From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/fs/crypto/hooks.c | 122 +++++++++++++++++++++++++---------------
1 files changed, 77 insertions(+), 45 deletions(-)
diff --git a/kernel/fs/crypto/hooks.c b/kernel/fs/crypto/hooks.c
index 7173233..be5c650 100644
--- a/kernel/fs/crypto/hooks.c
+++ b/kernel/fs/crypto/hooks.c
@@ -1,10 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
* fs/crypto/hooks.c
*
* Encryption hooks for higher-level filesystem operations.
*/
-
-#include <linux/key.h>
#include "fscrypt_private.h"
@@ -53,15 +52,12 @@
int __fscrypt_prepare_link(struct inode *inode, struct inode *dir,
struct dentry *dentry)
{
- int err;
-
- err = fscrypt_require_key(dir);
- if (err)
- return err;
-
- /* ... in case we looked up no-key name before key was added */
if (fscrypt_is_nokey_name(dentry))
return -ENOKEY;
+ /*
+ * We don't need to separately check that the directory inode's key is
+ * available, as it's implied by the dentry not being a no-key name.
+ */
if (!fscrypt_has_permitted_context(dir, inode))
return -EXDEV;
@@ -74,20 +70,13 @@
struct inode *new_dir, struct dentry *new_dentry,
unsigned int flags)
{
- int err;
-
- err = fscrypt_require_key(old_dir);
- if (err)
- return err;
-
- err = fscrypt_require_key(new_dir);
- if (err)
- return err;
-
- /* ... in case we looked up no-key name(s) before key was added */
if (fscrypt_is_nokey_name(old_dentry) ||
fscrypt_is_nokey_name(new_dentry))
return -ENOKEY;
+ /*
+ * We don't need to separately check that the directory inodes' keys are
+ * available, as it's implied by the dentries not being no-key names.
+ */
if (old_dir != new_dir) {
if (IS_ENCRYPTED(new_dir) &&
@@ -113,14 +102,28 @@
if (err && err != -ENOENT)
return err;
- if (fname->is_ciphertext_name) {
+ if (fname->is_nokey_name) {
spin_lock(&dentry->d_lock);
- dentry->d_flags |= DCACHE_ENCRYPTED_NAME;
+ dentry->d_flags |= DCACHE_NOKEY_NAME;
spin_unlock(&dentry->d_lock);
}
return err;
}
EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup);
+
+int __fscrypt_prepare_readdir(struct inode *dir)
+{
+ return fscrypt_get_encryption_info(dir, true);
+}
+EXPORT_SYMBOL_GPL(__fscrypt_prepare_readdir);
+
+int __fscrypt_prepare_setattr(struct dentry *dentry, struct iattr *attr)
+{
+ if (attr->ia_valid & ATTR_SIZE)
+ return fscrypt_require_key(d_inode(dentry));
+ return 0;
+}
+EXPORT_SYMBOL_GPL(__fscrypt_prepare_setattr);
/**
* fscrypt_prepare_setflags() - prepare to change flags with FS_IOC_SETFLAGS
@@ -152,38 +155,63 @@
ci = inode->i_crypt_info;
if (ci->ci_policy.version != FSCRYPT_POLICY_V2)
return -EINVAL;
- mk = ci->ci_master_key->payload.data[0];
- down_read(&mk->mk_secret_sem);
+ mk = ci->ci_master_key;
+ down_read(&mk->mk_sem);
if (is_master_key_secret_present(&mk->mk_secret))
err = fscrypt_derive_dirhash_key(ci, mk);
else
err = -ENOKEY;
- up_read(&mk->mk_secret_sem);
+ up_read(&mk->mk_sem);
return err;
}
return 0;
}
-int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
- unsigned int max_len,
- struct fscrypt_str *disk_link)
+/**
+ * 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.
+ */
+int fscrypt_prepare_symlink(struct inode *dir, const char *target,
+ unsigned int len, unsigned int max_len,
+ struct fscrypt_str *disk_link)
{
- int err;
+ const union fscrypt_policy *policy;
/*
* 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;
+ policy = fscrypt_policy_to_inherit(dir);
+ if (policy == NULL) {
+ /* Not encrypted */
+ disk_link->name = (unsigned char *)target;
+ disk_link->len = len + 1;
+ if (disk_link->len > max_len)
+ return -ENAMETOOLONG;
+ return 0;
+ }
+ if (IS_ERR(policy))
+ return PTR_ERR(policy);
/*
* Calculate the size of the encrypted symlink and verify it won't
@@ -196,7 +224,7 @@
* counting it (even though it is meaningless for ciphertext) is simpler
* for now since filesystems will assume it is there and subtract it.
*/
- if (!fscrypt_fname_encrypted_size(dir, len,
+ if (!fscrypt_fname_encrypted_size(policy, len,
max_len - sizeof(struct fscrypt_symlink_data),
&disk_link->len))
return -ENAMETOOLONG;
@@ -205,7 +233,7 @@
disk_link->name = NULL;
return 0;
}
-EXPORT_SYMBOL_GPL(__fscrypt_prepare_symlink);
+EXPORT_SYMBOL_GPL(fscrypt_prepare_symlink);
int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
unsigned int len, struct fscrypt_str *disk_link)
@@ -215,9 +243,13 @@
struct fscrypt_symlink_data *sd;
unsigned int ciphertext_len;
- err = fscrypt_require_key(inode);
- if (err)
- return err;
+ /*
+ * fscrypt_prepare_new_inode() should have already set up the new
+ * symlink inode's encryption key. We don't wait until now to do it,
+ * since we may be in a filesystem transaction now.
+ */
+ if (WARN_ON_ONCE(!fscrypt_has_encryption_key(inode)))
+ return -ENOKEY;
if (disk_link->name) {
/* filesystem-provided buffer */
@@ -295,7 +327,7 @@
* 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);
+ err = fscrypt_get_encryption_info(inode, false);
if (err)
return ERR_PTR(err);
has_key = fscrypt_has_encryption_key(inode);
@@ -317,7 +349,7 @@
if (cstr.len + sizeof(*sd) - 1 > max_size)
return ERR_PTR(-EUCLEAN);
- err = fscrypt_fname_alloc_buffer(inode, cstr.len, &pstr);
+ err = fscrypt_fname_alloc_buffer(cstr.len, &pstr);
if (err)
return ERR_PTR(err);
--
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