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Ts'o" , Jaegeuk Kim , Eric Biggers , Chris Mason , Josef Bacik , David Sterba , linux-fscrypt@vger.kernel.org, linux-btrfs@vger.kernel.org, kernel-team@meta.com Cc: Omar Sandoval , Sweet Tea Dorminy Subject: [PATCH v5 02/18] fscrypt: add fscrypt_have_same_policy() to check inode compatibility Date: Wed, 2 Nov 2022 07:52:51 -0400 Message-Id: <0c9c616c46ae86e51d153316d55918eac74b83ad.1667389115.git.sweettea-kernel@dorminy.me> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org From: Omar Sandoval Btrfs will need to check whether inode policies are identical for various purposes: if two inodes want to share an extent, they must have the same policy, including key identifier; symlinks must not span the encrypted/unencrypted border; and certain encryption policies will allow btrfs to store one fscrypt_context for multiple objects. Therefore, add a function which allows checking the encryption policies of two inodes to ensure they are identical. Signed-off-by: Omar Sandoval Signed-off-by: Sweet Tea Dorminy --- fs/crypto/policy.c | 35 +++++++++++++++++++++++++++++++++++ include/linux/fscrypt.h | 8 ++++++++ 2 files changed, 43 insertions(+) diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c index 46757c3052ef..715870d4e530 100644 --- a/fs/crypto/policy.c +++ b/fs/crypto/policy.c @@ -415,6 +415,41 @@ static int fscrypt_get_policy(struct inode *inode, union fscrypt_policy *policy) return fscrypt_policy_from_context(policy, &ctx, ret); } +/** + * fscrypt_have_same_policy() - check whether two inodes have the same policy + * @inode1: the first inode + * @inode2: the second inode + * @same_ptr: a pointer to return whether they are the same + * + * Return: 0 or an error code. + */ +int fscrypt_have_same_policy(struct inode *inode1, struct inode *inode2, + bool *same_ptr) +{ + union fscrypt_policy policy1, policy2; + int err; + + if (!IS_ENCRYPTED(inode1) && !IS_ENCRYPTED(inode2)) { + *same_ptr = true; + return 0; + } + if (!IS_ENCRYPTED(inode1) || !IS_ENCRYPTED(inode2)) { + *same_ptr = false; + return 0; + } + + err = fscrypt_get_policy(inode1, &policy1); + if (err) + return err; + err = fscrypt_get_policy(inode2, &policy2); + if (err) + return err; + + *same_ptr = fscrypt_policies_equal(&policy1, &policy2); + return 0; +} +EXPORT_SYMBOL(fscrypt_have_same_policy); + static int set_encryption_policy(struct inode *inode, const union fscrypt_policy *policy) { diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index 7661db0b5bec..0069f92ee3da 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -313,6 +313,8 @@ static inline struct page *fscrypt_pagecache_page(struct page *bounce_page) void fscrypt_free_bounce_page(struct page *bounce_page); /* policy.c */ +int fscrypt_have_same_policy(struct inode *inode1, struct inode *inode2, + bool *same_ptr); int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg); int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg); int fscrypt_ioctl_get_policy_ex(struct file *filp, void __user *arg); @@ -490,6 +492,12 @@ static inline void fscrypt_free_bounce_page(struct page *bounce_page) } /* policy.c */ +static inline int fscrypt_have_same_policy(struct inode *inode1, + struct inode *inode2) +{ + return 1; +} + static inline int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg) { -- 2.37.3