This patch is to support the following ext4 crypto change.
commit 28b4c263961c47da84ed8b5be0b5116bad1133eb
Author: Theodore Ts'o <ty...@mit.edu>
Date: Sun Feb 7 19:35:05 2016 -0500
ext4 crypto: revalidate dentry after adding or removing the key
Cc: Theodore Ts'o <ty...@mit.edu>
Cc: Al Viro <v...@ftp.linux.org.uk>
Signed-off-by: Jaegeuk Kim <jaeg...@kernel.org>
---
fs/crypto/crypto.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/dcache.h | 2 ++
include/linux/fscrypto.h | 20 ++++++++++++++++++++
3 files changed, 71 insertions(+)
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 928a34b..96b18a7 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -27,6 +27,7 @@
#include <linux/scatterlist.h>
#include <linux/ratelimit.h>
#include <linux/bio.h>
+#include <linux/dcache.h>
#include <linux/fscrypto.h>
static unsigned int num_prealloc_crypto_pages = 32;
@@ -339,6 +340,54 @@ errout:
EXPORT_SYMBOL(fscrypt_zeroout_range);
/*
+ * Validate dentries for encrypted directories to make sure we aren't
+ * potentially caching stale data after a key has been added or
+ * removed.
+ */
+static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
+{
+ struct inode *dir = d_inode(dentry->d_parent);
+ struct fscrypt_info *ci = dir->i_crypt_info;
+ int dir_has_key, cached_with_key;
+
+ if (!dir->i_sb->s_cop->is_encrypted(dir))
+ return 0;
+
+ if (ci && ci->ci_keyring_key &&
+ (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) |
+ (1 << KEY_FLAG_REVOKED) |
+ (1 << KEY_FLAG_DEAD))))
+ ci = NULL;
+
+ /* this should eventually be an flag in d_flags */
+ spin_lock(&dentry->d_lock);
+ cached_with_key = dentry->d_flags & DCACHE_ENCRYPTED_WITH_KEY;
+ spin_unlock(&dentry->d_lock);
+ dir_has_key = (ci != NULL);
+
+ /*
+ * If the dentry was cached without the key, and it is a
+ * negative dentry, it might be a valid name. We can't check
+ * if the key has since been made available due to locking
+ * reasons, so we fail the validation so ext4_lookup() can do
+ * this check.
+ *
+ * We also fail the validation if the dentry was created with
+ * the key present, but we no longer have the key, or vice versa.
+ */
+ if ((!cached_with_key && d_is_negative(dentry)) ||
+ (!cached_with_key && dir_has_key) ||
+ (cached_with_key && !dir_has_key))
+ return 0;
+ return 1;
+}
+
+const struct dentry_operations fscrypt_d_ops = {
+ .d_revalidate = fscrypt_d_revalidate,
+};
+EXPORT_SYMBOL(fscrypt_d_ops);
+
+/*
* Call fscrypt_decrypt_page on every single page, reusing the encryption
* context.
*/
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 7781ce11..c7bdfc5 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -228,6 +228,8 @@ struct dentry_operations {
#define DCACHE_FALLTHRU 0x01000000 /* Fall through to
lower layer */
#define DCACHE_OP_SELECT_INODE 0x02000000 /* Unioned entry: dcache op
selects inode */
+#define DCACHE_ENCRYPTED_WITH_KEY 0x04000000 /* dir is encrypted with a
valid key */
+
extern seqlock_t rename_lock;
/*
diff --git a/include/linux/fscrypto.h b/include/linux/fscrypto.h
index 144541b..895cdac 100644
--- a/include/linux/fscrypto.h
+++ b/include/linux/fscrypto.h
@@ -237,6 +237,26 @@ static inline int fscrypt_has_encryption_key(struct inode
*inode)
#endif
}
+static inline void fscrypt_set_encrypted_dentry(struct dentry *dentry)
+{
+#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
+ spin_lock(&dentry->d_lock);
+ dentry->d_flags |= DCACHE_ENCRYPTED_WITH_KEY;
+ spin_unlock(&dentry->d_lock);
+#endif
+}
+
+#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
+extern const struct dentry_operations fscrypt_d_ops;
+#endif
+
+static inline void fscrypt_set_d_op(struct dentry *dentry)
+{
+#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
+ d_set_d_op(dentry, &fscrypt_d_ops);
+#endif
+}
+
#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
/* crypto.c */
extern struct kmem_cache *fscrypt_info_cachep;
--
2.6.3
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