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From: Jeff Layton <jlayton@kernel.org>
To: ceph-devel@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, linux-fscrypt@vger.kernel.org,
	ebiggers@kernel.org
Subject: [RFC PATCH v2 07/18] lib: lift fscrypt base64 conversion into lib/
Date: Fri,  4 Sep 2020 12:05:26 -0400
Message-ID: <20200904160537.76663-8-jlayton@kernel.org> (raw)
In-Reply-To: <20200904160537.76663-1-jlayton@kernel.org>

Once we allow encrypted filenames on ceph we'll end up with names that
may have illegal characters in them (embedded '\0' or '/'), or
characters that aren't printable.

It will be safer to use strings that are printable. It turns out that the
MDS doesn't really care about the length of filenames, so we can just
base64 encode and decode filenames before writing and reading them.

Lift the base64 implementation that's in fscrypt into lib/. Make fscrypt
select it when it's enabled.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 fs/crypto/Kconfig            |  1 +
 fs/crypto/fname.c            | 64 ++------------------------------
 include/linux/base64_fname.h | 11 ++++++
 lib/Kconfig                  |  3 ++
 lib/Makefile                 |  1 +
 lib/base64_fname.c           | 71 ++++++++++++++++++++++++++++++++++++
 6 files changed, 90 insertions(+), 61 deletions(-)
 create mode 100644 include/linux/base64_fname.h
 create mode 100644 lib/base64_fname.c

diff --git a/fs/crypto/Kconfig b/fs/crypto/Kconfig
index a5f5c30368a2..6b27d105420c 100644
--- a/fs/crypto/Kconfig
+++ b/fs/crypto/Kconfig
@@ -6,6 +6,7 @@ config FS_ENCRYPTION
 	select CRYPTO_SKCIPHER
 	select CRYPTO_LIB_SHA256
 	select KEYS
+	select BASE64_FNAME
 	help
 	  Enable encryption of files and directories.  This
 	  feature is similar to ecryptfs, but it is more memory
diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index 09f09def87fc..89e26e923547 100644
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -11,6 +11,7 @@
  * This has not yet undergone a rigorous security audit.
  */
 
+#include <linux/base64_fname.h>
 #include <linux/namei.h>
 #include <linux/scatterlist.h>
 #include <crypto/hash.h>
@@ -184,64 +185,6 @@ static int fname_decrypt(const struct inode *inode,
 	return 0;
 }
 
-static const char lookup_table[65] =
-	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
-
-#define BASE64_CHARS(nbytes)	DIV_ROUND_UP((nbytes) * 4, 3)
-
-/**
- * base64_encode() - base64-encode some bytes
- * @src: the bytes to encode
- * @len: number of bytes to encode
- * @dst: (output) the base64-encoded string.  Not NUL-terminated.
- *
- * Encodes the input string using characters from the set [A-Za-z0-9+,].
- * The encoded string is roughly 4/3 times the size of the input string.
- *
- * Return: length of the encoded string
- */
-static int base64_encode(const u8 *src, int len, char *dst)
-{
-	int i, bits = 0, ac = 0;
-	char *cp = dst;
-
-	for (i = 0; i < len; i++) {
-		ac += src[i] << bits;
-		bits += 8;
-		do {
-			*cp++ = lookup_table[ac & 0x3f];
-			ac >>= 6;
-			bits -= 6;
-		} while (bits >= 6);
-	}
-	if (bits)
-		*cp++ = lookup_table[ac & 0x3f];
-	return cp - dst;
-}
-
-static int base64_decode(const char *src, int len, u8 *dst)
-{
-	int i, bits = 0, ac = 0;
-	const char *p;
-	u8 *cp = dst;
-
-	for (i = 0; i < len; i++) {
-		p = strchr(lookup_table, src[i]);
-		if (p == NULL || src[i] == 0)
-			return -2;
-		ac += (p - lookup_table) << bits;
-		bits += 6;
-		if (bits >= 8) {
-			*cp++ = ac & 0xff;
-			ac >>= 8;
-			bits -= 8;
-		}
-	}
-	if (ac)
-		return -1;
-	return cp - dst;
-}
-
 bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
 				  u32 max_len, u32 *encrypted_len_ret)
 {
@@ -335,7 +278,7 @@ void fscrypt_encode_nokey_name(u32 hash, u32 minor_hash,
 				  nokey_name.sha256);
 		size = FSCRYPT_NOKEY_NAME_MAX;
 	}
-	oname->len = base64_encode((const u8 *)&nokey_name, size, oname->name);
+	oname->len = base64_encode_fname((const u8 *)&nokey_name, size, oname->name);
 }
 EXPORT_SYMBOL(fscrypt_encode_nokey_name);
 
@@ -380,7 +323,6 @@ int fscrypt_fname_disk_to_usr(const struct inode *inode,
 	if (fscrypt_has_encryption_key(inode))
 		return fname_decrypt(inode, iname, oname);
 
-	fscrypt_encode_nokey_name(hash, minor_hash, iname, oname);
 	return 0;
 }
 EXPORT_SYMBOL(fscrypt_fname_disk_to_usr);
@@ -460,7 +402,7 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
 	if (fname->crypto_buf.name == NULL)
 		return -ENOMEM;
 
-	ret = base64_decode(iname->name, iname->len, fname->crypto_buf.name);
+	ret = base64_decode_fname(iname->name, iname->len, fname->crypto_buf.name);
 	if (ret < (int)offsetof(struct fscrypt_nokey_name, bytes[1]) ||
 	    (ret > offsetof(struct fscrypt_nokey_name, sha256) &&
 	     ret != FSCRYPT_NOKEY_NAME_MAX)) {
diff --git a/include/linux/base64_fname.h b/include/linux/base64_fname.h
new file mode 100644
index 000000000000..d98d79b4c95c
--- /dev/null
+++ b/include/linux/base64_fname.h
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#ifndef _LIB_BASE64_FNAME_H
+#define _LIB_BASE64_FNAME_H
+#include <linux/types.h>
+
+#define BASE64_CHARS(nbytes)	DIV_ROUND_UP((nbytes) * 4, 3)
+
+int base64_encode_fname(const u8 *src, int len, char *dst);
+int base64_decode_fname(const char *src, int len, u8 *dst);
+#endif /* _LIB_BASE64_FNAME_H */
diff --git a/lib/Kconfig b/lib/Kconfig
index b4b98a03ff98..94f3939c4cfa 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -684,3 +684,6 @@ config GENERIC_LIB_UCMPDI2
 config PLDMFW
 	bool
 	default n
+
+config BASE64_FNAME
+	tristate
diff --git a/lib/Makefile b/lib/Makefile
index a4a4c6864f51..4e77167d6252 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -171,6 +171,7 @@ obj-$(CONFIG_LIBCRC32C)	+= libcrc32c.o
 obj-$(CONFIG_CRC8)	+= crc8.o
 obj-$(CONFIG_XXHASH)	+= xxhash.o
 obj-$(CONFIG_GENERIC_ALLOCATOR) += genalloc.o
+obj-$(CONFIG_BASE64_FNAME) += base64_fname.o
 
 obj-$(CONFIG_842_COMPRESS) += 842/
 obj-$(CONFIG_842_DECOMPRESS) += 842/
diff --git a/lib/base64_fname.c b/lib/base64_fname.c
new file mode 100644
index 000000000000..7638c45e4035
--- /dev/null
+++ b/lib/base64_fname.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Modified base64 encode/decode functions, suitable for use as filename components.
+ *
+ * Originally lifted from fs/crypto/fname.c
+ *
+ * Copyright (C) 2015, Jaegeuk Kim
+ * Copyright (C) 2015, Eric Biggers
+ */
+
+#include <linux/types.h>
+#include <linux/export.h>
+#include <linux/string.h>
+
+static const char lookup_table[65] =
+	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
+
+/**
+ * base64_encode() - base64-encode some bytes
+ * @src: the bytes to encode
+ * @len: number of bytes to encode
+ * @dst: (output) the base64-encoded string.  Not NUL-terminated.
+ *
+ * Encodes the input string using characters from the set [A-Za-z0-9+,].
+ * The encoded string is roughly 4/3 times the size of the input string.
+ *
+ * Return: length of the encoded string
+ */
+int base64_encode_fname(const u8 *src, int len, char *dst)
+{
+	int i, bits = 0, ac = 0;
+	char *cp = dst;
+
+	for (i = 0; i < len; i++) {
+		ac += src[i] << bits;
+		bits += 8;
+		do {
+			*cp++ = lookup_table[ac & 0x3f];
+			ac >>= 6;
+			bits -= 6;
+		} while (bits >= 6);
+	}
+	if (bits)
+		*cp++ = lookup_table[ac & 0x3f];
+	return cp - dst;
+}
+EXPORT_SYMBOL(base64_encode_fname);
+
+int base64_decode_fname(const char *src, int len, u8 *dst)
+{
+	int i, bits = 0, ac = 0;
+	const char *p;
+	u8 *cp = dst;
+
+	for (i = 0; i < len; i++) {
+		p = strchr(lookup_table, src[i]);
+		if (p == NULL || src[i] == 0)
+			return -2;
+		ac += (p - lookup_table) << bits;
+		bits += 6;
+		if (bits >= 8) {
+			*cp++ = ac & 0xff;
+			ac >>= 8;
+			bits -= 8;
+		}
+	}
+	if (ac)
+		return -1;
+	return cp - dst;
+}
+EXPORT_SYMBOL(base64_decode_fname);
-- 
2.26.2


  parent reply index

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-04 16:05 [RFC PATCH v2 00/18] ceph+fscrypt: context, filename and symlink support Jeff Layton
2020-09-04 16:05 ` [RFC PATCH v2 01/18] vfs: export new_inode_pseudo Jeff Layton
2020-09-08  3:38   ` Eric Biggers
2020-09-08 11:27     ` Jeff Layton
2020-09-08 22:31       ` Eric Biggers
2020-09-09 10:47         ` Jeff Layton
2020-09-09 16:12           ` Eric Biggers
2020-09-09 16:51             ` Jeff Layton
2020-09-09 18:49               ` Eric Biggers
2020-09-09 19:24                 ` Jeff Layton
2020-09-04 16:05 ` [RFC PATCH v2 02/18] fscrypt: drop unused inode argument from fscrypt_fname_alloc_buffer Jeff Layton
2020-09-04 16:05 ` [RFC PATCH v2 03/18] fscrypt: export fscrypt_d_revalidate Jeff Layton
2020-09-04 16:05 ` [RFC PATCH v2 04/18] fscrypt: add fscrypt_new_context_from_inode Jeff Layton
2020-09-08  3:48   ` Eric Biggers
2020-09-08 11:29     ` Jeff Layton
2020-09-08 12:29     ` Jeff Layton
2020-09-08 22:34       ` Eric Biggers
2020-09-04 16:05 ` [RFC PATCH v2 05/18] fscrypt: don't balk when inode is already marked encrypted Jeff Layton
2020-09-08  3:52   ` Eric Biggers
2020-09-08 12:54     ` Jeff Layton
2020-09-08 23:08       ` Eric Biggers
2020-09-04 16:05 ` [RFC PATCH v2 06/18] fscrypt: move nokey_name conversion to separate function and export it Jeff Layton
2020-09-08  3:55   ` Eric Biggers
2020-09-08 12:50     ` Jeff Layton
2020-09-08 22:53       ` Eric Biggers
2020-09-09 16:02         ` Jeff Layton
2020-09-04 16:05 ` Jeff Layton [this message]
2020-09-08  3:59   ` [RFC PATCH v2 07/18] lib: lift fscrypt base64 conversion into lib/ Eric Biggers
2020-09-08 12:51     ` Jeff Layton
2020-09-04 16:05 ` [RFC PATCH v2 08/18] ceph: add fscrypt ioctls Jeff Layton
2020-09-04 16:05 ` [RFC PATCH v2 09/18] ceph: crypto context handling for ceph Jeff Layton
2020-09-08  4:29   ` Eric Biggers
2020-09-08 16:14     ` Jeff Layton
2020-09-04 16:05 ` [RFC PATCH v2 10/18] ceph: preallocate inode for ops that may create one Jeff Layton
2020-09-04 16:05 ` [RFC PATCH v2 11/18] ceph: add routine to create context prior to RPC Jeff Layton
2020-09-08  4:43   ` Eric Biggers
2020-09-04 16:05 ` [RFC PATCH v2 12/18] ceph: set S_ENCRYPTED bit if new inode has encryption.ctx xattr Jeff Layton
2020-09-08  4:57   ` Eric Biggers
2020-09-09 12:20     ` Jeff Layton
2020-09-09 15:53     ` Jeff Layton
2020-09-09 16:33       ` Eric Biggers
2020-09-09 17:19         ` Jeff Layton
2020-09-04 16:05 ` [RFC PATCH v2 13/18] ceph: make ceph_msdc_build_path use ref-walk Jeff Layton
2020-09-04 16:05 ` [RFC PATCH v2 14/18] ceph: add encrypted fname handling to ceph_mdsc_build_path Jeff Layton
2020-09-08  5:06   ` Eric Biggers
2020-09-09 12:24     ` Jeff Layton
2020-09-04 16:05 ` [RFC PATCH v2 15/18] ceph: make d_revalidate call fscrypt revalidator for encrypted dentries Jeff Layton
2020-09-08  5:12   ` Eric Biggers
2020-09-09 12:26     ` Jeff Layton
2020-09-09 16:18       ` Eric Biggers
2020-09-04 16:05 ` [RFC PATCH v2 16/18] ceph: add support to readdir for encrypted filenames Jeff Layton
2020-09-08  5:34   ` Eric Biggers
2020-09-09 13:02     ` Jeff Layton
2020-09-04 16:05 ` [RFC PATCH v2 17/18] ceph: add fscrypt support to ceph_fill_trace Jeff Layton
2020-09-04 16:05 ` [RFC PATCH v2 18/18] ceph: create symlinks with encrypted and base64-encoded targets Jeff Layton
2020-09-04 16:11   ` Jeff Layton
2020-09-08  5:43   ` Eric Biggers
2020-09-08  5:54 ` [RFC PATCH v2 00/18] ceph+fscrypt: context, filename and symlink support Eric Biggers
2020-09-08 12:09   ` Jeff Layton

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