From: Eric Biggers <ebiggers@xxxxxxxxxx>
Update the fscrypt internals to handle v2 encryption policies. This
includes supporting getting and setting them, translating them to/from
the on-disk fscrypt_context. It also includes storing either a v1 or v2
policy struct in the fscrypt_info for use by fscrypt_inherit_context()
and fscrypt_has_permitted_context(). (Previously we were storing the
individual fields, but it is a bit easier to store a policy struct.)
An fscrypt_policy_v1 (previously 'fscrypt_policy') maps to/from an
fscrypt_context_v1 (previously 'fscrypt_context'), while an
fscrypt_policy_v2 maps to/from an fscrypt_context_v2.
Key management for v2 policies will be implemented by later patches.
For now, attempting to set up an inode's key just fails with EOPNOTSUPP.
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
fs/crypto/fname.c | 4 +-
fs/crypto/fscrypt_private.h | 172 ++++++++++++++++---
fs/crypto/keyinfo.c | 70 ++++----
fs/crypto/policy.c | 368 ++++++++++++++++++++++++++++------------
include/linux/fscrypt.h | 2 +-
include/linux/fscrypt_notsupp.h | 6 +
include/linux/fscrypt_supp.h | 1 +
7 files changed, 452 insertions(+), 171 deletions(-)
diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index c91bcef65b9f..78dc0e3f6328 100644
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -46,7 +46,7 @@ static int fname_encrypt(struct inode *inode,
int res = 0;
char iv[FS_CRYPTO_BLOCK_SIZE];
struct scatterlist sg;
- int padding = 4 << (ci->ci_flags & FSCRYPT_POLICY_FLAGS_PAD_MASK);
+ int padding = fscrypt_policy_fname_padding(&ci->ci_policy);
unsigned int lim;
unsigned int cryptlen;
@@ -217,7 +217,7 @@ u32 fscrypt_fname_encrypted_size(const struct inode *inode, u32 ilen)
struct fscrypt_info *ci = inode->i_crypt_info;
if (ci)
- padding = 4 << (ci->ci_flags & FSCRYPT_POLICY_FLAGS_PAD_MASK);
+ padding = fscrypt_policy_fname_padding(&ci->ci_policy);
ilen = max(ilen, (u32)FS_CRYPTO_BLOCK_SIZE);
return round_up(ilen, padding);
}
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 2fdc4e5c0771..dec85c4b14a8 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -29,39 +29,159 @@
#define FSCRYPT_MIN_KEY_SIZE 16
-/**
- * Encryption context for inode
- *
- * Protector format:
- * 1 byte: Protector format (1 = this version)
- * 1 byte: File contents encryption mode
- * 1 byte: File names encryption mode
- * 1 byte: Flags
- * 8 bytes: Master Key descriptor
- * 16 bytes: Encryption Key derivation nonce
- */
-struct fscrypt_context {
- u8 format;
+struct fscrypt_context_v1 {
+
+ u8 version; /* FSCRYPT_CONTEXT_V1 */
+
+ /* Same meaning as in v2 context --- see below */
u8 contents_encryption_mode;
u8 filenames_encryption_mode;
u8 flags;
+
+ /*
+ * Descriptor for this file's master key in a process-subscribed keyring
+ * --- typically a session keyring, or a user keyring linked into a
+ * session or user session keyring. This is an arbitrary value, chosen
+ * by userspace when it set the encryption policy. It is *not*
+ * necessarily tied to the actual key payload.
+ */
u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
+
+ /*
+ * A unique value used in combination with the master key to derive the
+ * file's actual encryption key
+ */
u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
-} __packed;
+};
+
+struct fscrypt_context_v2 {
+
+ u8 version; /* FSCRYPT_CONTEXT_V2 */
+
+ /* Encryption mode for the contents of regular files */
+ u8 contents_encryption_mode;
-#define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1
+ /* Encryption mode for filenames in directories and symlink targets */
+ u8 filenames_encryption_mode;
+
+ /* Options that affect how encryption is done (e.g. padding amount) */
+ u8 flags;
+
+ /* Reserved, must be 0 */
+ u8 reserved[4];
+
+ /*
+ * A cryptographic hash of the master key with which this file is
+ * encrypted
+ */
+ u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE];
+
+ /*
+ * A unique value used in combination with the master key to derive the
+ * file's actual encryption key
+ */
+ u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
+};
+
+/**
+ * fscrypt_context - the encryption context for an inode
+ *
+ * Filesystems usually store this in an extended attribute. It identifies the
+ * encryption algorithm and key with which the file is encrypted.
+ *
+ * Since this is stored on-disk, be careful not to reorder fields or add any
+ * implicit padding bytes!
+ */
+union fscrypt_context {
+ struct fscrypt_context_v1 v1;
+ struct fscrypt_context_v2 v2;
+};
+
+#define FSCRYPT_CONTEXT_V1 1
+#define FSCRYPT_CONTEXT_V2 2
+
+static inline int fscrypt_context_size(const union fscrypt_context *ctx)
+{
+ switch (ctx->v1.version) {
+ case FSCRYPT_CONTEXT_V1:
+ return sizeof(ctx->v1);
+ case FSCRYPT_CONTEXT_V2:
+ return sizeof(ctx->v2);
+ }
+ return 0;
+}
+
+static inline bool
+fscrypt_valid_context_format(const union fscrypt_context *ctx, int size)
+{
+ return size >= 1 && size == fscrypt_context_size(ctx);
+}
+
+#undef fscrypt_policy
+union fscrypt_policy {
+ struct fscrypt_policy_v1 v1;
+ struct fscrypt_policy_v2 v2;
+};
+
+static inline int fscrypt_policy_size(const union fscrypt_policy *policy)
+{
+ switch (policy->v1.version) {
+ case FSCRYPT_POLICY_VERSION_LEGACY:
+ return sizeof(policy->v1);
+ case FSCRYPT_POLICY_VERSION_2:
+ return sizeof(policy->v2);
+ }
+ return 0;
+}
+
+static inline u8
+fscrypt_policy_contents_mode(const union fscrypt_policy *policy)
+{
+ switch (policy->v1.version) {
+ case FSCRYPT_POLICY_VERSION_LEGACY:
+ return policy->v1.contents_encryption_mode;
+ case FSCRYPT_POLICY_VERSION_2:
+ return policy->v2.contents_encryption_mode;
+ }
+ BUG();
+}
+
+static inline u8
+fscrypt_policy_fnames_mode(const union fscrypt_policy *policy)
+{
+ switch (policy->v1.version) {
+ case FSCRYPT_POLICY_VERSION_LEGACY:
+ return policy->v1.filenames_encryption_mode;
+ case FSCRYPT_POLICY_VERSION_2:
+ return policy->v2.filenames_encryption_mode;
+ }
+ BUG();
+}
+
+static inline int
+fscrypt_policy_fname_padding(const union fscrypt_policy *policy)
+{
+ switch (policy->v1.version) {
+ case FSCRYPT_POLICY_VERSION_LEGACY:
+ return 4 << (policy->v1.flags & FSCRYPT_POLICY_FLAGS_PAD_MASK);
+ case FSCRYPT_POLICY_VERSION_2:
+ return 4 << (policy->v2.flags & FSCRYPT_POLICY_FLAGS_PAD_MASK);
+ }
+ BUG();
+}
/*
- * A pointer to this structure is stored in the file system's in-core
- * representation of an inode.
+ * fscrypt_info - the "encryption key" for an inode
+ *
+ * When an encrypted file's key is made available, an instance of this struct is
+ * allocated and stored in ->i_crypt_info. Once created, it remains until the
+ * inode is evicted.
*/
struct fscrypt_info {
- u8 ci_data_mode;
- u8 ci_filename_mode;
- u8 ci_flags;
+
+ /* The actual crypto transforms needed for encryption and decryption */
struct crypto_skcipher *ci_ctfm;
struct crypto_cipher *ci_essiv_tfm;
- u8 ci_master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
/*
* The master key with which this inode was unlocked (decrypted). This
@@ -78,6 +198,9 @@ struct fscrypt_info {
* ->ci_master_key is set.
*/
struct inode *ci_inode;
+
+ /* The encryption policy used by this file */
+ union fscrypt_policy ci_policy;
};
typedef enum {
@@ -114,4 +237,11 @@ extern struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
extern struct key_type key_type_fscrypt_mk;
extern void __exit fscrypt_essiv_cleanup(void);
+/* policy.c */
+extern bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
+ const union fscrypt_policy *policy2);
+extern bool fscrypt_supported_policy(const union fscrypt_policy *policy_u);
+extern void fscrypt_context_to_policy(const union fscrypt_context *ctx_u,
+ union fscrypt_policy *policy_u);
+
#endif /* _FSCRYPT_PRIVATE_H */
diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c
index 4052030a4c96..937a678ebba1 100644
--- a/fs/crypto/keyinfo.c
+++ b/fs/crypto/keyinfo.c
@@ -649,7 +649,7 @@ static void derive_crypt_complete(struct crypto_async_request *req, int rc)
* key is longer, then only the first 'derived_keysize' bytes are used.
*/
static int derive_key_aes(const u8 *master_key,
- const struct fscrypt_context *ctx,
+ const struct fscrypt_context_v1 *ctx,
u8 *derived_key, unsigned int derived_keysize)
{
int err;
@@ -751,7 +751,7 @@ find_and_lock_process_key(const char *prefix,
}
static int find_and_derive_key_legacy(const struct inode *inode,
- const struct fscrypt_context *ctx,
+ const struct fscrypt_context_v1 *ctx,
u8 *derived_key,
unsigned int derived_keysize)
{
@@ -786,7 +786,7 @@ static int find_and_derive_key_legacy(const struct inode *inode,
* its fscrypt_info into ->mk_decrypted_inodes.
*/
static int find_and_derive_key(const struct inode *inode,
- const struct fscrypt_context *ctx,
+ const union fscrypt_context *ctx,
u8 *derived_key, unsigned int derived_keysize,
struct key **master_key_ret)
{
@@ -795,9 +795,15 @@ static int find_and_derive_key(const struct inode *inode,
struct fscrypt_key_specifier mk_spec;
int err;
- mk_spec.type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR;
- memcpy(mk_spec.descriptor, ctx->master_key_descriptor,
- FSCRYPT_KEY_DESCRIPTOR_SIZE);
+ switch (ctx->v1.version) {
+ case FSCRYPT_CONTEXT_V1:
+ mk_spec.type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR;
+ memcpy(mk_spec.descriptor, ctx->v1.master_key_descriptor,
+ FSCRYPT_KEY_DESCRIPTOR_SIZE);
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
key = find_master_key(inode->i_sb, &mk_spec);
if (IS_ERR(key)) {
@@ -807,7 +813,7 @@ static int find_and_derive_key(const struct inode *inode,
* As a legacy fallback, we search the current task's subscribed
* keyrings in addition to ->s_master_keys.
*/
- return find_and_derive_key_legacy(inode, ctx, derived_key,
+ return find_and_derive_key_legacy(inode, &ctx->v1, derived_key,
derived_keysize);
}
mk = key->payload.data[0];
@@ -833,7 +839,7 @@ static int find_and_derive_key(const struct inode *inode,
goto out_release_key;
}
- err = derive_key_aes(mk->mk_secret.raw, ctx,
+ err = derive_key_aes(mk->mk_secret.raw, &ctx->v1,
derived_key, derived_keysize);
if (err)
goto out_release_key;
@@ -862,17 +868,10 @@ static int determine_cipher_type(struct fscrypt_info *ci, struct inode *inode,
{
u32 mode;
- if (!fscrypt_valid_enc_modes(ci->ci_data_mode, ci->ci_filename_mode)) {
- pr_warn_ratelimited("fscrypt: inode %lu uses unsupported encryption modes (contents mode %d, filenames mode %d)\n",
- inode->i_ino,
- ci->ci_data_mode, ci->ci_filename_mode);
- return -EINVAL;
- }
-
if (S_ISREG(inode->i_mode)) {
- mode = ci->ci_data_mode;
+ mode = fscrypt_policy_contents_mode(&ci->ci_policy);
} else if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) {
- mode = ci->ci_filename_mode;
+ mode = fscrypt_policy_fnames_mode(&ci->ci_policy);
} else {
WARN_ONCE(1, "fscrypt: filesystem tried to load encryption info for inode %lu, which is not encryptable (file type %d)\n",
inode->i_ino, (inode->i_mode & S_IFMT));
@@ -984,7 +983,7 @@ void __exit fscrypt_essiv_cleanup(void)
int fscrypt_get_encryption_info(struct inode *inode)
{
struct fscrypt_info *crypt_info;
- struct fscrypt_context ctx;
+ union fscrypt_context ctx;
struct crypto_skcipher *ctfm;
const char *cipher_str;
unsigned int derived_keysize;
@@ -1006,33 +1005,31 @@ int fscrypt_get_encryption_info(struct inode *inode)
return res;
/* Fake up a context for an unencrypted directory */
memset(&ctx, 0, sizeof(ctx));
- ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1;
- ctx.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
- ctx.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
- memset(ctx.master_key_descriptor, 0x42,
+ ctx.v1.version = FSCRYPT_CONTEXT_V1;
+ ctx.v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
+ ctx.v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
+ memset(ctx.v1.master_key_descriptor, 0x42,
FSCRYPT_KEY_DESCRIPTOR_SIZE);
- } else if (res != sizeof(ctx)) {
- return -EINVAL;
+ res = sizeof(ctx.v1);
}
- if (ctx.format != FS_ENCRYPTION_CONTEXT_FORMAT_V1)
- return -EINVAL;
-
- if (ctx.flags & ~FSCRYPT_POLICY_FLAGS_VALID)
+ if (!fscrypt_valid_context_format(&ctx, res))
return -EINVAL;
crypt_info = kmem_cache_zalloc(fscrypt_info_cachep, GFP_NOFS);
if (!crypt_info)
return -ENOMEM;
- crypt_info->ci_flags = ctx.flags;
- crypt_info->ci_data_mode = ctx.contents_encryption_mode;
- crypt_info->ci_filename_mode = ctx.filenames_encryption_mode;
- memcpy(crypt_info->ci_master_key_descriptor, ctx.master_key_descriptor,
- FSCRYPT_KEY_DESCRIPTOR_SIZE);
+ fscrypt_context_to_policy(&ctx, &crypt_info->ci_policy);
+ if (!fscrypt_supported_policy(&crypt_info->ci_policy)) {
+ res = -EINVAL;
+ pr_warn_ratelimited("fscrypt: inode %lu uses unsupported encryption policy\n",
+ inode->i_ino);
+ goto out;
+ }
- res = determine_cipher_type(crypt_info, inode,
- &cipher_str, &derived_keysize);
+ res = determine_cipher_type(crypt_info, inode, &cipher_str,
+ &derived_keysize);
if (res)
goto out;
@@ -1065,7 +1062,8 @@ int fscrypt_get_encryption_info(struct inode *inode)
goto out;
if (S_ISREG(inode->i_mode) &&
- crypt_info->ci_data_mode == FSCRYPT_MODE_AES_128_CBC) {
+ (fscrypt_policy_contents_mode(&crypt_info->ci_policy) ==
+ FSCRYPT_MODE_AES_128_CBC)) {
res = init_essiv_generator(crypt_info, derived_key,
derived_keysize);
if (res) {
diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index a856c8941be6..27a391038f73 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -6,6 +6,7 @@
*
* Written by Michael Halcrow, 2015.
* Modified by Jaegeuk Kim, 2015.
+ * Modified by Eric Biggers, 2017 for v2 policy support.
*/
#include <linux/random.h>
@@ -13,84 +14,227 @@
#include <linux/mount.h>
#include "fscrypt_private.h"
-/*
- * check whether an encryption policy is consistent with an encryption context
- */
-static bool is_encryption_context_consistent_with_policy(
- const struct fscrypt_context *ctx,
- const struct fscrypt_policy *policy)
+bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
+ const union fscrypt_policy *policy2)
+{
+ if (policy1->v1.version != policy2->v1.version)
+ return false;
+
+ return !memcmp(policy1, policy2, fscrypt_policy_size(policy1));
+}
+
+bool fscrypt_supported_policy(const union fscrypt_policy *policy_u)
+{
+ switch (policy_u->v1.version) {
+ case FSCRYPT_POLICY_VERSION_LEGACY: {
+ const struct fscrypt_policy_v1 *policy = &policy_u->v1;
+
+ if (!fscrypt_valid_enc_modes(policy->contents_encryption_mode,
+ policy->filenames_encryption_mode))
+ return false;
+
+ if (policy->flags & ~FSCRYPT_POLICY_FLAGS_VALID)
+ return false;
+
+ return true;
+ }
+ case FSCRYPT_POLICY_VERSION_2: {
+ const struct fscrypt_policy_v2 *policy = &policy_u->v2;
+
+ if (!fscrypt_valid_enc_modes(policy->contents_encryption_mode,
+ policy->filenames_encryption_mode))
+ return false;
+
+ if (policy->flags & ~FSCRYPT_POLICY_FLAGS_VALID)
+ return false;
+
+ if (memchr_inv(policy->reserved, 0, sizeof(policy->reserved)))
+ return false;
+
+ return true;
+ }
+ }
+ return false;
+}
+
+static void fscrypt_policy_to_context(const union fscrypt_policy *policy_u,
+ union fscrypt_context *ctx_u)
{
- return memcmp(ctx->master_key_descriptor, policy->master_key_descriptor,
- FSCRYPT_KEY_DESCRIPTOR_SIZE) == 0 &&
- (ctx->flags == policy->flags) &&
- (ctx->contents_encryption_mode ==
- policy->contents_encryption_mode) &&
- (ctx->filenames_encryption_mode ==
- policy->filenames_encryption_mode);
+ memset(ctx_u, 0, sizeof(*ctx_u));
+
+ switch (policy_u->v1.version) {
+ case FSCRYPT_POLICY_VERSION_LEGACY: {
+ const struct fscrypt_policy_v1 *policy = &policy_u->v1;
+ struct fscrypt_context_v1 *ctx = &ctx_u->v1;
+
+ ctx->version = FSCRYPT_CONTEXT_V1;
+ ctx->contents_encryption_mode =
+ policy->contents_encryption_mode;
+ ctx->filenames_encryption_mode =
+ policy->filenames_encryption_mode;
+ ctx->flags = policy->flags;
+ memcpy(ctx->master_key_descriptor,
+ policy->master_key_descriptor,
+ sizeof(ctx->master_key_descriptor));
+ get_random_bytes(ctx->nonce, sizeof(ctx->nonce));
+ break;
+ }
+ case FSCRYPT_POLICY_VERSION_2: {
+ const struct fscrypt_policy_v2 *policy = &policy_u->v2;
+ struct fscrypt_context_v2 *ctx = &ctx_u->v2;
+
+ ctx->version = FSCRYPT_CONTEXT_V2;
+ ctx->contents_encryption_mode =
+ policy->contents_encryption_mode;
+ ctx->filenames_encryption_mode =
+ policy->filenames_encryption_mode;
+ ctx->flags = policy->flags;
+ memcpy(ctx->reserved, policy->reserved, sizeof(ctx->reserved));
+ memcpy(ctx->master_key_identifier,
+ policy->master_key_identifier,
+ sizeof(ctx->master_key_identifier));
+ get_random_bytes(ctx->nonce, sizeof(ctx->nonce));
+ break;
+ }
+ default:
+ BUG();
+ }
}
-static int create_encryption_context_from_policy(struct inode *inode,
- const struct fscrypt_policy *policy)
+void fscrypt_context_to_policy(const union fscrypt_context *ctx_u,
+ union fscrypt_policy *policy_u)
{
- struct fscrypt_context ctx;
+ memset(policy_u, 0, sizeof(*policy_u));
+
+ switch (ctx_u->v1.version) {
+ case FSCRYPT_CONTEXT_V1: {
+ const struct fscrypt_context_v1 *ctx = &ctx_u->v1;
+ struct fscrypt_policy_v1 *policy = &policy_u->v1;
+
+ policy->version = FSCRYPT_POLICY_VERSION_LEGACY;
+ policy->contents_encryption_mode =
+ ctx->contents_encryption_mode;
+ policy->filenames_encryption_mode =
+ ctx->filenames_encryption_mode;
+ policy->flags = ctx->flags;
+ memcpy(policy->master_key_descriptor,
+ ctx->master_key_descriptor,
+ sizeof(policy->master_key_descriptor));
+ return;
+ }
+ case FSCRYPT_CONTEXT_V2: {
+ const struct fscrypt_context_v2 *ctx = &ctx_u->v2;
+ struct fscrypt_policy_v2 *policy = &policy_u->v2;
+
+ policy->version = FSCRYPT_POLICY_VERSION_2;
+ policy->contents_encryption_mode =
+ ctx->contents_encryption_mode;
+ policy->filenames_encryption_mode =
+ ctx->filenames_encryption_mode;
+ policy->flags = ctx->flags;
+ memcpy(policy->reserved, ctx->reserved,
+ sizeof(policy->reserved));
+ memcpy(policy->master_key_identifier,
+ ctx->master_key_identifier,
+ sizeof(policy->master_key_identifier));
+ return;
+ }
+ default:
+ BUG();
+ }
+}
- ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1;
- memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
- FSCRYPT_KEY_DESCRIPTOR_SIZE);
+static int fscrypt_get_policy(struct inode *inode, union fscrypt_policy *policy)
+{
+ union fscrypt_context ctx;
+ int ret;
+
+ if (inode->i_crypt_info) {
+ *policy = inode->i_crypt_info->ci_policy;
+ return 0;
+ }
+
+ if (!IS_ENCRYPTED(inode))
+ return -ENODATA;
- if (!fscrypt_valid_enc_modes(policy->contents_encryption_mode,
- policy->filenames_encryption_mode))
+ ret = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
+ if (ret < 0)
+ return (ret == -ERANGE) ? -EINVAL : ret;
+ if (!fscrypt_valid_context_format(&ctx, ret))
return -EINVAL;
+ fscrypt_context_to_policy(&ctx, policy);
+ return 0;
+}
+
+static int set_encryption_policy(struct inode *inode,
+ const union fscrypt_policy *policy)
+{
+ union fscrypt_context ctx;
- if (policy->flags & ~FSCRYPT_POLICY_FLAGS_VALID)
+ if (!fscrypt_supported_policy(policy))
return -EINVAL;
- ctx.contents_encryption_mode = policy->contents_encryption_mode;
- ctx.filenames_encryption_mode = policy->filenames_encryption_mode;
- ctx.flags = policy->flags;
- BUILD_BUG_ON(sizeof(ctx.nonce) != FS_KEY_DERIVATION_NONCE_SIZE);
- get_random_bytes(ctx.nonce, FS_KEY_DERIVATION_NONCE_SIZE);
+ fscrypt_policy_to_context(policy, &ctx);
+
+ if (policy->v1.version == FSCRYPT_POLICY_VERSION_LEGACY) {
+ /*
+ * The original encryption policy version provided no way of
+ * verifying that the correct master key was supplied, which was
+ * insecure in scenarios where multiple users have access to the
+ * same encrypted files (even just read-only access). The new
+ * encryption policy version fixes this and also implies use of
+ * an improved key derivation function and allows non-root users
+ * to securely remove keys. So as long as compatibility with
+ * old kernels isn't required, it is recommended to use the new
+ * policy version for all new encrypted directories.
+ */
+ pr_warn_once("%s (pid %d) is setting less secure v1 encryption policy; recommend upgrading to v2.\n",
+ current->comm, current->pid);
+ }
- return inode->i_sb->s_cop->set_context(inode, &ctx, sizeof(ctx), NULL);
+ return inode->i_sb->s_cop->set_context(inode, &ctx,
+ fscrypt_context_size(&ctx),
+ NULL);
}
int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg)
{
- struct fscrypt_policy policy;
+ union fscrypt_policy policy;
+ union fscrypt_policy existing_policy;
struct inode *inode = file_inode(filp);
+ int size;
int ret;
- struct fscrypt_context ctx;
- if (copy_from_user(&policy, arg, sizeof(policy)))
+ if (copy_from_user(&policy, arg, sizeof(u8)))
+ return -EFAULT;
+
+ size = fscrypt_policy_size(&policy);
+ if (size == 0)
+ return -EINVAL;
+
+ if (copy_from_user((u8 *)&policy + 1, arg + 1, size - 1))
return -EFAULT;
if (!inode_owner_or_capable(inode))
return -EACCES;
- if (policy.version != 0)
- return -EINVAL;
-
ret = mnt_want_write_file(filp);
if (ret)
return ret;
inode_lock(inode);
- ret = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
+ ret = fscrypt_get_policy(inode, &existing_policy);
if (ret == -ENODATA) {
if (!S_ISDIR(inode->i_mode))
ret = -ENOTDIR;
else if (!inode->i_sb->s_cop->empty_dir(inode))
ret = -ENOTEMPTY;
else
- ret = create_encryption_context_from_policy(inode,
- &policy);
- } else if (ret == sizeof(ctx) &&
- is_encryption_context_consistent_with_policy(&ctx,
- &policy)) {
- /* The file already uses the same encryption policy. */
- ret = 0;
- } else if (ret >= 0 || ret == -ERANGE) {
+ ret = set_encryption_policy(inode, &policy);
+ } else if (ret == -EINVAL ||
+ (ret == 0 && !fscrypt_policies_equal(&policy,
+ &existing_policy))) {
/* The file already uses a different encryption policy. */
ret = -EEXIST;
}
@@ -102,36 +246,61 @@ int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg)
}
EXPORT_SYMBOL(fscrypt_ioctl_set_policy);
+/* Original ioctl version; can only get the original policy version */
int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg)
{
- struct inode *inode = file_inode(filp);
- struct fscrypt_context ctx;
- struct fscrypt_policy policy;
- int res;
+ union fscrypt_policy policy;
+ int err;
- if (!IS_ENCRYPTED(inode))
- return -ENODATA;
+ err = fscrypt_get_policy(file_inode(filp), &policy);
+ if (err)
+ return err;
- res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
- if (res < 0 && res != -ERANGE)
- return res;
- if (res != sizeof(ctx))
+ if (policy.v1.version != FSCRYPT_POLICY_VERSION_LEGACY)
return -EINVAL;
- if (ctx.format != FS_ENCRYPTION_CONTEXT_FORMAT_V1)
+
+ if (copy_to_user(arg, &policy, sizeof(policy.v1)))
+ return -EFAULT;
+ return 0;
+}
+EXPORT_SYMBOL(fscrypt_ioctl_get_policy);
+
+/* Extended ioctl version; can get policies of any version */
+int fscrypt_ioctl_get_policy_ex(struct file *filp, void __user *_arg)
+{
+ struct fscrypt_get_policy_ex_args __user *arg = _arg;
+ __u64 size;
+ __u64 actual_size;
+ size_t policy_size;
+ union fscrypt_policy policy;
+ int err;
+
+ if (get_user(size, &arg->size))
+ return -EFAULT;
+
+ if (size <= offsetof(struct fscrypt_get_policy_ex_args, policy) ||
+ size >= 65536)
return -EINVAL;
- policy.version = 0;
- policy.contents_encryption_mode = ctx.contents_encryption_mode;
- policy.filenames_encryption_mode = ctx.filenames_encryption_mode;
- policy.flags = ctx.flags;
- memcpy(policy.master_key_descriptor, ctx.master_key_descriptor,
- FSCRYPT_KEY_DESCRIPTOR_SIZE);
+ err = fscrypt_get_policy(file_inode(filp), &policy);
+ if (err)
+ return err;
+
+ policy_size = fscrypt_policy_size(&policy);
+ actual_size = offsetof(struct fscrypt_get_policy_ex_args, policy) +
+ policy_size;
- if (copy_to_user(arg, &policy, sizeof(policy)))
+ if (size < actual_size)
+ return -EOVERFLOW;
+
+ if (put_user(actual_size, &arg->size))
+ return -EFAULT;
+
+ if (copy_to_user(&arg->policy, &policy, policy_size))
return -EFAULT;
return 0;
}
-EXPORT_SYMBOL(fscrypt_ioctl_get_policy);
+EXPORT_SYMBOL(fscrypt_ioctl_get_policy_ex);
/**
* fscrypt_has_permitted_context() - is a file's encryption policy permitted
@@ -155,10 +324,8 @@ EXPORT_SYMBOL(fscrypt_ioctl_get_policy);
*/
int fscrypt_has_permitted_context(struct inode *parent, struct inode *child)
{
- const struct fscrypt_operations *cops = parent->i_sb->s_cop;
- const struct fscrypt_info *parent_ci, *child_ci;
- struct fscrypt_context parent_ctx, child_ctx;
- int res;
+ union fscrypt_policy parent_policy, child_policy;
+ int err;
/* No restrictions on file types which are never encrypted */
if (!S_ISREG(child->i_mode) && !S_ISDIR(child->i_mode) &&
@@ -188,41 +355,22 @@ int fscrypt_has_permitted_context(struct inode *parent, struct inode *child)
* In any case, if an unexpected error occurs, fall back to "forbidden".
*/
- res = fscrypt_get_encryption_info(parent);
- if (res)
+ err = fscrypt_get_encryption_info(parent);
+ if (err)
return 0;
- res = fscrypt_get_encryption_info(child);
- if (res)
+ err = fscrypt_get_encryption_info(child);
+ if (err)
return 0;
- parent_ci = parent->i_crypt_info;
- child_ci = child->i_crypt_info;
-
- if (parent_ci && child_ci) {
- return memcmp(parent_ci->ci_master_key_descriptor,
- child_ci->ci_master_key_descriptor,
- FSCRYPT_KEY_DESCRIPTOR_SIZE) == 0 &&
- (parent_ci->ci_data_mode == child_ci->ci_data_mode) &&
- (parent_ci->ci_filename_mode ==
- child_ci->ci_filename_mode) &&
- (parent_ci->ci_flags == child_ci->ci_flags);
- }
- res = cops->get_context(parent, &parent_ctx, sizeof(parent_ctx));
- if (res != sizeof(parent_ctx))
+ err = fscrypt_get_policy(parent, &parent_policy);
+ if (err)
return 0;
- res = cops->get_context(child, &child_ctx, sizeof(child_ctx));
- if (res != sizeof(child_ctx))
+ err = fscrypt_get_policy(child, &child_policy);
+ if (err)
return 0;
- return memcmp(parent_ctx.master_key_descriptor,
- child_ctx.master_key_descriptor,
- FSCRYPT_KEY_DESCRIPTOR_SIZE) == 0 &&
- (parent_ctx.contents_encryption_mode ==
- child_ctx.contents_encryption_mode) &&
- (parent_ctx.filenames_encryption_mode ==
- child_ctx.filenames_encryption_mode) &&
- (parent_ctx.flags == child_ctx.flags);
+ return fscrypt_policies_equal(&parent_policy, &child_policy);
}
EXPORT_SYMBOL(fscrypt_has_permitted_context);
@@ -238,30 +386,28 @@ EXPORT_SYMBOL(fscrypt_has_permitted_context);
int fscrypt_inherit_context(struct inode *parent, struct inode *child,
void *fs_data, bool preload)
{
- struct fscrypt_context ctx;
- struct fscrypt_info *ci;
- int res;
+ int err;
+ const struct fscrypt_info *ci;
+ union fscrypt_context ctx;
- res = fscrypt_get_encryption_info(parent);
- if (res < 0)
- return res;
+ err = fscrypt_get_encryption_info(parent);
+ if (err)
+ return err;
ci = parent->i_crypt_info;
if (ci == NULL)
return -ENOKEY;
- ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1;
- ctx.contents_encryption_mode = ci->ci_data_mode;
- ctx.filenames_encryption_mode = ci->ci_filename_mode;
- ctx.flags = ci->ci_flags;
- memcpy(ctx.master_key_descriptor, ci->ci_master_key_descriptor,
- FSCRYPT_KEY_DESCRIPTOR_SIZE);
- get_random_bytes(ctx.nonce, FS_KEY_DERIVATION_NONCE_SIZE);
BUILD_BUG_ON(sizeof(ctx) != FSCRYPT_SET_CONTEXT_MAX_SIZE);
- res = parent->i_sb->s_cop->set_context(child, &ctx,
- sizeof(ctx), fs_data);
- if (res)
- return res;
+
+ fscrypt_policy_to_context(&ci->ci_policy, &ctx);
+
+ err = parent->i_sb->s_cop->set_context(child, &ctx,
+ fscrypt_context_size(&ctx),
+ fs_data);
+ if (err)
+ return err;
+
return preload ? fscrypt_get_encryption_info(child): 0;
}
EXPORT_SYMBOL(fscrypt_inherit_context);
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 671ce57e4673..aa8c6e8bfed8 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -86,7 +86,7 @@ struct fscrypt_operations {
};
/* Maximum value for the third parameter of fscrypt_operations.set_context(). */
-#define FSCRYPT_SET_CONTEXT_MAX_SIZE 28
+#define FSCRYPT_SET_CONTEXT_MAX_SIZE 40
static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
{
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index bd60f951b06a..41bd5b70e343 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -70,6 +70,12 @@ static inline int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg)
return -EOPNOTSUPP;
}
+static inline int fscrypt_ioctl_get_policy_ex(struct file *filp,
+ void __user *arg)
+{
+ return -EOPNOTSUPP;
+}
+
static inline int fscrypt_has_permitted_context(struct inode *parent,
struct inode *child)
{
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index ace278056dbe..a11b0b2d14b0 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -38,6 +38,7 @@ static inline void fscrypt_set_encrypted_dentry(struct dentry *dentry)
/* policy.c */
extern int fscrypt_ioctl_set_policy(struct file *, const void __user *);
extern int fscrypt_ioctl_get_policy(struct file *, void __user *);
+extern int fscrypt_ioctl_get_policy_ex(struct file *, void __user *);
extern int fscrypt_has_permitted_context(struct inode *, struct inode *);
extern int fscrypt_inherit_context(struct inode *, struct inode *,
void *, bool);
--
2.15.0.rc0.271.g36b669edcc-goog
--
To unsubscribe from this list: send the line "unsubscribe linux-api" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
