.. | .. |
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89 | 89 | */ |
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90 | 90 | |
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91 | 91 | /* Compute number of levels and the number of blocks in each level */ |
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92 | | - blocks = (inode->i_size + params->block_size - 1) >> log_blocksize; |
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| 92 | + blocks = ((u64)inode->i_size + params->block_size - 1) >> log_blocksize; |
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93 | 93 | pr_debug("Data is %lld bytes (%llu blocks)\n", inode->i_size, blocks); |
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94 | 94 | while (blocks > 1) { |
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95 | 95 | if (params->num_levels >= FS_VERITY_MAX_LEVELS) { |
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.. | .. |
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142 | 142 | } |
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143 | 143 | |
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144 | 144 | /* |
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145 | | - * Validate the given fsverity_descriptor and create a new fsverity_info from |
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146 | | - * it. The signature (if present) is also checked. |
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| 145 | + * Create a new fsverity_info from the given fsverity_descriptor (with optional |
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| 146 | + * appended signature), and check the signature if present. The |
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| 147 | + * fsverity_descriptor must have already undergone basic validation. |
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147 | 148 | */ |
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148 | 149 | struct fsverity_info *fsverity_create_info(const struct inode *inode, |
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149 | | - void *_desc, size_t desc_size) |
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| 150 | + struct fsverity_descriptor *desc, |
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| 151 | + size_t desc_size) |
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150 | 152 | { |
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151 | | - struct fsverity_descriptor *desc = _desc; |
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152 | 153 | struct fsverity_info *vi; |
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153 | 154 | int err; |
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154 | | - |
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155 | | - if (desc_size < sizeof(*desc)) { |
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156 | | - fsverity_err(inode, "Unrecognized descriptor size: %zu bytes", |
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157 | | - desc_size); |
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158 | | - return ERR_PTR(-EINVAL); |
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159 | | - } |
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160 | | - |
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161 | | - if (desc->version != 1) { |
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162 | | - fsverity_err(inode, "Unrecognized descriptor version: %u", |
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163 | | - desc->version); |
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164 | | - return ERR_PTR(-EINVAL); |
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165 | | - } |
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166 | | - |
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167 | | - if (memchr_inv(desc->__reserved, 0, sizeof(desc->__reserved))) { |
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168 | | - fsverity_err(inode, "Reserved bits set in descriptor"); |
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169 | | - return ERR_PTR(-EINVAL); |
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170 | | - } |
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171 | | - |
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172 | | - if (desc->salt_size > sizeof(desc->salt)) { |
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173 | | - fsverity_err(inode, "Invalid salt_size: %u", desc->salt_size); |
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174 | | - return ERR_PTR(-EINVAL); |
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175 | | - } |
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176 | | - |
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177 | | - if (le64_to_cpu(desc->data_size) != inode->i_size) { |
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178 | | - fsverity_err(inode, |
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179 | | - "Wrong data_size: %llu (desc) != %lld (inode)", |
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180 | | - le64_to_cpu(desc->data_size), inode->i_size); |
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181 | | - return ERR_PTR(-EINVAL); |
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182 | | - } |
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183 | 155 | |
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184 | 156 | vi = kmem_cache_zalloc(fsverity_info_cachep, GFP_KERNEL); |
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185 | 157 | if (!vi) |
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.. | .. |
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209 | 181 | vi->tree_params.hash_alg->name, |
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210 | 182 | vi->tree_params.digest_size, vi->file_digest); |
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211 | 183 | |
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212 | | - err = fsverity_verify_signature(vi, desc, desc_size); |
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| 184 | + err = fsverity_verify_signature(vi, desc->signature, |
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| 185 | + le32_to_cpu(desc->sig_size)); |
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213 | 186 | out: |
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214 | 187 | if (err) { |
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215 | 188 | fsverity_free_info(vi); |
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.. | .. |
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221 | 194 | void fsverity_set_info(struct inode *inode, struct fsverity_info *vi) |
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222 | 195 | { |
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223 | 196 | /* |
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224 | | - * Multiple processes may race to set ->i_verity_info, so use cmpxchg. |
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225 | | - * This pairs with the READ_ONCE() in fsverity_get_info(). |
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| 197 | + * Multiple tasks may race to set ->i_verity_info, so use |
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| 198 | + * cmpxchg_release(). This pairs with the smp_load_acquire() in |
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| 199 | + * fsverity_get_info(). I.e., here we publish ->i_verity_info with a |
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| 200 | + * RELEASE barrier so that other tasks can ACQUIRE it. |
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226 | 201 | */ |
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227 | | - if (cmpxchg(&inode->i_verity_info, NULL, vi) != NULL) |
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| 202 | + if (cmpxchg_release(&inode->i_verity_info, NULL, vi) != NULL) { |
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| 203 | + /* Lost the race, so free the fsverity_info we allocated. */ |
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228 | 204 | fsverity_free_info(vi); |
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| 205 | + /* |
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| 206 | + * Afterwards, the caller may access ->i_verity_info directly, |
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| 207 | + * so make sure to ACQUIRE the winning fsverity_info. |
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| 208 | + */ |
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| 209 | + (void)fsverity_get_info(inode); |
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| 210 | + } |
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229 | 211 | } |
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230 | 212 | |
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231 | 213 | void fsverity_free_info(struct fsverity_info *vi) |
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.. | .. |
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236 | 218 | kmem_cache_free(fsverity_info_cachep, vi); |
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237 | 219 | } |
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238 | 220 | |
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239 | | -/* Ensure the inode has an ->i_verity_info */ |
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240 | | -static int ensure_verity_info(struct inode *inode) |
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| 221 | +static bool validate_fsverity_descriptor(struct inode *inode, |
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| 222 | + const struct fsverity_descriptor *desc, |
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| 223 | + size_t desc_size) |
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241 | 224 | { |
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242 | | - struct fsverity_info *vi = fsverity_get_info(inode); |
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243 | | - struct fsverity_descriptor *desc; |
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244 | | - int res; |
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| 225 | + if (desc_size < sizeof(*desc)) { |
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| 226 | + fsverity_err(inode, "Unrecognized descriptor size: %zu bytes", |
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| 227 | + desc_size); |
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| 228 | + return false; |
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| 229 | + } |
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245 | 230 | |
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246 | | - if (vi) |
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247 | | - return 0; |
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| 231 | + if (desc->version != 1) { |
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| 232 | + fsverity_err(inode, "Unrecognized descriptor version: %u", |
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| 233 | + desc->version); |
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| 234 | + return false; |
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| 235 | + } |
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| 236 | + |
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| 237 | + if (memchr_inv(desc->__reserved, 0, sizeof(desc->__reserved))) { |
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| 238 | + fsverity_err(inode, "Reserved bits set in descriptor"); |
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| 239 | + return false; |
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| 240 | + } |
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| 241 | + |
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| 242 | + if (desc->salt_size > sizeof(desc->salt)) { |
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| 243 | + fsverity_err(inode, "Invalid salt_size: %u", desc->salt_size); |
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| 244 | + return false; |
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| 245 | + } |
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| 246 | + |
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| 247 | + if (le64_to_cpu(desc->data_size) != inode->i_size) { |
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| 248 | + fsverity_err(inode, |
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| 249 | + "Wrong data_size: %llu (desc) != %lld (inode)", |
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| 250 | + le64_to_cpu(desc->data_size), inode->i_size); |
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| 251 | + return false; |
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| 252 | + } |
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| 253 | + |
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| 254 | + if (le32_to_cpu(desc->sig_size) > desc_size - sizeof(*desc)) { |
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| 255 | + fsverity_err(inode, "Signature overflows verity descriptor"); |
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| 256 | + return false; |
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| 257 | + } |
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| 258 | + |
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| 259 | + return true; |
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| 260 | +} |
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| 261 | + |
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| 262 | +/* |
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| 263 | + * Read the inode's fsverity_descriptor (with optional appended signature) from |
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| 264 | + * the filesystem, and do basic validation of it. |
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| 265 | + */ |
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| 266 | +int fsverity_get_descriptor(struct inode *inode, |
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| 267 | + struct fsverity_descriptor **desc_ret, |
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| 268 | + size_t *desc_size_ret) |
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| 269 | +{ |
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| 270 | + int res; |
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| 271 | + struct fsverity_descriptor *desc; |
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248 | 272 | |
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249 | 273 | res = inode->i_sb->s_vop->get_verity_descriptor(inode, NULL, 0); |
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250 | 274 | if (res < 0) { |
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.. | .. |
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263 | 287 | res = inode->i_sb->s_vop->get_verity_descriptor(inode, desc, res); |
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264 | 288 | if (res < 0) { |
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265 | 289 | fsverity_err(inode, "Error %d reading verity descriptor", res); |
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266 | | - goto out_free_desc; |
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| 290 | + kfree(desc); |
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| 291 | + return res; |
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267 | 292 | } |
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268 | 293 | |
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269 | | - vi = fsverity_create_info(inode, desc, res); |
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| 294 | + if (!validate_fsverity_descriptor(inode, desc, res)) { |
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| 295 | + kfree(desc); |
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| 296 | + return -EINVAL; |
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| 297 | + } |
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| 298 | + |
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| 299 | + *desc_ret = desc; |
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| 300 | + *desc_size_ret = res; |
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| 301 | + return 0; |
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| 302 | +} |
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| 303 | + |
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| 304 | +/* Ensure the inode has an ->i_verity_info */ |
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| 305 | +static int ensure_verity_info(struct inode *inode) |
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| 306 | +{ |
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| 307 | + struct fsverity_info *vi = fsverity_get_info(inode); |
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| 308 | + struct fsverity_descriptor *desc; |
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| 309 | + size_t desc_size; |
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| 310 | + int err; |
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| 311 | + |
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| 312 | + if (vi) |
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| 313 | + return 0; |
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| 314 | + |
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| 315 | + err = fsverity_get_descriptor(inode, &desc, &desc_size); |
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| 316 | + if (err) |
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| 317 | + return err; |
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| 318 | + |
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| 319 | + vi = fsverity_create_info(inode, desc, desc_size); |
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270 | 320 | if (IS_ERR(vi)) { |
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271 | | - res = PTR_ERR(vi); |
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| 321 | + err = PTR_ERR(vi); |
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272 | 322 | goto out_free_desc; |
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273 | 323 | } |
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274 | 324 | |
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275 | 325 | fsverity_set_info(inode, vi); |
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276 | | - res = 0; |
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| 326 | + err = 0; |
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277 | 327 | out_free_desc: |
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278 | 328 | kfree(desc); |
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279 | | - return res; |
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| 329 | + return err; |
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280 | 330 | } |
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281 | 331 | |
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282 | 332 | /** |
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