--- /dev/null
+commit d0a722cb8fb886380e24e8261e8efca09a3262d6
+Author: Sebastien Buisson <sbuisson@ddn.com>
+AuthorDate: Tue Dec 20 15:40:52 2022 +0100
+Commit: Oleg Drokin <green@whamcloud.com>
+CommitDate: Thu Aug 31 06:28:45 2023 +0000
+LU-16374 ldiskfs: implement security.encdata xattr
+
+security.encdata is a virtual xattr containing information related
+to encrypted files. It is expressed as ASCII text with a "key: value"
+format, and space as field separator. For instance:
+
+ { encoding: base64url, size: 3012, enc_ctx: YWJjZGVmZ2hpamtsbW
+ 5vcHFyc3R1dnd4eXphYmNkZWZnaGlqa2xtbg, enc_name: ZmlsZXdpdGh2ZX
+ J5bG9uZ25hbWVmaWxld2l0aHZlcnlsb25nbmFtZWZpbGV3aXRodmVyeWxvbmdu
+ YW1lZmlsZXdpdGg }
+
+'encoding' is the encoding method used for binary data, assume name
+can be up to 255 chars.
+'size' is the clear text file data length in bytes.
+'enc_ctx' is encoded encryption context, 40 bytes for v2.
+'enc_name' is encoded encrypted name, 256 bytes max.
+So on overall, this xattr is at most 727 chars plus terminating '0'.
+
+On get, the value of the security.encdata xattr is computed from
+encrypted file's information.
+On set, encrypted file's information is restored from xattr value.
+The encrypted name is stored temporarily in a dedicated xattr
+LDISKFS_XATTR_NAME_RAWENCNAME, that will be used to set correct name
+at linkat.
+
+Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
+Change-Id: Ia318c39d403b1c448e71bcd5b29862d022d05d0a
+Reviewed-on: https://review.whamcloud.com/49456
+Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
+Reviewed-by: Li Dongyang <dongyangli@ddn.com>
+---
+ fs/ext4/encdata.h | 128 ++++++++++++++++++++++++
+ fs/ext4/inode.c | 6 ++
+ fs/ext4/super.c | 8 ++
+ fs/ext4/xattr.h | 2 +
+ fs/ext4/xattr_security.c | 209 ++++++++++++++++++++++++++++++++++++++-
+ 5 files changed, 352 insertions(+), 1 deletion(-)
+ create mode 100644 fs/ext4/encdata.h
+
+diff --git a/fs/ext4/encdata.h b/fs/ext4/encdata.h
+new file mode 100644
+index 00000000..aa83832f
+--- /dev/null
++++ b/fs/ext4/encdata.h
+@@ -0,0 +1,128 @@
++/*
++ * encdata.h
++ *
++ * Copyright (c) 2022 Whamcloud
++ */
++
++#ifndef _ENCDATA_H
++#define _ENCDATA_H
++
++/* Define a fixed 4096-byte encryption unit size */
++/* Must be identical to LUSTRE_ENCRYPTION_UNIT_SIZE */
++#define EXT4_ENCRYPTION_BLOCKBITS 12
++#define EXT4_ENCRYPTION_UNIT_SIZE ((size_t)1 << EXT4_ENCRYPTION_BLOCKBITS)
++#define EXT4_ENCRYPTION_MASK (~(EXT4_ENCRYPTION_UNIT_SIZE - 1))
++#define LLCRYPT_SET_CONTEXT_MAX_SIZE 40
++#define ENCDATA_XATTR_FMT_1 "{ encoding: "
++#define ENCDATA_XATTR_FMT_2 ", size: "
++#define ENCDATA_XATTR_FMT_3 ", enc_ctx: "
++#define ENCDATA_XATTR_FMT_4 ", enc_name: "
++#define ENCDATA_XATTR_FMT_END " }"
++#define ENCDATA_XATTR_FMT_COMP ENCDATA_XATTR_FMT_1 ENCDATA_XATTR_FMT_2 \
++ ENCDATA_XATTR_FMT_3 ENCDATA_XATTR_FMT_4 \
++ ENCDATA_XATTR_FMT_END
++
++extern char encdata_xattr_fmt[NAME_MAX];
++
++/*
++ * base64url encoding, lifted from fs/crypto/fname.c.
++ */
++
++static const char base64url_table[] =
++ "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
++
++#define BASE64URL_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3)
++
++/**
++ * base64url_encode() - base64url-encode some binary data
++ * @src: the binary data to encode
++ * @srclen: the length of @src in bytes
++ * @dst: (output) the base64url-encoded string. Not NUL-terminated.
++ *
++ * Encodes data using base64url encoding, i.e. the "Base 64 Encoding with URL
++ * and Filename Safe Alphabet" specified by RFC 4648. '='-padding isn't used,
++ * as it's unneeded and not required by the RFC. base64url is used instead of
++ * base64 to avoid the '/' character, which isn't allowed in filenames.
++ *
++ * Return: the length of the resulting base64url-encoded string in bytes.
++ * This will be equal to LLCRYPT_BASE64URL_CHARS(srclen).
++ */
++static inline int base64url_encode(const u8 *src, int srclen, char *dst)
++{
++ u32 ac = 0;
++ int bits = 0;
++ int i;
++ char *cp = dst;
++
++ for (i = 0; i < srclen; i++) {
++ ac = (ac << 8) | src[i];
++ bits += 8;
++ do {
++ bits -= 6;
++ *cp++ = base64url_table[(ac >> bits) & 0x3f];
++ } while (bits >= 6);
++ }
++ if (bits)
++ *cp++ = base64url_table[(ac << (6 - bits)) & 0x3f];
++ return cp - dst;
++}
++
++/**
++ * base64url_decode() - base64url-decode a string
++ * @src: the string to decode. Doesn't need to be NUL-terminated.
++ * @srclen: the length of @src in bytes
++ * @dst: (output) the decoded binary data
++ *
++ * Decodes a string using base64url encoding, i.e. the "Base 64 Encoding with
++ * URL and Filename Safe Alphabet" specified by RFC 4648. '='-padding isn't
++ * accepted, nor are non-encoding characters such as whitespace.
++ *
++ * This implementation hasn't been optimized for performance.
++ *
++ * Return: the length of the resulting decoded binary data in bytes,
++ * or -1 if the string isn't a valid base64url string.
++ */
++static inline int base64url_decode(const char *src, int srclen, u8 *dst)
++{
++ u32 ac = 0;
++ int bits = 0;
++ int i;
++ u8 *bp = dst;
++
++ for (i = 0; i < srclen; i++) {
++ const char *p = strchr(base64url_table, src[i]);
++
++ if (p == NULL || src[i] == 0)
++ return -1;
++ ac = (ac << 6) | (p - base64url_table);
++ bits += 6;
++ if (bits >= 8) {
++ bits -= 8;
++ *bp++ = (u8)(ac >> bits);
++ }
++ }
++ if (ac & ((1 << bits) - 1))
++ return -1;
++ return bp - dst;
++}
++
++/* This version of the code uses base64url encoding for binary data. */
++#define ENCDATA_ENCODING "base64url"
++
++/* Wrappers to support various encodings. Add new methods in there.
++ */
++static inline int encode(const u8 *src, int srclen, char *dst, char *encoding)
++{
++ if (!strcmp(encoding, "base64url"))
++ return base64url_encode(src, srclen, dst);
++ return -EINVAL;
++}
++
++static inline int decode(const char *src, int srclen, u8 *dst, char *encoding)
++{
++ if (!strcmp(encoding, "base64url"))
++ return base64url_decode(src, srclen, dst);
++ return -EINVAL;
++}
++
++#endif /* _ENCDATA_H */
+diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
+index 9256cf36..e8a665fa 100644
+--- a/fs/ext4/inode.c
++++ b/fs/ext4/inode.c
+@@ -47,6 +47,7 @@
+ #include "xattr.h"
+ #include "acl.h"
+ #include "truncate.h"
++#include "encdata.h"
+
+ #include <trace/events/ext4.h>
+
+@@ -5775,6 +5776,11 @@ int ext4_getattr(struct mnt_idmap *idmap, const struct path *path,
+ STATX_ATTR_NODUMP |
+ STATX_ATTR_VERITY);
+
++ if (flags & EXT4_ENCRYPT_FL &&
++ unlikely(!IS_LUSTRE_MOUNT(inode->i_sb)))
++ stat->size = round_up(stat->size,
++ EXT4_ENCRYPTION_UNIT_SIZE);
++
+ generic_fillattr(idmap, inode, stat);
+ return 0;
+ }
+diff --git a/fs/ext4/super.c b/fs/ext4/super.c
+index 0468d740..05d6ce05 100644
+--- a/fs/ext4/super.c
++++ b/fs/ext4/super.c
+@@ -55,6 +55,7 @@
+ #include "acl.h"
+ #include "mballoc.h"
+ #include "fsmap.h"
++#include "encdata.h"
+
+ #define CREATE_TRACE_POINTS
+ #include <trace/events/ext4.h>
+@@ -7424,6 +7425,7 @@ MODULE_ALIAS_FS("ext4");
+
+ /* Shared across all ext4 file systems */
+ wait_queue_head_t ext4__ioend_wq[EXT4_WQ_HASH_SZ];
++char encdata_xattr_fmt[NAME_MAX];
+
+ static int __init ext4_init_fs(void)
+ {
+@@ -7477,6 +7479,12 @@ static int __init ext4_init_fs(void)
+ if (err)
+ goto out;
+
++ snprintf(encdata_xattr_fmt, sizeof(encdata_xattr_fmt),
++ ENCDATA_XATTR_FMT_1"%%%u[^,]"ENCDATA_XATTR_FMT_2"%%llu"
++ ENCDATA_XATTR_FMT_3"%%%us"ENCDATA_XATTR_FMT_4"%%%us",
++ NAME_MAX, BASE64URL_CHARS(LLCRYPT_SET_CONTEXT_MAX_SIZE),
++ BASE64URL_CHARS(NAME_MAX));
++
+ return 0;
+ out:
+ ext4_fc_destroy_dentry_cache();
+diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h
+index 824faf0b..1e8aa6f2 100644
+--- a/fs/ext4/xattr.h
++++ b/fs/ext4/xattr.h
+@@ -140,6 +140,8 @@ extern const struct xattr_handler ext4_xattr_security_handler;
+ extern const struct xattr_handler ext4_xattr_hurd_handler;
+
+ #define EXT4_XATTR_NAME_ENCRYPTION_CONTEXT "c"
++#define EXT4_XATTR_NAME_ENCDATA "encdata"
++#define EXT4_XATTR_NAME_RAWENCNAME "rawencname"
+
+ /*
+ * The EXT4_STATE_NO_EXPAND is overloaded and used for two purposes.
+diff --git a/fs/ext4/xattr_security.c b/fs/ext4/xattr_security.c
+index 776cf11d..80cad6e0 100644
+--- a/fs/ext4/xattr_security.c
++++ b/fs/ext4/xattr_security.c
+@@ -10,13 +10,217 @@
+ #include <linux/slab.h>
+ #include "ext4_jbd2.h"
+ #include "ext4.h"
++#include "critical_encode.h"
++#include "encdata.h"
+ #include "xattr.h"
+
++/* security.encdata is a virtual xattr containing information related
++ * to encrypted files. It is expressed as ASCII text with a "key: value"
++ * format, and space as field separator. For instance:
++ *
++ * { encoding: base64url, size: 3012, enc_ctx: YWJjZGVmZ2hpamtsbW
++ * 5vcHFyc3R1dnd4eXphYmNkZWZnaGlqa2xtbg, enc_name: ZmlsZXdpdGh2ZX
++ * J5bG9uZ25hbWVmaWxld2l0aHZlcnlsb25nbmFtZWZpbGV3aXRodmVyeWxvbmdu
++ * YW1lZmlsZXdpdGg }
++ *
++ * 'encoding' is the encoding method used for binary data, assume name
++ * can be up to 255 chars.
++ * 'size' is the clear text file data length in bytes.
++ * 'enc_ctx' is encoded encryption context, 40 bytes for v2.
++ * 'enc_name' is encoded encrypted name, 256 bytes max.
++ * So on overall, this xattr is at most 727 chars plus terminating '\0'.
++ */
++static int ext4_build_xattr_encdata(struct dentry *dentry,
++ struct inode *inode,
++ void *buffer, size_t size)
++{
++ char encoded_enc_ctx[BASE64URL_CHARS(LLCRYPT_SET_CONTEXT_MAX_SIZE) + 1];
++ unsigned char enc_ctx[LLCRYPT_SET_CONTEXT_MAX_SIZE];
++ char encoded_name[BASE64URL_CHARS(NAME_MAX) + 1];
++ struct ext4_filename fname = { 0 };
++ struct inode *parent = NULL;
++ int encoded_enc_ctx_len = 0;
++ int encoded_name_len = 0;
++ char size_str[32];
++ int retval;
++
++ if (!IS_ENCRYPTED(inode)) {
++ retval = -ENODATA;
++ goto out;
++ }
++
++ /* get size */
++ retval = snprintf(size_str, sizeof(size_str), "%llu",
++ S_ISDIR(inode->i_mode) ? 0 : inode->i_size);
++ if (retval >= sizeof(size_str)) {
++ retval = -ERANGE;
++ goto out;
++ }
++
++ /* get raw name */
++ if (dentry && dentry->d_parent)
++ parent = dentry->d_parent->d_inode;
++
++ retval = ext4_setup_filename(parent, &dentry->d_name, 1, &fname);
++ if (retval)
++ goto out;
++
++ /* base64url-encode raw name */
++ encoded_name_len = encode(fname.disk_name.name, fname.disk_name.len,
++ encoded_name, ENCDATA_ENCODING);
++ if (encoded_name_len == -EINVAL) {
++ retval = -EINVAL;
++ goto out;
++ }
++ encoded_name[encoded_name_len] = '\0';
++
++ if (!buffer) {
++ /* Return exact xattr length we would return if called with
++ * non-NULL buffer.
++ */
++ retval = sizeof(ENCDATA_XATTR_FMT_COMP) - 1 +
++ sizeof(ENCDATA_ENCODING) - 1 + strlen(size_str) +
++ BASE64URL_CHARS(LLCRYPT_SET_CONTEXT_MAX_SIZE) +
++ encoded_name_len;
++ goto out;
++ }
++
++ /* get encryption context */
++ retval = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,
++ EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
++ enc_ctx, sizeof(enc_ctx));
++
++ if (retval < 0)
++ goto out;
++
++ /* base64url-encode encryption context */
++ encoded_enc_ctx_len = encode(enc_ctx, retval, encoded_enc_ctx,
++ ENCDATA_ENCODING);
++ if (encoded_enc_ctx_len == -EINVAL) {
++ retval = -EINVAL;
++ goto out;
++ }
++ encoded_enc_ctx[encoded_enc_ctx_len] = '\0';
++
++ /* write EXT4_XATTR_ENCDATA info into buffer */
++ retval = snprintf(buffer, size,
++ ENCDATA_XATTR_FMT_1 ENCDATA_ENCODING
++ ENCDATA_XATTR_FMT_2"%s"ENCDATA_XATTR_FMT_3"%s"
++ ENCDATA_XATTR_FMT_4"%s"ENCDATA_XATTR_FMT_END,
++ size_str, encoded_enc_ctx,
++ encoded_name_len ? encoded_name : "");
++ if (retval >= size)
++ retval = -ERANGE;
++
++out:
++ if (fname.disk_name.name != dentry->d_name.name)
++ kfree(fname.disk_name.name);
++
++ return retval;
++}
++
++static int ext4_process_xattr_encdata(struct inode *inode,
++ const void *value, size_t size,
++ int flags)
++{
++ char encoded_enc_ctx[BASE64URL_CHARS(LLCRYPT_SET_CONTEXT_MAX_SIZE) + 1];
++ unsigned char enc_ctx[LLCRYPT_SET_CONTEXT_MAX_SIZE];
++ char encoded_name[BASE64URL_CHARS(NAME_MAX) + 1];
++ char encoding[NAME_MAX + 1];
++ char name[NAME_MAX + 1];
++ loff_t disk_size = 0;
++ char *buffer = NULL;
++ int enc_ctx_len = 0;
++ int name_len = 0;
++ int retval = 0;
++
++ if (IS_ENCRYPTED(inode) || !value || flags & XATTR_REPLACE) {
++ retval = -EINVAL;
++ goto out;
++ }
++
++ buffer = kmalloc(size + 1, GFP_NOFS);
++ if (!buffer) {
++ retval = -ENOMEM;
++ goto out;
++ }
++ memcpy(buffer, value, size);
++ buffer[size] = '\0';
++
++ retval = sscanf(buffer, encdata_xattr_fmt,
++ encoding, &disk_size, encoded_enc_ctx, encoded_name);
++ if (retval < 4) {
++ retval = -EINVAL;
++ goto out;
++ }
++
++ /* get former encryption context: should not exist */
++ retval = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,
++ EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, NULL, 0);
++ if (retval != -ENODATA) {
++ retval = -EINVAL;
++ goto out;
++ }
++
++ if (strlen(encoded_enc_ctx) >
++ BASE64URL_CHARS(LLCRYPT_SET_CONTEXT_MAX_SIZE)) {
++ retval = -EINVAL;
++ goto out;
++ }
++
++ /* base64url-decode encryption context */
++ retval = decode(encoded_enc_ctx, strlen(encoded_enc_ctx),
++ enc_ctx, encoding);
++ if (retval < 0) {
++ retval = -EINVAL;
++ goto out;
++ }
++ enc_ctx_len = retval;
++
++ /* set encryption context, this will set encryption flag */
++ retval = ext4_xattr_set(inode, EXT4_XATTR_INDEX_ENCRYPTION,
++ EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
++ enc_ctx, enc_ctx_len, XATTR_CREATE);
++ if (retval < 0)
++ goto out;
++
++ if (disk_size) {
++ /* set size on inode */
++ spin_lock(&inode->i_lock);
++ i_size_write(inode, disk_size);
++ EXT4_I(inode)->i_disksize = disk_size;
++ spin_unlock(&inode->i_lock);
++ mark_inode_dirty(inode);
++ }
++
++ /* put raw encrypted name in EXT4_XATTR_NAME_RAWENCNAME xattr,
++ * for later use, but base64url-decode first
++ */
++ retval = decode(encoded_name, strlen(encoded_name), name, encoding);
++ if (retval < 0) {
++ retval = -EINVAL;
++ goto out;
++ }
++ name_len = retval;
++
++ retval = ext4_xattr_set(inode, EXT4_XATTR_INDEX_LUSTRE,
++ EXT4_XATTR_NAME_RAWENCNAME,
++ name, name_len, XATTR_CREATE);
++
++out:
++ kfree(buffer);
++
++ return retval;
++}
++
+ static int
+ ext4_xattr_security_get(const struct xattr_handler *handler,
+- struct dentry *unused, struct inode *inode,
++ struct dentry *dentry, struct inode *inode,
+ const char *name, void *buffer, size_t size)
+ {
++ if (!strncmp(name, EXT4_XATTR_NAME_ENCDATA, strlen(name)))
++ return ext4_build_xattr_encdata(dentry, inode, buffer, size);
++
+ return ext4_xattr_get(inode, EXT4_XATTR_INDEX_SECURITY,
+ name, buffer, size);
+ }
+@@ -28,6 +232,9 @@ ext4_xattr_security_set(const struct xattr_handler *handler,
+ const char *name, const void *value,
+ size_t size, int flags)
+ {
++ if (!strncmp(name, EXT4_XATTR_NAME_ENCDATA, strlen(name)))
++ return ext4_process_xattr_encdata(inode, value, size, flags);
++
+ return ext4_xattr_set(inode, EXT4_XATTR_INDEX_SECURITY,
+ name, value, size, flags);
+ }
+--
+2.45.2
+
git://git.whamcloud.com / fs / lustre-release.git / commitdiff