1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2020-2024 Microsoft Corporation. All rights reserved. 4 */ 5 6 #include <linux/fs.h> 7 #include <linux/fs_struct.h> 8 #include <linux/types.h> 9 #include <linux/binfmts.h> 10 #include <linux/mman.h> 11 #include <linux/blk_types.h> 12 13 #include "ipe.h" 14 #include "hooks.h" 15 #include "eval.h" 16 #include "digest.h" 17 18 /** 19 * ipe_bprm_check_security() - ipe security hook function for bprm check. 20 * @bprm: Supplies a pointer to a linux_binprm structure to source the file 21 * being evaluated. 22 * 23 * This LSM hook is called when a binary is loaded through the exec 24 * family of system calls. 25 * 26 * Return: 27 * * %0 - Success 28 * * %-EACCES - Did not pass IPE policy 29 */ 30 int ipe_bprm_check_security(struct linux_binprm *bprm) 31 { 32 struct ipe_eval_ctx ctx = IPE_EVAL_CTX_INIT; 33 34 ipe_build_eval_ctx(&ctx, bprm->file, IPE_OP_EXEC, IPE_HOOK_BPRM_CHECK); 35 return ipe_evaluate_event(&ctx); 36 } 37 38 /** 39 * ipe_mmap_file() - ipe security hook function for mmap check. 40 * @f: File being mmap'd. Can be NULL in the case of anonymous memory. 41 * @reqprot: The requested protection on the mmap, passed from usermode. 42 * @prot: The effective protection on the mmap, resolved from reqprot and 43 * system configuration. 44 * @flags: Unused. 45 * 46 * This hook is called when a file is loaded through the mmap 47 * family of system calls. 48 * 49 * Return: 50 * * %0 - Success 51 * * %-EACCES - Did not pass IPE policy 52 */ 53 int ipe_mmap_file(struct file *f, unsigned long reqprot __always_unused, 54 unsigned long prot, unsigned long flags) 55 { 56 struct ipe_eval_ctx ctx = IPE_EVAL_CTX_INIT; 57 58 if (prot & PROT_EXEC) { 59 ipe_build_eval_ctx(&ctx, f, IPE_OP_EXEC, IPE_HOOK_MMAP); 60 return ipe_evaluate_event(&ctx); 61 } 62 63 return 0; 64 } 65 66 /** 67 * ipe_file_mprotect() - ipe security hook function for mprotect check. 68 * @vma: Existing virtual memory area created by mmap or similar. 69 * @reqprot: The requested protection on the mmap, passed from usermode. 70 * @prot: The effective protection on the mmap, resolved from reqprot and 71 * system configuration. 72 * 73 * This LSM hook is called when a mmap'd region of memory is changing 74 * its protections via mprotect. 75 * 76 * Return: 77 * * %0 - Success 78 * * %-EACCES - Did not pass IPE policy 79 */ 80 int ipe_file_mprotect(struct vm_area_struct *vma, 81 unsigned long reqprot __always_unused, 82 unsigned long prot) 83 { 84 struct ipe_eval_ctx ctx = IPE_EVAL_CTX_INIT; 85 86 /* Already Executable */ 87 if (vma->vm_flags & VM_EXEC) 88 return 0; 89 90 if (prot & PROT_EXEC) { 91 ipe_build_eval_ctx(&ctx, vma->vm_file, IPE_OP_EXEC, IPE_HOOK_MPROTECT); 92 return ipe_evaluate_event(&ctx); 93 } 94 95 return 0; 96 } 97 98 /** 99 * ipe_kernel_read_file() - ipe security hook function for kernel read. 100 * @file: Supplies a pointer to the file structure being read in from disk. 101 * @id: Supplies the enumeration identifying the purpose of the read. 102 * @contents: Unused. 103 * 104 * This LSM hook is called when a file is read from disk in the kernel. 105 * 106 * Return: 107 * * %0 - Success 108 * * %-EACCES - Did not pass IPE policy 109 */ 110 int ipe_kernel_read_file(struct file *file, enum kernel_read_file_id id, 111 bool contents) 112 { 113 struct ipe_eval_ctx ctx = IPE_EVAL_CTX_INIT; 114 enum ipe_op_type op; 115 116 switch (id) { 117 case READING_FIRMWARE: 118 op = IPE_OP_FIRMWARE; 119 break; 120 case READING_MODULE: 121 op = IPE_OP_KERNEL_MODULE; 122 break; 123 case READING_KEXEC_INITRAMFS: 124 op = IPE_OP_KEXEC_INITRAMFS; 125 break; 126 case READING_KEXEC_IMAGE: 127 op = IPE_OP_KEXEC_IMAGE; 128 break; 129 case READING_POLICY: 130 op = IPE_OP_POLICY; 131 break; 132 case READING_X509_CERTIFICATE: 133 op = IPE_OP_X509; 134 break; 135 default: 136 op = IPE_OP_INVALID; 137 WARN(1, "no rule setup for kernel_read_file enum %d", id); 138 } 139 140 ipe_build_eval_ctx(&ctx, file, op, IPE_HOOK_KERNEL_READ); 141 return ipe_evaluate_event(&ctx); 142 } 143 144 /** 145 * ipe_kernel_load_data() - ipe security hook function for kernel load data. 146 * @id: Supplies the enumeration identifying the purpose of the load. 147 * @contents: Unused. 148 * 149 * This LSM hook is called when a data buffer provided by userspace is loading 150 * into the kernel. 151 * 152 * Return: 153 * * %0 - Success 154 * * %-EACCES - Did not pass IPE policy 155 */ 156 int ipe_kernel_load_data(enum kernel_load_data_id id, bool contents) 157 { 158 struct ipe_eval_ctx ctx = IPE_EVAL_CTX_INIT; 159 enum ipe_op_type op; 160 161 switch (id) { 162 case LOADING_FIRMWARE: 163 op = IPE_OP_FIRMWARE; 164 break; 165 case LOADING_MODULE: 166 op = IPE_OP_KERNEL_MODULE; 167 break; 168 case LOADING_KEXEC_INITRAMFS: 169 op = IPE_OP_KEXEC_INITRAMFS; 170 break; 171 case LOADING_KEXEC_IMAGE: 172 op = IPE_OP_KEXEC_IMAGE; 173 break; 174 case LOADING_POLICY: 175 op = IPE_OP_POLICY; 176 break; 177 case LOADING_X509_CERTIFICATE: 178 op = IPE_OP_X509; 179 break; 180 default: 181 op = IPE_OP_INVALID; 182 WARN(1, "no rule setup for kernel_load_data enum %d", id); 183 } 184 185 ipe_build_eval_ctx(&ctx, NULL, op, IPE_HOOK_KERNEL_LOAD); 186 return ipe_evaluate_event(&ctx); 187 } 188 189 /** 190 * ipe_unpack_initramfs() - Mark the current rootfs as initramfs. 191 */ 192 void ipe_unpack_initramfs(void) 193 { 194 ipe_sb(current->fs->root.mnt->mnt_sb)->initramfs = true; 195 } 196 197 #ifdef CONFIG_IPE_PROP_DM_VERITY 198 /** 199 * ipe_bdev_free_security() - Free IPE's LSM blob of block_devices. 200 * @bdev: Supplies a pointer to a block_device that contains the structure 201 * to free. 202 */ 203 void ipe_bdev_free_security(struct block_device *bdev) 204 { 205 struct ipe_bdev *blob = ipe_bdev(bdev); 206 207 ipe_digest_free(blob->root_hash); 208 } 209 210 #ifdef CONFIG_IPE_PROP_DM_VERITY_SIGNATURE 211 static void ipe_set_dmverity_signature(struct ipe_bdev *blob, 212 const void *value, 213 size_t size) 214 { 215 blob->dm_verity_signed = size > 0 && value; 216 } 217 #else 218 static inline void ipe_set_dmverity_signature(struct ipe_bdev *blob, 219 const void *value, 220 size_t size) 221 { 222 } 223 #endif /* CONFIG_IPE_PROP_DM_VERITY_SIGNATURE */ 224 225 /** 226 * ipe_bdev_setintegrity() - Save integrity data from a bdev to IPE's LSM blob. 227 * @bdev: Supplies a pointer to a block_device that contains the LSM blob. 228 * @type: Supplies the integrity type. 229 * @value: Supplies the value to store. 230 * @size: The size of @value. 231 * 232 * This hook is currently used to save dm-verity's root hash or the existence 233 * of a validated signed dm-verity root hash into LSM blob. 234 * 235 * Return: %0 on success. If an error occurs, the function will return the 236 * -errno. 237 */ 238 int ipe_bdev_setintegrity(struct block_device *bdev, enum lsm_integrity_type type, 239 const void *value, size_t size) 240 { 241 const struct dm_verity_digest *digest = NULL; 242 struct ipe_bdev *blob = ipe_bdev(bdev); 243 struct digest_info *info = NULL; 244 245 if (type == LSM_INT_DMVERITY_SIG_VALID) { 246 ipe_set_dmverity_signature(blob, value, size); 247 248 return 0; 249 } 250 251 if (type != LSM_INT_DMVERITY_ROOTHASH) 252 return -EINVAL; 253 254 if (!value) { 255 ipe_digest_free(blob->root_hash); 256 blob->root_hash = NULL; 257 258 return 0; 259 } 260 digest = value; 261 262 info = kzalloc(sizeof(*info), GFP_KERNEL); 263 if (!info) 264 return -ENOMEM; 265 266 info->digest = kmemdup(digest->digest, digest->digest_len, GFP_KERNEL); 267 if (!info->digest) 268 goto err; 269 270 info->alg = kstrdup(digest->alg, GFP_KERNEL); 271 if (!info->alg) 272 goto err; 273 274 info->digest_len = digest->digest_len; 275 276 ipe_digest_free(blob->root_hash); 277 blob->root_hash = info; 278 279 return 0; 280 err: 281 ipe_digest_free(info); 282 283 return -ENOMEM; 284 } 285 #endif /* CONFIG_IPE_PROP_DM_VERITY */ 286 287 #ifdef CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG 288 /** 289 * ipe_inode_setintegrity() - save integrity data from a inode to IPE's LSM blob. 290 * @inode: The inode to source the security blob from. 291 * @type: Supplies the integrity type. 292 * @value: The value to be stored. 293 * @size: The size of @value. 294 * 295 * This hook is currently used to save the existence of a validated fs-verity 296 * builtin signature into LSM blob. 297 * 298 * Return: %0 on success. If an error occurs, the function will return the 299 * -errno. 300 */ 301 int ipe_inode_setintegrity(const struct inode *inode, 302 enum lsm_integrity_type type, 303 const void *value, size_t size) 304 { 305 struct ipe_inode *inode_sec = ipe_inode(inode); 306 307 if (type == LSM_INT_FSVERITY_BUILTINSIG_VALID) { 308 inode_sec->fs_verity_signed = size > 0 && value; 309 return 0; 310 } 311 312 return -EINVAL; 313 } 314 #endif /* CONFIG_CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */ 315