diff options
| -rw-r--r-- | fs/crypto/hooks.c | 32 |
1 files changed, 26 insertions, 6 deletions
diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c index 104771c3d3f6a..d8d5049b8fe1f 100644 --- a/fs/crypto/hooks.c +++ b/fs/crypto/hooks.c @@ -30,21 +30,41 @@ int fscrypt_file_open(struct inode *inode, struct file *filp) { int err; - struct dentry *dir; + struct dentry *dentry, *dentry_parent; + struct inode *inode_parent; err = fscrypt_require_key(inode); if (err) return err; - dir = dget_parent(file_dentry(filp)); - if (IS_ENCRYPTED(d_inode(dir)) && - !fscrypt_has_permitted_context(d_inode(dir), inode)) { + dentry = file_dentry(filp); + + /* + * Getting a reference to the parent dentry is needed for the actual + * encryption policy comparison, but it's expensive on multi-core + * systems. Since this function runs on unencrypted files too, start + * with a lightweight RCU-mode check for the parent directory being + * unencrypted (in which case it's fine for the child to be either + * unencrypted, or encrypted with any policy). Only continue on to the + * full policy check if the parent directory is actually encrypted. + */ + rcu_read_lock(); + dentry_parent = READ_ONCE(dentry->d_parent); + inode_parent = d_inode_rcu(dentry_parent); + if (inode_parent != NULL && !IS_ENCRYPTED(inode_parent)) { + rcu_read_unlock(); + return 0; + } + rcu_read_unlock(); + + dentry_parent = dget_parent(dentry); + if (!fscrypt_has_permitted_context(d_inode(dentry_parent), inode)) { fscrypt_warn(inode, "Inconsistent encryption context (parent directory: %lu)", - d_inode(dir)->i_ino); + d_inode(dentry_parent)->i_ino); err = -EPERM; } - dput(dir); + dput(dentry_parent); return err; } EXPORT_SYMBOL_GPL(fscrypt_file_open); |