With the introduction of IMA-appraisal and the need to write file hashes as security xattrs, IMA needed to take the global i_mutex lock. process_measurement() took the iint->mutex first and then the i_mutex, while setxattr, chmod and chown took the locks in reverse order. To resolve this potential deadlock, the iint->mutex was removed. Some filesystems have recently replaced their filesystem dependent lock with the global i_rwsem (formerly the i_mutex) to read a file. As a result, when IMA attempts to calculate the file hash, reading the file attempts to take the i_rwsem again. To resolve this locking problem, this patch set introduces a new ->integrity_read file operation method. Until all filesystems define the new ->integrity_read method, files that were previously measured might not be currently measured and files that were previously appraised might fail to be appraised properly. Version 2 of this patch set, introduces measurement entries and IMA-audit messages containing file hash values containing 0's, instead of the actual file hash, for files which the file hash could not be calculated. Like for any other file signature verification error, file access/execute permission will be denied, for files in policy that the file hash could not be calculated. To override the IMA policy, allowing unverified code to be accessed/executed on filesystems not supported by IMA, version 2 of this patch set defines a new pseudo policy "action" named "dont_failsafe" and a new builtin policy named "fs_unsafe", which can be specified on the boot command line. Mimi Changelog v1: - Don't silently drop file measurements on failure to "collect" the file hash, add an entry in the measurement list and IMA-audit log the file. - Define a pseudo policy action named "dont_failsafe". - Define a new builtin IMA policy named "fs_unsafe". - Instead of calling the existing read_iter method, when defined as generic_file_read_iter(), define an ->integrity_read method for each file system. - Expanded/clarified motivation in the patch description for using the ->read method. - Use kvec, not iovec. (Reported by zero day testing) Christoph Hellwig (1): ima: use fs method to read integrity data Mimi Zohar (9): ima: always measure and audit files in policy ima: define "dont_failsafe" policy action rule ima: define "fs_unsafe" builtin policy tmpfs: define integrity_read method fs: define integrity_read method for ext2, gfs2, f2fs, jfs, ramfs ocfs2: define integrity_read method jffs2: define integrity_read method ubifs: define integrity_read method ima: use existing read file operation method to calculate file hash Documentation/ABI/testing/ima_policy | 3 ++- Documentation/admin-guide/kernel-parameters.txt | 8 ++++++- fs/btrfs/file.c | 1 + fs/ext2/file.c | 1 + fs/ext4/file.c | 1 + fs/f2fs/file.c | 1 + fs/gfs2/file.c | 2 ++ fs/jffs2/file.c | 1 + fs/jfs/file.c | 1 + fs/ocfs2/file.c | 1 + fs/ramfs/file-mmu.c | 1 + fs/ramfs/file-nommu.c | 1 + fs/ubifs/file.c | 1 + fs/xfs/xfs_file.c | 21 +++++++++++++++++ include/linux/fs.h | 1 + mm/shmem.c | 1 + security/integrity/iint.c | 31 +++++++++++++++++++------ security/integrity/ima/ima.h | 1 + security/integrity/ima/ima_api.c | 7 ++++-- security/integrity/ima/ima_main.c | 15 +++++++++--- security/integrity/ima/ima_policy.c | 16 ++++++++++++- 21 files changed, 101 insertions(+), 15 deletions(-) -- 2.7.4
