diff options
| -rw-r--r-- | fs/crypto/fscrypt_private.h | 3 | ||||
| -rw-r--r-- | fs/crypto/keyring.c | 117 |
2 files changed, 77 insertions, 43 deletions
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h index 20cbd9a4b28b..855ea935f5a6 100644 --- a/fs/crypto/fscrypt_private.h +++ b/fs/crypto/fscrypt_private.h @@ -437,6 +437,9 @@ struct key * fscrypt_find_master_key(struct super_block *sb, const struct fscrypt_key_specifier *mk_spec); +int fscrypt_add_test_dummy_key(struct super_block *sb, + struct fscrypt_key_specifier *key_spec); + int fscrypt_verify_key_added(struct super_block *sb, const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]); diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c index ab41b25d4fa1..c983ddfde8ad 100644 --- a/fs/crypto/keyring.c +++ b/fs/crypto/keyring.c @@ -20,6 +20,7 @@ #include <crypto/skcipher.h> #include <linux/key-type.h> +#include <linux/random.h> #include <linux/seq_file.h> #include "fscrypt_private.h" @@ -424,9 +425,9 @@ static int add_existing_master_key(struct fscrypt_master_key *mk, return 0; } -static int add_master_key(struct super_block *sb, - struct fscrypt_master_key_secret *secret, - const struct fscrypt_key_specifier *mk_spec) +static int do_add_master_key(struct super_block *sb, + struct fscrypt_master_key_secret *secret, + const struct fscrypt_key_specifier *mk_spec) { static DEFINE_MUTEX(fscrypt_add_key_mutex); struct key *key; @@ -465,6 +466,35 @@ out_unlock: return err; } +static int add_master_key(struct super_block *sb, + struct fscrypt_master_key_secret *secret, + struct fscrypt_key_specifier *key_spec) +{ + int err; + + if (key_spec->type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER) { + err = fscrypt_init_hkdf(&secret->hkdf, secret->raw, + secret->size); + if (err) + return err; + + /* + * Now that the HKDF context is initialized, the raw key is no + * longer needed. + */ + memzero_explicit(secret->raw, secret->size); + + /* Calculate the key identifier */ + err = fscrypt_hkdf_expand(&secret->hkdf, + HKDF_CONTEXT_KEY_IDENTIFIER, NULL, 0, + key_spec->u.identifier, + FSCRYPT_KEY_IDENTIFIER_SIZE); + if (err) + return err; + } + return do_add_master_key(sb, secret, key_spec); +} + static int fscrypt_provisioning_key_preparse(struct key_preparsed_payload *prep) { const struct fscrypt_provisioning_key_payload *payload = prep->data; @@ -609,6 +639,15 @@ int fscrypt_ioctl_add_key(struct file *filp, void __user *_uarg) if (memchr_inv(arg.__reserved, 0, sizeof(arg.__reserved))) return -EINVAL; + /* + * Only root can add keys that are identified by an arbitrary descriptor + * rather than by a cryptographic hash --- since otherwise a malicious + * user could add the wrong key. + */ + if (arg.key_spec.type == FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR && + !capable(CAP_SYS_ADMIN)) + return -EACCES; + memset(&secret, 0, sizeof(secret)); if (arg.key_id) { if (arg.raw_size != 0) @@ -626,48 +665,17 @@ int fscrypt_ioctl_add_key(struct file *filp, void __user *_uarg) goto out_wipe_secret; } - switch (arg.key_spec.type) { - case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR: - /* - * Only root can add keys that are identified by an arbitrary - * descriptor rather than by a cryptographic hash --- since - * otherwise a malicious user could add the wrong key. - */ - err = -EACCES; - if (!capable(CAP_SYS_ADMIN)) - goto out_wipe_secret; - break; - case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER: - err = fscrypt_init_hkdf(&secret.hkdf, secret.raw, secret.size); - if (err) - goto out_wipe_secret; - - /* - * Now that the HKDF context is initialized, the raw key is no - * longer needed. - */ - memzero_explicit(secret.raw, secret.size); - - /* Calculate the key identifier and return it to userspace. */ - err = fscrypt_hkdf_expand(&secret.hkdf, - HKDF_CONTEXT_KEY_IDENTIFIER, - NULL, 0, arg.key_spec.u.identifier, - FSCRYPT_KEY_IDENTIFIER_SIZE); - if (err) - goto out_wipe_secret; - err = -EFAULT; - if (copy_to_user(uarg->key_spec.u.identifier, - arg.key_spec.u.identifier, - FSCRYPT_KEY_IDENTIFIER_SIZE)) - goto out_wipe_secret; - break; - default: - WARN_ON(1); - err = -EINVAL; + err = add_master_key(sb, &secret, &arg.key_spec); + if (err) goto out_wipe_secret; - } - err = add_master_key(sb, &secret, &arg.key_spec); + /* Return the key identifier to userspace, if applicable */ + err = -EFAULT; + if (arg.key_spec.type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER && + copy_to_user(uarg->key_spec.u.identifier, arg.key_spec.u.identifier, + FSCRYPT_KEY_IDENTIFIER_SIZE)) + goto out_wipe_secret; + err = 0; out_wipe_secret: wipe_master_key_secret(&secret); return err; @@ -675,6 +683,29 @@ out_wipe_secret: EXPORT_SYMBOL_GPL(fscrypt_ioctl_add_key); /* + * Add the key for '-o test_dummy_encryption' to the filesystem keyring. + * + * Use a per-boot random key to prevent people from misusing this option. + */ +int fscrypt_add_test_dummy_key(struct super_block *sb, + struct fscrypt_key_specifier *key_spec) +{ + static u8 test_key[FSCRYPT_MAX_KEY_SIZE]; + struct fscrypt_master_key_secret secret; + int err; + + get_random_once(test_key, FSCRYPT_MAX_KEY_SIZE); + + memset(&secret, 0, sizeof(secret)); + secret.size = FSCRYPT_MAX_KEY_SIZE; + memcpy(secret.raw, test_key, FSCRYPT_MAX_KEY_SIZE); + + err = add_master_key(sb, &secret, key_spec); + wipe_master_key_secret(&secret); + return err; +} + +/* * Verify that the current user has added a master key with the given identifier * (returns -ENOKEY if not). This is needed to prevent a user from encrypting * their files using some other user's key which they don't actually know. |