1 files changed, 68 insertions, 21 deletions

diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c
index 7b8c5a1104b5..b97de0d1430f 100644
--- a/fs/crypto/hooks.c
+++ b/fs/crypto/hooks.c
@@ -5,6 +5,8 @@
  * Encryption hooks for higher-level filesystem operations.
  */
 
+#include <linux/export.h>
+
 #include "fscrypt_private.h"
 
 /**
@@ -30,21 +32,41 @@
 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);
@@ -102,15 +124,40 @@ int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
 	if (err && err != -ENOENT)
 		return err;
 
-	if (fname->is_nokey_name) {
-		spin_lock(&dentry->d_lock);
-		dentry->d_flags |= DCACHE_NOKEY_NAME;
-		spin_unlock(&dentry->d_lock);
-	}
+	fscrypt_prepare_dentry(dentry, fname->is_nokey_name);
+
 	return err;
 }
 EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup);
 
+/**
+ * fscrypt_prepare_lookup_partial() - prepare lookup without filename setup
+ * @dir: the encrypted directory being searched
+ * @dentry: the dentry being looked up in @dir
+ *
+ * This function should be used by the ->lookup and ->atomic_open methods of
+ * filesystems that handle filename encryption and no-key name encoding
+ * themselves and thus can't use fscrypt_prepare_lookup().  Like
+ * fscrypt_prepare_lookup(), this will try to set up the directory's encryption
+ * key and will set DCACHE_NOKEY_NAME on the dentry if the key is unavailable.
+ * However, this function doesn't set up a struct fscrypt_name for the filename.
+ *
+ * Return: 0 on success; -errno on error.  Note that the encryption key being
+ *	   unavailable is not considered an error.  It is also not an error if
+ *	   the encryption policy is unsupported by this kernel; that is treated
+ *	   like the key being unavailable, so that files can still be deleted.
+ */
+int fscrypt_prepare_lookup_partial(struct inode *dir, struct dentry *dentry)
+{
+	int err = fscrypt_get_encryption_info(dir, true);
+	bool is_nokey_name = (!err && !fscrypt_has_encryption_key(dir));
+
+	fscrypt_prepare_dentry(dentry, is_nokey_name);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(fscrypt_prepare_lookup_partial);
+
 int __fscrypt_prepare_readdir(struct inode *dir)
 {
 	return fscrypt_get_encryption_info(dir, true);
@@ -139,7 +186,7 @@ EXPORT_SYMBOL_GPL(__fscrypt_prepare_setattr);
 int fscrypt_prepare_setflags(struct inode *inode,
 			     unsigned int oldflags, unsigned int flags)
 {
-	struct fscrypt_info *ci;
+	struct fscrypt_inode_info *ci;
 	struct fscrypt_master_key *mk;
 	int err;
 
@@ -152,13 +199,13 @@ int fscrypt_prepare_setflags(struct inode *inode,
 		err = fscrypt_require_key(inode);
 		if (err)
 			return err;
-		ci = inode->i_crypt_info;
+		ci = fscrypt_get_inode_info_raw(inode);
 		if (ci->ci_policy.version != FSCRYPT_POLICY_V2)
 			return -EINVAL;
 		mk = ci->ci_master_key;
 		down_read(&mk->mk_sem);
-		if (is_master_key_secret_present(&mk->mk_secret))
-			err = fscrypt_derive_dirhash_key(ci, mk);
+		if (mk->mk_present)
+			fscrypt_derive_dirhash_key(ci, mk);
 		else
 			err = -ENOKEY;
 		up_read(&mk->mk_sem);
@@ -225,10 +272,10 @@ int fscrypt_prepare_symlink(struct inode *dir, const char *target,
 	 * for now since filesystems will assume it is there and subtract it.
 	 */
 	if (!__fscrypt_fname_encrypted_size(policy, len,
-					    max_len - sizeof(struct fscrypt_symlink_data),
+					    max_len - sizeof(struct fscrypt_symlink_data) - 1,
 					    &disk_link->len))
 		return -ENAMETOOLONG;
-	disk_link->len += sizeof(struct fscrypt_symlink_data);
+	disk_link->len += sizeof(struct fscrypt_symlink_data) + 1;
 
 	disk_link->name = NULL;
 	return 0;
@@ -259,7 +306,7 @@ int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
 		if (!sd)
 			return -ENOMEM;
 	}
-	ciphertext_len = disk_link->len - sizeof(*sd);
+	ciphertext_len = disk_link->len - sizeof(*sd) - 1;
 	sd->len = cpu_to_le16(ciphertext_len);
 
 	err = fscrypt_fname_encrypt(inode, &iname, sd->encrypted_path,
@@ -315,7 +362,7 @@ const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
 	int err;
 
 	/* This is for encrypted symlinks only */
-	if (WARN_ON(!IS_ENCRYPTED(inode)))
+	if (WARN_ON_ONCE(!IS_ENCRYPTED(inode)))
 		return ERR_PTR(-EINVAL);
 
 	/* If the decrypted target is already cached, just return it. */
@@ -337,7 +384,7 @@ const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
 	 * the ciphertext length, even though this is redundant with i_size.
 	 */
 
-	if (max_size < sizeof(*sd))
+	if (max_size < sizeof(*sd) + 1)
 		return ERR_PTR(-EUCLEAN);
 	sd = caddr;
 	cstr.name = (unsigned char *)sd->encrypted_path;
@@ -346,7 +393,7 @@ const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
 	if (cstr.len == 0)
 		return ERR_PTR(-EUCLEAN);
 
-	if (cstr.len + sizeof(*sd) - 1 > max_size)
+	if (cstr.len + sizeof(*sd) > max_size)
 		return ERR_PTR(-EUCLEAN);
 
 	err = fscrypt_fname_alloc_buffer(cstr.len, &pstr);