Pull lsm updates from Paul Moore:

 - Improve the error handling in the device cgroup such that memory
   allocation failures when updating the access policy do not
   potentially alter the policy.

 - Some minor fixes to reiserfs to ensure that it properly releases
   LSM-related xattr values.

 - Update the security_socket_getpeersec_stream() LSM hook to take
   sockptr_t values.

   Previously the net/BPF folks updated the getsockopt code in the
   network stack to leverage the sockptr_t type to make it easier to
   pass both kernel and __user pointers, but unfortunately when they did
   so they didn't convert the LSM hook.

   While there was/is no immediate risk by not converting the LSM hook,
   it seems like this is a mistake waiting to happen so this patch
   proactively does the LSM hook conversion.

 - Convert vfs_getxattr_alloc() to return an int instead of a ssize_t
   and cleanup the callers. Internally the function was never going to
   return anything larger than an int and the callers were doing some
   very odd things casting the return value; this patch fixes all that
   and helps bring a bit of sanity to vfs_getxattr_alloc() and its
   callers.

 - More verbose, and helpful, LSM debug output when the system is booted
   with "lsm.debug" on the command line. There are examples in the
   commit description, but the quick summary is that this patch provides
   better information about which LSMs are enabled and the ordering in
   which they are processed.

 - General comment and kernel-doc fixes and cleanups.

* tag 'lsm-pr-20221212' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm:
  lsm: Fix description of fs_context_parse_param
  lsm: Add/fix return values in lsm_hooks.h and fix formatting
  lsm: Clarify documentation of vm_enough_memory hook
  reiserfs: Add missing calls to reiserfs_security_free()
  lsm,fs: fix vfs_getxattr_alloc() return type and caller error paths
  device_cgroup: Roll back to original exceptions after copy failure
  LSM: Better reporting of actual LSMs at boot
  lsm: make security_socket_getpeersec_stream() sockptr_t safe
  audit: Fix some kernel-doc warnings
  lsm: remove obsoleted comments for security hooks
  fs: edit a comment made in bad taste

The vfs_getxattr_alloc() function currently returns a ssize_t value
despite the fact that it only uses int values internally for return
values.  Fix this by converting vfs_getxattr_alloc() to return an
int type and adjust the callers as necessary.  As part of these
caller modifications, some of the callers are fixed to properly free
the xattr value buffer on both success and failure to ensure that
memory is not leaked in the failure case.

Reviewed-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

When evm_status is INTEGRITY_PASS then this function returns early and so
later codepaths that check for evm_status != INTEGRITY_PASS can be removed
as they are dead code.

Fixes: e61b135f7bfe ("integrity: implement get and set acl hook")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

The security and integrity infrastructure has dedicated hooks now so
evm_xattr_acl_change() is dead code. Before this commit the callchain was:

evm_protect_xattr()
-> evm_xattr_change()
   -> evm_xattr_acl_change()

where evm_protect_xattr() was hit from evm_inode_setxattr() and
evm_inode_removexattr(). But now we have evm_inode_set_acl() and
evm_inode_remove_acl() and have switched over the vfs to rely on the posix
acl api so the code isn't hit anymore.

Suggested-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

The current way of setting and getting posix acls through the generic
xattr interface is error prone and type unsafe. The vfs needs to
interpret and fixup posix acls before storing or reporting it to
userspace. Various hacks exist to make this work. The code is hard to
understand and difficult to maintain in it's current form. Instead of
making this work by hacking posix acls through xattr handlers we are
building a dedicated posix acl api around the get and set inode
operations. This removes a lot of hackiness and makes the codepaths
easier to maintain. A lot of background can be found in [1].

So far posix acls were passed as a void blob to the security and
integrity modules. Some of them like evm then proceed to interpret the
void pointer and convert it into the kernel internal struct posix acl
representation to perform their integrity checking magic. This is
obviously pretty problematic as that requires knowledge that only the
vfs is guaranteed to have and has lead to various bugs. Add a proper
security hook for setting posix acls and pass down the posix acls in
their appropriate vfs format instead of hacking it through a void
pointer stored in the uapi format.

I spent considerate time in the security module and integrity
infrastructure and audited all codepaths. EVM is the only part that
really has restrictions based on the actual posix acl values passed
through it (e.g., i_mode). Before this dedicated hook EVM used to translate
from the uapi posix acl format sent to it in the form of a void pointer
into the vfs format. This is not a good thing. Instead of hacking around in
the uapi struct give EVM the posix acls in the appropriate vfs format and
perform sane permissions checks that mirror what it used to to in the
generic xattr hook.

IMA doesn't have any restrictions on posix acls. When posix acls are
changed it just wants to update its appraisal status to trigger an EVM
revalidation.

The removal of posix acls is equivalent to passing NULL to the posix set
acl hooks. This is the same as before through the generic xattr api.

Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1]
Acked-by: Paul Moore <paul@paul-moore.com> (LSM)
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

The uapi POSIX ACL struct passed through the value argument during
setxattr() contains {g,u}id values encoded via ACL_{GROUP,USER} entries
that should actually be stored in the form of k{g,u}id_t (See [1] for a
long explanation of the issue.).

In 0c5fd887d2bb ("acl: move idmapped mount fixup into vfs_{g,s}etxattr()")
we took the mount's idmapping into account in order to let overlayfs
handle POSIX ACLs on idmapped layers correctly. The fixup is currently
performed directly in vfs_setxattr() which piles on top of the earlier
hackiness by handling the mount's idmapping and stuff the vfs{g,u}id_t
values into the uapi struct as well. While that is all correct and works
fine it's just ugly.

Now that we have introduced vfs_make_posix_acl() earlier move handling
idmapped mounts out of vfs_setxattr() and into the POSIX ACL handler
where it belongs.

Note that we also need to call vfs_make_posix_acl() for EVM which
interpretes POSIX ACLs during security_inode_setxattr(). Leave them a
longer comment for future reference.

All filesystems that support idmapped mounts via FS_ALLOW_IDMAP use the
standard POSIX ACL xattr handlers and are covered by this change. This
includes overlayfs which simply calls vfs_{g,s}etxattr().

The following filesystems use custom POSIX ACL xattr handlers: 9p, cifs,
ecryptfs, and ntfs3 (and overlayfs but we've covered that in the paragraph
above) and none of them support idmapped mounts yet.

Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org/ [1]
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>

Pull integrity updates from Mimi Zohar:
 "Aside from the one EVM cleanup patch, all the other changes are kexec
  related.

  On different architectures different keyrings are used to verify the
  kexec'ed kernel image signature. Here are a number of preparatory
  cleanup patches and the patches themselves for making the keyrings -
  builtin_trusted_keyring, .machine, .secondary_trusted_keyring, and
  .platform - consistent across the different architectures"

* tag 'integrity-v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  kexec, KEYS, s390: Make use of built-in and secondary keyring for signature verification
  arm64: kexec_file: use more system keyrings to verify kernel image signature
  kexec, KEYS: make the code in bzImage64_verify_sig generic
  kexec: clean up arch_kexec_kernel_verify_sig
  kexec: drop weak attribute from functions
  kexec_file: drop weak attribute from functions
  evm: Use IS_ENABLED to initialize .enabled

Pull fs idmapping updates from Christian Brauner:
 "This introduces the new vfs{g,u}id_t types we agreed on. Similar to
  k{g,u}id_t the new types are just simple wrapper structs around
  regular {g,u}id_t types.

  They allow to establish a type safety boundary in the VFS for idmapped
  mounts preventing confusion betwen {g,u}ids mapped into an idmapped
  mount and {g,u}ids mapped into the caller's or the filesystem's
  idmapping.

  An initial set of helpers is introduced that allows to operate on
  vfs{g,u}id_t types. We will remove all references to non-type safe
  idmapped mounts helpers in the very near future. The patches do
  already exist.

  This converts the core attribute changing codepaths which become
  significantly easier to reason about because of this change.

  Just a few highlights here as the patches give detailed overviews of
  what is happening in the commit messages:

   - The kernel internal struct iattr contains type safe vfs{g,u}id_t
     values clearly communicating that these values have to take a given
     mount's idmapping into account.

   - The ownership values placed in struct iattr to change ownership are
     identical for idmapped and non-idmapped mounts going forward. This
     also allows to simplify stacking filesystems such as overlayfs that
     change attributes In other words, they always represent the values.

   - Instead of open coding checks for whether ownership changes have
     been requested and an actual update of the inode is required we now
     have small static inline wrappers that abstract this logic away
     removing a lot of code duplication from individual filesystems that
     all open-coded the same checks"

* tag 'fs.idmapped.vfsuid.v5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  mnt_idmapping: align kernel doc and parameter order
  mnt_idmapping: use new helpers in mapped_fs{g,u}id()
  fs: port HAS_UNMAPPED_ID() to vfs{g,u}id_t
  mnt_idmapping: return false when comparing two invalid ids
  attr: fix kernel doc
  attr: port attribute changes to new types
  security: pass down mount idmapping to setattr hook
  quota: port quota helpers mount ids
  fs: port to iattr ownership update helpers
  fs: introduce tiny iattr ownership update helpers
  fs: use mount types in iattr
  fs: add two type safe mapping helpers
  mnt_idmapping: add vfs{g,u}id_t

Use IS_ENABLED(CONFIG_XXX) instead of #ifdef/#endif statements to
initialize .enabled, minor simplicity improvement.

Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

Now that we introduced new infrastructure to increase the type safety
for filesystems supporting idmapped mounts port the first part of the
vfs over to them.

This ports the attribute changes codepaths to rely on the new better
helpers using a dedicated type.

Before this change we used to take a shortcut and place the actual
values that would be written to inode->i_{g,u}id into struct iattr. This
had the advantage that we moved idmappings mostly out of the picture
early on but it made reasoning about changes more difficult than it
should be.

The filesystem was never explicitly told that it dealt with an idmapped
mount. The transition to the value that needed to be stored in
inode->i_{g,u}id appeared way too early and increased the probability of
bugs in various codepaths.

We know place the same value in struct iattr no matter if this is an
idmapped mount or not. The vfs will only deal with type safe
vfs{g,u}id_t. This makes it massively safer to perform permission checks
as the type will tell us what checks we need to perform and what helpers
we need to use.

Fileystems raising FS_ALLOW_IDMAP can't simply write ia_vfs{g,u}id to
inode->i_{g,u}id since they are different types. Instead they need to
use the dedicated vfs{g,u}id_to_k{g,u}id() helpers that map the
vfs{g,u}id into the filesystem.

The other nice effect is that filesystems like overlayfs don't need to
care about idmappings explicitly anymore and can simply set up struct
iattr accordingly directly.

Link: https://lore.kernel.org/lkml/CAHk-=win6+ahs1EwLkcq8apqLi_1wXFWbrPf340zYEhObpz4jA@mail.gmail.com [1]
Link: https://lore.kernel.org/r/20220621141454.2914719-9-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>