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 = vfs_setxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, 69 buf, sizeof(struct cachefiles_xattr) + len, 0); 70 if (ret < 0) { 71 trace_cachefiles_vfs_error(object, file_inode(file), ret, 72 cachefiles_trace_setxattr_error); 73 trace_cachefiles_coherency(object, file_inode(file)->i_ino, 74 buf->content, 75 cachefiles_coherency_set_fail); 76 if (ret != -ENOMEM) 77 cachefiles_io_error_obj( 78 object, 79 "Failed to set xattr with error %d", ret); 80 } else { 81 trace_cachefiles_coherency(object, file_inode(file)->i_ino, 82 buf->content, 83 cachefiles_coherency_set_ok); 84 } 85 86 kfree(buf); 87 _leave(" = %d", ret); 88 return ret; 89 } 90 91 /* 92 * check the consistency between the backing cache and the FS-Cache cookie 93 */ 94 int cachefiles_check_auxdata(struct cachefiles_object *object, struct file *file) 95 { 96 struct cachefiles_xattr *buf; 97 struct dentry *dentry = file->f_path.dentry; 98 unsigned int len = object->cookie->aux_len, tlen; 99 const void *p = fscache_get_aux(object->cookie); 100 enum cachefiles_coherency_trace why; 101 ssize_t xlen; 102 int ret = -ESTALE; 103 104 tlen = sizeof(struct cachefiles_xattr) + len; 105 buf = kmalloc(tlen, GFP_KERNEL); 106 if (!buf) 107 return -ENOMEM; 108 109 xlen = cachefiles_inject_read_error(); 110 if (xlen == 0) 111 xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, tlen); 112 if (xlen != tlen) { 113 if (xlen < 0) { 114 ret = xlen; 115 trace_cachefiles_vfs_error(object, file_inode(file), xlen, 116 cachefiles_trace_getxattr_error); 117 } 118 if (xlen == -EIO) 119 cachefiles_io_error_obj( 120 object, 121 "Failed to read aux with error %zd", xlen); 122 why = cachefiles_coherency_check_xattr; 123 } else if (buf->type != CACHEFILES_COOKIE_TYPE_DATA) { 124 why = cachefiles_coherency_check_type; 125 } else if (memcmp(buf->data, p, len) != 0) { 126 why = cachefiles_coherency_check_aux; 127 } else if (be64_to_cpu(buf->object_size) != object->cookie->object_size) { 128 why = cachefiles_coherency_check_objsize; 129 } else if (buf->content == CACHEFILES_CONTENT_DIRTY) { 130 // TODO: Begin conflict resolution 131 pr_warn("Dirty object in cache\n"); 132 why = cachefiles_coherency_check_dirty; 133 } else { 134 why = cachefiles_coherency_check_ok; 135 ret = 0; 136 } 137 138 trace_cachefiles_coherency(object, file_inode(file)->i_ino, 139 buf->content, why); 140 kfree(buf); 141 return ret; 142 } 143 144 /* 145 * remove the object's xattr to mark it stale 146 */ 147 int cachefiles_remove_object_xattr(struct cachefiles_cache *cache, 148 struct cachefiles_object *object, 149 struct dentry *dentry) 150 { 151 int ret; 152 153 ret = cachefiles_inject_remove_error(); 154 if (ret == 0) 155 ret = vfs_removexattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache); 156 if (ret < 0) { 157 trace_cachefiles_vfs_error(object, d_inode(dentry), ret, 158 cachefiles_trace_remxattr_error); 159 if (ret == -ENOENT || ret == -ENODATA) 160 ret = 0; 161 else if (ret != -ENOMEM) 162 cachefiles_io_error(cache, 163 "Can't remove xattr from %lu" 164 " (error %d)", 165 d_backing_inode(dentry)->i_ino, -ret); 166 } 167 168 _leave(" = %d", ret); 169 return ret; 170 } 171 172 /* 173 * Stick a marker on the cache object to indicate that it's dirty. 174 */ 175 void cachefiles_prepare_to_write(struct fscache_cookie *cookie) 176 { 177 const struct cred *saved_cred; 178 struct cachefiles_object *object = cookie->cache_priv; 179 struct cachefiles_cache *cache = object->volume->cache; 180 181 _enter("c=%08x", object->cookie->debug_id); 182 183 if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) { 184 cachefiles_begin_secure(cache, &saved_cred); 185 cachefiles_set_object_xattr(object); 186 cachefiles_end_secure(cache, saved_cred); 187 } 188 } 189 190 /* 191 * Set the state xattr on a volume directory. 192 */ 193 bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume) 194 { 195 struct cachefiles_vol_xattr *buf; 196 unsigned int len = volume->vcookie->coherency_len; 197 const void *p = volume->vcookie->coherency; 198 struct dentry *dentry = volume->dentry; 199 int ret; 200 201 _enter("%x,#%d", volume->vcookie->debug_id, len); 202 203 len += sizeof(*buf); 204 buf = kmalloc(len, GFP_KERNEL); 205 if (!buf) 206 return false; 207 buf->reserved = cpu_to_be32(0); 208 memcpy(buf->data, p, volume->vcookie->coherency_len); 209 210 ret = cachefiles_inject_write_error(); 211 if (ret == 0) 212 ret = vfs_setxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, 213 buf, len, 0); 214 if (ret < 0) { 215 trace_cachefiles_vfs_error(NULL, d_inode(dentry), ret, 216 cachefiles_trace_setxattr_error); 217 trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino, 218 cachefiles_coherency_vol_set_fail); 219 if (ret != -ENOMEM) 220 cachefiles_io_error( 221 volume->cache, "Failed to set xattr with error %d", ret); 222 } else { 223 trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino, 224 cachefiles_coherency_vol_set_ok); 225 } 226 227 kfree(buf); 228 _leave(" = %d", ret); 229 return ret == 0; 230 } 231 232 /* 233 * Check the consistency between the backing cache and the volume cookie. 234 */ 235 int cachefiles_check_volume_xattr(struct cachefiles_volume *volume) 236 { 237 struct cachefiles_vol_xattr *buf; 238 struct dentry *dentry = volume->dentry; 239 unsigned int len = volume->vcookie->coherency_len; 240 const void *p = volume->vcookie->coherency; 241 enum cachefiles_coherency_trace why; 242 ssize_t xlen; 243 int ret = -ESTALE; 244 245 _enter(""); 246 247 len += sizeof(*buf); 248 buf = kmalloc(len, GFP_KERNEL); 249 if (!buf) 250 return -ENOMEM; 251 252 xlen = cachefiles_inject_read_error(); 253 if (xlen == 0) 254 xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, len); 255 if (xlen != len) { 256 if (xlen < 0) { 257 ret = xlen; 258 trace_cachefiles_vfs_error(NULL, d_inode(dentry), xlen, 259 cachefiles_trace_getxattr_error); 260 if (xlen == -EIO) 261 cachefiles_io_error( 262 volume->cache, 263 "Failed to read xattr with error %zd", xlen); 264 } 265 why = cachefiles_coherency_vol_check_xattr; 266 } else if (buf->reserved != cpu_to_be32(0)) { 267 why = cachefiles_coherency_vol_check_resv; 268 } else if (memcmp(buf->data, p, len - sizeof(*buf)) != 0) { 269 why = cachefiles_coherency_vol_check_cmp; 270 } else { 271 why = cachefiles_coherency_vol_check_ok; 272 ret = 0; 273 } 274 275 trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino, why); 276 kfree(buf); 277 _leave(" = %d", ret); 278 return ret; 279 } 280