eCryptfs: add key list structure; search keyring

Add support structures for handling multiple keys.  The list in crypt_stat
contains the key identifiers for all of the keys that should be used for
encrypting each file's File Encryption Key (FEK).  For now, each inode
inherits this list from the mount-wide crypt_stat struct, via the
ecryptfs_copy_mount_wide_sigs_to_inode_sigs() function.

This patch also removes the global key tfm from the mount-wide crypt_stat
struct, instead keeping a list of tfm's meant for dealing with the various
inode FEK's.  eCryptfs will now search the user's keyring for FEK's parsed
from the existing file metadata, so the user can make keys available at any
time before or after mounting.

Now that multiple FEK packets can be written to the file metadata, we need to
be more meticulous about size limits.  The updates to the code for writing out
packets to the file metadata makes sizes and limits more explicit, uniformly
expressed, and (hopefully) easier to follow.

Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 59 insertions, 12 deletions

diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index 1b9dd9a96f19..6ddab6c856ac 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -48,10 +48,12 @@
 #define ECRYPTFS_VERSIONING_PLAINTEXT_PASSTHROUGH 0x00000004
 #define ECRYPTFS_VERSIONING_POLICY                0x00000008
 #define ECRYPTFS_VERSIONING_XATTR                 0x00000010
+#define ECRYPTFS_VERSIONING_MULTKEY               0x00000020
 #define ECRYPTFS_VERSIONING_MASK (ECRYPTFS_VERSIONING_PASSPHRASE \
                                   | ECRYPTFS_VERSIONING_PLAINTEXT_PASSTHROUGH \
                                   | ECRYPTFS_VERSIONING_PUBKEY \
-                                  | ECRYPTFS_VERSIONING_XATTR)
+                                  | ECRYPTFS_VERSIONING_XATTR \
+                                  | ECRYPTFS_VERSIONING_MULTKEY)
 #define ECRYPTFS_MAX_PASSWORD_LENGTH 64
 #define ECRYPTFS_MAX_PASSPHRASE_BYTES ECRYPTFS_MAX_PASSWORD_LENGTH
 #define ECRYPTFS_SALT_SIZE 8
@@ -144,6 +146,7 @@ struct ecryptfs_private_key {
 struct ecryptfs_auth_tok {
         u16 version; /* 8-bit major and 8-bit minor */
         u16 token_type;
+#define ECRYPTFS_ENCRYPT_ONLY 0x00000001
         u32 flags;
         struct ecryptfs_session_key session_key;
         u8 reserved[32];
@@ -153,6 +156,7 @@ struct ecryptfs_auth_tok {
         } token;
 } __attribute__ ((packed));
 
+int ecryptfs_get_auth_tok_sig(char **sig, struct ecryptfs_auth_tok *auth_tok);
 void ecryptfs_dump_auth_tok(struct ecryptfs_auth_tok *auth_tok);
 extern void ecryptfs_to_hex(char *dst, char *src, size_t src_size);
 extern void ecryptfs_from_hex(char *dst, char *src, int dst_size);
@@ -194,7 +198,6 @@ ecryptfs_get_key_payload_data(struct key *key)
 #define ECRYPTFS_MAX_KEYSET_SIZE 1024
 #define ECRYPTFS_MAX_CIPHER_NAME_SIZE 32
 #define ECRYPTFS_MAX_NUM_ENC_KEYS 64
-#define ECRYPTFS_MAX_NUM_KEYSIGS 2 /* TODO: Make this a linked list */
 #define ECRYPTFS_MAX_IV_BYTES 16        /* 128 bits */
 #define ECRYPTFS_SALT_BYTES 2
 #define MAGIC_ECRYPTFS_MARKER 0x3c81b7f5
@@ -212,6 +215,11 @@ ecryptfs_get_key_payload_data(struct key *key)
 #define ECRYPTFS_TAG_67_PACKET_TYPE 0x43
 #define MD5_DIGEST_SIZE 16
 
+struct ecryptfs_key_sig {
+        struct list_head crypt_stat_list;
+        char keysig[ECRYPTFS_SIG_SIZE_HEX];
+};
+
 /**
  * This is the primary struct associated with each encrypted file.
  *
@@ -231,7 +239,6 @@ struct ecryptfs_crypt_stat {
         u32 flags;
         unsigned int file_version;
         size_t iv_bytes;
-        size_t num_keysigs;
         size_t header_extent_size;
         size_t num_header_extents_at_front;
         size_t extent_size; /* Data extent size; default is 4096 */
@@ -245,7 +252,8 @@ struct ecryptfs_crypt_stat {
         unsigned char cipher[ECRYPTFS_MAX_CIPHER_NAME_SIZE];
         unsigned char key[ECRYPTFS_MAX_KEY_BYTES];
         unsigned char root_iv[ECRYPTFS_MAX_IV_BYTES];
-        unsigned char keysigs[ECRYPTFS_MAX_NUM_KEYSIGS][ECRYPTFS_SIG_SIZE_HEX];
+        struct list_head keysig_list;
+        struct mutex keysig_list_mutex;
         struct mutex cs_tfm_mutex;
         struct mutex cs_hash_tfm_mutex;
         struct mutex cs_mutex;
@@ -265,6 +273,26 @@ struct ecryptfs_dentry_info {
         struct ecryptfs_crypt_stat *crypt_stat;
 };
 
+struct ecryptfs_global_auth_tok {
+#define ECRYPTFS_AUTH_TOK_INVALID 0x00000001
+        u32 flags;
+        struct list_head mount_crypt_stat_list;
+        struct key *global_auth_tok_key;
+        struct ecryptfs_auth_tok *global_auth_tok;
+        unsigned char sig[ECRYPTFS_SIG_SIZE_HEX + 1];
+};
+
+struct ecryptfs_key_tfm {
+        struct crypto_blkcipher *key_tfm;
+        size_t key_size;
+        struct mutex key_tfm_mutex;
+        struct list_head key_tfm_list;
+        unsigned char cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1];
+};
+
+extern struct list_head key_tfm_list;
+extern struct mutex key_tfm_list_mutex;
+
 /**
  * This struct is to enable a mount-wide passphrase/salt combo. This
  * is more or less a stopgap to provide similar functionality to other
@@ -276,15 +304,14 @@ struct ecryptfs_mount_crypt_stat {
 #define ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED 0x00000001
 #define ECRYPTFS_XATTR_METADATA_ENABLED        0x00000002
 #define ECRYPTFS_ENCRYPTED_VIEW_ENABLED        0x00000004
+#define ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED  0x00000008
         u32 flags;
-        struct ecryptfs_auth_tok *global_auth_tok;
-        struct key *global_auth_tok_key;
+        struct list_head global_auth_tok_list;
+        struct mutex global_auth_tok_list_mutex;
+        size_t num_global_auth_toks;
         size_t global_default_cipher_key_size;
-        struct crypto_blkcipher *global_key_tfm;
-        struct mutex global_key_tfm_mutex;
         unsigned char global_default_cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE
                                                  + 1];
-        unsigned char global_auth_tok_sig[ECRYPTFS_SIG_SIZE_HEX + 1];
 };
 
 /* superblock private data. */
@@ -468,6 +495,9 @@ extern struct kmem_cache *ecryptfs_header_cache_2;
 extern struct kmem_cache *ecryptfs_xattr_cache;
 extern struct kmem_cache *ecryptfs_lower_page_cache;
 extern struct kmem_cache *ecryptfs_key_record_cache;
+extern struct kmem_cache *ecryptfs_key_sig_cache;
+extern struct kmem_cache *ecryptfs_global_auth_tok_cache;
+extern struct kmem_cache *ecryptfs_key_tfm_cache;
 
 int ecryptfs_interpose(struct dentry *hidden_dentry,
                        struct dentry *this_dentry, struct super_block *sb,
@@ -538,9 +568,8 @@ int
 ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
                           unsigned char *src, struct dentry *ecryptfs_dentry);
 int ecryptfs_truncate(struct dentry *dentry, loff_t new_length);
-int
-ecryptfs_process_cipher(struct crypto_blkcipher **key_tfm, char *cipher_name,
-                        size_t *key_size);
+int ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
+                                char *cipher_name, size_t *key_size);
 int ecryptfs_inode_test(struct inode *inode, void *candidate_lower_inode);
 int ecryptfs_inode_set(struct inode *inode, void *lower_inode);
 void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode);
@@ -580,6 +609,24 @@ void
 ecryptfs_write_header_metadata(char *virt,
                                struct ecryptfs_crypt_stat *crypt_stat,
                                size_t *written);
+int ecryptfs_add_keysig(struct ecryptfs_crypt_stat *crypt_stat, char *sig);
+int
+ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
+                           char *sig);
+int ecryptfs_get_global_auth_tok_for_sig(
+        struct ecryptfs_global_auth_tok **global_auth_tok,
+        struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig);
+int
+ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
+                         size_t key_size);
+int ecryptfs_init_crypto(void);
+int ecryptfs_destruct_crypto(void);
+int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
+                                               struct mutex **tfm_mutex,
+                                               char *cipher_name);
+int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
+                                      struct ecryptfs_auth_tok **auth_tok,
+                                      char *sig);
 int ecryptfs_write_zeros(struct file *file, pgoff_t index, int start,
                          int num_zeros);