1 /* 2 * fs/crypto/hooks.c 3 * 4 * Encryption hooks for higher-level filesystem operations. 5 */ 6 7 #include <linux/ratelimit.h> 8 #include "fscrypt_private.h" 9 10 /** 11 * fscrypt_file_open - prepare to open a possibly-encrypted regular file 12 * @inode: the inode being opened 13 * @filp: the struct file being set up 14 * 15 * Currently, an encrypted regular file can only be opened if its encryption key 16 * is available; access to the raw encrypted contents is not supported. 17 * Therefore, we first set up the inode's encryption key (if not already done) 18 * and return an error if it's unavailable. 19 * 20 * We also verify that if the parent directory (from the path via which the file 21 * is being opened) is encrypted, then the inode being opened uses the same 22 * encryption policy. This is needed as part of the enforcement that all files 23 * in an encrypted directory tree use the same encryption policy, as a 24 * protection against certain types of offline attacks. Note that this check is 25 * needed even when opening an *unencrypted* file, since it's forbidden to have 26 * an unencrypted file in an encrypted directory. 27 * 28 * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code 29 */ 30 int fscrypt_file_open(struct inode *inode, struct file *filp) 31 { 32 int err; 33 struct dentry *dir; 34 35 err = fscrypt_require_key(inode); 36 if (err) 37 return err; 38 39 dir = dget_parent(file_dentry(filp)); 40 if (IS_ENCRYPTED(d_inode(dir)) && 41 !fscrypt_has_permitted_context(d_inode(dir), inode)) { 42 pr_warn_ratelimited("fscrypt: inconsistent encryption contexts: %lu/%lu", 43 d_inode(dir)->i_ino, inode->i_ino); 44 err = -EPERM; 45 } 46 dput(dir); 47 return err; 48 } 49 EXPORT_SYMBOL_GPL(fscrypt_file_open); 50