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 /* This is an append-only list, no need to hold the RCU read lock */ 41 list_for_each_entry_rcu(qe, &ima_measurements, later, true) { 42 if (file.count < file.size) { 43 khdr.count++; 44 ima_measurements_show(&file, qe); 45 } else { 46 ret = -EINVAL; 47 break; 48 } 49 } 50 51 if (ret < 0) 52 goto out; 53 54 /* 55 * fill in reserved space with some buffer details 56 * (eg. version, buffer size, number of measurements) 57 */ 58 khdr.buffer_size = file.count; 59 if (ima_canonical_fmt) { 60 khdr.version = cpu_to_le16(khdr.version); 61 khdr.count = cpu_to_le64(khdr.count); 62 khdr.buffer_size = cpu_to_le64(khdr.buffer_size); 63 } 64 memcpy(file.buf, &khdr, sizeof(khdr)); 65 66 print_hex_dump_debug("ima dump: ", DUMP_PREFIX_NONE, 16, 1, 67 file.buf, file.count < 100 ? file.count : 100, 68 true); 69 70 *buffer_size = file.count; 71 *buffer = file.buf; 72 out: 73 if (ret == -EINVAL) 74 vfree(file.buf); 75 return ret; 76 } 77 78 /* 79 * Called during kexec_file_load so that IMA can add a segment to the kexec 80 * image for the measurement list for the next kernel. 81 * 82 * This function assumes that kexec_lock is held. 83 */ 84 void ima_add_kexec_buffer(struct kimage *image) 85 { 86 struct kexec_buf kbuf = { .image = image, .buf_align = PAGE_SIZE, 87 .buf_min = 0, .buf_max = ULONG_MAX, 88 .top_down = true }; 89 unsigned long binary_runtime_size; 90 91 /* use more understandable variable names than defined in kbuf */ 92 void *kexec_buffer = NULL; 93 size_t kexec_buffer_size; 94 size_t kexec_segment_size; 95 int ret; 96 97 /* 98 * Reserve an extra half page of memory for additional measurements 99 * added during the kexec load. 100 */ 101 binary_runtime_size = ima_get_binary_runtime_size(); 102 if (binary_runtime_size >= ULONG_MAX - PAGE_SIZE) 103 kexec_segment_size = ULONG_MAX; 104 else 105 kexec_segment_size = ALIGN(ima_get_binary_runtime_size() + 106 PAGE_SIZE / 2, PAGE_SIZE); 107 if ((kexec_segment_size == ULONG_MAX) || 108 ((kexec_segment_size >> PAGE_SHIFT) > totalram_pages() / 2)) { 109 pr_err("Binary measurement list too large.\n"); 110 return; 111 } 112 113 ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer, 114 kexec_segment_size); 115 if (!kexec_buffer) { 116 pr_err("Not enough memory for the kexec measurement buffer.\n"); 117 return; 118 } 119 120 kbuf.buffer = kexec_buffer; 121 kbuf.bufsz = kexec_buffer_size; 122 kbuf.memsz = kexec_segment_size; 123 ret = kexec_add_buffer(&kbuf); 124 if (ret) { 125 pr_err("Error passing over kexec measurement buffer.\n"); 126 vfree(kexec_buffer); 127 return; 128 } 129 130 image->ima_buffer_addr = kbuf.mem; 131 image->ima_buffer_size = kexec_segment_size; 132 image->ima_buffer = kexec_buffer; 133 134 kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n", 135 kbuf.mem); 136 } 137 #endif /* IMA_KEXEC */ 138 139 /* 140 * Restore the measurement list from the previous kernel. 141 */ 142 void __init ima_load_kexec_buffer(void) 143 { 144 void *kexec_buffer = NULL; 145 size_t kexec_buffer_size = 0; 146 int rc; 147 148 rc = ima_get_kexec_buffer(&kexec_buffer, &kexec_buffer_size); 149 switch (rc) { 150 case 0: 151 rc = ima_restore_measurement_list(kexec_buffer_size, 152 kexec_buffer); 153 if (rc != 0) 154 pr_err("Failed to restore the measurement list: %d\n", 155 rc); 156 157 ima_free_kexec_buffer(); 158 break; 159 case -ENOTSUPP: 160 pr_debug("Restoring the measurement list not supported\n"); 161 break; 162 case -ENOENT: 163 pr_debug("No measurement list to restore\n"); 164 break; 165 default: 166 pr_debug("Error restoring the measurement list: %d\n", rc); 167 } 168 } 169