fscrypt: updates on 4.15-rc4

Cherry-picked from origin/upstream-f2fs-stable-linux-4.4.y:

ba1ade7101 fscrypt: resolve some cherry-pick bugs
9e32f17d24 fscrypt: move to generic async completion
4ecacbed6e crypto: introduce crypto wait for async op
42d89da82b fscrypt: lock mutex before checking for bounce page pool
2286508d17 fscrypt: new helper function - fscrypt_prepare_setattr()
5cbdd42ad2 fscrypt: new helper function - fscrypt_prepare_lookup()
a31feba5c1 fscrypt: new helper function - fscrypt_prepare_rename()
95efafb623 fscrypt: new helper function - fscrypt_prepare_link()
2b4b4f98dd fscrypt: new helper function - fscrypt_file_open()
8c815f381c fscrypt: new helper function - fscrypt_require_key()
272e435025 fscrypt: remove unneeded empty fscrypt_operations structs
1034eeec51 fscrypt: remove ->is_encrypted()
32c0d3ae9d fscrypt: switch from ->is_encrypted() to IS_ENCRYPTED()
a4781dd1f1 fs, fscrypt: add an S_ENCRYPTED inode flag
ff0a3dbc93 fscrypt: clean up include file mess
bc4a61c60b fscrypt: fix dereference of NULL user_key_payload
a53dc7e005 fscrypt: make ->dummy_context() return bool

Change-Id: I461d742adc7b77177df91429a1fd9c8624a698d6
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>

crypto/api.c

@@ -24,6 +24,7 @@
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/completion.h>
 #include "internal.h"
 
 LIST_HEAD(crypto_alg_list);
@@ -611,5 +612,17 @@ int crypto_has_alg(const char *name, u32 type, u32 mask)
 }
 EXPORT_SYMBOL_GPL(crypto_has_alg);
 
+void crypto_req_done(struct crypto_async_request *req, int err)
+{
+	struct crypto_wait *wait = req->data;
+
+	if (err == -EINPROGRESS)
+		return;
+
+	wait->err = err;
+	complete(&wait->completion);
+}
+EXPORT_SYMBOL_GPL(crypto_req_done);
+
 MODULE_DESCRIPTION("Cryptographic core API");
 MODULE_LICENSE("GPL");

fs/crypto/Makefile

@@ -1,4 +1,4 @@
 obj-$(CONFIG_FS_ENCRYPTION)	+= fscrypto.o
 
-fscrypto-y := crypto.o fname.o policy.o keyinfo.o
+fscrypto-y := crypto.o fname.o hooks.o keyinfo.o policy.o
 fscrypto-$(CONFIG_BLOCK) += bio.o

fs/crypto/crypto.c

@@ -126,21 +126,6 @@ struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *inode, gfp_t gfp_flags)
 }
 EXPORT_SYMBOL(fscrypt_get_ctx);
 
-/**
- * page_crypt_complete() - completion callback for page crypto
- * @req: The asynchronous cipher request context
- * @res: The result of the cipher operation
- */
-static void page_crypt_complete(struct crypto_async_request *req, int res)
-{
-	struct fscrypt_completion_result *ecr = req->data;
-
-	if (res == -EINPROGRESS)
-		return;
-	ecr->res = res;
-	complete(&ecr->completion);
-}
-
 int fscrypt_do_page_crypto(const struct inode *inode, fscrypt_direction_t rw,
 			   u64 lblk_num, struct page *src_page,
 			   struct page *dest_page, unsigned int len,
@@ -151,7 +136,7 @@ int fscrypt_do_page_crypto(const struct inode *inode, fscrypt_direction_t rw,
 		u8 padding[FS_IV_SIZE - sizeof(__le64)];
 	} iv;
 	struct skcipher_request *req = NULL;
-	DECLARE_FS_COMPLETION_RESULT(ecr);
+	DECLARE_CRYPTO_WAIT(wait);
 	struct scatterlist dst, src;
 	struct fscrypt_info *ci = inode->i_crypt_info;
 	struct crypto_skcipher *tfm = ci->ci_ctfm;
@@ -179,7 +164,7 @@ int fscrypt_do_page_crypto(const struct inode *inode, fscrypt_direction_t rw,
 
 	skcipher_request_set_callback(
 		req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
-		page_crypt_complete, &ecr);
+		crypto_req_done, &wait);
 
 	sg_init_table(&dst, 1);
 	sg_set_page(&dst, dest_page, len, offs);
@@ -187,14 +172,9 @@ int fscrypt_do_page_crypto(const struct inode *inode, fscrypt_direction_t rw,
 	sg_set_page(&src, src_page, len, offs);
 	skcipher_request_set_crypt(req, &src, &dst, len, &iv);
 	if (rw == FS_DECRYPT)
-		res = crypto_skcipher_decrypt(req);
+		res = crypto_wait_req(crypto_skcipher_decrypt(req), &wait);
 	else
-		res = crypto_skcipher_encrypt(req);
-	if (res == -EINPROGRESS || res == -EBUSY) {
-		BUG_ON(req->base.data != &ecr);
-		wait_for_completion(&ecr.completion);
-		res = ecr.res;
-	}
+		res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
 	skcipher_request_free(req);
 	if (res) {
 		printk_ratelimited(KERN_ERR
@@ -340,7 +320,7 @@ static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
 		return -ECHILD;
 
 	dir = dget_parent(dentry);
-	if (!d_inode(dir)->i_sb->s_cop->is_encrypted(d_inode(dir))) {
+	if (!IS_ENCRYPTED(d_inode(dir))) {
 		dput(dir);
 		return 0;
 	}
@@ -410,11 +390,8 @@ int fscrypt_initialize(unsigned int cop_flags)
 {
 	int i, res = -ENOMEM;
 
-	/*
-	 * No need to allocate a bounce page pool if there already is one or
-	 * this FS won't use it.
-	 */
-	if (cop_flags & FS_CFLG_OWN_PAGES || fscrypt_bounce_page_pool)
+	/* No need to allocate a bounce page pool if this FS won't use it. */
+	if (cop_flags & FS_CFLG_OWN_PAGES)
 		return 0;
 
 	mutex_lock(&fscrypt_init_mutex);

fs/crypto/fname.c

@@ -14,21 +14,6 @@
 #include <linux/ratelimit.h>
 #include "fscrypt_private.h"
 
-/**
- * fname_crypt_complete() - completion callback for filename crypto
- * @req: The asynchronous cipher request context
- * @res: The result of the cipher operation
- */
-static void fname_crypt_complete(struct crypto_async_request *req, int res)
-{
-	struct fscrypt_completion_result *ecr = req->data;
-
-	if (res == -EINPROGRESS)
-		return;
-	ecr->res = res;
-	complete(&ecr->completion);
-}
-
 /**
  * fname_encrypt() - encrypt a filename
  *
@@ -40,7 +25,7 @@ static int fname_encrypt(struct inode *inode,
 			const struct qstr *iname, struct fscrypt_str *oname)
 {
 	struct skcipher_request *req = NULL;
-	DECLARE_FS_COMPLETION_RESULT(ecr);
+	DECLARE_CRYPTO_WAIT(wait);
 	struct fscrypt_info *ci = inode->i_crypt_info;
 	struct crypto_skcipher *tfm = ci->ci_ctfm;
 	int res = 0;
@@ -76,17 +61,12 @@ static int fname_encrypt(struct inode *inode,
 	}
 	skcipher_request_set_callback(req,
 			CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
-			fname_crypt_complete, &ecr);
+			crypto_req_done, &wait);
 	sg_init_one(&sg, oname->name, cryptlen);
 	skcipher_request_set_crypt(req, &sg, &sg, cryptlen, iv);
 
 	/* Do the encryption */
-	res = crypto_skcipher_encrypt(req);
-	if (res == -EINPROGRESS || res == -EBUSY) {
-		/* Request is being completed asynchronously; wait for it */
-		wait_for_completion(&ecr.completion);
-		res = ecr.res;
-	}
+	res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
 	skcipher_request_free(req);
 	if (res < 0) {
 		printk_ratelimited(KERN_ERR
@@ -110,7 +90,7 @@ static int fname_decrypt(struct inode *inode,
 				struct fscrypt_str *oname)
 {
 	struct skcipher_request *req = NULL;
-	DECLARE_FS_COMPLETION_RESULT(ecr);
+	DECLARE_CRYPTO_WAIT(wait);
 	struct scatterlist src_sg, dst_sg;
 	struct fscrypt_info *ci = inode->i_crypt_info;
 	struct crypto_skcipher *tfm = ci->ci_ctfm;
@@ -131,7 +111,7 @@ static int fname_decrypt(struct inode *inode,
 	}
 	skcipher_request_set_callback(req,
 		CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
-		fname_crypt_complete, &ecr);
+		crypto_req_done, &wait);
 
 	/* Initialize IV */
 	memset(iv, 0, FS_CRYPTO_BLOCK_SIZE);
@@ -140,11 +120,7 @@ static int fname_decrypt(struct inode *inode,
 	sg_init_one(&src_sg, iname->name, iname->len);
 	sg_init_one(&dst_sg, oname->name, oname->len);
 	skcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv);
-	res = crypto_skcipher_decrypt(req);
-	if (res == -EINPROGRESS || res == -EBUSY) {
-		wait_for_completion(&ecr.completion);
-		res = ecr.res;
-	}
+	res = crypto_wait_req(crypto_skcipher_decrypt(req), &wait);
 	skcipher_request_free(req);
 	if (res < 0) {
 		printk_ratelimited(KERN_ERR
@@ -382,8 +358,7 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
 	memset(fname, 0, sizeof(struct fscrypt_name));
 	fname->usr_fname = iname;
 
-	if (!dir->i_sb->s_cop->is_encrypted(dir) ||
-				fscrypt_is_dot_dotdot(iname)) {
+	if (!IS_ENCRYPTED(dir) || fscrypt_is_dot_dotdot(iname)) {
 		fname->disk_name.name = (unsigned char *)iname->name;
 		fname->disk_name.len = iname->len;
 		return 0;

fs/crypto/fscrypt_private.h

@@ -11,7 +11,8 @@
 #ifndef _FSCRYPT_PRIVATE_H
 #define _FSCRYPT_PRIVATE_H
 
-#include <linux/fscrypt_supp.h>
+#define __FS_HAS_ENCRYPTION 1
+#include <linux/fscrypt.h>
 #include <crypto/hash.h>
 
 /* Encryption parameters */
@@ -69,15 +70,6 @@ typedef enum {
 #define FS_CTX_REQUIRES_FREE_ENCRYPT_FL		0x00000001
 #define FS_CTX_HAS_BOUNCE_BUFFER_FL		0x00000002
 
-struct fscrypt_completion_result {
-	struct completion completion;
-	int res;
-};
-
-#define DECLARE_FS_COMPLETION_RESULT(ecr) \
-	struct fscrypt_completion_result ecr = { \
-		COMPLETION_INITIALIZER_ONSTACK((ecr).completion), 0 }
-
 /* bio stuffs */
 #define REQ_OP_READ	READ
 #define REQ_OP_WRITE	WRITE

fs/crypto/hooks.c

@@ -0,0 +1,112 @@
+/*
+ * fs/crypto/hooks.c
+ *
+ * Encryption hooks for higher-level filesystem operations.
+ */
+
+#include <linux/ratelimit.h>
+#include "fscrypt_private.h"
+
+/**
+ * fscrypt_file_open - prepare to open a possibly-encrypted regular file
+ * @inode: the inode being opened
+ * @filp: the struct file being set up
+ *
+ * Currently, an encrypted regular file can only be opened if its encryption key
+ * is available; access to the raw encrypted contents is not supported.
+ * Therefore, we first set up the inode's encryption key (if not already done)
+ * and return an error if it's unavailable.
+ *
+ * We also verify that if the parent directory (from the path via which the file
+ * is being opened) is encrypted, then the inode being opened uses the same
+ * encryption policy.  This is needed as part of the enforcement that all files
+ * in an encrypted directory tree use the same encryption policy, as a
+ * protection against certain types of offline attacks.  Note that this check is
+ * needed even when opening an *unencrypted* file, since it's forbidden to have
+ * an unencrypted file in an encrypted directory.
+ *
+ * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
+ */
+int fscrypt_file_open(struct inode *inode, struct file *filp)
+{
+	int err;
+	struct dentry *dir;
+
+	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)) {
+		pr_warn_ratelimited("fscrypt: inconsistent encryption contexts: %lu/%lu",
+				    d_inode(dir)->i_ino, inode->i_ino);
+		err = -EPERM;
+	}
+	dput(dir);
+	return err;
+}
+EXPORT_SYMBOL_GPL(fscrypt_file_open);
+
+int __fscrypt_prepare_link(struct inode *inode, struct inode *dir)
+{
+	int err;
+
+	err = fscrypt_require_key(dir);
+	if (err)
+		return err;
+
+	if (!fscrypt_has_permitted_context(dir, inode))
+		return -EPERM;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(__fscrypt_prepare_link);
+
+int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry,
+			     struct inode *new_dir, struct dentry *new_dentry,
+			     unsigned int flags)
+{
+	int err;
+
+	err = fscrypt_require_key(old_dir);
+	if (err)
+		return err;
+
+	err = fscrypt_require_key(new_dir);
+	if (err)
+		return err;
+
+	if (old_dir != new_dir) {
+		if (IS_ENCRYPTED(new_dir) &&
+		    !fscrypt_has_permitted_context(new_dir,
+						   d_inode(old_dentry)))
+			return -EPERM;
+
+		if ((flags & RENAME_EXCHANGE) &&
+		    IS_ENCRYPTED(old_dir) &&
+		    !fscrypt_has_permitted_context(old_dir,
+						   d_inode(new_dentry)))
+			return -EPERM;
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(__fscrypt_prepare_rename);
+
+int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry)
+{
+	int err = fscrypt_get_encryption_info(dir);
+
+	if (err)
+		return err;
+
+	if (fscrypt_has_encryption_key(dir)) {
+		spin_lock(&dentry->d_lock);
+		dentry->d_flags |= DCACHE_ENCRYPTED_WITH_KEY;
+		spin_unlock(&dentry->d_lock);
+	}
+
+	d_set_d_op(dentry, &fscrypt_d_ops);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup);

fs/crypto/keyinfo.c

@@ -17,17 +17,6 @@
 
 static struct crypto_shash *essiv_hash_tfm;
 
-static void derive_crypt_complete(struct crypto_async_request *req, int rc)
-{
-	struct fscrypt_completion_result *ecr = req->data;
-
-	if (rc == -EINPROGRESS)
-		return;
-
-	ecr->res = rc;
-	complete(&ecr->completion);
-}
-
 /**
  * derive_key_aes() - Derive a key using AES-128-ECB
  * @deriving_key: Encryption key used for derivation.
@@ -42,7 +31,7 @@ static int derive_key_aes(u8 deriving_key[FS_AES_128_ECB_KEY_SIZE],
 {
 	int res = 0;
 	struct skcipher_request *req = NULL;
-	DECLARE_FS_COMPLETION_RESULT(ecr);
+	DECLARE_CRYPTO_WAIT(wait);
 	struct scatterlist src_sg, dst_sg;
 	struct crypto_skcipher *tfm = crypto_alloc_skcipher("ecb(aes)", 0, 0);
 
@@ -59,7 +48,7 @@ static int derive_key_aes(u8 deriving_key[FS_AES_128_ECB_KEY_SIZE],
 	}
 	skcipher_request_set_callback(req,
 			CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
-			derive_crypt_complete, &ecr);
+			crypto_req_done, &wait);
 	res = crypto_skcipher_setkey(tfm, deriving_key,
 					FS_AES_128_ECB_KEY_SIZE);
 	if (res < 0)
@@ -69,11 +58,7 @@ static int derive_key_aes(u8 deriving_key[FS_AES_128_ECB_KEY_SIZE],
 	sg_init_one(&dst_sg, derived_raw_key, source_key->size);
 	skcipher_request_set_crypt(req, &src_sg, &dst_sg, source_key->size,
 				   NULL);
-	res = crypto_skcipher_encrypt(req);
-	if (res == -EINPROGRESS || res == -EBUSY) {
-		wait_for_completion(&ecr.completion);
-		res = ecr.res;
-	}
+	res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
 out:
 	skcipher_request_free(req);
 	crypto_free_skcipher(tfm);
@@ -109,6 +94,11 @@ static int validate_user_key(struct fscrypt_info *crypt_info,
 		goto out;
 	}
 	ukp = user_key_payload(keyring_key);
+	if (!ukp) {
+		/* key was revoked before we acquired its semaphore */
+		res = -EKEYREVOKED;
+		goto out;
+	}
 	if (ukp->datalen != sizeof(struct fscrypt_key)) {
 		res = -EINVAL;
 		goto out;
@@ -268,7 +258,7 @@ int fscrypt_get_encryption_info(struct inode *inode)
 	res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
 	if (res < 0) {
 		if (!fscrypt_dummy_context_enabled(inode) ||
-		    inode->i_sb->s_cop->is_encrypted(inode))
+		    IS_ENCRYPTED(inode))
 			return res;
 		/* Fake up a context for an unencrypted directory */
 		memset(&ctx, 0, sizeof(ctx));

fs/crypto/policy.c

@@ -109,7 +109,7 @@ int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg)
 	struct fscrypt_policy policy;
 	int res;
 
-	if (!inode->i_sb->s_cop->is_encrypted(inode))
+	if (!IS_ENCRYPTED(inode))
 		return -ENODATA;
 
 	res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
@@ -166,11 +166,11 @@ int fscrypt_has_permitted_context(struct inode *parent, struct inode *child)
 		return 1;
 
 	/* No restrictions if the parent directory is unencrypted */
-	if (!cops->is_encrypted(parent))
+	if (!IS_ENCRYPTED(parent))
 		return 1;
 
 	/* Encrypted directories must not contain unencrypted files */
-	if (!cops->is_encrypted(child))
+	if (!IS_ENCRYPTED(child))
 		return 0;
 
 	/*

fs/ext4/inode.c

@@ -4194,8 +4194,11 @@ void ext4_set_inode_flags(struct inode *inode)
 		new_fl |= S_DIRSYNC;
 	if (test_opt(inode->i_sb, DAX))
 		new_fl |= S_DAX;
+	if (flags & EXT4_ENCRYPT_FL)
+		new_fl |= S_ENCRYPTED;
 	inode_set_flags(inode, new_fl,
-			S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_DAX);
+			S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_DAX|
+			S_ENCRYPTED);
 }
 
 /* Propagate flags from i_flags to EXT4_I(inode)->i_flags */

fs/f2fs/f2fs.h

@@ -23,14 +23,12 @@
 #include <linux/bio.h>
 #include <linux/blkdev.h>
 #include <linux/quotaops.h>
-#ifdef CONFIG_F2FS_FS_ENCRYPTION
-#include <linux/fscrypt_supp.h>
-#else
-#include <linux/fscrypt_notsupp.h>
-#endif
 #include <crypto/hash.h>
 #include <linux/writeback.h>
 
+#define __FS_HAS_ENCRYPTION IS_ENABLED(CONFIG_F2FS_FS_ENCRYPTION)
+#include <linux/fscrypt.h>
+
 #ifdef CONFIG_F2FS_CHECK_FS
 #define f2fs_bug_on(sbi, condition)	BUG_ON(condition)
 #else
@@ -3152,6 +3150,7 @@ static inline void f2fs_set_encrypted_inode(struct inode *inode)
 {
 #ifdef CONFIG_F2FS_FS_ENCRYPTION
 	file_set_encrypt(inode);
+	inode->i_flags |= S_ENCRYPTED;
 #endif
 }
 

fs/f2fs/inode.c

@@ -43,8 +43,11 @@ void f2fs_set_inode_flags(struct inode *inode)
 		new_fl |= S_NOATIME;
 	if (flags & FS_DIRSYNC_FL)
 		new_fl |= S_DIRSYNC;
+	if (f2fs_encrypted_inode(inode))
+		new_fl |= S_ENCRYPTED;
 	inode_set_flags(inode, new_fl,
-			S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
+			S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|
+			S_ENCRYPTED);
 }
 
 static void __get_inode_rdev(struct inode *inode, struct f2fs_inode *ri)

fs/f2fs/super.c

@@ -1742,14 +1742,9 @@ static const struct fscrypt_operations f2fs_cryptops = {
 	.key_prefix	= "f2fs:",
 	.get_context	= f2fs_get_context,
 	.set_context	= f2fs_set_context,
-	.is_encrypted	= f2fs_encrypted_inode,
 	.empty_dir	= f2fs_empty_dir,
 	.max_namelen	= f2fs_max_namelen,
 };
-#else
-static const struct fscrypt_operations f2fs_cryptops = {
-	.is_encrypted	= f2fs_encrypted_inode,
-};
 #endif
 
 static struct inode *f2fs_nfs_get_inode(struct super_block *sb,
@@ -2478,7 +2473,9 @@ try_onemore:
 #endif
 
 	sb->s_op = &f2fs_sops;
+#ifdef CONFIG_F2FS_FS_ENCRYPTION
 	sb->s_cop = &f2fs_cryptops;
+#endif
 	sb->s_xattr = f2fs_xattr_handlers;
 	sb->s_export_op = &f2fs_export_ops;
 	sb->s_magic = F2FS_SUPER_MAGIC;

include/linux/crypto.h

@@ -24,6 +24,7 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/uaccess.h>
+#include <linux/completion.h>
 
 /*
  * Autoloaded crypto modules should only use a prefixed name to avoid allowing
@@ -469,6 +470,45 @@ struct crypto_alg {
 	struct module *cra_module;
 } CRYPTO_MINALIGN_ATTR;
 
+/*
+ * A helper struct for waiting for completion of async crypto ops
+ */
+struct crypto_wait {
+	struct completion completion;
+	int err;
+};
+
+/*
+ * Macro for declaring a crypto op async wait object on stack
+ */
+#define DECLARE_CRYPTO_WAIT(_wait) \
+	struct crypto_wait _wait = { \
+		COMPLETION_INITIALIZER_ONSTACK((_wait).completion), 0 }
+
+/*
+ * Async ops completion helper functioons
+ */
+void crypto_req_done(struct crypto_async_request *req, int err);
+
+static inline int crypto_wait_req(int err, struct crypto_wait *wait)
+{
+	switch (err) {
+	case -EINPROGRESS:
+	case -EBUSY:
+		wait_for_completion(&wait->completion);
+		reinit_completion(&wait->completion);
+		err = wait->err;
+		break;
+	};
+
+	return err;
+}
+
+static inline void crypto_init_wait(struct crypto_wait *wait)
+{
+	init_completion(&wait->completion);
+}
+
 /*
  * Algorithm registration interface.
  */

include/linux/fs.h

@@ -1798,6 +1798,7 @@ struct super_operations {
 #else
 #define S_DAX		0	/* Make all the DAX code disappear */
 #endif
+#define S_ENCRYPTED	16384	/* Encrypted file (using fs/crypto/) */
 
 /*
  * Note that nosuid etc flags are inode-specific: setting some file-system
@@ -1836,6 +1837,7 @@ struct super_operations {
 #define IS_AUTOMOUNT(inode)	((inode)->i_flags & S_AUTOMOUNT)
 #define IS_NOSEC(inode)		((inode)->i_flags & S_NOSEC)
 #define IS_DAX(inode)		((inode)->i_flags & S_DAX)
+#define IS_ENCRYPTED(inode)	((inode)->i_flags & S_ENCRYPTED)
 
 #define IS_WHITEOUT(inode)	(S_ISCHR(inode->i_mode) && \
 				 (inode)->i_rdev == WHITEOUT_DEV)

include/linux/fscrypt.h

@@ -0,0 +1,290 @@
+/*
+ * fscrypt.h: declarations for per-file encryption
+ *
+ * Filesystems that implement per-file encryption include this header
+ * file with the __FS_HAS_ENCRYPTION set according to whether that filesystem
+ * is being built with encryption support or not.
+ *
+ * Copyright (C) 2015, Google, Inc.
+ *
+ * Written by Michael Halcrow, 2015.
+ * Modified by Jaegeuk Kim, 2015.
+ */
+#ifndef _LINUX_FSCRYPT_H
+#define _LINUX_FSCRYPT_H
+
+#include <linux/key.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/bio.h>
+#include <linux/dcache.h>
+#include <crypto/skcipher.h>
+#include <uapi/linux/fs.h>
+
+#define FS_CRYPTO_BLOCK_SIZE		16
+
+struct fscrypt_info;
+
+struct fscrypt_ctx {
+	union {
+		struct {
+			struct page *bounce_page;	/* Ciphertext page */
+			struct page *control_page;	/* Original page  */
+		} w;
+		struct {
+			struct bio *bio;
+			struct work_struct work;
+		} r;
+		struct list_head free_list;	/* Free list */
+	};
+	u8 flags;				/* Flags */
+};
+
+/**
+ * For encrypted symlinks, the ciphertext length is stored at the beginning
+ * of the string in little-endian format.
+ */
+struct fscrypt_symlink_data {
+	__le16 len;
+	char encrypted_path[1];
+} __packed;
+
+struct fscrypt_str {
+	unsigned char *name;
+	u32 len;
+};
+
+struct fscrypt_name {
+	const struct qstr *usr_fname;
+	struct fscrypt_str disk_name;
+	u32 hash;
+	u32 minor_hash;
+	struct fscrypt_str crypto_buf;
+};
+
+#define FSTR_INIT(n, l)		{ .name = n, .len = l }
+#define FSTR_TO_QSTR(f)		QSTR_INIT((f)->name, (f)->len)
+#define fname_name(p)		((p)->disk_name.name)
+#define fname_len(p)		((p)->disk_name.len)
+
+/*
+ * fscrypt superblock flags
+ */
+#define FS_CFLG_OWN_PAGES (1U << 1)
+
+/*
+ * crypto opertions for filesystems
+ */
+struct fscrypt_operations {
+	unsigned int flags;
+	const char *key_prefix;
+	int (*get_context)(struct inode *, void *, size_t);
+	int (*set_context)(struct inode *, const void *, size_t, void *);
+	bool (*dummy_context)(struct inode *);
+	bool (*empty_dir)(struct inode *);
+	unsigned (*max_namelen)(struct inode *);
+};
+
+static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
+{
+	if (inode->i_sb->s_cop->dummy_context &&
+				inode->i_sb->s_cop->dummy_context(inode))
+		return true;
+	return false;
+}
+
+static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
+					u32 filenames_mode)
+{
+	if (contents_mode == FS_ENCRYPTION_MODE_AES_128_CBC &&
+	    filenames_mode == FS_ENCRYPTION_MODE_AES_128_CTS)
+		return true;
+
+	if (contents_mode == FS_ENCRYPTION_MODE_AES_256_XTS &&
+	    filenames_mode == FS_ENCRYPTION_MODE_AES_256_CTS)
+		return true;
+
+	return false;
+}
+
+static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
+{
+	if (str->len == 1 && str->name[0] == '.')
+		return true;
+
+	if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
+		return true;
+
+	return false;
+}
+
+#if __FS_HAS_ENCRYPTION
+
+static inline struct page *fscrypt_control_page(struct page *page)
+{
+	return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
+}
+
+static inline bool fscrypt_has_encryption_key(const struct inode *inode)
+{
+	return (inode->i_crypt_info != NULL);
+}
+
+#include <linux/fscrypt_supp.h>
+
+#else /* !__FS_HAS_ENCRYPTION */
+
+static inline struct page *fscrypt_control_page(struct page *page)
+{
+	WARN_ON_ONCE(1);
+	return ERR_PTR(-EINVAL);
+}
+
+static inline bool fscrypt_has_encryption_key(const struct inode *inode)
+{
+	return 0;
+}
+
+#include <linux/fscrypt_notsupp.h>
+#endif /* __FS_HAS_ENCRYPTION */
+
+/**
+ * fscrypt_require_key - require an inode's encryption key
+ * @inode: the inode we need the key for
+ *
+ * If the inode is encrypted, set up its encryption key if not already done.
+ * Then require that the key be present and return -ENOKEY otherwise.
+ *
+ * No locks are needed, and the key will live as long as the struct inode --- so
+ * it won't go away from under you.
+ *
+ * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
+ * if a problem occurred while setting up the encryption key.
+ */
+static inline int fscrypt_require_key(struct inode *inode)
+{
+	if (IS_ENCRYPTED(inode)) {
+		int err = fscrypt_get_encryption_info(inode);
+
+		if (err)
+			return err;
+		if (!fscrypt_has_encryption_key(inode))
+			return -ENOKEY;
+	}
+	return 0;
+}
+
+/**
+ * fscrypt_prepare_link - prepare to link an inode into a possibly-encrypted directory
+ * @old_dentry: an existing dentry for the inode being linked
+ * @dir: the target directory
+ * @dentry: negative dentry for the target filename
+ *
+ * A new link can only be added to an encrypted directory if the directory's
+ * encryption key is available --- since otherwise we'd have no way to encrypt
+ * the filename.  Therefore, we first set up the directory's encryption key (if
+ * not already done) and return an error if it's unavailable.
+ *
+ * We also verify that the link will not violate the constraint that all files
+ * in an encrypted directory tree use the same encryption policy.
+ *
+ * Return: 0 on success, -ENOKEY if the directory's encryption key is missing,
+ * -EPERM if the link would result in an inconsistent encryption policy, or
+ * another -errno code.
+ */
+static inline int fscrypt_prepare_link(struct dentry *old_dentry,
+				       struct inode *dir,
+				       struct dentry *dentry)
+{
+	if (IS_ENCRYPTED(dir))
+		return __fscrypt_prepare_link(d_inode(old_dentry), dir);
+	return 0;
+}
+
+/**
+ * fscrypt_prepare_rename - prepare for a rename between possibly-encrypted directories
+ * @old_dir: source directory
+ * @old_dentry: dentry for source file
+ * @new_dir: target directory
+ * @new_dentry: dentry for target location (may be negative unless exchanging)
+ * @flags: rename flags (we care at least about %RENAME_EXCHANGE)
+ *
+ * Prepare for ->rename() where the source and/or target directories may be
+ * encrypted.  A new link can only be added to an encrypted directory if the
+ * directory's encryption key is available --- since otherwise we'd have no way
+ * to encrypt the filename.  A rename to an existing name, on the other hand,
+ * *is* cryptographically possible without the key.  However, we take the more
+ * conservative approach and just forbid all no-key renames.
+ *
+ * We also verify that the rename will not violate the constraint that all files
+ * in an encrypted directory tree use the same encryption policy.
+ *
+ * Return: 0 on success, -ENOKEY if an encryption key is missing, -EPERM if the
+ * rename would cause inconsistent encryption policies, or another -errno code.
+ */
+static inline int fscrypt_prepare_rename(struct inode *old_dir,
+					 struct dentry *old_dentry,
+					 struct inode *new_dir,
+					 struct dentry *new_dentry,
+					 unsigned int flags)
+{
+	if (IS_ENCRYPTED(old_dir) || IS_ENCRYPTED(new_dir))
+		return __fscrypt_prepare_rename(old_dir, old_dentry,
+						new_dir, new_dentry, flags);
+	return 0;
+}
+
+/**
+ * fscrypt_prepare_lookup - prepare to lookup a name in a possibly-encrypted directory
+ * @dir: directory being searched
+ * @dentry: filename being looked up
+ * @flags: lookup flags
+ *
+ * Prepare for ->lookup() in a directory which may be encrypted.  Lookups can be
+ * done with or without the directory's encryption key; without the key,
+ * filenames are presented in encrypted form.  Therefore, we'll try to set up
+ * the directory's encryption key, but even without it the lookup can continue.
+ *
+ * To allow invalidating stale dentries if the directory's encryption key is
+ * added later, we also install a custom ->d_revalidate() method and use the
+ * DCACHE_ENCRYPTED_WITH_KEY flag to indicate whether a given dentry is a
+ * plaintext name (flag set) or a ciphertext name (flag cleared).
+ *
+ * Return: 0 on success, -errno if a problem occurred while setting up the
+ * encryption key
+ */
+static inline int fscrypt_prepare_lookup(struct inode *dir,
+					 struct dentry *dentry,
+					 unsigned int flags)
+{
+	if (IS_ENCRYPTED(dir))
+		return __fscrypt_prepare_lookup(dir, dentry);
+	return 0;
+}
+
+/**
+ * fscrypt_prepare_setattr - prepare to change a possibly-encrypted inode's attributes
+ * @dentry: dentry through which the inode is being changed
+ * @attr: attributes to change
+ *
+ * Prepare for ->setattr() on a possibly-encrypted inode.  On an encrypted file,
+ * most attribute changes are allowed even without the encryption key.  However,
+ * without the encryption key we do have to forbid truncates.  This is needed
+ * because the size being truncated to may not be a multiple of the filesystem
+ * block size, and in that case we'd have to decrypt the final block, zero the
+ * portion past i_size, and re-encrypt it.  (We *could* allow truncating to a
+ * filesystem block boundary, but it's simpler to just forbid all truncates ---
+ * and we already forbid all other contents modifications without the key.)
+ *
+ * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
+ * if a problem occurred while setting up the encryption key.
+ */
+static inline int fscrypt_prepare_setattr(struct dentry *dentry,
+					  struct iattr *attr)
+{
+	if (attr->ia_valid & ATTR_SIZE)
+		return fscrypt_require_key(d_inode(dentry));
+	return 0;
+}
+
+#endif	/* _LINUX_FSCRYPT_H */

include/linux/fscrypt_common.h

@@ -1,138 +0,0 @@
-/*
- * fscrypt_common.h: common declarations for per-file encryption
- *
- * Copyright (C) 2015, Google, Inc.
- *
- * Written by Michael Halcrow, 2015.
- * Modified by Jaegeuk Kim, 2015.
- */
-
-#ifndef _LINUX_FSCRYPT_COMMON_H
-#define _LINUX_FSCRYPT_COMMON_H
-
-#include <linux/key.h>
-#include <linux/fs.h>
-#include <linux/mm.h>
-#include <linux/bio.h>
-#include <linux/dcache.h>
-#include <crypto/skcipher.h>
-#include <uapi/linux/fs.h>
-
-#define FS_CRYPTO_BLOCK_SIZE		16
-
-struct fscrypt_info;
-
-struct fscrypt_ctx {
-	union {
-		struct {
-			struct page *bounce_page;	/* Ciphertext page */
-			struct page *control_page;	/* Original page  */
-		} w;
-		struct {
-			struct bio *bio;
-			struct work_struct work;
-		} r;
-		struct list_head free_list;	/* Free list */
-	};
-	u8 flags;				/* Flags */
-};
-
-/**
- * For encrypted symlinks, the ciphertext length is stored at the beginning
- * of the string in little-endian format.
- */
-struct fscrypt_symlink_data {
-	__le16 len;
-	char encrypted_path[1];
-} __packed;
-
-struct fscrypt_str {
-	unsigned char *name;
-	u32 len;
-};
-
-struct fscrypt_name {
-	const struct qstr *usr_fname;
-	struct fscrypt_str disk_name;
-	u32 hash;
-	u32 minor_hash;
-	struct fscrypt_str crypto_buf;
-};
-
-#define FSTR_INIT(n, l)		{ .name = n, .len = l }
-#define FSTR_TO_QSTR(f)		QSTR_INIT((f)->name, (f)->len)
-#define fname_name(p)		((p)->disk_name.name)
-#define fname_len(p)		((p)->disk_name.len)
-
-/*
- * fscrypt superblock flags
- */
-#define FS_CFLG_OWN_PAGES (1U << 1)
-
-/*
- * crypto opertions for filesystems
- */
-struct fscrypt_operations {
-	unsigned int flags;
-	const char *key_prefix;
-	int (*get_context)(struct inode *, void *, size_t);
-	int (*set_context)(struct inode *, const void *, size_t, void *);
-	int (*dummy_context)(struct inode *);
-	bool (*is_encrypted)(struct inode *);
-	bool (*empty_dir)(struct inode *);
-	unsigned (*max_namelen)(struct inode *);
-};
-
-static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
-{
-	if (inode->i_sb->s_cop->dummy_context &&
-				inode->i_sb->s_cop->dummy_context(inode))
-		return true;
-	return false;
-}
-
-static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
-					u32 filenames_mode)
-{
-	if (contents_mode == FS_ENCRYPTION_MODE_AES_128_CBC &&
-	    filenames_mode == FS_ENCRYPTION_MODE_AES_128_CTS)
-		return true;
-
-	if (contents_mode == FS_ENCRYPTION_MODE_AES_256_XTS &&
-	    filenames_mode == FS_ENCRYPTION_MODE_AES_256_CTS)
-		return true;
-
-	return false;
-}
-
-static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
-{
-	if (str->len == 1 && str->name[0] == '.')
-		return true;
-
-	if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
-		return true;
-
-	return false;
-}
-
-static inline struct page *fscrypt_control_page(struct page *page)
-{
-#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
-	return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
-#else
-	WARN_ON_ONCE(1);
-	return ERR_PTR(-EINVAL);
-#endif
-}
-
-static inline int fscrypt_has_encryption_key(const struct inode *inode)
-{
-#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
-	return (inode->i_crypt_info != NULL);
-#else
-	return 0;
-#endif
-}
-
-#endif	/* _LINUX_FSCRYPT_COMMON_H */

include/linux/fscrypt_notsupp.h

@@ -3,13 +3,16 @@
  *
  * This stubs out the fscrypt functions for filesystems configured without
  * encryption support.
+ *
+ * Do not include this file directly. Use fscrypt.h instead!
  */
+#ifndef _LINUX_FSCRYPT_H
+#error "Incorrect include of linux/fscrypt_notsupp.h!"
+#endif
 
 #ifndef _LINUX_FSCRYPT_NOTSUPP_H
 #define _LINUX_FSCRYPT_NOTSUPP_H
 
-#include <linux/fscrypt_common.h>
-
 /* crypto.c */
 static inline struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *inode,
 						  gfp_t gfp_flags)
@@ -97,7 +100,7 @@ static inline int fscrypt_setup_filename(struct inode *dir,
 					 const struct qstr *iname,
 					 int lookup, struct fscrypt_name *fname)
 {
-	if (dir->i_sb->s_cop->is_encrypted(dir))
+	if (IS_ENCRYPTED(dir))
 		return -EOPNOTSUPP;
 
 	memset(fname, 0, sizeof(struct fscrypt_name));
@@ -174,4 +177,34 @@ static inline int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 	return -EOPNOTSUPP;
 }
 
+/* hooks.c */
+
+static inline int fscrypt_file_open(struct inode *inode, struct file *filp)
+{
+	if (IS_ENCRYPTED(inode))
+		return -EOPNOTSUPP;
+	return 0;
+}
+
+static inline int __fscrypt_prepare_link(struct inode *inode,
+					 struct inode *dir)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __fscrypt_prepare_rename(struct inode *old_dir,
+					   struct dentry *old_dentry,
+					   struct inode *new_dir,
+					   struct dentry *new_dentry,
+					   unsigned int flags)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __fscrypt_prepare_lookup(struct inode *dir,
+					   struct dentry *dentry)
+{
+	return -EOPNOTSUPP;
+}
+
 #endif	/* _LINUX_FSCRYPT_NOTSUPP_H */

include/linux/fscrypt_supp.h

@@ -1,14 +1,15 @@
 /*
  * fscrypt_supp.h
  *
- * This is included by filesystems configured with encryption support.
+ * Do not include this file directly. Use fscrypt.h instead!
  */
+#ifndef _LINUX_FSCRYPT_H
+#error "Incorrect include of linux/fscrypt_supp.h!"
+#endif
 
 #ifndef _LINUX_FSCRYPT_SUPP_H
 #define _LINUX_FSCRYPT_SUPP_H
 
-#include <linux/fscrypt_common.h>
-
 /* crypto.c */
 extern struct kmem_cache *fscrypt_info_cachep;
 extern struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *, gfp_t);
@@ -142,4 +143,14 @@ extern void fscrypt_pullback_bio_page(struct page **, bool);
 extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t,
 				 unsigned int);
 
+/* hooks.c */
+extern int fscrypt_file_open(struct inode *inode, struct file *filp);
+extern int __fscrypt_prepare_link(struct inode *inode, struct inode *dir);
+extern int __fscrypt_prepare_rename(struct inode *old_dir,
+				    struct dentry *old_dentry,
+				    struct inode *new_dir,
+				    struct dentry *new_dentry,
+				    unsigned int flags);
+extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry);
+
 #endif	/* _LINUX_FSCRYPT_SUPP_H */