kernel/linux.git/include/linux/lsm_hooks.h, branch v6.6.132

security: Allow all LSMs to provide xattrs for inode_init_security hook

2023-07-10T17:59:37+00:00

Currently, the LSM infrastructure supports only one LSM providing an xattr and EVM calculating the HMAC on that xattr, plus other inode metadata. Allow all LSMs to provide one or multiple xattrs, by extending the security blob reservation mechanism. Introduce the new lbs_xattr_count field of the lsm_blob_sizes structure, so that each LSM can specify how many xattrs it needs, and the LSM infrastructure knows how many xattr slots it should allocate. Modify the inode_init_security hook definition, by passing the full xattr array allocated in security_inode_init_security(), and the current number of xattr slots in that array filled by LSMs. The first parameter would allow EVM to access and calculate the HMAC on xattrs supplied by other LSMs, the second to not leave gaps in the xattr array, when an LSM requested but did not provide xattrs (e.g. if it is not initialized). Introduce lsm_get_xattr_slot(), which LSMs can call as many times as the number specified in the lbs_xattr_count field of the lsm_blob_sizes structure. During each call, lsm_get_xattr_slot() increments the number of filled xattrs, so that at the next invocation it returns the next xattr slot to fill. Cleanup security_inode_init_security(). Unify the !initxattrs and initxattrs case by simply not allocating the new_xattrs array in the former. Update the documentation to reflect the changes, and fix the description of the xattr name, as it is not allocated anymore. Adapt both SELinux and Smack to use the new definition of the inode_init_security hook, and to call lsm_get_xattr_slot() to obtain and fill the reserved slots in the xattr array. Move the xattr->name assignment after the xattr->value one, so that it is done only in case of successful memory allocation. Finally, change the default return value of the inode_init_security hook from zero to -EOPNOTSUPP, so that BPF LSM correctly follows the hook conventions. Reported-by: Nicolas Bouchinet Link: https://lore.kernel.org/linux-integrity/Y1FTSIo+1x+4X0LS@archlinux/ Signed-off-by: Roberto Sassu Acked-by: Casey Schaufler [PM: minor comment and variable tweaks, approved by RS] Signed-off-by: Paul Moore

Merge tag 'lsm-pr-20230420' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm

2023-04-24T18:21:50+00:00

Pull lsm updates from Paul Moore: - Move the LSM hook comment blocks into security/security.c For many years the LSM hook comment blocks were located in a very odd place, include/linux/lsm_hooks.h, where they lived on their own, disconnected from both the function prototypes and definitions. In keeping with current kernel conventions, this moves all of these comment blocks to the top of the function definitions, transforming them into the kdoc format in the process. This should make it much easier to maintain these comments, which are the main source of LSM hook documentation. For the most part the comment contents were left as-is, although some glaring errors were corrected. Expect additional edits in the future as we slowly update and correct the comment blocks. This is the bulk of the diffstat. - Introduce LSM_ORDER_LAST Similar to how LSM_ORDER_FIRST is used to specify LSMs which should be ordered before "normal" LSMs, the LSM_ORDER_LAST is used to specify LSMs which should be ordered after "normal" LSMs. This is one of the prerequisites for transitioning IMA/EVM to a proper LSM. - Remove the security_old_inode_init_security() hook The security_old_inode_init_security() LSM hook only allows for a single xattr which is problematic both for LSM stacking and the IMA/EVM-as-a-LSM effort. This finishes the conversion over to the security_inode_init_security() hook and removes the single-xattr LSM hook. - Fix a reiserfs problem with security xattrs During the security_old_inode_init_security() removal work it became clear that reiserfs wasn't handling security xattrs properly so we fixed it. * tag 'lsm-pr-20230420' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm: (32 commits) reiserfs: Add security prefix to xattr name in reiserfs_security_write() security: Remove security_old_inode_init_security() ocfs2: Switch to security_inode_init_security() reiserfs: Switch to security_inode_init_security() security: Remove integrity from the LSM list in Kconfig Revert "integrity: double check iint_cache was initialized" security: Introduce LSM_ORDER_LAST and set it for the integrity LSM device_cgroup: Fix typo in devcgroup_css_alloc description lsm: fix a badly named parameter in security_get_getsecurity() lsm: fix doc warnings in the LSM hook comments lsm: styling fixes to security/security.c lsm: move the remaining LSM hook comments to security/security.c lsm: move the io_uring hook comments to security/security.c lsm: move the perf hook comments to security/security.c lsm: move the bpf hook comments to security/security.c lsm: move the audit hook comments to security/security.c lsm: move the binder hook comments to security/security.c lsm: move the sysv hook comments to security/security.c lsm: move the key hook comments to security/security.c lsm: move the xfrm hook comments to security/security.c ...

selinux: clean up dead code after removing runtime disable

2023-03-24T20:15:42+00:00

Commit f22f9aaf6c3d ("selinux: remove the runtime disable functionality") removes the config SECURITY_SELINUX_DISABLE. This results in some dead code in lsm_hooks.h. Remove this dead code. Signed-off-by: Lukas Bulwahn Signed-off-by: Paul Moore

selinux: remove the runtime disable functionality

2023-03-20T16:34:23+00:00

After working with the larger SELinux-based distros for several years, we're finally at a place where we can disable the SELinux runtime disable functionality. The existing kernel deprecation notice explains the functionality and why we want to remove it: The selinuxfs "disable" node allows SELinux to be disabled at runtime prior to a policy being loaded into the kernel. If disabled via this mechanism, SELinux will remain disabled until the system is rebooted. The preferred method of disabling SELinux is via the "selinux=0" boot parameter, but the selinuxfs "disable" node was created to make it easier for systems with primitive bootloaders that did not allow for easy modification of the kernel command line. Unfortunately, allowing for SELinux to be disabled at runtime makes it difficult to secure the kernel's LSM hooks using the "__ro_after_init" feature. It is that last sentence, mentioning the '__ro_after_init' hardening, which is the real motivation for this change, and if you look at the diffstat you'll see that the impact of this patch reaches across all the different LSMs, helping prevent tampering at the LSM hook level. From a SELinux perspective, it is important to note that if you continue to disable SELinux via "/etc/selinux/config" it may appear that SELinux is disabled, but it is simply in an uninitialized state. If you load a policy with `load_policy -i`, you will see SELinux come alive just as if you had loaded the policy during early-boot. It is also worth noting that the "/sys/fs/selinux/disable" file is always writable now, regardless of the Kconfig settings, but writing to the file has no effect on the system, other than to display an error on the console if a non-zero/true value is written. Finally, in the several years where we have been working on deprecating this functionality, there has only been one instance of someone mentioning any user visible breakage. In this particular case it was an individual's kernel test system, and the workaround documented in the deprecation notice ("selinux=0" on the kernel command line) resolved the issue without problem. Acked-by: Casey Schaufler Signed-off-by: Paul Moore

security: Introduce LSM_ORDER_LAST and set it for the integrity LSM

2023-03-10T23:31:35+00:00

Introduce LSM_ORDER_LAST, to satisfy the requirement of LSMs needing to be last, e.g. the 'integrity' LSM, without changing the kernel command line or configuration. Also, set this order for the 'integrity' LSM. While not enforced, this is the only LSM expected to use it. Similarly to LSM_ORDER_FIRST, LSMs with LSM_ORDER_LAST are always enabled and put at the end of the LSM list, if selected in the kernel configuration. Setting one of these orders alone, does not cause the LSMs to be selected and compiled built-in in the kernel. Finally, for LSM_ORDER_MUTABLE LSMs, set the found variable to true if an LSM is found, regardless of its order. In this way, the kernel would not wrongly report that the LSM is not built-in in the kernel if its order is LSM_ORDER_LAST. Fixes: 79f7865d844c ("LSM: Introduce "lsm=" for boottime LSM selection") Signed-off-by: Roberto Sassu Acked-by: Mimi Zohar Signed-off-by: Paul Moore

lsm: move the remaining LSM hook comments to security/security.c

2023-03-06T18:41:07+00:00

This patch relocates the LSM hook function comments to the function definitions, in keeping with the current kernel conventions. This should make the hook descriptions more easily discoverable and easier to maintain. While formatting changes have been done to better fit the kernel-doc style, content changes have been kept to a minimum and limited to text which was obviously incorrect and/or outdated. It is expected the future patches will improve the quality of the function header comments. Acked-by: Casey Schaufler Signed-off-by: Paul Moore

lsm: move the io_uring hook comments to security/security.c

2023-03-06T18:41:07+00:00

lsm: move the perf hook comments to security/security.c

2023-03-06T18:41:07+00:00

lsm: move the bpf hook comments to security/security.c

2023-03-06T18:41:07+00:00

lsm: move the audit hook comments to security/security.c

2023-03-06T18:41:07+00:00