dbfc6584b3
Add a new fscrypt ioctl, FS_IOC_GET_ENCRYPTION_KEY_STATUS. Given a key specified by 'struct fscrypt_key_specifier' (the same way a key is specified for the other fscrypt key management ioctls), it returns status information in a 'struct fscrypt_get_key_status_arg'. The main motivation for this is that applications need to be able to check whether an encrypted directory is "unlocked" or not, so that they can add the key if it is not, and avoid adding the key (which may involve prompting the user for a passphrase) if it already is. It's possible to use some workarounds such as checking whether opening a regular file fails with ENOKEY, or checking whether the filenames "look like gibberish" or not. However, no workaround is usable in all cases. Like the other key management ioctls, the keyrings syscalls may seem at first to be a good fit for this. Unfortunately, they are not. Even if we exposed the keyring ID of the ->s_master_keys keyring and gave everyone Search permission on it (note: currently the keyrings permission system would also allow everyone to "invalidate" the keyring too), the fscrypt keys have an additional state that doesn't map cleanly to the keyrings API: the secret can be removed, but we can be still tracking the files that were using the key, and the removal can be re-attempted or the secret added again. After later patches, some applications will also need a way to determine whether a key was added by the current user vs. by some other user. Reserved fields are included in fscrypt_get_key_status_arg for this and other future extensions. Reviewed-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Eric Biggers <ebiggers@google.com>
136 lines
4.5 KiB
C
136 lines
4.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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/*
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* fscrypt user API
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*
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* These ioctls can be used on filesystems that support fscrypt. See the
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* "User API" section of Documentation/filesystems/fscrypt.rst.
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*/
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#ifndef _UAPI_LINUX_FSCRYPT_H
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#define _UAPI_LINUX_FSCRYPT_H
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#include <linux/types.h>
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#define FSCRYPT_KEY_DESCRIPTOR_SIZE 8
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/* Encryption policy flags */
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#define FSCRYPT_POLICY_FLAGS_PAD_4 0x00
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#define FSCRYPT_POLICY_FLAGS_PAD_8 0x01
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#define FSCRYPT_POLICY_FLAGS_PAD_16 0x02
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#define FSCRYPT_POLICY_FLAGS_PAD_32 0x03
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#define FSCRYPT_POLICY_FLAGS_PAD_MASK 0x03
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#define FSCRYPT_POLICY_FLAG_DIRECT_KEY 0x04 /* use master key directly */
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#define FSCRYPT_POLICY_FLAGS_VALID 0x07
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/* Encryption algorithms */
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#define FSCRYPT_MODE_AES_256_XTS 1
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#define FSCRYPT_MODE_AES_256_CTS 4
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#define FSCRYPT_MODE_AES_128_CBC 5
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#define FSCRYPT_MODE_AES_128_CTS 6
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#define FSCRYPT_MODE_ADIANTUM 9
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struct fscrypt_policy {
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__u8 version;
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__u8 contents_encryption_mode;
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__u8 filenames_encryption_mode;
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__u8 flags;
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__u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
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};
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/*
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* Process-subscribed "logon" key description prefix and payload format.
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* Deprecated; prefer FS_IOC_ADD_ENCRYPTION_KEY instead.
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*/
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#define FSCRYPT_KEY_DESC_PREFIX "fscrypt:"
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#define FSCRYPT_KEY_DESC_PREFIX_SIZE 8
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#define FSCRYPT_MAX_KEY_SIZE 64
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struct fscrypt_key {
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__u32 mode;
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__u8 raw[FSCRYPT_MAX_KEY_SIZE];
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__u32 size;
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};
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/*
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* Keys are specified by an arbitrary 8-byte key "descriptor",
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* matching fscrypt_policy::master_key_descriptor.
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*/
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#define FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR 1
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/*
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* Specifies a key. This doesn't contain the actual key itself; this is just
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* the "name" of the key.
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*/
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struct fscrypt_key_specifier {
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__u32 type; /* one of FSCRYPT_KEY_SPEC_TYPE_* */
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__u32 __reserved;
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union {
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__u8 __reserved[32]; /* reserve some extra space */
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__u8 descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
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} u;
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};
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/* Struct passed to FS_IOC_ADD_ENCRYPTION_KEY */
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struct fscrypt_add_key_arg {
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struct fscrypt_key_specifier key_spec;
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__u32 raw_size;
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__u32 __reserved[9];
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__u8 raw[];
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};
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/* Struct passed to FS_IOC_REMOVE_ENCRYPTION_KEY */
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struct fscrypt_remove_key_arg {
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struct fscrypt_key_specifier key_spec;
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#define FSCRYPT_KEY_REMOVAL_STATUS_FLAG_FILES_BUSY 0x00000001
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__u32 removal_status_flags; /* output */
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__u32 __reserved[5];
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};
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/* Struct passed to FS_IOC_GET_ENCRYPTION_KEY_STATUS */
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struct fscrypt_get_key_status_arg {
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/* input */
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struct fscrypt_key_specifier key_spec;
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__u32 __reserved[6];
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/* output */
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#define FSCRYPT_KEY_STATUS_ABSENT 1
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#define FSCRYPT_KEY_STATUS_PRESENT 2
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#define FSCRYPT_KEY_STATUS_INCOMPLETELY_REMOVED 3
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__u32 status;
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__u32 __out_reserved[15];
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};
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#define FS_IOC_SET_ENCRYPTION_POLICY _IOR('f', 19, struct fscrypt_policy)
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#define FS_IOC_GET_ENCRYPTION_PWSALT _IOW('f', 20, __u8[16])
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#define FS_IOC_GET_ENCRYPTION_POLICY _IOW('f', 21, struct fscrypt_policy)
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#define FS_IOC_ADD_ENCRYPTION_KEY _IOWR('f', 23, struct fscrypt_add_key_arg)
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#define FS_IOC_REMOVE_ENCRYPTION_KEY _IOWR('f', 24, struct fscrypt_remove_key_arg)
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#define FS_IOC_GET_ENCRYPTION_KEY_STATUS _IOWR('f', 26, struct fscrypt_get_key_status_arg)
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/**********************************************************************/
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/* old names; don't add anything new here! */
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#ifndef __KERNEL__
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#define FS_KEY_DESCRIPTOR_SIZE FSCRYPT_KEY_DESCRIPTOR_SIZE
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#define FS_POLICY_FLAGS_PAD_4 FSCRYPT_POLICY_FLAGS_PAD_4
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#define FS_POLICY_FLAGS_PAD_8 FSCRYPT_POLICY_FLAGS_PAD_8
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#define FS_POLICY_FLAGS_PAD_16 FSCRYPT_POLICY_FLAGS_PAD_16
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#define FS_POLICY_FLAGS_PAD_32 FSCRYPT_POLICY_FLAGS_PAD_32
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#define FS_POLICY_FLAGS_PAD_MASK FSCRYPT_POLICY_FLAGS_PAD_MASK
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#define FS_POLICY_FLAG_DIRECT_KEY FSCRYPT_POLICY_FLAG_DIRECT_KEY
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#define FS_POLICY_FLAGS_VALID FSCRYPT_POLICY_FLAGS_VALID
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#define FS_ENCRYPTION_MODE_INVALID 0 /* never used */
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#define FS_ENCRYPTION_MODE_AES_256_XTS FSCRYPT_MODE_AES_256_XTS
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#define FS_ENCRYPTION_MODE_AES_256_GCM 2 /* never used */
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#define FS_ENCRYPTION_MODE_AES_256_CBC 3 /* never used */
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#define FS_ENCRYPTION_MODE_AES_256_CTS FSCRYPT_MODE_AES_256_CTS
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#define FS_ENCRYPTION_MODE_AES_128_CBC FSCRYPT_MODE_AES_128_CBC
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#define FS_ENCRYPTION_MODE_AES_128_CTS FSCRYPT_MODE_AES_128_CTS
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#define FS_ENCRYPTION_MODE_SPECK128_256_XTS 7 /* removed */
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#define FS_ENCRYPTION_MODE_SPECK128_256_CTS 8 /* removed */
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#define FS_ENCRYPTION_MODE_ADIANTUM FSCRYPT_MODE_ADIANTUM
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#define FS_KEY_DESC_PREFIX FSCRYPT_KEY_DESC_PREFIX
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#define FS_KEY_DESC_PREFIX_SIZE FSCRYPT_KEY_DESC_PREFIX_SIZE
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#define FS_MAX_KEY_SIZE FSCRYPT_MAX_KEY_SIZE
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#endif /* !__KERNEL__ */
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#endif /* _UAPI_LINUX_FSCRYPT_H */
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