1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2016 IBM Corporation
4 *
5 * Authors:
6 * Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
7 * Mimi Zohar <zohar@linux.vnet.ibm.com>
8 */
9
10 #include <linux/seq_file.h>
11 #include <linux/vmalloc.h>
12 #include <linux/kexec.h>
13 #include <linux/of.h>
14 #include <linux/ima.h>
15 #include "ima.h"
16
17 #ifdef CONFIG_IMA_KEXEC
18 static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
19 unsigned long segment_size)
20 {
21 struct ima_queue_entry *qe;
22 struct seq_file file;
23 struct ima_kexec_hdr khdr;
24 int ret = 0;
25
26 /* segment size can't change between kexec load and execute */
27 file.buf = vmalloc(segment_size);
28 if (!file.buf) {
29 ret = -ENOMEM;
30 goto out;
31 }
32
33 file.file = NULL;
34 file.size = segment_size;
35 file.read_pos = 0;
36 file.count = sizeof(khdr); /* reserved space */
37
38 memset(&khdr, 0, sizeof(khdr));
39 khdr.version = 1;
40 list_for_each_entry_rcu(qe, &ima_measurements, later) {
41 if (file.count < file.size) {
42 khdr.count++;
43 ima_measurements_show(&file, qe);
44 } else {
45 ret = -EINVAL;
46 break;
47 }
48 }
49
50 if (ret < 0)
51 goto out;
52
53 /*
54 * fill in reserved space with some buffer details
55 * (eg. version, buffer size, number of measurements)
56 */
57 khdr.buffer_size = file.count;
58 if (ima_canonical_fmt) {
59 khdr.version = cpu_to_le16(khdr.version);
60 khdr.count = cpu_to_le64(khdr.count);
61 khdr.buffer_size = cpu_to_le64(khdr.buffer_size);
62 }
63 memcpy(file.buf, &khdr, sizeof(khdr));
64
65 print_hex_dump_debug("ima dump: ", DUMP_PREFIX_NONE, 16, 1,
66 file.buf, file.count < 100 ? file.count : 100,
67 true);
68
69 *buffer_size = file.count;
70 *buffer = file.buf;
71 out:
72 if (ret == -EINVAL)
73 vfree(file.buf);
74 return ret;
75 }
76
77 /*
78 * Called during kexec_file_load so that IMA can add a segment to the kexec
79 * image for the measurement list for the next kernel.
80 *
81 * This function assumes that kexec_lock is held.
82 */
83 void ima_add_kexec_buffer(struct kimage *image)
84 {
85 struct kexec_buf kbuf = { .image = image, .buf_align = PAGE_SIZE,
86 .buf_min = 0, .buf_max = ULONG_MAX,
87 .top_down = true };
88 unsigned long binary_runtime_size;
89
90 /* use more understandable variable names than defined in kbuf */
91 void *kexec_buffer = NULL;
92 size_t kexec_buffer_size;
93 size_t kexec_segment_size;
94 int ret;
95
96 /*
97 * Reserve an extra half page of memory for additional measurements
98 * added during the kexec load.
99 */
100 binary_runtime_size = ima_get_binary_runtime_size();
101 if (binary_runtime_size >= ULONG_MAX - PAGE_SIZE)
102 kexec_segment_size = ULONG_MAX;
103 else
104 kexec_segment_size = ALIGN(ima_get_binary_runtime_size() +
105 PAGE_SIZE / 2, PAGE_SIZE);
106 if ((kexec_segment_size == ULONG_MAX) ||
107 ((kexec_segment_size >> PAGE_SHIFT) > totalram_pages() / 2)) {
108 pr_err("Binary measurement list too large.\n");
109 return;
110 }
111
112 ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
113 kexec_segment_size);
114 if (!kexec_buffer) {
115 pr_err("Not enough memory for the kexec measurement buffer.\n");
116 return;
117 }
118
119 kbuf.buffer = kexec_buffer;
120 kbuf.bufsz = kexec_buffer_size;
121 kbuf.memsz = kexec_segment_size;
122 ret = kexec_add_buffer(&kbuf);
123 if (ret) {
124 pr_err("Error passing over kexec measurement buffer.\n");
125 vfree(kexec_buffer);
126 return;
127 }
128
129 image->ima_buffer_addr = kbuf.mem;
130 image->ima_buffer_size = kexec_segment_size;
131 image->ima_buffer = kexec_buffer;
132
133 kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n",
134 kbuf.mem);
135 }
136 #endif /* IMA_KEXEC */
137
138 /*
139 * Restore the measurement list from the previous kernel.
140 */
141 void __init ima_load_kexec_buffer(void)
142 {
143 void *kexec_buffer = NULL;
144 size_t kexec_buffer_size = 0;
145 int rc;
146
147 rc = ima_get_kexec_buffer(&kexec_buffer, &kexec_buffer_size);
148 switch (rc) {
149 case 0:
150 rc = ima_restore_measurement_list(kexec_buffer_size,
151 kexec_buffer);
152 if (rc != 0)
153 pr_err("Failed to restore the measurement list: %d\n",
154 rc);
155
156 ima_free_kexec_buffer();
157 break;
158 case -ENOTSUPP:
159 pr_debug("Restoring the measurement list not supported\n");
160 break;
161 case -ENOENT:
162 pr_debug("No measurement list to restore\n");
163 break;
164 default:
165 pr_debug("Error restoring the measurement list: %d\n", rc);
166 }
167 }
168
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