diff options
Diffstat (limited to 'fs/ext4/crypto_policy.c')
| -rw-r--r-- | fs/ext4/crypto_policy.c | 84 |
1 files changed, 58 insertions, 26 deletions
diff --git a/fs/ext4/crypto_policy.c b/fs/ext4/crypto_policy.c index 8a9feb341f31..818fa45ecf08 100644 --- a/fs/ext4/crypto_policy.c +++ b/fs/ext4/crypto_policy.c @@ -60,16 +60,12 @@ static int ext4_create_encryption_context_from_policy( ctx.format = EXT4_ENCRYPTION_CONTEXT_FORMAT_V1; memcpy(ctx.master_key_descriptor, policy->master_key_descriptor, EXT4_KEY_DESCRIPTOR_SIZE); - if (!ext4_valid_contents_enc_mode(policy->contents_encryption_mode)) { + if (!ext4_valid_enc_modes(policy->contents_encryption_mode, + policy->filenames_encryption_mode)) { printk(KERN_WARNING - "%s: Invalid contents encryption mode %d\n", __func__, - policy->contents_encryption_mode); - return -EINVAL; - } - if (!ext4_valid_filenames_enc_mode(policy->filenames_encryption_mode)) { - printk(KERN_WARNING - "%s: Invalid filenames encryption mode %d\n", __func__, - policy->filenames_encryption_mode); + "%s: Invalid encryption modes (contents %d, filenames %d)\n", + __func__, policy->contents_encryption_mode, + policy->filenames_encryption_mode); return -EINVAL; } if (policy->flags & ~EXT4_POLICY_FLAGS_VALID) @@ -148,20 +144,38 @@ int ext4_get_policy(struct inode *inode, struct ext4_encryption_policy *policy) int ext4_is_child_context_consistent_with_parent(struct inode *parent, struct inode *child) { - struct ext4_crypt_info *parent_ci, *child_ci; + const struct ext4_crypt_info *parent_ci, *child_ci; + struct ext4_encryption_context parent_ctx, child_ctx; int res; - if ((parent == NULL) || (child == NULL)) { - pr_err("parent %p child %p\n", parent, child); - WARN_ON(1); /* Should never happen */ - return 0; - } - /* no restrictions if the parent directory is not encrypted */ + /* No restrictions on file types which are never encrypted */ + if (!S_ISREG(child->i_mode) && !S_ISDIR(child->i_mode) && + !S_ISLNK(child->i_mode)) + return 1; + + /* No restrictions if the parent directory is unencrypted */ if (!ext4_encrypted_inode(parent)) return 1; - /* if the child directory is not encrypted, this is always a problem */ + + /* Encrypted directories must not contain unencrypted files */ if (!ext4_encrypted_inode(child)) return 0; + + /* + * Both parent and child are encrypted, so verify they use the same + * encryption policy. Compare the fscrypt_info structs if the keys are + * available, otherwise retrieve and compare the fscrypt_contexts. + * + * Note that the fscrypt_context retrieval will be required frequently + * when accessing an encrypted directory tree without the key. + * Performance-wise this is not a big deal because we already don't + * really optimize for file access without the key (to the extent that + * such access is even possible), given that any attempted access + * already causes a fscrypt_context retrieval and keyring search. + * + * In any case, if an unexpected error occurs, fall back to "forbidden". + */ + res = ext4_get_encryption_info(parent); if (res) return 0; @@ -170,17 +184,35 @@ int ext4_is_child_context_consistent_with_parent(struct inode *parent, return 0; parent_ci = EXT4_I(parent)->i_crypt_info; child_ci = EXT4_I(child)->i_crypt_info; - if (!parent_ci && !child_ci) - return 1; - if (!parent_ci || !child_ci) + if (parent_ci && child_ci) { + return memcmp(parent_ci->ci_master_key, child_ci->ci_master_key, + EXT4_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 = ext4_xattr_get(parent, EXT4_XATTR_INDEX_ENCRYPTION, + EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, + &parent_ctx, sizeof(parent_ctx)); + if (res != sizeof(parent_ctx)) + return 0; + + res = ext4_xattr_get(child, EXT4_XATTR_INDEX_ENCRYPTION, + EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, + &child_ctx, sizeof(child_ctx)); + if (res != sizeof(child_ctx)) return 0; - return (memcmp(parent_ci->ci_master_key, - child_ci->ci_master_key, - EXT4_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)); + return memcmp(parent_ctx.master_key_descriptor, + child_ctx.master_key_descriptor, + EXT4_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); } /** |