[mirror_ubuntu-hirsute-kernel.git] / fs / crypto / hooks.c

/*
 * fs/crypto/hooks.c
 *
 * Encryption hooks for higher-level filesystem operations.
 */

#include <linux/ratelimit.h>
#include "fscrypt_private.h"

/**
 * fscrypt_file_open - prepare to open a possibly-encrypted regular file
 * @inode: the inode being opened
 * @filp: the struct file being set up
 *
 * Currently, an encrypted regular file can only be opened if its encryption key
 * is available; access to the raw encrypted contents is not supported.
 * Therefore, we first set up the inode's encryption key (if not already done)
 * and return an error if it's unavailable.
 *
 * We also verify that if the parent directory (from the path via which the file
 * is being opened) is encrypted, then the inode being opened uses the same
 * encryption policy.  This is needed as part of the enforcement that all files
 * in an encrypted directory tree use the same encryption policy, as a
 * protection against certain types of offline attacks.  Note that this check is
 * needed even when opening an *unencrypted* file, since it's forbidden to have
 * an unencrypted file in an encrypted directory.
 *
 * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
 */
int fscrypt_file_open(struct inode *inode, struct file *filp)
{
	int err;
	struct dentry *dir;

	err = fscrypt_require_key(inode);
	if (err)
		return err;

	dir = dget_parent(file_dentry(filp));
	if (IS_ENCRYPTED(d_inode(dir)) &&
	    !fscrypt_has_permitted_context(d_inode(dir), inode)) {
		pr_warn_ratelimited("fscrypt: inconsistent encryption contexts: %lu/%lu",
				    d_inode(dir)->i_ino, inode->i_ino);
		err = -EPERM;
	}
	dput(dir);
	return err;
}
EXPORT_SYMBOL_GPL(fscrypt_file_open);

int __fscrypt_prepare_link(struct inode *inode, struct inode *dir)
{
	int err;

	err = fscrypt_require_key(dir);
	if (err)
		return err;

	if (!fscrypt_has_permitted_context(dir, inode))
		return -EPERM;

	return 0;
}
EXPORT_SYMBOL_GPL(__fscrypt_prepare_link);

int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry,
			     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;

	if (old_dir != new_dir) {
		if (IS_ENCRYPTED(new_dir) &&
		    !fscrypt_has_permitted_context(new_dir,
						   d_inode(old_dentry)))
			return -EPERM;

		if ((flags & RENAME_EXCHANGE) &&
		    IS_ENCRYPTED(old_dir) &&
		    !fscrypt_has_permitted_context(old_dir,
						   d_inode(new_dentry)))
			return -EPERM;
	}
	return 0;
}
EXPORT_SYMBOL_GPL(__fscrypt_prepare_rename);

int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry)
{
	int err = fscrypt_get_encryption_info(dir);

	if (err)
		return err;

	if (fscrypt_has_encryption_key(dir)) {
		spin_lock(&dentry->d_lock);
		dentry->d_flags |= DCACHE_ENCRYPTED_WITH_KEY;
		spin_unlock(&dentry->d_lock);
	}

	d_set_d_op(dentry, &fscrypt_d_ops);
	return 0;
}
EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup);
Commit	Line	Data
efcc7ae2 EB	1	/*
	2	* fs/crypto/hooks.c
	3	*
	4	* Encryption hooks for higher-level filesystem operations.
	5	*/
	6
	7	#include <linux/ratelimit.h>
	8	#include "fscrypt_private.h"
	9
	10	/**
	11	* fscrypt_file_open - prepare to open a possibly-encrypted regular file
	12	* @inode: the inode being opened
	13	* @filp: the struct file being set up
	14	*
	15	* Currently, an encrypted regular file can only be opened if its encryption key
	16	* is available; access to the raw encrypted contents is not supported.
	17	* Therefore, we first set up the inode's encryption key (if not already done)
	18	* and return an error if it's unavailable.
	19	*
	20	* We also verify that if the parent directory (from the path via which the file
	21	* is being opened) is encrypted, then the inode being opened uses the same
	22	* encryption policy. This is needed as part of the enforcement that all files
	23	* in an encrypted directory tree use the same encryption policy, as a
	24	* protection against certain types of offline attacks. Note that this check is
	25	* needed even when opening an unencrypted file, since it's forbidden to have
	26	* an unencrypted file in an encrypted directory.
	27	*
	28	* Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
	29	*/
	30	int fscrypt_file_open(struct inode inode, struct file filp)
	31	{
	32	int err;
	33	struct dentry *dir;
	34
	35	err = fscrypt_require_key(inode);
	36	if (err)
	37	return err;
	38
	39	dir = dget_parent(file_dentry(filp));
	40	if (IS_ENCRYPTED(d_inode(dir)) &&
	41	!fscrypt_has_permitted_context(d_inode(dir), inode)) {
	42	pr_warn_ratelimited("fscrypt: inconsistent encryption contexts: %lu/%lu",
	43	d_inode(dir)->i_ino, inode->i_ino);
	44	err = -EPERM;
	45	}
	46	dput(dir);
	47	return err;
	48	}
	49	EXPORT_SYMBOL_GPL(fscrypt_file_open);
0ea87a96 EB	50
	51	int __fscrypt_prepare_link(struct inode inode, struct inode dir)
	52	{
	53	int err;
	54
	55	err = fscrypt_require_key(dir);
	56	if (err)
	57	return err;
	58
	59	if (!fscrypt_has_permitted_context(dir, inode))
	60	return -EPERM;
	61
	62	return 0;
	63	}
	64	EXPORT_SYMBOL_GPL(__fscrypt_prepare_link);
94b26f36 EB	65
	66	int __fscrypt_prepare_rename(struct inode old_dir, struct dentry old_dentry,
	67	struct inode new_dir, struct dentry new_dentry,
	68	unsigned int flags)
	69	{
	70	int err;
	71
	72	err = fscrypt_require_key(old_dir);
	73	if (err)
	74	return err;
	75
	76	err = fscrypt_require_key(new_dir);
	77	if (err)
	78	return err;
	79
	80	if (old_dir != new_dir) {
	81	if (IS_ENCRYPTED(new_dir) &&
	82	!fscrypt_has_permitted_context(new_dir,
	83	d_inode(old_dentry)))
	84	return -EPERM;
	85
	86	if ((flags & RENAME_EXCHANGE) &&
	87	IS_ENCRYPTED(old_dir) &&
	88	!fscrypt_has_permitted_context(old_dir,
	89	d_inode(new_dentry)))
	90	return -EPERM;
	91	}
	92	return 0;
	93	}
	94	EXPORT_SYMBOL_GPL(__fscrypt_prepare_rename);
32c3cf02 EB	95
	96	int __fscrypt_prepare_lookup(struct inode dir, struct dentry dentry)
	97	{
	98	int err = fscrypt_get_encryption_info(dir);
	99
	100	if (err)
	101	return err;
	102
	103	if (fscrypt_has_encryption_key(dir)) {
	104	spin_lock(&dentry->d_lock);
	105	dentry->d_flags \|= DCACHE_ENCRYPTED_WITH_KEY;
	106	spin_unlock(&dentry->d_lock);
	107	}
	108
	109	d_set_d_op(dentry, &fscrypt_d_ops);
	110	return 0;
	111	}
	112	EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup);