From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Date: Fri, 13 Mar 2020 15:20:59 +0000 Subject: [PATCH v3 0/3] KEYS: Read keys to internal buffer & then copy to userspace Message-Id: <20200313152102.1707-1-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit List-Id: To: David Howells , Jarkko Sakkinen , James Morris , "Serge E. Hallyn" , Mimi Zohar Cc: keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-integrity@vger.kernel.org, Sumit Garg , Jerry Snitselaar , Roberto Sassu , Eric Biggers , Chris von Recklinghausen , Waiman Long v3: - Reorganize the keyctl_read_key() code to make it more readable as suggested by Jarkko Sakkinen. - Add patch 3 to use kvmalloc() for safer large buffer allocation as suggested by David Howells. v2: - Handle NULL buffer and buflen properly in patch 1. - Fix a bug in big_key.c. - Add patch 2 to handle arbitrary large user-supplied buflen. The current security key read methods are called with the key semaphore held. The methods then copy out the key data to userspace which is subjected to page fault and may acquire the mmap semaphore. That can result in circular lock dependency and hence a chance to get into deadlock. To avoid such a deadlock, an internal buffer is now allocated for getting out the necessary data first. After releasing the key semaphore, the key data are then copied out to userspace sidestepping the circular lock dependency. The keyutils test suite was run and the test passed with these patchset applied without any falure. Waiman Long (3): KEYS: Don't write out to userspace while holding key semaphore KEYS: Avoid false positive ENOMEM error on key read KEYS: Use kvmalloc() to better handle large buffer allocation include/linux/key-type.h | 2 +- security/keys/big_key.c | 11 ++- security/keys/encrypted-keys/encrypted.c | 7 +- security/keys/internal.h | 14 ++++ security/keys/keyctl.c | 87 ++++++++++++++++++++--- security/keys/keyring.c | 6 +- security/keys/request_key_auth.c | 7 +- security/keys/trusted-keys/trusted_tpm1.c | 14 +--- security/keys/user_defined.c | 5 +- 9 files changed, 107 insertions(+), 46 deletions(-) -- 2.18.1