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