[PATCH 00/28] security: Move IMA and EVM to the LSM infrastructure

[Roberto Sassu]

From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>

This patch set depends on:
- https://lore.kernel.org/linux-integrity/20221201104125.919483-1-roberto.sassu@xxxxxxxxxxxxxxx/ (there will be a v8 shortly)
- https://lore.kernel.org/linux-security-module/20230217032625.678457-1-paul@xxxxxxxxxxxxxx/

IMA and EVM are not effectively LSMs, especially due the fact that in the
past they could not provide a security blob while there is another LSM
active.

That changed in the recent years, the LSM stacking feature now makes it
possible to stack together multiple LSMs, and allows them to provide a
security blob for most kernel objects. While the LSM stacking feature has
some limitations being worked out, it is already suitable to make IMA and
EVM as LSMs.

In short, while this patch set is big, it does not make any functional
change to IMA and EVM. IMA and EVM functions are called by the LSM
infrastructure in the same places as before (except ima_post_path_mknod()),
rather being hardcoded calls, and the inode metadata pointer is directly
stored in the inode security blob rather than in a separate rbtree.

More specifically, patches 1-13 make IMA and EVM functions suitable to
be registered to the LSM infrastructure, by aligning function parameters.

Patches 14-22 add new LSM hooks in the same places where IMA and EVM
functions are called, if there is no LSM hook already.

Patch 23 adds the 'last' ordering strategy for LSMs, so that IMA and EVM
functions are called in the same order as of today. Also, like with the
'first' strategy, LSMs using it are always enabled, so IMA and EVM
functions will be always called (if IMA and EVM are compiled built-in).

Patches 24-27 do the bulk of the work, remove hardcoded calls to IMA and
EVM functions, register those functions in the LSM infrastructure, and let
the latter call them. In addition, they also reserve one slot for EVM to 
supply an xattr to the inode_init_security hook.

Finally, patch 28 removes the rbtree used to bind metadata to the inodes,
and instead reserve a space in the inode security blob to store the pointer
to metadata. This also brings performance improvements due to retrieving
metadata in constant time, as opposed to logarithmic.

Roberto Sassu (28):
  ima: Align ima_inode_post_setattr() definition with LSM infrastructure
  ima: Align ima_post_path_mknod() definition with LSM infrastructure
  ima: Align ima_post_create_tmpfile() definition with LSM
    infrastructure
  ima: Align ima_file_mprotect() definition with LSM infrastructure
  ima: Align ima_inode_setxattr() definition with LSM infrastructure
  ima: Align ima_inode_removexattr() definition with LSM infrastructure
  ima: Align ima_post_read_file() definition with LSM infrastructure
  evm: Align evm_inode_post_setattr() definition with LSM infrastructure
  evm: Align evm_inode_setxattr() definition with LSM infrastructure
  evm: Align evm_inode_post_setxattr() definition with LSM
    infrastructure
  evm: Complete description of evm_inode_setattr()
  fs: Fix description of vfs_tmpfile()
  security: Align inode_setattr hook definition with EVM
  security: Introduce inode_post_setattr hook
  security: Introduce inode_post_removexattr hook
  security: Introduce file_post_open hook
  security: Introduce file_pre_free_security hook
  security: Introduce path_post_mknod hook
  security: Introduce inode_post_create_tmpfile hook
  security: Introduce inode_post_set_acl hook
  security: Introduce inode_post_remove_acl hook
  security: Introduce key_post_create_or_update hook
  security: Introduce LSM_ORDER_LAST
  ima: Move to LSM infrastructure
  ima: Move IMA-Appraisal to LSM infrastructure
  evm: Move to LSM infrastructure
  integrity: Move integrity functions to the LSM infrastructure
  integrity: Switch from rbtree to LSM-managed blob for
    integrity_iint_cache

 fs/attr.c                             |   5 +-
 fs/file_table.c                       |   3 +-
 fs/namei.c                            |  13 +-
 fs/nfsd/vfs.c                         |   3 +-
 fs/open.c                             |   1 -
 fs/posix_acl.c                        |   5 +-
 fs/xattr.c                            |   3 +-
 include/linux/evm.h                   | 112 -----------
 include/linux/ima.h                   | 142 -------------
 include/linux/integrity.h             |  26 ---
 include/linux/lsm_hook_defs.h         |  21 +-
 include/linux/lsm_hooks.h             |   1 +
 include/linux/security.h              |  65 ++++++
 security/integrity/evm/evm_main.c     | 109 ++++++++--
 security/integrity/iint.c             |  90 +++------
 security/integrity/ima/ima.h          |  12 ++
 security/integrity/ima/ima_appraise.c |  38 +++-
 security/integrity/ima/ima_main.c     |  77 +++++--
 security/integrity/integrity.h        |  44 +++-
 security/keys/key.c                   |  10 +-
 security/security.c                   | 276 ++++++++++++++++----------
 security/selinux/hooks.c              |   3 +-
 security/smack/smack_lsm.c            |   4 +-
 23 files changed, 550 insertions(+), 513 deletions(-)

-- 
2.25.1