29 else
30 entry = ehdr->e_entry;
31
32 phdr = (void *)ehdr + ehdr->e_phoff;
33 for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
34 if (phdr->p_type != PT_LOAD)
35 continue;
36
37 buf.buffer = kernel + phdr->p_offset;
38 buf.bufsz = phdr->p_filesz;
39
40 buf.mem = ALIGN(phdr->p_paddr, phdr->p_align);
41 buf.memsz = phdr->p_memsz;
42
43 if (entry - phdr->p_paddr < phdr->p_memsz) {
44 data->kernel_buf = buf.buffer;
45 data->memsz += STARTUP_NORMAL_OFFSET;
46
47 buf.buffer += STARTUP_NORMAL_OFFSET;
48 buf.bufsz -= STARTUP_NORMAL_OFFSET;
49
50 buf.mem += STARTUP_NORMAL_OFFSET;
51 buf.memsz -= STARTUP_NORMAL_OFFSET;
52 }
53
54 if (image->type == KEXEC_TYPE_CRASH)
55 buf.mem += crashk_res.start;
56
57 ret = kexec_add_buffer(&buf);
58 if (ret)
59 return ret;
60
61 data->memsz = ALIGN(data->memsz, phdr->p_align) + buf.memsz;
62 }
63
64 return 0;
65 }
66
s390_elf_load(struct kimage * image,char * kernel,unsigned long kernel_len,char * initrd,unsigned long initrd_len,char * cmdline,unsigned long cmdline_len)67 static void *s390_elf_load(struct kimage *image,
68 char *kernel, unsigned long kernel_len,
69 char *initrd, unsigned long initrd_len,
70 char *cmdline, unsigned long cmdline_len)
71 {
72 struct s390_load_data data = {0};
73 const Elf_Ehdr *ehdr;
74 const Elf_Phdr *phdr;
75 size_t size;
76 int i, ret;
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 ret = kexec_file_add_elf_kernel(image, &data, kernel, kernel_len);
110 if (ret)
111 return ERR_PTR(ret);
112
113 if (!data.memsz)
114 return ERR_PTR(-EINVAL);
115
116 if (initrd) {
117 ret = kexec_file_add_initrd(image, &data, initrd, initrd_len);
118 if (ret)
119 return ERR_PTR(ret);
120 }
121
122 ret = kexec_file_add_purgatory(image, &data);
123 if (ret)
124 return ERR_PTR(ret);
125
126 return kexec_file_update_kernel(image, &data);
127 }
128
s390_elf_probe(const char * buf,unsigned long len)129 static int s390_elf_probe(const char *buf, unsigned long len)
130 {
131 const Elf_Ehdr *ehdr;
132
133 if (len < sizeof(Elf_Ehdr))
134 return -ENOEXEC;
135
136 ehdr = (Elf_Ehdr *)buf;
137
138 /* Only check the ELF magic number here and do proper validity check
139 * in the loader. Any check here that fails would send the erroneous
140 * ELF file to the image loader that does not care what it gets.
141 * (Most likely) causing behavior not intended by the user.
142 */
143 if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0)
144 return -ENOEXEC;
145
146 return 0;
147 }
148
149 const struct kexec_file_ops s390_kexec_elf_ops = {
150 .probe = s390_elf_probe,
151 .load = s390_elf_load,
152 };
153