1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* CacheFiles extended attribute management 3 * 4 * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #include <linux/module.h> 9 #include <linux/sched.h> 10 #include <linux/file.h> 11 #include <linux/fs.h> 12 #include <linux/fsnotify.h> 13 #include <linux/quotaops.h> 14 #include <linux/xattr.h> 15 #include <linux/slab.h> 16 #include "internal.h" 17 18 #define CACHEFILES_COOKIE_TYPE_DATA 1 19 20 struct cachefiles_xattr { 21 __be64 object_size; /* Actual size of the object */ 22 __be64 zero_point; /* Size after which server has no data not written by us */ 23 __u8 type; /* Type of object */ 24 __u8 content; /* Content presence (enum cachefiles_content) */ 25 __u8 data[]; /* netfs coherency data */ 26 } __packed; 27 28 static const char cachefiles_xattr_cache[] = 29 XATTR_USER_PREFIX "CacheFiles.cache"; 30 31 struct cachefiles_vol_xattr { 32 __be32 reserved; /* Reserved, should be 0 */ 33 __u8 data[]; /* netfs volume coherency data */ 34 } __packed; 35 36 /* 37 * set the state xattr on a cache file 38 */ 39 int cachefiles_set_object_xattr(struct cachefiles_object *object) 40 { 41 struct cachefiles_xattr *buf; 42 struct dentry *dentry; 43 struct file *file = object->file; 44 unsigned int len = object->cookie->aux_len; 45 int ret; 46 47 if (!file) 48 return -ESTALE; 49 dentry = file->f_path.dentry; 50 51 _enter("%x,#%d", object->debug_id, len); 52 53 buf = kmalloc(sizeof(struct cachefiles_xattr) + len, GFP_KERNEL); 54 if (!buf) 55 return -ENOMEM; 56 57 buf->object_size = cpu_to_be64(object->cookie->object_size); 58 buf->zero_point = 0; 59 buf->type = CACHEFILES_COOKIE_TYPE_DATA; 60 buf->content = object->content_info; 61 if (test_bit(FSCACHE_COOKIE_LOCAL_WRITE, &object->cookie->flags)) 62 buf->content = CACHEFILES_CONTENT_DIRTY; 63 if (len > 0) 64 memcpy(buf->data, fscache_get_aux(object->cookie), len); 65 66 ret = cachefiles_inject_write_error(); 67 if (ret == 0) { 68 ret = mnt_want_write_file(file); 69 if (ret == 0) { 70 ret = vfs_setxattr(&nop_mnt_idmap, dentry, 71 cachefiles_xattr_cache, buf, 72 sizeof(struct cachefiles_xattr) + len, 0); 73 mnt_drop_write_file(file); 74 } 75 } 76 if (ret < 0) { 77 trace_cachefiles_vfs_error(object, file_inode(file), ret, 78 cachefiles_trace_setxattr_error); 79 trace_cachefiles_coherency(object, file_inode(file)->i_ino, 80 buf->content, 81 cachefiles_coherency_set_fail); 82 if (ret != -ENOMEM) 83 cachefiles_io_error_obj( 84 object, 85 "Failed to set xattr with error %d", ret); 86 } else { 87 trace_cachefiles_coherency(object, file_inode(file)->i_ino, 88 buf->content, 89 cachefiles_coherency_set_ok); 90 } 91 92 kfree(buf); 93 _leave(" = %d", ret); 94 return ret; 95 } 96 97 /* 98 * check the consistency between the backing cache and the FS-Cache cookie 99 */ 100 int cachefiles_check_auxdata(struct cachefiles_object *object, struct file *file) 101 { 102 struct cachefiles_xattr *buf; 103 struct dentry *dentry = file->f_path.dentry; 104 unsigned int len = object->cookie->aux_len, tlen; 105 const void *p = fscache_get_aux(object->cookie); 106 enum cachefiles_coherency_trace why; 107 ssize_t xlen; 108 int ret = -ESTALE; 109 110 tlen = sizeof(struct cachefiles_xattr) + len; 111 buf = kmalloc(tlen, GFP_KERNEL); 112 if (!buf) 113 return -ENOMEM; 114 115 xlen = cachefiles_inject_read_error(); 116 if (xlen == 0) 117 xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, tlen); 118 if (xlen != tlen) { 119 if (xlen < 0) { 120 ret = xlen; 121 trace_cachefiles_vfs_error(object, file_inode(file), xlen, 122 cachefiles_trace_getxattr_error); 123 } 124 if (xlen == -EIO) 125 cachefiles_io_error_obj( 126 object, 127 "Failed to read aux with error %zd", xlen); 128 why = cachefiles_coherency_check_xattr; 129 } else if (buf->type != CACHEFILES_COOKIE_TYPE_DATA) { 130 why = cachefiles_coherency_check_type; 131 } else if (memcmp(buf->data, p, len) != 0) { 132 why = cachefiles_coherency_check_aux; 133 } else if (be64_to_cpu(buf->object_size) != object->cookie->object_size) { 134 why = cachefiles_coherency_check_objsize; 135 } else if (buf->content == CACHEFILES_CONTENT_DIRTY) { 136 // TODO: Begin conflict resolution 137 pr_warn("Dirty object in cache\n"); 138 why = cachefiles_coherency_check_dirty; 139 } else { 140 why = cachefiles_coherency_check_ok; 141 ret = 0; 142 } 143 144 trace_cachefiles_coherency(object, file_inode(file)->i_ino, 145 buf->content, why); 146 kfree(buf); 147 return ret; 148 } 149 150 /* 151 * remove the object's xattr to mark it stale 152 */ 153 int cachefiles_remove_object_xattr(struct cachefiles_cache *cache, 154 struct cachefiles_object *object, 155 struct dentry *dentry) 156 { 157 int ret; 158 159 ret = cachefiles_inject_remove_error(); 160 if (ret == 0) { 161 ret = mnt_want_write(cache->mnt); 162 if (ret == 0) { 163 ret = vfs_removexattr(&nop_mnt_idmap, dentry, 164 cachefiles_xattr_cache); 165 mnt_drop_write(cache->mnt); 166 } 167 } 168 if (ret < 0) { 169 trace_cachefiles_vfs_error(object, d_inode(dentry), ret, 170 cachefiles_trace_remxattr_error); 171 if (ret == -ENOENT || ret == -ENODATA) 172 ret = 0; 173 else if (ret != -ENOMEM) 174 cachefiles_io_error(cache, 175 "Can't remove xattr from %lu" 176 " (error %d)", 177 d_backing_inode(dentry)->i_ino, -ret); 178 } 179 180 _leave(" = %d", ret); 181 return ret; 182 } 183 184 /* 185 * Stick a marker on the cache object to indicate that it's dirty. 186 */ 187 void cachefiles_prepare_to_write(struct fscache_cookie *cookie) 188 { 189 const struct cred *saved_cred; 190 struct cachefiles_object *object = cookie->cache_priv; 191 struct cachefiles_cache *cache = object->volume->cache; 192 193 _enter("c=%08x", object->cookie->debug_id); 194 195 if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) { 196 cachefiles_begin_secure(cache, &saved_cred); 197 cachefiles_set_object_xattr(object); 198 cachefiles_end_secure(cache, saved_cred); 199 } 200 } 201 202 /* 203 * Set the state xattr on a volume directory. 204 */ 205 bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume) 206 { 207 struct cachefiles_vol_xattr *buf; 208 unsigned int len = volume->vcookie->coherency_len; 209 const void *p = volume->vcookie->coherency; 210 struct dentry *dentry = volume->dentry; 211 int ret; 212 213 _enter("%x,#%d", volume->vcookie->debug_id, len); 214 215 len += sizeof(*buf); 216 buf = kmalloc(len, GFP_KERNEL); 217 if (!buf) 218 return false; 219 buf->reserved = cpu_to_be32(0); 220 memcpy(buf->data, p, volume->vcookie->coherency_len); 221 222 ret = cachefiles_inject_write_error(); 223 if (ret == 0) { 224 ret = mnt_want_write(volume->cache->mnt); 225 if (ret == 0) { 226 ret = vfs_setxattr(&nop_mnt_idmap, dentry, 227 cachefiles_xattr_cache, 228 buf, len, 0); 229 mnt_drop_write(volume->cache->mnt); 230 } 231 } 232 if (ret < 0) { 233 trace_cachefiles_vfs_error(NULL, d_inode(dentry), ret, 234 cachefiles_trace_setxattr_error); 235 trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino, 236 cachefiles_coherency_vol_set_fail); 237 if (ret != -ENOMEM) 238 cachefiles_io_error( 239 volume->cache, "Failed to set xattr with error %d", ret); 240 } else { 241 trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino, 242 cachefiles_coherency_vol_set_ok); 243 } 244 245 kfree(buf); 246 _leave(" = %d", ret); 247 return ret == 0; 248 } 249 250 /* 251 * Check the consistency between the backing cache and the volume cookie. 252 */ 253 int cachefiles_check_volume_xattr(struct cachefiles_volume *volume) 254 { 255 struct cachefiles_vol_xattr *buf; 256 struct dentry *dentry = volume->dentry; 257 unsigned int len = volume->vcookie->coherency_len; 258 const void *p = volume->vcookie->coherency; 259 enum cachefiles_coherency_trace why; 260 ssize_t xlen; 261 int ret = -ESTALE; 262 263 _enter(""); 264 265 len += sizeof(*buf); 266 buf = kmalloc(len, GFP_KERNEL); 267 if (!buf) 268 return -ENOMEM; 269 270 xlen = cachefiles_inject_read_error(); 271 if (xlen == 0) 272 xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, len); 273 if (xlen != len) { 274 if (xlen < 0) { 275 ret = xlen; 276 trace_cachefiles_vfs_error(NULL, d_inode(dentry), xlen, 277 cachefiles_trace_getxattr_error); 278 if (xlen == -EIO) 279 cachefiles_io_error( 280 volume->cache, 281 "Failed to read xattr with error %zd", xlen); 282 } 283 why = cachefiles_coherency_vol_check_xattr; 284 } else if (buf->reserved != cpu_to_be32(0)) { 285 why = cachefiles_coherency_vol_check_resv; 286 } else if (memcmp(buf->data, p, len - sizeof(*buf)) != 0) { 287 why = cachefiles_coherency_vol_check_cmp; 288 } else { 289 why = cachefiles_coherency_vol_check_ok; 290 ret = 0; 291 } 292 293 trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino, why); 294 kfree(buf); 295 _leave(" = %d", ret); 296 return ret; 297 } 298