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