From e4de782a0960b9620c084881f12fb5e73ebff82b Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Fri, 5 Jan 2018 10:44:54 -0800
Subject: fscrypt: move fscrypt_info_cachep declaration to fscrypt_private.h

The fscrypt_info kmem_cache is internal to fscrypt; filesystems don't
need to access it.  So move its declaration into fscrypt_private.h.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/crypto/fscrypt_private.h | 1 +
 1 file changed, 1 insertion(+)

(limited to 'fs')

diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index c0b4f5597e1a..823c43a00bf7 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -72,6 +72,7 @@ typedef enum {
 #define FS_CTX_HAS_BOUNCE_BUFFER_FL		0x00000002
 
 /* crypto.c */
+extern struct kmem_cache *fscrypt_info_cachep;
 extern int fscrypt_initialize(unsigned int cop_flags);
 extern struct workqueue_struct *fscrypt_read_workqueue;
 extern int fscrypt_do_page_crypto(const struct inode *inode,
-- 
cgit v1.2.3


From bb8179e5a8509876415c0eac6f6ba8a130b3cb47 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Fri, 5 Jan 2018 10:44:58 -0800
Subject: fscrypt: move fscrypt_valid_enc_modes() to fscrypt_private.h

The encryption modes are validated by fs/crypto/, not by individual
filesystems.  Therefore, move fscrypt_valid_enc_modes() from fscrypt.h
to fscrypt_private.h.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/crypto/fscrypt_private.h | 14 ++++++++++++++
 include/linux/fscrypt.h     | 14 --------------
 2 files changed, 14 insertions(+), 14 deletions(-)

(limited to 'fs')

diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 823c43a00bf7..2b848e7c92f0 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -71,6 +71,20 @@ typedef enum {
 #define FS_CTX_REQUIRES_FREE_ENCRYPT_FL		0x00000001
 #define FS_CTX_HAS_BOUNCE_BUFFER_FL		0x00000002
 
+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;
+}
+
 /* crypto.c */
 extern struct kmem_cache *fscrypt_info_cachep;
 extern int fscrypt_initialize(unsigned int cop_flags);
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 33b95a91f720..2e4dce0365cf 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -57,20 +57,6 @@ struct fscrypt_name {
 /* Maximum value for the third parameter of fscrypt_operations.set_context(). */
 #define FSCRYPT_SET_CONTEXT_MAX_SIZE	28
 
-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] == '.')
-- 
cgit v1.2.3


From dcf0db9e5df369461c9d55282abbf66d263ef2db Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Fri, 5 Jan 2018 10:44:59 -0800
Subject: fscrypt: move fscrypt_is_dot_dotdot() to fs/crypto/fname.c

Only fs/crypto/fname.c cares about treating the "." and ".." filenames
specially with regards to encryption, so move fscrypt_is_dot_dotdot()
from fscrypt.h to there.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/crypto/fname.c       | 11 +++++++++++
 include/linux/fscrypt.h | 11 -----------
 2 files changed, 11 insertions(+), 11 deletions(-)

(limited to 'fs')

diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index 305541bcd108..b8c5061553b1 100644
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -15,6 +15,17 @@
 #include <linux/ratelimit.h>
 #include "fscrypt_private.h"
 
+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;
+}
+
 /**
  * fname_encrypt() - encrypt a filename
  *
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 2e4dce0365cf..3045fc49d3ca 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -57,17 +57,6 @@ struct fscrypt_name {
 /* Maximum value for the third parameter of fscrypt_operations.set_context(). */
 #define FSCRYPT_SET_CONTEXT_MAX_SIZE	28
 
-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
 #include <linux/fscrypt_supp.h>
 #else
-- 
cgit v1.2.3


From a575784c6c13b8f1bae05fbba873e326ec73e289 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Fri, 5 Jan 2018 10:45:00 -0800
Subject: fscrypt: trim down fscrypt.h includes

fscrypt.h included way too many other headers, given that it is included
by filesystems both with and without encryption support.  Trim down the
includes list by moving the needed includes into more appropriate
places, and removing the unneeded ones.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/crypto/crypto.c           | 1 +
 fs/crypto/fname.c            | 1 +
 fs/crypto/keyinfo.c          | 1 +
 include/linux/fscrypt.h      | 6 ------
 include/linux/fscrypt_supp.h | 3 +++
 5 files changed, 6 insertions(+), 6 deletions(-)

(limited to 'fs')

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 732a786cce9d..ce654526c0fb 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -27,6 +27,7 @@
 #include <linux/dcache.h>
 #include <linux/namei.h>
 #include <crypto/aes.h>
+#include <crypto/skcipher.h>
 #include "fscrypt_private.h"
 
 static unsigned int num_prealloc_crypto_pages = 32;
diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index b8c5061553b1..52d4dbe1e8e7 100644
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -13,6 +13,7 @@
 
 #include <linux/scatterlist.h>
 #include <linux/ratelimit.h>
+#include <crypto/skcipher.h>
 #include "fscrypt_private.h"
 
 static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c
index 5e6e846f5a24..c115eac4b4cf 100644
--- a/fs/crypto/keyinfo.c
+++ b/fs/crypto/keyinfo.c
@@ -14,6 +14,7 @@
 #include <linux/ratelimit.h>
 #include <crypto/aes.h>
 #include <crypto/sha.h>
+#include <crypto/skcipher.h>
 #include "fscrypt_private.h"
 
 static struct crypto_shash *essiv_hash_tfm;
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 3045fc49d3ca..071ebabfc287 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -14,13 +14,7 @@
 #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
 
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index ce61caf26f40..562a9bc04560 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -11,6 +11,9 @@
 #ifndef _LINUX_FSCRYPT_SUPP_H
 #define _LINUX_FSCRYPT_SUPP_H
 
+#include <linux/mm.h>
+#include <linux/slab.h>
+
 /*
  * fscrypt superblock flags
  */
-- 
cgit v1.2.3


From 76e81d6d50481144824237e6843122824b0a55c0 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Fri, 5 Jan 2018 10:45:01 -0800
Subject: fscrypt: new helper functions for ->symlink()

Currently, filesystems supporting fscrypt need to implement some tricky
logic when creating encrypted symlinks, including handling a peculiar
on-disk format (struct fscrypt_symlink_data) and correctly calculating
the size of the encrypted symlink.  Introduce helper functions to make
things a bit easier:

- fscrypt_prepare_symlink() computes and validates the size the symlink
  target will require on-disk.
- fscrypt_encrypt_symlink() creates the encrypted target if needed.

The new helpers actually fix some subtle bugs.  First, when checking
whether the symlink target was too long, filesystems didn't account for
the fact that the NUL padding is meant to be truncated if it would cause
the maximum length to be exceeded, as is done for filenames in
directories.  Consequently users would receive ENAMETOOLONG when
creating symlinks close to what is supposed to be the maximum length.
For example, with EXT4 with a 4K block size, the maximum symlink target
length in an encrypted directory is supposed to be 4093 bytes (in
comparison to 4095 in an unencrypted directory), but in
FS_POLICY_FLAGS_PAD_32-mode only up to 4064 bytes were accepted.

Second, symlink targets of "." and ".." were not being encrypted, even
though they should be, as these names are special in *directory entries*
but not in symlink targets.  Fortunately, we can fix this simply by
starting to encrypt them, as old kernels already accept them in
encrypted form.

Third, the output string length the filesystems were providing when
doing the actual encryption was incorrect, as it was forgotten to
exclude 'sizeof(struct fscrypt_symlink_data)'.  Fortunately though, this
bug didn't make a difference.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/crypto/fname.c               |  8 ++--
 fs/crypto/fscrypt_private.h     |  4 ++
 fs/crypto/hooks.c               | 90 +++++++++++++++++++++++++++++++++++++++++
 include/linux/fscrypt.h         | 64 +++++++++++++++++++++++++++++
 include/linux/fscrypt_notsupp.h | 16 ++++++++
 include/linux/fscrypt_supp.h    |  6 +++
 6 files changed, 185 insertions(+), 3 deletions(-)

(limited to 'fs')

diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index 52d4dbe1e8e7..62f13d533439 100644
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -34,8 +34,8 @@ static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
  *
  * Return: 0 on success, -errno on failure
  */
-static int fname_encrypt(struct inode *inode,
-			const struct qstr *iname, struct fscrypt_str *oname)
+int fname_encrypt(struct inode *inode,
+		  const struct qstr *iname, struct fscrypt_str *oname)
 {
 	struct skcipher_request *req = NULL;
 	DECLARE_CRYPTO_WAIT(wait);
@@ -56,9 +56,11 @@ static int fname_encrypt(struct inode *inode,
 	 * Copy the filename to the output buffer for encrypting in-place and
 	 * pad it with the needed number of NUL bytes.
 	 */
+	if (WARN_ON(oname->len < iname->len))
+		return -ENOBUFS;
 	cryptlen = max_t(unsigned int, iname->len, FS_CRYPTO_BLOCK_SIZE);
 	cryptlen = round_up(cryptlen, padding);
-	cryptlen = min(cryptlen, lim);
+	cryptlen = min3(cryptlen, lim, oname->len);
 	memcpy(oname->name, iname->name, iname->len);
 	memset(oname->name + iname->len, 0, cryptlen - iname->len);
 
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 2b848e7c92f0..6995bca5006b 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -98,6 +98,10 @@ extern int fscrypt_do_page_crypto(const struct inode *inode,
 extern struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
 					      gfp_t gfp_flags);
 
+/* fname.c */
+extern int fname_encrypt(struct inode *inode,
+			 const struct qstr *iname, struct fscrypt_str *oname);
+
 /* keyinfo.c */
 extern void __exit fscrypt_essiv_cleanup(void);
 
diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c
index 9f5fb2eb9cf7..4b83e4af2e41 100644
--- a/fs/crypto/hooks.c
+++ b/fs/crypto/hooks.c
@@ -110,3 +110,93 @@ int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup);
+
+int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
+			      unsigned int max_len,
+			      struct fscrypt_str *disk_link)
+{
+	int err;
+
+	/*
+	 * To calculate the size of the encrypted symlink target we need to know
+	 * the amount of NUL padding, which is determined by the flags set in
+	 * the encryption policy which will be inherited from the directory.
+	 * The easiest way to get access to this is to just load the directory's
+	 * fscrypt_info, since we'll need it to create the dir_entry anyway.
+	 *
+	 * Note: in test_dummy_encryption mode, @dir may be unencrypted.
+	 */
+	err = fscrypt_get_encryption_info(dir);
+	if (err)
+		return err;
+	if (!fscrypt_has_encryption_key(dir))
+		return -ENOKEY;
+
+	/*
+	 * Calculate the size of the encrypted symlink and verify it won't
+	 * exceed max_len.  Note that for historical reasons, encrypted symlink
+	 * targets are prefixed with the ciphertext length, despite this
+	 * actually being redundant with i_size.  This decreases by 2 bytes the
+	 * longest symlink target we can accept.
+	 *
+	 * We could recover 1 byte by not counting a null terminator, but
+	 * counting it (even though it is meaningless for ciphertext) is simpler
+	 * for now since filesystems will assume it is there and subtract it.
+	 */
+	if (sizeof(struct fscrypt_symlink_data) + len > max_len)
+		return -ENAMETOOLONG;
+	disk_link->len = min_t(unsigned int,
+			       sizeof(struct fscrypt_symlink_data) +
+					fscrypt_fname_encrypted_size(dir, len),
+			       max_len);
+	disk_link->name = NULL;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(__fscrypt_prepare_symlink);
+
+int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
+			      unsigned int len, struct fscrypt_str *disk_link)
+{
+	int err;
+	struct qstr iname = { .name = target, .len = len };
+	struct fscrypt_symlink_data *sd;
+	unsigned int ciphertext_len;
+	struct fscrypt_str oname;
+
+	err = fscrypt_require_key(inode);
+	if (err)
+		return err;
+
+	if (disk_link->name) {
+		/* filesystem-provided buffer */
+		sd = (struct fscrypt_symlink_data *)disk_link->name;
+	} else {
+		sd = kmalloc(disk_link->len, GFP_NOFS);
+		if (!sd)
+			return -ENOMEM;
+	}
+	ciphertext_len = disk_link->len - sizeof(*sd);
+	sd->len = cpu_to_le16(ciphertext_len);
+
+	oname.name = sd->encrypted_path;
+	oname.len = ciphertext_len;
+	err = fname_encrypt(inode, &iname, &oname);
+	if (err) {
+		if (!disk_link->name)
+			kfree(sd);
+		return err;
+	}
+	BUG_ON(oname.len != ciphertext_len);
+
+	/*
+	 * Null-terminating the ciphertext doesn't make sense, but we still
+	 * count the null terminator in the length, so we might as well
+	 * initialize it just in case the filesystem writes it out.
+	 */
+	sd->encrypted_path[ciphertext_len] = '\0';
+
+	if (!disk_link->name)
+		disk_link->name = (unsigned char *)sd;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(__fscrypt_encrypt_symlink);
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 071ebabfc287..6a678d0e956a 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -196,4 +196,68 @@ static inline int fscrypt_prepare_setattr(struct dentry *dentry,
 	return 0;
 }
 
+/**
+ * fscrypt_prepare_symlink - prepare to create a possibly-encrypted symlink
+ * @dir: directory in which the symlink is being created
+ * @target: plaintext symlink target
+ * @len: length of @target excluding null terminator
+ * @max_len: space the filesystem has available to store the symlink target
+ * @disk_link: (out) the on-disk symlink target being prepared
+ *
+ * This function computes the size the symlink target will require on-disk,
+ * stores it in @disk_link->len, and validates it against @max_len.  An
+ * encrypted symlink may be longer than the original.
+ *
+ * Additionally, @disk_link->name is set to @target if the symlink will be
+ * unencrypted, but left NULL if the symlink will be encrypted.  For encrypted
+ * symlinks, the filesystem must call fscrypt_encrypt_symlink() to create the
+ * on-disk target later.  (The reason for the two-step process is that some
+ * filesystems need to know the size of the symlink target before creating the
+ * inode, e.g. to determine whether it will be a "fast" or "slow" symlink.)
+ *
+ * Return: 0 on success, -ENAMETOOLONG if the symlink target is too long,
+ * -ENOKEY if the encryption key is missing, or another -errno code if a problem
+ * occurred while setting up the encryption key.
+ */
+static inline int fscrypt_prepare_symlink(struct inode *dir,
+					  const char *target,
+					  unsigned int len,
+					  unsigned int max_len,
+					  struct fscrypt_str *disk_link)
+{
+	if (IS_ENCRYPTED(dir) || fscrypt_dummy_context_enabled(dir))
+		return __fscrypt_prepare_symlink(dir, len, max_len, disk_link);
+
+	disk_link->name = (unsigned char *)target;
+	disk_link->len = len + 1;
+	if (disk_link->len > max_len)
+		return -ENAMETOOLONG;
+	return 0;
+}
+
+/**
+ * fscrypt_encrypt_symlink - encrypt the symlink target if needed
+ * @inode: symlink inode
+ * @target: plaintext symlink target
+ * @len: length of @target excluding null terminator
+ * @disk_link: (in/out) the on-disk symlink target being prepared
+ *
+ * If the symlink target needs to be encrypted, then this function encrypts it
+ * into @disk_link->name.  fscrypt_prepare_symlink() must have been called
+ * previously to compute @disk_link->len.  If the filesystem did not allocate a
+ * buffer for @disk_link->name after calling fscrypt_prepare_link(), then one
+ * will be kmalloc()'ed and the filesystem will be responsible for freeing it.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static inline int fscrypt_encrypt_symlink(struct inode *inode,
+					  const char *target,
+					  unsigned int len,
+					  struct fscrypt_str *disk_link)
+{
+	if (IS_ENCRYPTED(inode))
+		return __fscrypt_encrypt_symlink(inode, target, len, disk_link);
+	return 0;
+}
+
 #endif	/* _LINUX_FSCRYPT_H */
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index 81e02201b215..02ec0aa894d8 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -223,4 +223,20 @@ static inline int __fscrypt_prepare_lookup(struct inode *dir,
 	return -EOPNOTSUPP;
 }
 
+static inline int __fscrypt_prepare_symlink(struct inode *dir,
+					    unsigned int len,
+					    unsigned int max_len,
+					    struct fscrypt_str *disk_link)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __fscrypt_encrypt_symlink(struct inode *inode,
+					    const char *target,
+					    unsigned int len,
+					    struct fscrypt_str *disk_link)
+{
+	return -EOPNOTSUPP;
+}
+
 #endif	/* _LINUX_FSCRYPT_NOTSUPP_H */
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index 562a9bc04560..7e0b67ccd816 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -205,5 +205,11 @@ extern int __fscrypt_prepare_rename(struct inode *old_dir,
 				    struct dentry *new_dentry,
 				    unsigned int flags);
 extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry);
+extern int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
+				     unsigned int max_len,
+				     struct fscrypt_str *disk_link);
+extern int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
+				     unsigned int len,
+				     struct fscrypt_str *disk_link);
 
 #endif	/* _LINUX_FSCRYPT_SUPP_H */
-- 
cgit v1.2.3


From 3b0d8837a79ba7b7cc324d1f2b206c074e9c6182 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Fri, 5 Jan 2018 10:45:02 -0800
Subject: fscrypt: new helper function - fscrypt_get_symlink()

Filesystems also have duplicate code to support ->get_link() on
encrypted symlinks.  Factor it out into a new function
fscrypt_get_symlink().  It takes in the contents of the encrypted
symlink on-disk and provides the target (decrypted or encoded) that
should be returned from ->get_link().

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/crypto/hooks.c               | 73 +++++++++++++++++++++++++++++++++++++++++
 include/linux/fscrypt_notsupp.h |  8 +++++
 include/linux/fscrypt_supp.h    |  3 ++
 3 files changed, 84 insertions(+)

(limited to 'fs')

diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c
index 4b83e4af2e41..8900e348ba6e 100644
--- a/fs/crypto/hooks.c
+++ b/fs/crypto/hooks.c
@@ -200,3 +200,76 @@ int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
 	return 0;
 }
 EXPORT_SYMBOL_GPL(__fscrypt_encrypt_symlink);
+
+/**
+ * fscrypt_get_symlink - get the target of an encrypted symlink
+ * @inode: the symlink inode
+ * @caddr: the on-disk contents of the symlink
+ * @max_size: size of @caddr buffer
+ * @done: if successful, will be set up to free the returned target
+ *
+ * If the symlink's encryption key is available, we decrypt its target.
+ * Otherwise, we encode its target for presentation.
+ *
+ * This may sleep, so the filesystem must have dropped out of RCU mode already.
+ *
+ * Return: the presentable symlink target or an ERR_PTR()
+ */
+const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
+				unsigned int max_size,
+				struct delayed_call *done)
+{
+	const struct fscrypt_symlink_data *sd;
+	struct fscrypt_str cstr, pstr;
+	int err;
+
+	/* This is for encrypted symlinks only */
+	if (WARN_ON(!IS_ENCRYPTED(inode)))
+		return ERR_PTR(-EINVAL);
+
+	/*
+	 * Try to set up the symlink's encryption key, but we can continue
+	 * regardless of whether the key is available or not.
+	 */
+	err = fscrypt_get_encryption_info(inode);
+	if (err)
+		return ERR_PTR(err);
+
+	/*
+	 * For historical reasons, encrypted symlink targets are prefixed with
+	 * the ciphertext length, even though this is redundant with i_size.
+	 */
+
+	if (max_size < sizeof(*sd))
+		return ERR_PTR(-EUCLEAN);
+	sd = caddr;
+	cstr.name = (unsigned char *)sd->encrypted_path;
+	cstr.len = le16_to_cpu(sd->len);
+
+	if (cstr.len == 0)
+		return ERR_PTR(-EUCLEAN);
+
+	if (cstr.len + sizeof(*sd) - 1 > max_size)
+		return ERR_PTR(-EUCLEAN);
+
+	err = fscrypt_fname_alloc_buffer(inode, cstr.len, &pstr);
+	if (err)
+		return ERR_PTR(err);
+
+	err = fscrypt_fname_disk_to_usr(inode, 0, 0, &cstr, &pstr);
+	if (err)
+		goto err_kfree;
+
+	err = -EUCLEAN;
+	if (pstr.name[0] == '\0')
+		goto err_kfree;
+
+	pstr.name[pstr.len] = '\0';
+	set_delayed_call(done, kfree_link, pstr.name);
+	return pstr.name;
+
+err_kfree:
+	kfree(pstr.name);
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(fscrypt_get_symlink);
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index 02ec0aa894d8..dd106640c6ea 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -239,4 +239,12 @@ static inline int __fscrypt_encrypt_symlink(struct inode *inode,
 	return -EOPNOTSUPP;
 }
 
+static inline const char *fscrypt_get_symlink(struct inode *inode,
+					      const void *caddr,
+					      unsigned int max_size,
+					      struct delayed_call *done)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
 #endif	/* _LINUX_FSCRYPT_NOTSUPP_H */
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index 7e0b67ccd816..dc2babf3f7d3 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -211,5 +211,8 @@ extern int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
 extern int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
 				     unsigned int len,
 				     struct fscrypt_str *disk_link);
+extern const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
+				       unsigned int max_size,
+				       struct delayed_call *done);
 
 #endif	/* _LINUX_FSCRYPT_SUPP_H */
-- 
cgit v1.2.3


From 78e1060c9474da8760ac91fa2deea70bd41d2821 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 11 Jan 2018 22:10:40 -0500
Subject: ext4: switch to fscrypt ->symlink() helper functions

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/ext4/namei.c | 58 +++++++++++++++------------------------------------------
 1 file changed, 15 insertions(+), 43 deletions(-)

(limited to 'fs')

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index e750d68fbcb5..727675794a45 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3056,39 +3056,19 @@ static int ext4_symlink(struct inode *dir,
 	struct inode *inode;
 	int err, len = strlen(symname);
 	int credits;
-	bool encryption_required;
 	struct fscrypt_str disk_link;
-	struct fscrypt_symlink_data *sd = NULL;
 
 	if (unlikely(ext4_forced_shutdown(EXT4_SB(dir->i_sb))))
 		return -EIO;
 
-	disk_link.len = len + 1;
-	disk_link.name = (char *) symname;
-
-	encryption_required = (ext4_encrypted_inode(dir) ||
-			       DUMMY_ENCRYPTION_ENABLED(EXT4_SB(dir->i_sb)));
-	if (encryption_required) {
-		err = fscrypt_get_encryption_info(dir);
-		if (err)
-			return err;
-		if (!fscrypt_has_encryption_key(dir))
-			return -ENOKEY;
-		disk_link.len = (fscrypt_fname_encrypted_size(dir, len) +
-				 sizeof(struct fscrypt_symlink_data));
-		sd = kzalloc(disk_link.len, GFP_KERNEL);
-		if (!sd)
-			return -ENOMEM;
-	}
-
-	if (disk_link.len > dir->i_sb->s_blocksize) {
-		err = -ENAMETOOLONG;
-		goto err_free_sd;
-	}
+	err = fscrypt_prepare_symlink(dir, symname, len, dir->i_sb->s_blocksize,
+				      &disk_link);
+	if (err)
+		return err;
 
 	err = dquot_initialize(dir);
 	if (err)
-		goto err_free_sd;
+		return err;
 
 	if ((disk_link.len > EXT4_N_BLOCKS * 4)) {
 		/*
@@ -3117,27 +3097,18 @@ static int ext4_symlink(struct inode *dir,
 	if (IS_ERR(inode)) {
 		if (handle)
 			ext4_journal_stop(handle);
-		err = PTR_ERR(inode);
-		goto err_free_sd;
+		return PTR_ERR(inode);
 	}
 
-	if (encryption_required) {
-		struct qstr istr;
-		struct fscrypt_str ostr =
-			FSTR_INIT(sd->encrypted_path, disk_link.len);
-
-		istr.name = (const unsigned char *) symname;
-		istr.len = len;
-		err = fscrypt_fname_usr_to_disk(inode, &istr, &ostr);
+	if (IS_ENCRYPTED(inode)) {
+		err = fscrypt_encrypt_symlink(inode, symname, len, &disk_link);
 		if (err)
 			goto err_drop_inode;
-		sd->len = cpu_to_le16(ostr.len);
-		disk_link.name = (char *) sd;
 		inode->i_op = &ext4_encrypted_symlink_inode_operations;
 	}
 
 	if ((disk_link.len > EXT4_N_BLOCKS * 4)) {
-		if (!encryption_required)
+		if (!IS_ENCRYPTED(inode))
 			inode->i_op = &ext4_symlink_inode_operations;
 		inode_nohighmem(inode);
 		ext4_set_aops(inode);
@@ -3179,7 +3150,7 @@ static int ext4_symlink(struct inode *dir,
 	} else {
 		/* clear the extent format for fast symlink */
 		ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS);
-		if (!encryption_required) {
+		if (!IS_ENCRYPTED(inode)) {
 			inode->i_op = &ext4_fast_symlink_inode_operations;
 			inode->i_link = (char *)&EXT4_I(inode)->i_data;
 		}
@@ -3194,16 +3165,17 @@ static int ext4_symlink(struct inode *dir,
 
 	if (handle)
 		ext4_journal_stop(handle);
-	kfree(sd);
-	return err;
+	goto out_free_encrypted_link;
+
 err_drop_inode:
 	if (handle)
 		ext4_journal_stop(handle);
 	clear_nlink(inode);
 	unlock_new_inode(inode);
 	iput(inode);
-err_free_sd:
-	kfree(sd);
+out_free_encrypted_link:
+	if (disk_link.name != (unsigned char *)symname)
+		kfree(disk_link.name);
 	return err;
 }
 
-- 
cgit v1.2.3


From 6a9269c83851993ee679c17b7254a9f675581134 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 11 Jan 2018 22:10:40 -0500
Subject: ext4: switch to fscrypt_get_symlink()

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/ext4/symlink.c | 43 ++++++-------------------------------------
 1 file changed, 6 insertions(+), 37 deletions(-)

(limited to 'fs')

diff --git a/fs/ext4/symlink.c b/fs/ext4/symlink.c
index a2006c9af1d9..dd05af983092 100644
--- a/fs/ext4/symlink.c
+++ b/fs/ext4/symlink.c
@@ -28,59 +28,28 @@ static const char *ext4_encrypted_get_link(struct dentry *dentry,
 					   struct delayed_call *done)
 {
 	struct page *cpage = NULL;
-	char *caddr, *paddr = NULL;
-	struct fscrypt_str cstr, pstr;
-	struct fscrypt_symlink_data *sd;
-	int res;
-	u32 max_size = inode->i_sb->s_blocksize;
+	const void *caddr;
+	unsigned int max_size;
+	const char *paddr;
 
 	if (!dentry)
 		return ERR_PTR(-ECHILD);
 
-	res = fscrypt_get_encryption_info(inode);
-	if (res)
-		return ERR_PTR(res);
-
 	if (ext4_inode_is_fast_symlink(inode)) {
-		caddr = (char *) EXT4_I(inode)->i_data;
+		caddr = EXT4_I(inode)->i_data;
 		max_size = sizeof(EXT4_I(inode)->i_data);
 	} else {
 		cpage = read_mapping_page(inode->i_mapping, 0, NULL);
 		if (IS_ERR(cpage))
 			return ERR_CAST(cpage);
 		caddr = page_address(cpage);
+		max_size = inode->i_sb->s_blocksize;
 	}
 
-	/* Symlink is encrypted */
-	sd = (struct fscrypt_symlink_data *)caddr;
-	cstr.name = sd->encrypted_path;
-	cstr.len  = le16_to_cpu(sd->len);
-	if ((cstr.len + sizeof(struct fscrypt_symlink_data) - 1) > max_size) {
-		/* Symlink data on the disk is corrupted */
-		res = -EFSCORRUPTED;
-		goto errout;
-	}
-
-	res = fscrypt_fname_alloc_buffer(inode, cstr.len, &pstr);
-	if (res)
-		goto errout;
-	paddr = pstr.name;
-
-	res = fscrypt_fname_disk_to_usr(inode, 0, 0, &cstr, &pstr);
-	if (res)
-		goto errout;
-
-	/* Null-terminate the name */
-	paddr[pstr.len] = '\0';
+	paddr = fscrypt_get_symlink(inode, caddr, max_size, done);
 	if (cpage)
 		put_page(cpage);
-	set_delayed_call(done, kfree_link, paddr);
 	return paddr;
-errout:
-	if (cpage)
-		put_page(cpage);
-	kfree(paddr);
-	return ERR_PTR(res);
 }
 
 const struct inode_operations ext4_encrypted_symlink_inode_operations = {
-- 
cgit v1.2.3


From 393c038f5c55efc61aa1412954548a9947a45cd4 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 11 Jan 2018 23:26:49 -0500
Subject: f2fs: switch to fscrypt ->symlink() helper functions

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/f2fs/namei.c | 66 ++++++++++++++-------------------------------------------
 1 file changed, 16 insertions(+), 50 deletions(-)

(limited to 'fs')

diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index 28bdf8828e73..5b114844806c 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -496,27 +496,16 @@ static int f2fs_symlink(struct inode *dir, struct dentry *dentry,
 	struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
 	struct inode *inode;
 	size_t len = strlen(symname);
-	struct fscrypt_str disk_link = FSTR_INIT((char *)symname, len + 1);
-	struct fscrypt_symlink_data *sd = NULL;
+	struct fscrypt_str disk_link;
 	int err;
 
 	if (unlikely(f2fs_cp_error(sbi)))
 		return -EIO;
 
-	if (f2fs_encrypted_inode(dir)) {
-		err = fscrypt_get_encryption_info(dir);
-		if (err)
-			return err;
-
-		if (!fscrypt_has_encryption_key(dir))
-			return -ENOKEY;
-
-		disk_link.len = (fscrypt_fname_encrypted_size(dir, len) +
-				sizeof(struct fscrypt_symlink_data));
-	}
-
-	if (disk_link.len > dir->i_sb->s_blocksize)
-		return -ENAMETOOLONG;
+	err = fscrypt_prepare_symlink(dir, symname, len, dir->i_sb->s_blocksize,
+				      &disk_link);
+	if (err)
+		return err;
 
 	err = dquot_initialize(dir);
 	if (err)
@@ -526,7 +515,7 @@ static int f2fs_symlink(struct inode *dir, struct dentry *dentry,
 	if (IS_ERR(inode))
 		return PTR_ERR(inode);
 
-	if (f2fs_encrypted_inode(inode))
+	if (IS_ENCRYPTED(inode))
 		inode->i_op = &f2fs_encrypted_symlink_inode_operations;
 	else
 		inode->i_op = &f2fs_symlink_inode_operations;
@@ -536,38 +525,13 @@ static int f2fs_symlink(struct inode *dir, struct dentry *dentry,
 	f2fs_lock_op(sbi);
 	err = f2fs_add_link(dentry, inode);
 	if (err)
-		goto out;
+		goto out_handle_failed_inode;
 	f2fs_unlock_op(sbi);
 	alloc_nid_done(sbi, inode->i_ino);
 
-	if (f2fs_encrypted_inode(inode)) {
-		struct qstr istr = QSTR_INIT(symname, len);
-		struct fscrypt_str ostr;
-
-		sd = kzalloc(disk_link.len, GFP_NOFS);
-		if (!sd) {
-			err = -ENOMEM;
-			goto err_out;
-		}
-
-		err = fscrypt_get_encryption_info(inode);
-		if (err)
-			goto err_out;
-
-		if (!fscrypt_has_encryption_key(inode)) {
-			err = -ENOKEY;
-			goto err_out;
-		}
-
-		ostr.name = sd->encrypted_path;
-		ostr.len = disk_link.len;
-		err = fscrypt_fname_usr_to_disk(inode, &istr, &ostr);
-		if (err)
-			goto err_out;
-
-		sd->len = cpu_to_le16(ostr.len);
-		disk_link.name = (char *)sd;
-	}
+	err = fscrypt_encrypt_symlink(inode, symname, len, &disk_link);
+	if (err)
+		goto err_out;
 
 	err = page_symlink(inode, disk_link.name, disk_link.len);
 
@@ -594,12 +558,14 @@ err_out:
 		f2fs_unlink(dir, dentry);
 	}
 
-	kfree(sd);
-
 	f2fs_balance_fs(sbi, true);
-	return err;
-out:
+	goto out_free_encrypted_link;
+
+out_handle_failed_inode:
 	handle_failed_inode(inode);
+out_free_encrypted_link:
+	if (disk_link.name != (unsigned char *)symname)
+		kfree(disk_link.name);
 	return err;
 }
 
-- 
cgit v1.2.3


From f2329cb687d63b73072281aba5646154237b05d2 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 11 Jan 2018 23:26:49 -0500
Subject: f2fs: switch to fscrypt_get_symlink()

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/f2fs/namei.c | 66 ++++++++-------------------------------------------------
 1 file changed, 9 insertions(+), 57 deletions(-)

(limited to 'fs')

diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index 5b114844806c..37816d2ebb93 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -1137,68 +1137,20 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry,
 					   struct inode *inode,
 					   struct delayed_call *done)
 {
-	struct page *cpage = NULL;
-	char *caddr, *paddr = NULL;
-	struct fscrypt_str cstr = FSTR_INIT(NULL, 0);
-	struct fscrypt_str pstr = FSTR_INIT(NULL, 0);
-	struct fscrypt_symlink_data *sd;
-	u32 max_size = inode->i_sb->s_blocksize;
-	int res;
+	struct page *page;
+	const char *target;
 
 	if (!dentry)
 		return ERR_PTR(-ECHILD);
 
-	res = fscrypt_get_encryption_info(inode);
-	if (res)
-		return ERR_PTR(res);
-
-	cpage = read_mapping_page(inode->i_mapping, 0, NULL);
-	if (IS_ERR(cpage))
-		return ERR_CAST(cpage);
-	caddr = page_address(cpage);
-
-	/* Symlink is encrypted */
-	sd = (struct fscrypt_symlink_data *)caddr;
-	cstr.name = sd->encrypted_path;
-	cstr.len = le16_to_cpu(sd->len);
-
-	/* this is broken symlink case */
-	if (unlikely(cstr.len == 0)) {
-		res = -ENOENT;
-		goto errout;
-	}
-
-	if ((cstr.len + sizeof(struct fscrypt_symlink_data) - 1) > max_size) {
-		/* Symlink data on the disk is corrupted */
-		res = -EIO;
-		goto errout;
-	}
-	res = fscrypt_fname_alloc_buffer(inode, cstr.len, &pstr);
-	if (res)
-		goto errout;
-
-	res = fscrypt_fname_disk_to_usr(inode, 0, 0, &cstr, &pstr);
-	if (res)
-		goto errout;
-
-	/* this is broken symlink case */
-	if (unlikely(pstr.name[0] == 0)) {
-		res = -ENOENT;
-		goto errout;
-	}
-
-	paddr = pstr.name;
-
-	/* Null-terminate the name */
-	paddr[pstr.len] = '\0';
+	page = read_mapping_page(inode->i_mapping, 0, NULL);
+	if (IS_ERR(page))
+		return ERR_CAST(page);
 
-	put_page(cpage);
-	set_delayed_call(done, kfree_link, paddr);
-	return paddr;
-errout:
-	fscrypt_fname_free_buffer(&pstr);
-	put_page(cpage);
-	return ERR_PTR(res);
+	target = fscrypt_get_symlink(inode, page_address(page),
+				     inode->i_sb->s_blocksize, done);
+	put_page(page);
+	return target;
 }
 
 const struct inode_operations f2fs_encrypted_symlink_inode_operations = {
-- 
cgit v1.2.3


From 6b46d444146eb8d0b99562795cea8086639d7282 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 11 Jan 2018 23:27:00 -0500
Subject: ubifs: free the encrypted symlink target

ubifs_symlink() forgot to free the kmalloc()'ed buffer holding the
encrypted symlink target, creating a memory leak.  Fix it.

(UBIFS could actually encrypt directly into ui->data, removing the
temporary buffer, but that is left for the patch that switches to use
the symlink helper functions.)

Fixes: ca7f85be8d6c ("ubifs: Add support for encrypted symlinks")
Cc: <stable@vger.kernel.org> # v4.10+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/ubifs/dir.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

(limited to 'fs')

diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index 417fe0b29f23..ef820f803176 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -1216,10 +1216,8 @@ static int ubifs_symlink(struct inode *dir, struct dentry *dentry,
 		ostr.len = disk_link.len;
 
 		err = fscrypt_fname_usr_to_disk(inode, &istr, &ostr);
-		if (err) {
-			kfree(sd);
+		if (err)
 			goto out_inode;
-		}
 
 		sd->len = cpu_to_le16(ostr.len);
 		disk_link.name = (char *)sd;
@@ -1251,11 +1249,10 @@ static int ubifs_symlink(struct inode *dir, struct dentry *dentry,
 		goto out_cancel;
 	mutex_unlock(&dir_ui->ui_mutex);
 
-	ubifs_release_budget(c, &req);
 	insert_inode_hash(inode);
 	d_instantiate(dentry, inode);
-	fscrypt_free_filename(&nm);
-	return 0;
+	err = 0;
+	goto out_fname;
 
 out_cancel:
 	dir->i_size -= sz_change;
@@ -1268,6 +1265,7 @@ out_fname:
 	fscrypt_free_filename(&nm);
 out_budg:
 	ubifs_release_budget(c, &req);
+	kfree(sd);
 	return err;
 }
 
-- 
cgit v1.2.3


From 0e4dda290779aa5ceaa5ee8c79961146124d78e7 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 11 Jan 2018 23:27:00 -0500
Subject: ubifs: switch to fscrypt ->symlink() helper functions

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/ubifs/dir.c | 55 ++++++++++++-------------------------------------------
 1 file changed, 12 insertions(+), 43 deletions(-)

(limited to 'fs')

diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index ef820f803176..518c10255881 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -1149,38 +1149,24 @@ static int ubifs_symlink(struct inode *dir, struct dentry *dentry,
 	struct ubifs_info *c = dir->i_sb->s_fs_info;
 	int err, len = strlen(symname);
 	int sz_change = CALC_DENT_SIZE(len);
-	struct fscrypt_str disk_link = FSTR_INIT((char *)symname, len + 1);
-	struct fscrypt_symlink_data *sd = NULL;
+	struct fscrypt_str disk_link;
 	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
 					.new_ino_d = ALIGN(len, 8),
 					.dirtied_ino = 1 };
 	struct fscrypt_name nm;
 
-	if (ubifs_crypt_is_encrypted(dir)) {
-		err = fscrypt_get_encryption_info(dir);
-		if (err)
-			goto out_budg;
-
-		if (!fscrypt_has_encryption_key(dir)) {
-			err = -EPERM;
-			goto out_budg;
-		}
+	dbg_gen("dent '%pd', target '%s' in dir ino %lu", dentry,
+		symname, dir->i_ino);
 
-		disk_link.len = (fscrypt_fname_encrypted_size(dir, len) +
-				sizeof(struct fscrypt_symlink_data));
-	}
+	err = fscrypt_prepare_symlink(dir, symname, len, UBIFS_MAX_INO_DATA,
+				      &disk_link);
+	if (err)
+		return err;
 
 	/*
 	 * Budget request settings: new inode, new direntry and changing parent
 	 * directory inode.
 	 */
-
-	dbg_gen("dent '%pd', target '%s' in dir ino %lu", dentry,
-		symname, dir->i_ino);
-
-	if (disk_link.len > UBIFS_MAX_INO_DATA)
-		return -ENAMETOOLONG;
-
 	err = ubifs_budget_space(c, &req);
 	if (err)
 		return err;
@@ -1202,36 +1188,20 @@ static int ubifs_symlink(struct inode *dir, struct dentry *dentry,
 		goto out_inode;
 	}
 
-	if (ubifs_crypt_is_encrypted(dir)) {
-		struct qstr istr = QSTR_INIT(symname, len);
-		struct fscrypt_str ostr;
-
-		sd = kzalloc(disk_link.len, GFP_NOFS);
-		if (!sd) {
-			err = -ENOMEM;
-			goto out_inode;
-		}
-
-		ostr.name = sd->encrypted_path;
-		ostr.len = disk_link.len;
-
-		err = fscrypt_fname_usr_to_disk(inode, &istr, &ostr);
+	if (IS_ENCRYPTED(inode)) {
+		disk_link.name = ui->data; /* encrypt directly into ui->data */
+		err = fscrypt_encrypt_symlink(inode, symname, len, &disk_link);
 		if (err)
 			goto out_inode;
-
-		sd->len = cpu_to_le16(ostr.len);
-		disk_link.name = (char *)sd;
 	} else {
+		memcpy(ui->data, disk_link.name, disk_link.len);
 		inode->i_link = ui->data;
 	}
 
-	memcpy(ui->data, disk_link.name, disk_link.len);
-	((char *)ui->data)[disk_link.len - 1] = '\0';
-
 	/*
 	 * The terminating zero byte is not written to the flash media and it
 	 * is put just to make later in-memory string processing simpler. Thus,
-	 * data length is @len, not @len + %1.
+	 * data length is @disk_link.len - 1, not @disk_link.len.
 	 */
 	ui->data_len = disk_link.len - 1;
 	inode->i_size = ubifs_inode(inode)->ui_size = disk_link.len - 1;
@@ -1265,7 +1235,6 @@ out_fname:
 	fscrypt_free_filename(&nm);
 out_budg:
 	ubifs_release_budget(c, &req);
-	kfree(sd);
 	return err;
 }
 
-- 
cgit v1.2.3


From 81dd76b2a5ca4328b810ee9911ae72fb67b83096 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 11 Jan 2018 23:27:00 -0500
Subject: ubifs: switch to fscrypt_get_symlink()

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/ubifs/file.c | 36 ++----------------------------------
 1 file changed, 2 insertions(+), 34 deletions(-)

(limited to 'fs')

diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index dfe85069586e..3cfc578c42ea 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -1662,49 +1662,17 @@ static const char *ubifs_get_link(struct dentry *dentry,
 					    struct inode *inode,
 					    struct delayed_call *done)
 {
-	int err;
-	struct fscrypt_symlink_data *sd;
 	struct ubifs_inode *ui = ubifs_inode(inode);
-	struct fscrypt_str cstr;
-	struct fscrypt_str pstr;
 
-	if (!ubifs_crypt_is_encrypted(inode))
+	if (!IS_ENCRYPTED(inode))
 		return ui->data;
 
 	if (!dentry)
 		return ERR_PTR(-ECHILD);
 
-	err = fscrypt_get_encryption_info(inode);
-	if (err)
-		return ERR_PTR(err);
-
-	sd = (struct fscrypt_symlink_data *)ui->data;
-	cstr.name = sd->encrypted_path;
-	cstr.len = le16_to_cpu(sd->len);
-
-	if (cstr.len == 0)
-		return ERR_PTR(-ENOENT);
-
-	if ((cstr.len + sizeof(struct fscrypt_symlink_data) - 1) > ui->data_len)
-		return ERR_PTR(-EIO);
-
-	err = fscrypt_fname_alloc_buffer(inode, cstr.len, &pstr);
-	if (err)
-		return ERR_PTR(err);
-
-	err = fscrypt_fname_disk_to_usr(inode, 0, 0, &cstr, &pstr);
-	if (err) {
-		fscrypt_fname_free_buffer(&pstr);
-		return ERR_PTR(err);
-	}
-
-	pstr.name[pstr.len] = '\0';
-
-	set_delayed_call(done, kfree_link, pstr.name);
-	return pstr.name;
+	return fscrypt_get_symlink(inode, ui->data, ui->data_len, done);
 }
 
-
 const struct address_space_operations ubifs_file_address_operations = {
 	.readpage       = ubifs_readpage,
 	.writepage      = ubifs_writepage,
-- 
cgit v1.2.3


From 1e80ad712f69a34d1e3c556d1d674d04b266ad40 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 11 Jan 2018 23:30:08 -0500
Subject: fscrypt: remove fscrypt_fname_usr_to_disk()

fscrypt_fname_usr_to_disk() sounded very generic but was actually only
used to encrypt symlinks.  Remove it now that all filesystems have been
switched over to fscrypt_encrypt_symlink().

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/crypto/fname.c               | 29 -----------------------------
 include/linux/fscrypt_notsupp.h |  7 -------
 include/linux/fscrypt_supp.h    |  2 --
 3 files changed, 38 deletions(-)

(limited to 'fs')

diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index 62f13d533439..cae7d1bcc8c5 100644
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -311,35 +311,6 @@ int fscrypt_fname_disk_to_usr(struct inode *inode,
 }
 EXPORT_SYMBOL(fscrypt_fname_disk_to_usr);
 
-/**
- * fscrypt_fname_usr_to_disk() - converts a filename from user space to disk
- * space
- *
- * The caller must have allocated sufficient memory for the @oname string.
- *
- * Return: 0 on success, -errno on failure
- */
-int fscrypt_fname_usr_to_disk(struct inode *inode,
-			const struct qstr *iname,
-			struct fscrypt_str *oname)
-{
-	if (fscrypt_is_dot_dotdot(iname)) {
-		oname->name[0] = '.';
-		oname->name[iname->len - 1] = '.';
-		oname->len = iname->len;
-		return 0;
-	}
-	if (inode->i_crypt_info)
-		return fname_encrypt(inode, iname, oname);
-	/*
-	 * Without a proper key, a user is not allowed to modify the filenames
-	 * in a directory. Consequently, a user space name cannot be mapped to
-	 * a disk-space name
-	 */
-	return -ENOKEY;
-}
-EXPORT_SYMBOL(fscrypt_fname_usr_to_disk);
-
 /**
  * fscrypt_setup_filename() - prepare to search a possibly encrypted directory
  * @dir: the directory that will be searched
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index dd106640c6ea..0962f504aa91 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -159,13 +159,6 @@ static inline int fscrypt_fname_disk_to_usr(struct inode *inode,
 	return -EOPNOTSUPP;
 }
 
-static inline int fscrypt_fname_usr_to_disk(struct inode *inode,
-					    const struct qstr *iname,
-					    struct fscrypt_str *oname)
-{
-	return -EOPNOTSUPP;
-}
-
 static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
 				      const u8 *de_name, u32 de_name_len)
 {
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index dc2babf3f7d3..e00191deb0d6 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -113,8 +113,6 @@ extern int fscrypt_fname_alloc_buffer(const struct inode *, u32,
 extern void fscrypt_fname_free_buffer(struct fscrypt_str *);
 extern int fscrypt_fname_disk_to_usr(struct inode *, u32, u32,
 			const struct fscrypt_str *, struct fscrypt_str *);
-extern int fscrypt_fname_usr_to_disk(struct inode *, const struct qstr *,
-			struct fscrypt_str *);
 
 #define FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE	32
 
-- 
cgit v1.2.3


From 0eaab5b10621e84868df911dad43d330fa1b9bc8 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 11 Jan 2018 23:30:08 -0500
Subject: fscrypt: move fscrypt_symlink_data to fscrypt_private.h

Now that all filesystems have been converted to use the symlink helper
functions, they no longer need the declaration of 'struct
fscrypt_symlink_data'.  Move it from fscrypt.h to fscrypt_private.h.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/crypto/fscrypt_private.h | 9 +++++++++
 include/linux/fscrypt.h     | 9 ---------
 2 files changed, 9 insertions(+), 9 deletions(-)

(limited to 'fs')

diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 6995bca5006b..cec9ce309f41 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -50,6 +50,15 @@ struct fscrypt_context {
 
 #define FS_ENCRYPTION_CONTEXT_FORMAT_V1		1
 
+/**
+ * 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;
+
 /*
  * A pointer to this structure is stored in the file system's in-core
  * representation of an inode.
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 6a678d0e956a..952ab97af325 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -21,15 +21,6 @@
 struct fscrypt_ctx;
 struct fscrypt_info;
 
-/**
- * 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;
-- 
cgit v1.2.3


From 50c961de59ec841c1185c18457e6dab227f3bbf3 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 11 Jan 2018 23:30:08 -0500
Subject: fscrypt: calculate NUL-padding length in one place only

Currently, when encrypting a filename (either a real filename or a
symlink target) we calculate the amount of NUL-padding twice: once
before encryption and once during encryption in fname_encrypt().  It is
needed before encryption to allocate the needed buffer size as well as
calculate the size the symlink target will take up on-disk before
creating the symlink inode.  Calculating the size during encryption as
well is redundant.

Remove this redundancy by always calculating the exact size beforehand,
and making fname_encrypt() just add as much NUL padding as is needed to
fill the output buffer.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/crypto/fname.c           | 53 ++++++++++++++++++++++-----------------------
 fs/crypto/fscrypt_private.h |  4 ++--
 fs/crypto/hooks.c           |  7 +-----
 3 files changed, 29 insertions(+), 35 deletions(-)

(limited to 'fs')

diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index cae7d1bcc8c5..65424b89a1d1 100644
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -30,39 +30,29 @@ static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
 /**
  * fname_encrypt() - encrypt a filename
  *
- * The caller must have allocated sufficient memory for the @oname string.
+ * The output buffer must be at least as large as the input buffer.
+ * Any extra space is filled with NUL padding before encryption.
  *
  * Return: 0 on success, -errno on failure
  */
-int fname_encrypt(struct inode *inode,
-		  const struct qstr *iname, struct fscrypt_str *oname)
+int fname_encrypt(struct inode *inode, const struct qstr *iname,
+		  u8 *out, unsigned int olen)
 {
 	struct skcipher_request *req = NULL;
 	DECLARE_CRYPTO_WAIT(wait);
-	struct fscrypt_info *ci = inode->i_crypt_info;
-	struct crypto_skcipher *tfm = ci->ci_ctfm;
+	struct crypto_skcipher *tfm = inode->i_crypt_info->ci_ctfm;
 	int res = 0;
 	char iv[FS_CRYPTO_BLOCK_SIZE];
 	struct scatterlist sg;
-	int padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK);
-	unsigned int lim;
-	unsigned int cryptlen;
-
-	lim = inode->i_sb->s_cop->max_namelen(inode);
-	if (iname->len <= 0 || iname->len > lim)
-		return -EIO;
 
 	/*
 	 * Copy the filename to the output buffer for encrypting in-place and
 	 * pad it with the needed number of NUL bytes.
 	 */
-	if (WARN_ON(oname->len < iname->len))
+	if (WARN_ON(olen < iname->len))
 		return -ENOBUFS;
-	cryptlen = max_t(unsigned int, iname->len, FS_CRYPTO_BLOCK_SIZE);
-	cryptlen = round_up(cryptlen, padding);
-	cryptlen = min3(cryptlen, lim, oname->len);
-	memcpy(oname->name, iname->name, iname->len);
-	memset(oname->name + iname->len, 0, cryptlen - iname->len);
+	memcpy(out, iname->name, iname->len);
+	memset(out + iname->len, 0, olen - iname->len);
 
 	/* Initialize the IV */
 	memset(iv, 0, FS_CRYPTO_BLOCK_SIZE);
@@ -77,8 +67,8 @@ int fname_encrypt(struct inode *inode,
 	skcipher_request_set_callback(req,
 			CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
 			crypto_req_done, &wait);
-	sg_init_one(&sg, oname->name, cryptlen);
-	skcipher_request_set_crypt(req, &sg, &sg, cryptlen, iv);
+	sg_init_one(&sg, out, olen);
+	skcipher_request_set_crypt(req, &sg, &sg, olen, iv);
 
 	/* Do the encryption */
 	res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
@@ -89,7 +79,6 @@ int fname_encrypt(struct inode *inode,
 		return res;
 	}
 
-	oname->len = cryptlen;
 	return 0;
 }
 
@@ -354,11 +343,21 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
 		return ret;
 
 	if (dir->i_crypt_info) {
-		ret = fscrypt_fname_alloc_buffer(dir, iname->len,
-							&fname->crypto_buf);
-		if (ret)
-			return ret;
-		ret = fname_encrypt(dir, iname, &fname->crypto_buf);
+		unsigned int max_len = dir->i_sb->s_cop->max_namelen(dir);
+
+		if (iname->len > max_len)
+			return -ENAMETOOLONG;
+
+		fname->crypto_buf.len =
+			min(fscrypt_fname_encrypted_size(dir, iname->len),
+			    max_len);
+		fname->crypto_buf.name = kmalloc(fname->crypto_buf.len,
+						 GFP_NOFS);
+		if (!fname->crypto_buf.name)
+			return -ENOMEM;
+
+		ret = fname_encrypt(dir, iname, fname->crypto_buf.name,
+				    fname->crypto_buf.len);
 		if (ret)
 			goto errout;
 		fname->disk_name.name = fname->crypto_buf.name;
@@ -410,7 +409,7 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
 	return 0;
 
 errout:
-	fscrypt_fname_free_buffer(&fname->crypto_buf);
+	kfree(fname->crypto_buf.name);
 	return ret;
 }
 EXPORT_SYMBOL(fscrypt_setup_filename);
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index cec9ce309f41..053917587200 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -108,8 +108,8 @@ extern struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
 					      gfp_t gfp_flags);
 
 /* fname.c */
-extern int fname_encrypt(struct inode *inode,
-			 const struct qstr *iname, struct fscrypt_str *oname);
+extern int fname_encrypt(struct inode *inode, const struct qstr *iname,
+			 u8 *out, unsigned int olen);
 
 /* keyinfo.c */
 extern void __exit fscrypt_essiv_cleanup(void);
diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c
index 8900e348ba6e..5bf38d94c5d2 100644
--- a/fs/crypto/hooks.c
+++ b/fs/crypto/hooks.c
@@ -161,7 +161,6 @@ int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
 	struct qstr iname = { .name = target, .len = len };
 	struct fscrypt_symlink_data *sd;
 	unsigned int ciphertext_len;
-	struct fscrypt_str oname;
 
 	err = fscrypt_require_key(inode);
 	if (err)
@@ -178,16 +177,12 @@ int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
 	ciphertext_len = disk_link->len - sizeof(*sd);
 	sd->len = cpu_to_le16(ciphertext_len);
 
-	oname.name = sd->encrypted_path;
-	oname.len = ciphertext_len;
-	err = fname_encrypt(inode, &iname, &oname);
+	err = fname_encrypt(inode, &iname, sd->encrypted_path, ciphertext_len);
 	if (err) {
 		if (!disk_link->name)
 			kfree(sd);
 		return err;
 	}
-	BUG_ON(oname.len != ciphertext_len);
-
 	/*
 	 * Null-terminating the ciphertext doesn't make sense, but we still
 	 * count the null terminator in the length, so we might as well
-- 
cgit v1.2.3


From 2cbadadcfdf0d8a538ce32ed12e18ef487773b07 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 11 Jan 2018 23:30:08 -0500
Subject: fscrypt: define fscrypt_fname_alloc_buffer() to be for presented
 names

Previously fscrypt_fname_alloc_buffer() was used to allocate buffers for
both presented (decrypted or encoded) and encrypted filenames.  That was
confusing, because it had to allocate the worst-case size for either,
e.g. including NUL-padding even when it was meaningless.

But now that fscrypt_setup_filename() no longer calls it, it is only
used in the ->get_link() and ->readdir() paths, which specifically want
a buffer for presented filenames.  Therefore, switch the behavior over
to allocating the buffer for presented filenames only.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/crypto/fname.c               | 29 ++++++++++++++---------------
 include/linux/fscrypt_notsupp.h |  2 +-
 2 files changed, 15 insertions(+), 16 deletions(-)

(limited to 'fs')

diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index 65424b89a1d1..44ddd094b7c5 100644
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -204,37 +204,36 @@ u32 fscrypt_fname_encrypted_size(const struct inode *inode, u32 ilen)
 EXPORT_SYMBOL(fscrypt_fname_encrypted_size);
 
 /**
- * fscrypt_fname_crypto_alloc_obuff() -
+ * fscrypt_fname_alloc_buffer - allocate a buffer for presented filenames
  *
- * Allocates an output buffer that is sufficient for the crypto operation
- * specified by the context and the direction.
+ * Allocate a buffer that is large enough to hold any decrypted or encoded
+ * filename (null-terminated), for the given maximum encrypted filename length.
+ *
+ * Return: 0 on success, -errno on failure
  */
 int fscrypt_fname_alloc_buffer(const struct inode *inode,
-				u32 ilen, struct fscrypt_str *crypto_str)
+			       u32 max_encrypted_len,
+			       struct fscrypt_str *crypto_str)
 {
-	u32 olen = fscrypt_fname_encrypted_size(inode, ilen);
 	const u32 max_encoded_len =
 		max_t(u32, BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE),
 		      1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name)));
+	u32 max_presented_len;
 
-	crypto_str->len = olen;
-	olen = max(olen, max_encoded_len);
+	max_presented_len = max(max_encoded_len, max_encrypted_len);
 
-	/*
-	 * Allocated buffer can hold one more character to null-terminate the
-	 * string
-	 */
-	crypto_str->name = kmalloc(olen + 1, GFP_NOFS);
-	if (!(crypto_str->name))
+	crypto_str->name = kmalloc(max_presented_len + 1, GFP_NOFS);
+	if (!crypto_str->name)
 		return -ENOMEM;
+	crypto_str->len = max_presented_len;
 	return 0;
 }
 EXPORT_SYMBOL(fscrypt_fname_alloc_buffer);
 
 /**
- * fscrypt_fname_crypto_free_buffer() -
+ * fscrypt_fname_free_buffer - free the buffer for presented filenames
  *
- * Frees the buffer allocated for crypto operation.
+ * Free the buffer allocated by fscrypt_fname_alloc_buffer().
  */
 void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str)
 {
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index 0962f504aa91..c9592e307df5 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -140,7 +140,7 @@ static inline u32 fscrypt_fname_encrypted_size(const struct inode *inode,
 }
 
 static inline int fscrypt_fname_alloc_buffer(const struct inode *inode,
-					     u32 ilen,
+					     u32 max_encrypted_len,
 					     struct fscrypt_str *crypto_str)
 {
 	return -EOPNOTSUPP;
-- 
cgit v1.2.3


From b9db0b4a68d373897119d1e0a3beebe1c1a23936 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 11 Jan 2018 23:30:08 -0500
Subject: fscrypt: fix up fscrypt_fname_encrypted_size() for internal use

Filesystems don't need fscrypt_fname_encrypted_size() anymore, so
unexport it and move it to fscrypt_private.h.

We also never calculate the encrypted size of a filename without having
the fscrypt_info present since it is needed to know the amount of
NUL-padding which is determined by the encryption policy, and also we
will always truncate the NUL-padding to the maximum filename length.
Therefore, also make fscrypt_fname_encrypted_size() assume that the
fscrypt_info is present, and make it truncate the returned length to the
specified max_len.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/crypto/fname.c               | 31 +++++++++++++++----------------
 fs/crypto/fscrypt_private.h     |  3 +++
 fs/crypto/hooks.c               | 10 +++++-----
 include/linux/fscrypt_notsupp.h |  8 --------
 include/linux/fscrypt_supp.h    |  1 -
 5 files changed, 23 insertions(+), 30 deletions(-)

(limited to 'fs')

diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index 44ddd094b7c5..e33f3d3c5ade 100644
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -191,17 +191,20 @@ static int digest_decode(const char *src, int len, char *dst)
 	return cp - dst;
 }
 
-u32 fscrypt_fname_encrypted_size(const struct inode *inode, u32 ilen)
+bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
+				  u32 max_len, u32 *encrypted_len_ret)
 {
-	int padding = 32;
-	struct fscrypt_info *ci = inode->i_crypt_info;
-
-	if (ci)
-		padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK);
-	ilen = max(ilen, (u32)FS_CRYPTO_BLOCK_SIZE);
-	return round_up(ilen, padding);
+	int padding = 4 << (inode->i_crypt_info->ci_flags &
+			    FS_POLICY_FLAGS_PAD_MASK);
+	u32 encrypted_len;
+
+	if (orig_len > max_len)
+		return false;
+	encrypted_len = max(orig_len, (u32)FS_CRYPTO_BLOCK_SIZE);
+	encrypted_len = round_up(encrypted_len, padding);
+	*encrypted_len_ret = min(encrypted_len, max_len);
+	return true;
 }
-EXPORT_SYMBOL(fscrypt_fname_encrypted_size);
 
 /**
  * fscrypt_fname_alloc_buffer - allocate a buffer for presented filenames
@@ -342,14 +345,10 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
 		return ret;
 
 	if (dir->i_crypt_info) {
-		unsigned int max_len = dir->i_sb->s_cop->max_namelen(dir);
-
-		if (iname->len > max_len)
+		if (!fscrypt_fname_encrypted_size(dir, iname->len,
+						  dir->i_sb->s_cop->max_namelen(dir),
+						  &fname->crypto_buf.len))
 			return -ENAMETOOLONG;
-
-		fname->crypto_buf.len =
-			min(fscrypt_fname_encrypted_size(dir, iname->len),
-			    max_len);
 		fname->crypto_buf.name = kmalloc(fname->crypto_buf.len,
 						 GFP_NOFS);
 		if (!fname->crypto_buf.name)
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 053917587200..ad6722bae8b7 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -110,6 +110,9 @@ extern struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
 /* fname.c */
 extern int fname_encrypt(struct inode *inode, const struct qstr *iname,
 			 u8 *out, unsigned int olen);
+extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
+					 u32 orig_len, u32 max_len,
+					 u32 *encrypted_len_ret);
 
 /* keyinfo.c */
 extern void __exit fscrypt_essiv_cleanup(void);
diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c
index 5bf38d94c5d2..28f9f059571d 100644
--- a/fs/crypto/hooks.c
+++ b/fs/crypto/hooks.c
@@ -143,12 +143,12 @@ int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
 	 * counting it (even though it is meaningless for ciphertext) is simpler
 	 * for now since filesystems will assume it is there and subtract it.
 	 */
-	if (sizeof(struct fscrypt_symlink_data) + len > max_len)
+	if (!fscrypt_fname_encrypted_size(dir, len,
+					  max_len - sizeof(struct fscrypt_symlink_data),
+					  &disk_link->len))
 		return -ENAMETOOLONG;
-	disk_link->len = min_t(unsigned int,
-			       sizeof(struct fscrypt_symlink_data) +
-					fscrypt_fname_encrypted_size(dir, len),
-			       max_len);
+	disk_link->len += sizeof(struct fscrypt_symlink_data);
+
 	disk_link->name = NULL;
 	return 0;
 }
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index c9592e307df5..342eb97e0476 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -131,14 +131,6 @@ static inline void fscrypt_free_filename(struct fscrypt_name *fname)
 	return;
 }
 
-static inline u32 fscrypt_fname_encrypted_size(const struct inode *inode,
-					       u32 ilen)
-{
-	/* never happens */
-	WARN_ON(1);
-	return 0;
-}
-
 static inline int fscrypt_fname_alloc_buffer(const struct inode *inode,
 					     u32 max_encrypted_len,
 					     struct fscrypt_str *crypto_str)
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index e00191deb0d6..2dd5767c77b0 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -107,7 +107,6 @@ static inline void fscrypt_free_filename(struct fscrypt_name *fname)
 	kfree(fname->crypto_buf.name);
 }
 
-extern u32 fscrypt_fname_encrypted_size(const struct inode *, u32);
 extern int fscrypt_fname_alloc_buffer(const struct inode *, u32,
 				struct fscrypt_str *);
 extern void fscrypt_fname_free_buffer(struct fscrypt_str *);
-- 
cgit v1.2.3


From 3d204e24d452f96704f5feb83f6b7654245defc9 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 11 Jan 2018 23:30:13 -0500
Subject: fscrypt: remove 'ci' parameter from fscrypt_put_encryption_info()

fscrypt_put_encryption_info() is only called when evicting an inode, so
the 'struct fscrypt_info *ci' parameter is always NULL, and there cannot
be races with other threads.  This was cruft left over from the broken
key revocation code.  Remove the unused parameter and the cmpxchg().

Also remove the #ifdefs around the fscrypt_put_encryption_info() calls,
since fscrypt_notsupp.h defines a no-op stub for it.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/crypto/keyinfo.c             | 16 +++-------------
 fs/ext4/super.c                 |  4 +---
 fs/f2fs/inode.c                 |  2 +-
 fs/ubifs/super.c                |  4 +---
 include/linux/fscrypt_notsupp.h |  3 +--
 include/linux/fscrypt_supp.h    |  2 +-
 6 files changed, 8 insertions(+), 23 deletions(-)

(limited to 'fs')

diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c
index c115eac4b4cf..05f5ee1f0705 100644
--- a/fs/crypto/keyinfo.c
+++ b/fs/crypto/keyinfo.c
@@ -355,19 +355,9 @@ out:
 }
 EXPORT_SYMBOL(fscrypt_get_encryption_info);
 
-void fscrypt_put_encryption_info(struct inode *inode, struct fscrypt_info *ci)
+void fscrypt_put_encryption_info(struct inode *inode)
 {
-	struct fscrypt_info *prev;
-
-	if (ci == NULL)
-		ci = READ_ONCE(inode->i_crypt_info);
-	if (ci == NULL)
-		return;
-
-	prev = cmpxchg(&inode->i_crypt_info, ci, NULL);
-	if (prev != ci)
-		return;
-
-	put_crypt_info(ci);
+	put_crypt_info(inode->i_crypt_info);
+	inode->i_crypt_info = NULL;
 }
 EXPORT_SYMBOL(fscrypt_put_encryption_info);
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 7c46693a14d7..152d05d983f6 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1069,9 +1069,7 @@ void ext4_clear_inode(struct inode *inode)
 		jbd2_free_inode(EXT4_I(inode)->jinode);
 		EXT4_I(inode)->jinode = NULL;
 	}
-#ifdef CONFIG_EXT4_FS_ENCRYPTION
-	fscrypt_put_encryption_info(inode, NULL);
-#endif
+	fscrypt_put_encryption_info(inode);
 }
 
 static struct inode *ext4_nfs_get_inode(struct super_block *sb,
diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index b4c4f2b25304..22a5607a0518 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -569,7 +569,7 @@ no_delete:
 			!exist_written_data(sbi, inode->i_ino, ORPHAN_INO));
 	}
 out_clear:
-	fscrypt_put_encryption_info(inode, NULL);
+	fscrypt_put_encryption_info(inode);
 	clear_inode(inode);
 }
 
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 0beb285b143d..b16ef162344a 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -379,9 +379,7 @@ out:
 	}
 done:
 	clear_inode(inode);
-#ifdef CONFIG_UBIFS_FS_ENCRYPTION
-	fscrypt_put_encryption_info(inode, NULL);
-#endif
+	fscrypt_put_encryption_info(inode);
 }
 
 static void ubifs_dirty_inode(struct inode *inode, int flags)
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index 342eb97e0476..44b50c04bae9 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -105,8 +105,7 @@ static inline int fscrypt_get_encryption_info(struct inode *inode)
 	return -EOPNOTSUPP;
 }
 
-static inline void fscrypt_put_encryption_info(struct inode *inode,
-					       struct fscrypt_info *ci)
+static inline void fscrypt_put_encryption_info(struct inode *inode)
 {
 	return;
 }
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index 2dd5767c77b0..477a7a6504d2 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -96,7 +96,7 @@ extern int fscrypt_inherit_context(struct inode *, struct inode *,
 					void *, bool);
 /* keyinfo.c */
 extern int fscrypt_get_encryption_info(struct inode *);
-extern void fscrypt_put_encryption_info(struct inode *, struct fscrypt_info *);
+extern void fscrypt_put_encryption_info(struct inode *);
 
 /* fname.c */
 extern int fscrypt_setup_filename(struct inode *, const struct qstr *,
-- 
cgit v1.2.3


From 0b1dfa4cc6c60052b2c30ead316fa84c46d3c43c Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Fri, 19 Jan 2018 13:45:24 -0800
Subject: fscrypt: fix build with pre-4.6 gcc versions

gcc versions prior to 4.6 require an extra level of braces when using a
designated initializer for a member in an anonymous struct or union.
This caused a compile error with the 'struct qstr' initialization in
__fscrypt_encrypt_symlink().

Fix it by using QSTR_INIT().

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Fixes: 76e81d6d5048 ("fscrypt: new helper functions for ->symlink()")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/crypto/hooks.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'fs')

diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c
index 28f9f059571d..bec06490fb13 100644
--- a/fs/crypto/hooks.c
+++ b/fs/crypto/hooks.c
@@ -158,7 +158,7 @@ int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
 			      unsigned int len, struct fscrypt_str *disk_link)
 {
 	int err;
-	struct qstr iname = { .name = target, .len = len };
+	struct qstr iname = QSTR_INIT(target, len);
 	struct fscrypt_symlink_data *sd;
 	unsigned int ciphertext_len;
 
-- 
cgit v1.2.3