[PATCH v2 00/30] acl: add vfs posix acl api

[PATCH v2 00/30] acl: add vfs posix acl api

[Christian Brauner]

From: "Christian Brauner (Microsoft)" <brauner@kernel.org>

Hey everyone,

/* v2 */
This fixes various things pointed out during review. The individual
commits contain more details were appropriate.

As we discussed and seen multiple times the current state of how posix
acls are handled isn't nice and comes with a lot of problems. For a long
and detailed explanation for just some of the issues [1] provides a good
summary.

The current way of handling posix acls via the generic xattr api is
error prone, hard to maintain, and type unsafe for the vfs until we call
into the filesystem's dedicated get and set inode operations.

It is already the case that posix acls are special-cased to death all
the way through the vfs. There are an uncounted number of hacks that
operate on the uapi posix acl struct instead of the dedicated vfs struct
posix_acl. And the vfs must be involved in order to interpret and fixup
posix acls before storing them to the backing store, caching them,
reporting them to userspace, or for permission checking.

Currently a range of hacks and duct tape exist to make this work. As
with most things this is really no ones fault it's just something that
happened over time. But the code is hard to understand and difficult
to maintain and one is constantly at risk of introducing bugs and
regressions when having to touch it.

Instead of continuing to hack posix acls through the xattr handlers this
series builds a dedicated posix acl api solely around the get and set
inode operations. Going forward, the vfs_get_acl(), vfs_remove_acl(),
and vfs_set_acl() helpers must be used in order to interact with posix
acls. They operate directly on the vfs internal struct posix_acl instead
of abusing the uapi posix acl struct as we currently do. In the end this
removes all of the hackiness, makes the codepaths easier to maintain,
and gets us type safety.

This series passes the LTP and xfstests suites without any regressions.
For xfstests the following combinations were tested:

* xfs
* ext4
* btrfs
* overlayfs
* overlayfs on top of idmapped mounts

For people wanting to run their own xfstests I'd recommend to shorten
their test runs via:

./check -g acl,attr,cap,idmapped,io_uring,perms,subvol,unlink

I would appreciate if the 9p and cifs folks could run any posix acl
related tests as I have no setup to really do this without causing me a
lot of pain.

Very likely there's a lot more simplifications for posix acls that we
can make in the future if the basic api has made it.

A few implementation details:

* The series makes sure to retain exactly the same security and
  integrity module permission checks. See [2] for annotated callchains.
  Especially for the integrity modules this api is a win because right
  now they convert the uapi posix acl struct passed to them via a void
  pointer into the vfs struct posix_acl format to perform permission
  checking on the mode.

  There's a new dedicated security hook for setting posix acls which
  passes the vfs struct posix_acl not a void pointer. Basing checking on
  the posix acl stored in the uapi format is really unreliable. The vfs
  currently hacks around directly in the uapi struct storing values that
  frankly the security and integrity modules can't correctly interpret
  as evidenced by bugs we reported and fixed in this area. It's not
  necessarily even their fault it's just that the format we provide to
  them is sub optimal.

* Some filesystems like 9p and cifs need access to the dentry in order
  to get and set posix acls which is why they either only partially or
  not even at all implement get and set inode operations. For example,
  cifs allows setxattr() and getxattr() operations but doesn't allow
  permission checking based on posix acls because it can't implement a
  get acl inode operation.

  Thus, this patch series updates the set acl inode operation to take a
  dentry instead of an inode argument. However, for the get acl inode
  operation we can't do this as the old get acl method is called in
  e.g., generic_permission() and inode_permission(). These helpers in
  turn are called in various filesystem's permission inode operation. So
  passing a dentry argument to the old get acl inode operation would
  amount to passing a dentry to the permission inode operation which we
  shouldn't and probably can't do.

  So instead of extending the existing inode operation Christoph
  suggested to add a new one. He also requested to ensure that the get
  and set acl inode operation taking a dentry are consistently named. So
  for this version the old get acl operation is renamed to
  ->get_inode_acl() and a new ->get_acl() inode operation taking a
  dentry is added. With this we can give both 9p and cifs get and set
  acl inode operations and in turn remove their complex custom posix
  xattr handlers.

* I've done a full audit of every codepaths using variant of the
  current generic xattr api to get and set posix acls and surprisingly
  it isn't that many places. There's of course always a chance that I
  might have missed some and I'm sure we'll find them soon enough.

  The crucial codepaths to be converted are obviously stacking
  filesystems such as ecryptfs and overlayfs.

  For a list of all callers currently using generic xattr api helpers
  see [2] including comments whether they support posix acls or not.

* The old vfs generic posix acl infrastructure doesn't obey
  the create and replace semantics promised on the setxattr(2) manpage.
  This patch series doesn't address this. It really is something we
  should revisit later though.

The patch series is roughly organized as follows:

// intended to be a non-functional change
1. Change existing set acl inode operation to take a dentry argument.

// intended to be a non-functional change
2. Rename existing get acl method.

// intended to be a non-functional change
3. Implement get and set acl inode operations for filesystems that
   couldn't implement one before because of the missing dentry. That's
   mostly 9p and cifs.

// intended to be a non-functional change
4. Build posix acl api, i.e., add vfs_get_acl(), vfs_remove_acl(), and
   vfs_set_acl() including security and integrity hooks.

// intended to be a non-functional change
5. Implement get and set acl inode operations for stacking filesystems.

// semantical change
6. Switch posix acl handling in stacking filesystems to new posix acl
   api now that all filesystems it can stack upon support it.

// semantical change
7. Switch vfs to new posix acl api

8. Remove all now unused helpers

The series can be pulled from:

https://gitlab.com/brauner/linux/-/commits/fs.acl.rework
https://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping.git/log/?h=fs.acl.rework

The series contains a few preliminary patches which are scheduled for
the next merge window. It was just easier to base the series on top of
them. But if you pull this branch you'll get them included.

I've been working on this for a while and before going any further it'd
be nice to get some reviews. I think that it should be fine to have get
and set acl inode operations that operate on the dentry at least nothing
stuck out immediately that would prevent this. But obviously having
other people point out issues with that would be helpful.

Thanks to Seth for a lot of good discussion around this and
encouragement and input from Christoph.

[1]: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org
[2]: https://gist.github.com/brauner/12c795b93a05dc3b3056b1982549a633

v1: https://lore.kernel.org/linux-cifs/20220922151728.1557914-1-brauner@kernel.org

Thanks!
Christian

Christian Brauner (30):
  orangefs: rework posix acl handling when creating new filesystem
    objects
  fs: pass dentry to set acl method
  fs: rename current get acl method
  fs: add new get acl method
  cifs: implement get acl method
  cifs: implement set acl method
  9p: implement get acl method
  9p: implement set acl method
  acl: add vfs_set_acl()
  security: add set acl hook
  selinux: implement set acl hook
  smack: implement set acl hook
  evm: implement set acl hook
  acl: use set acl hook
  evm: add post set acl hook
  acl: add vfs_get_acl()
  acl: add vfs_remove_acl()
  evm: simplify evm_xattr_acl_change()
  ksmbd: use vfs_remove_acl()
  ecryptfs: implement get acl method
  ecryptfs: implement set acl method
  ovl: implement get acl method
  ovl: implement set acl method
  ovl: use posix acl api
  xattr: use posix acl api
  ecryptfs: use stub posix acl handlers
  ovl: use stub posix acl handlers
  cifs: use stub posix acl handlers
  9p: use stub posix acl handlers
  acl: remove a slew of now unused helpers

 Documentation/filesystems/locking.rst |   4 +-
 Documentation/filesystems/porting.rst |   4 +-
 Documentation/filesystems/vfs.rst     |   3 +-
 fs/9p/acl.c                           | 295 +++++------
 fs/9p/acl.h                           |   8 +-
 fs/9p/vfs_inode_dotl.c                |   4 +
 fs/9p/xattr.c                         |   7 +-
 fs/9p/xattr.h                         |   2 -
 fs/bad_inode.c                        |   4 +-
 fs/btrfs/acl.c                        |   3 +-
 fs/btrfs/ctree.h                      |   2 +-
 fs/btrfs/inode.c                      |   8 +-
 fs/ceph/acl.c                         |   3 +-
 fs/ceph/dir.c                         |   2 +-
 fs/ceph/inode.c                       |   4 +-
 fs/ceph/super.h                       |   2 +-
 fs/cifs/cifsacl.c                     | 141 ++++++
 fs/cifs/cifsfs.c                      |   4 +
 fs/cifs/cifsproto.h                   |  20 +-
 fs/cifs/cifssmb.c                     | 206 +++++---
 fs/cifs/xattr.c                       |  68 +--
 fs/ecryptfs/inode.c                   |  32 ++
 fs/erofs/inode.c                      |   6 +-
 fs/erofs/namei.c                      |   2 +-
 fs/ext2/acl.c                         |   3 +-
 fs/ext2/acl.h                         |   2 +-
 fs/ext2/file.c                        |   2 +-
 fs/ext2/inode.c                       |   2 +-
 fs/ext2/namei.c                       |   4 +-
 fs/ext4/acl.c                         |   3 +-
 fs/ext4/acl.h                         |   2 +-
 fs/ext4/file.c                        |   2 +-
 fs/ext4/inode.c                       |   2 +-
 fs/ext4/namei.c                       |   4 +-
 fs/f2fs/acl.c                         |   4 +-
 fs/f2fs/acl.h                         |   2 +-
 fs/f2fs/file.c                        |   4 +-
 fs/f2fs/namei.c                       |   4 +-
 fs/fuse/acl.c                         |   3 +-
 fs/fuse/dir.c                         |   4 +-
 fs/fuse/fuse_i.h                      |   2 +-
 fs/gfs2/acl.c                         |   3 +-
 fs/gfs2/acl.h                         |   2 +-
 fs/gfs2/inode.c                       |   6 +-
 fs/internal.h                         |   1 +
 fs/jffs2/acl.c                        |   3 +-
 fs/jffs2/acl.h                        |   2 +-
 fs/jffs2/dir.c                        |   2 +-
 fs/jffs2/file.c                       |   2 +-
 fs/jffs2/fs.c                         |   2 +-
 fs/jfs/acl.c                          |   3 +-
 fs/jfs/file.c                         |   4 +-
 fs/jfs/jfs_acl.h                      |   2 +-
 fs/jfs/namei.c                        |   2 +-
 fs/ksmbd/smb2pdu.c                    |   4 +-
 fs/ksmbd/smbacl.c                     |   4 +-
 fs/ksmbd/vfs.c                        |  17 +-
 fs/ksmbd/vfs.h                        |   4 +-
 fs/namei.c                            |   2 +-
 fs/nfs/nfs3_fs.h                      |   2 +-
 fs/nfs/nfs3acl.c                      |   3 +-
 fs/nfs/nfs3proc.c                     |   4 +-
 fs/nfsd/nfs2acl.c                     |   4 +-
 fs/nfsd/nfs3acl.c                     |   4 +-
 fs/nfsd/vfs.c                         |   4 +-
 fs/ntfs3/file.c                       |   4 +-
 fs/ntfs3/namei.c                      |   4 +-
 fs/ntfs3/ntfs_fs.h                    |   4 +-
 fs/ntfs3/xattr.c                      |   9 +-
 fs/ocfs2/acl.c                        |   3 +-
 fs/ocfs2/acl.h                        |   2 +-
 fs/ocfs2/file.c                       |   4 +-
 fs/ocfs2/namei.c                      |   2 +-
 fs/orangefs/acl.c                     |  47 +-
 fs/orangefs/inode.c                   |  47 +-
 fs/orangefs/namei.c                   |   2 +-
 fs/orangefs/orangefs-kernel.h         |   9 +-
 fs/orangefs/orangefs-utils.c          |  12 +-
 fs/overlayfs/copy_up.c                |  38 ++
 fs/overlayfs/dir.c                    |  22 +-
 fs/overlayfs/inode.c                  | 151 +++++-
 fs/overlayfs/overlayfs.h              |  34 +-
 fs/overlayfs/super.c                  | 107 +---
 fs/posix_acl.c                        | 681 +++++++++++++-------------
 fs/reiserfs/acl.h                     |   6 +-
 fs/reiserfs/file.c                    |   2 +-
 fs/reiserfs/inode.c                   |   2 +-
 fs/reiserfs/namei.c                   |   4 +-
 fs/reiserfs/xattr_acl.c               |   9 +-
 fs/xattr.c                            |  78 ++-
 fs/xfs/xfs_acl.c                      |   3 +-
 fs/xfs/xfs_acl.h                      |   2 +-
 fs/xfs/xfs_iops.c                     |  16 +-
 include/linux/evm.h                   |  23 +
 include/linux/fs.h                    |  10 +-
 include/linux/lsm_hook_defs.h         |   2 +
 include/linux/lsm_hooks.h             |   4 +
 include/linux/posix_acl.h             |  39 +-
 include/linux/posix_acl_xattr.h       |  43 +-
 include/linux/security.h              |  11 +
 include/linux/xattr.h                 |   8 +
 io_uring/xattr.c                      |   2 +
 mm/shmem.c                            |   2 +-
 security/integrity/evm/evm_main.c     | 128 +++--
 security/security.c                   |  16 +
 security/selinux/hooks.c              |   8 +
 security/smack/smack_lsm.c            |  24 +
 107 files changed, 1550 insertions(+), 1043 deletions(-)


base-commit: 38e316398e4e6338b80223fb5f74415c0513718f
-- 
2.34.1

[PATCH v2 05/30] cifs: implement get acl method

[Christian Brauner]

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].

In order to build a type safe posix api around get and set acl we need
all filesystem to implement get and set acl.

So far cifs wasn't able to implement get and set acl inode operations
because it needs access to the dentry. Now that we extended the set acl
inode operation to take a dentry argument and added a new get acl inode
operation that takes a dentry argument we can let cifs implement get and
set acl inode operations.

This is mostly a copy and paste of the codepaths currently used in cifs'
posix acl xattr handler. After we have fully implemented the posix acl
api and switched the vfs over to it, the cifs specific posix acl xattr
handler and associated code will be removed and the code duplication
will go away.

Note, until the vfs has been switched to the new posix acl api this
patch is a non-functional change.

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

Notes:
    /* v2 */
    Christian Brauner (Microsoft) <brauner@kernel.org>:
    - Surface acl error in all cases.

 fs/cifs/cifsacl.c   |  67 +++++++++++++++
 fs/cifs/cifsfs.c    |   2 +
 fs/cifs/cifsproto.h |   6 ++
 fs/cifs/cifssmb.c   | 196 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 271 insertions(+)

diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index fa480d62f313..a6730e0eb57b 100644
--- a/fs/cifs/cifsacl.c
+++ b/fs/cifs/cifsacl.c
@@ -13,6 +13,7 @@
 #include <linux/string.h>
 #include <linux/keyctl.h>
 #include <linux/key-type.h>
+#include <uapi/linux/posix_acl.h>
 #include <keys/user-type.h>
 #include "cifspdu.h"
 #include "cifsglob.h"
@@ -20,6 +21,8 @@
 #include "cifsproto.h"
 #include "cifs_debug.h"
 #include "fs_context.h"
+#include "cifs_fs_sb.h"
+#include "cifs_unicode.h"
 
 /* security id for everyone/world system group */
 static const struct cifs_sid sid_everyone = {
@@ -1668,3 +1671,67 @@ id_mode_to_cifs_acl(struct inode *inode, const char *path, __u64 *pnmode,
 	kfree(pntsd);
 	return rc;
 }
+
+struct posix_acl *cifs_get_acl(struct user_namespace *mnt_userns,
+			       struct dentry *dentry, int type)
+{
+#if defined(CONFIG_CIFS_ALLOW_INSECURE_LEGACY) && defined(CONFIG_CIFS_POSIX)
+	struct posix_acl *acl = NULL;
+	ssize_t rc = -EOPNOTSUPP;
+	unsigned int xid;
+	struct super_block *sb = dentry->d_sb;
+	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
+	struct tcon_link *tlink;
+	struct cifs_tcon *pTcon;
+	const char *full_path;
+	void *page;
+
+	tlink = cifs_sb_tlink(cifs_sb);
+	if (IS_ERR(tlink))
+		return ERR_CAST(tlink);
+	pTcon = tlink_tcon(tlink);
+
+	xid = get_xid();
+	page = alloc_dentry_path();
+
+	full_path = build_path_from_dentry(dentry, page);
+	if (IS_ERR(full_path)) {
+		acl = ERR_CAST(full_path);
+		goto out;
+	}
+
+	/* return alt name if available as pseudo attr */
+	switch (type) {
+	case ACL_TYPE_ACCESS:
+		if (sb->s_flags & SB_POSIXACL)
+			rc = cifs_do_get_acl(xid, pTcon, full_path, &acl,
+					     ACL_TYPE_ACCESS,
+					     cifs_sb->local_nls,
+					     cifs_remap(cifs_sb));
+		break;
+
+	case ACL_TYPE_DEFAULT:
+		if (sb->s_flags & SB_POSIXACL)
+			rc = cifs_do_get_acl(xid, pTcon, full_path, &acl,
+					     ACL_TYPE_DEFAULT,
+					     cifs_sb->local_nls,
+					     cifs_remap(cifs_sb));
+		break;
+	}
+
+	if (rc < 0) {
+		if (rc == -EINVAL)
+			acl = ERR_PTR(-EOPNOTSUPP);
+		else
+			acl = ERR_PTR(rc);
+	}
+
+out:
+	free_dentry_path(page);
+	free_xid(xid);
+	cifs_put_tlink(tlink);
+	return acl;
+#else
+	return ERR_PTR(-EOPNOTSUPP);
+#endif
+}
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index f54d8bf2732a..5c00d79fda99 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -1128,6 +1128,7 @@ const struct inode_operations cifs_dir_inode_ops = {
 	.symlink = cifs_symlink,
 	.mknod   = cifs_mknod,
 	.listxattr = cifs_listxattr,
+	.get_acl = cifs_get_acl,
 };
 
 const struct inode_operations cifs_file_inode_ops = {
@@ -1136,6 +1137,7 @@ const struct inode_operations cifs_file_inode_ops = {
 	.permission = cifs_permission,
 	.listxattr = cifs_listxattr,
 	.fiemap = cifs_fiemap,
+	.get_acl = cifs_get_acl,
 };
 
 const struct inode_operations cifs_symlink_inode_ops = {
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 3bc94bcc7177..953fd910da70 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -225,6 +225,8 @@ extern struct cifs_ntsd *get_cifs_acl(struct cifs_sb_info *, struct inode *,
 				      const char *, u32 *, u32);
 extern struct cifs_ntsd *get_cifs_acl_by_fid(struct cifs_sb_info *,
 				const struct cifs_fid *, u32 *, u32);
+extern struct posix_acl *cifs_get_acl(struct user_namespace *mnt_userns,
+				      struct dentry *dentry, int type);
 extern int set_cifs_acl(struct cifs_ntsd *, __u32, struct inode *,
 				const char *, int);
 extern unsigned int setup_authusers_ACE(struct cifs_ace *pace);
@@ -542,6 +544,10 @@ extern int CIFSSMBGetPosixACL(const unsigned int xid, struct cifs_tcon *tcon,
 		const unsigned char *searchName,
 		char *acl_inf, const int buflen, const int acl_type,
 		const struct nls_table *nls_codepage, int remap_special_chars);
+extern int cifs_do_get_acl(const unsigned int xid, struct cifs_tcon *tcon,
+			   const unsigned char *searchName,
+			   struct posix_acl **acl, const int acl_type,
+			   const struct nls_table *nls_codepage, int remap);
 extern int CIFSSMBSetPosixACL(const unsigned int xid, struct cifs_tcon *tcon,
 		const unsigned char *fileName,
 		const char *local_acl, const int buflen, const int acl_type,
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 7aa91e272027..4c0871771c76 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -3212,6 +3212,202 @@ CIFSSMBSetPosixACL(const unsigned int xid, struct cifs_tcon *tcon,
 	return rc;
 }
 
+#ifdef CONFIG_FS_POSIX_ACL
+/**
+ * cifs_init_posix_acl - convert ACL from cifs to POSIX ACL format
+ * @ace: POSIX ACL entry to store converted ACL into
+ * @cifs_ace: ACL in cifs format
+ *
+ * Convert an Access Control Entry from wire format to local POSIX xattr
+ * format.
+ *
+ * Note that the @cifs_uid member is used to store both {g,u}id_t.
+ */
+static void cifs_init_posix_acl(struct posix_acl_entry *ace,
+				struct cifs_posix_ace *cifs_ace)
+{
+	/* u8 cifs fields do not need le conversion */
+	ace->e_perm = cifs_ace->cifs_e_perm;
+	ace->e_tag = cifs_ace->cifs_e_tag;
+
+	switch (ace->e_tag) {
+	case ACL_USER:
+		ace->e_uid = make_kuid(&init_user_ns,
+				       le64_to_cpu(cifs_ace->cifs_uid));
+		break;
+	case ACL_GROUP:
+		ace->e_gid = make_kgid(&init_user_ns,
+				       le64_to_cpu(cifs_ace->cifs_uid));
+		break;
+	}
+	return;
+}
+
+/**
+ * cifs_to_posix_acl - copy cifs ACL format to POSIX ACL format
+ * @acl: ACLs returned in POSIX ACL format
+ * @src: ACLs in cifs format
+ * @acl_type: type of POSIX ACL requested
+ * @size_of_data_area: size of SMB we got
+ *
+ * This function converts ACLs from cifs format to POSIX ACL format.
+ * If @acl is NULL then the size of the buffer required to store POSIX ACLs in
+ * their uapi format is returned.
+ */
+static int cifs_to_posix_acl(struct posix_acl **acl, char *src,
+			     const int acl_type, const int size_of_data_area)
+{
+	int size =  0;
+	__u16 count;
+	struct cifs_posix_ace *pACE;
+	struct cifs_posix_acl *cifs_acl = (struct cifs_posix_acl *)src;
+	struct posix_acl *kacl = NULL;
+	struct posix_acl_entry *pa, *pe;
+
+	if (le16_to_cpu(cifs_acl->version) != CIFS_ACL_VERSION)
+		return -EOPNOTSUPP;
+
+	if (acl_type == ACL_TYPE_ACCESS) {
+		count = le16_to_cpu(cifs_acl->access_entry_count);
+		pACE = &cifs_acl->ace_array[0];
+		size = sizeof(struct cifs_posix_acl);
+		size += sizeof(struct cifs_posix_ace) * count;
+		/* check if we would go beyond end of SMB */
+		if (size_of_data_area < size) {
+			cifs_dbg(FYI, "bad CIFS POSIX ACL size %d vs. %d\n",
+				 size_of_data_area, size);
+			return -EINVAL;
+		}
+	} else if (acl_type == ACL_TYPE_DEFAULT) {
+		count = le16_to_cpu(cifs_acl->access_entry_count);
+		size = sizeof(struct cifs_posix_acl);
+		size += sizeof(struct cifs_posix_ace) * count;
+		/* skip past access ACEs to get to default ACEs */
+		pACE = &cifs_acl->ace_array[count];
+		count = le16_to_cpu(cifs_acl->default_entry_count);
+		size += sizeof(struct cifs_posix_ace) * count;
+		/* check if we would go beyond end of SMB */
+		if (size_of_data_area < size)
+			return -EINVAL;
+	} else {
+		/* illegal type */
+		return -EINVAL;
+	}
+
+	/* Allocate number of POSIX ACLs to store in VFS format. */
+	kacl = posix_acl_alloc(count, GFP_NOFS);
+	if (!kacl)
+		return -ENOMEM;
+
+	FOREACH_ACL_ENTRY(pa, kacl, pe) {
+		cifs_init_posix_acl(pa, pACE);
+		pACE++;
+	}
+
+	*acl = kacl;
+	return 0;
+}
+
+int cifs_do_get_acl(const unsigned int xid, struct cifs_tcon *tcon,
+		    const unsigned char *searchName, struct posix_acl **acl,
+		    const int acl_type, const struct nls_table *nls_codepage,
+		    int remap)
+{
+/* SMB_QUERY_POSIX_ACL */
+	TRANSACTION2_QPI_REQ *pSMB = NULL;
+	TRANSACTION2_QPI_RSP *pSMBr = NULL;
+	int rc = 0;
+	int bytes_returned;
+	int name_len;
+	__u16 params, byte_count;
+
+	cifs_dbg(FYI, "In GetPosixACL (Unix) for path %s\n", searchName);
+
+queryAclRetry:
+	rc = smb_init(SMB_COM_TRANSACTION2, 15, tcon, (void **) &pSMB,
+		(void **) &pSMBr);
+	if (rc)
+		return rc;
+
+	if (pSMB->hdr.Flags2 & SMBFLG2_UNICODE) {
+		name_len =
+			cifsConvertToUTF16((__le16 *) pSMB->FileName,
+					   searchName, PATH_MAX, nls_codepage,
+					   remap);
+		name_len++;     /* trailing null */
+		name_len *= 2;
+		pSMB->FileName[name_len] = 0;
+		pSMB->FileName[name_len+1] = 0;
+	} else {
+		name_len = copy_path_name(pSMB->FileName, searchName);
+	}
+
+	params = 2 /* level */  + 4 /* rsrvd */  + name_len /* incl null */ ;
+	pSMB->TotalDataCount = 0;
+	pSMB->MaxParameterCount = cpu_to_le16(2);
+	/* BB find exact max data count below from sess structure BB */
+	pSMB->MaxDataCount = cpu_to_le16(4000);
+	pSMB->MaxSetupCount = 0;
+	pSMB->Reserved = 0;
+	pSMB->Flags = 0;
+	pSMB->Timeout = 0;
+	pSMB->Reserved2 = 0;
+	pSMB->ParameterOffset = cpu_to_le16(
+		offsetof(struct smb_com_transaction2_qpi_req,
+			 InformationLevel) - 4);
+	pSMB->DataCount = 0;
+	pSMB->DataOffset = 0;
+	pSMB->SetupCount = 1;
+	pSMB->Reserved3 = 0;
+	pSMB->SubCommand = cpu_to_le16(TRANS2_QUERY_PATH_INFORMATION);
+	byte_count = params + 1 /* pad */ ;
+	pSMB->TotalParameterCount = cpu_to_le16(params);
+	pSMB->ParameterCount = pSMB->TotalParameterCount;
+	pSMB->InformationLevel = cpu_to_le16(SMB_QUERY_POSIX_ACL);
+	pSMB->Reserved4 = 0;
+	inc_rfc1001_len(pSMB, byte_count);
+	pSMB->ByteCount = cpu_to_le16(byte_count);
+
+	rc = SendReceive(xid, tcon->ses, (struct smb_hdr *) pSMB,
+		(struct smb_hdr *) pSMBr, &bytes_returned, 0);
+	cifs_stats_inc(&tcon->stats.cifs_stats.num_acl_get);
+	if (rc) {
+		cifs_dbg(FYI, "Send error in Query POSIX ACL = %d\n", rc);
+	} else {
+		/* decode response */
+
+		rc = validate_t2((struct smb_t2_rsp *)pSMBr);
+		/* BB also check enough total bytes returned */
+		if (rc || get_bcc(&pSMBr->hdr) < 2)
+			rc = -EIO;      /* bad smb */
+		else {
+			__u16 data_offset = le16_to_cpu(pSMBr->t2.DataOffset);
+			__u16 count = le16_to_cpu(pSMBr->t2.DataCount);
+			rc = cifs_to_posix_acl(acl,
+				(char *)&pSMBr->hdr.Protocol+data_offset,
+				acl_type, count);
+		}
+	}
+	cifs_buf_release(pSMB);
+	/*
+	 * The else branch after SendReceive() doesn't return EAGAIN so if we
+	 * allocated @acl in cifs_to_posix_acl() we are guaranteed to return
+	 * here and don't leak POSIX ACLs.
+	 */
+	if (rc == -EAGAIN)
+		goto queryAclRetry;
+	return rc;
+}
+#else
+int cifs_do_get_acl(const unsigned int xid, struct cifs_tcon *tcon,
+		    const unsigned char *searchName, struct posix_acl **acl,
+		    const int acl_type, const struct nls_table *nls_codepage,
+		    int remap)
+{
+	return -EOPNOTSUPP;
+}
+#endif /* CONFIG_FS_POSIX_ACL */
+
 int
 CIFSGetExtAttr(const unsigned int xid, struct cifs_tcon *tcon,
 	       const int netfid, __u64 *pExtAttrBits, __u64 *pMask)
-- 
2.34.1

[PATCH v2 06/30] cifs: implement set acl method

[Christian Brauner]

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].

In order to build a type safe posix api around get and set acl we need
all filesystem to implement get and set acl.

So far cifs wasn't able to implement get and set acl inode operations
because it needs access to the dentry. Now that we extended the set acl
inode operation to take a dentry argument and added a new get acl inode
operation that takes a dentry argument we can let cifs implement get and
set acl inode operations.

This is mostly a copy and paste of the codepaths currently used in cifs'
posix acl xattr handler. After we have fully implemented the posix acl
api and switched the vfs over to it, the cifs specific posix acl xattr
handler and associated code will be removed and the code duplication
will go away.

Note, until the vfs has been switched to the new posix acl api this
patch is a non-functional change.

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

Notes:
    /* v2 */
    unchanged

 fs/cifs/cifsacl.c   |  74 ++++++++++++++++++++
 fs/cifs/cifsfs.c    |   2 +
 fs/cifs/cifsproto.h |   6 ++
 fs/cifs/cifssmb.c   | 160 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 242 insertions(+)

diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index a6730e0eb57b..d068cdfd9ab5 100644
--- a/fs/cifs/cifsacl.c
+++ b/fs/cifs/cifsacl.c
@@ -14,6 +14,8 @@
 #include <linux/keyctl.h>
 #include <linux/key-type.h>
 #include <uapi/linux/posix_acl.h>
+#include <linux/posix_acl.h>
+#include <linux/posix_acl_xattr.h>
 #include <keys/user-type.h>
 #include "cifspdu.h"
 #include "cifsglob.h"
@@ -1735,3 +1737,75 @@ struct posix_acl *cifs_get_acl(struct user_namespace *mnt_userns,
 	return ERR_PTR(-EOPNOTSUPP);
 #endif
 }
+
+int cifs_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
+		 struct posix_acl *acl, int type)
+{
+	int rc = -EOPNOTSUPP;
+	unsigned int xid;
+	struct super_block *sb = dentry->d_sb;
+	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
+	struct tcon_link *tlink;
+	struct cifs_tcon *pTcon;
+	const char *full_path;
+	void *page;
+
+	tlink = cifs_sb_tlink(cifs_sb);
+	if (IS_ERR(tlink))
+		return PTR_ERR(tlink);
+	pTcon = tlink_tcon(tlink);
+
+	xid = get_xid();
+	page = alloc_dentry_path();
+
+	full_path = build_path_from_dentry(dentry, page);
+	if (IS_ERR(full_path)) {
+		rc = PTR_ERR(full_path);
+		goto out;
+	}
+	/* return dos attributes as pseudo xattr */
+	/* return alt name if available as pseudo attr */
+
+	/* if proc/fs/cifs/streamstoxattr is set then
+		search server for EAs or streams to
+		returns as xattrs */
+	if (posix_acl_xattr_size(acl->a_count) > CIFSMaxBufSize) {
+		cifs_dbg(FYI, "size of EA value too large\n");
+		rc = -EOPNOTSUPP;
+		goto out;
+	}
+
+	switch (type) {
+#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
+	case ACL_TYPE_ACCESS:
+#ifdef CONFIG_CIFS_POSIX
+		if (!acl)
+			goto out;
+		if (sb->s_flags & SB_POSIXACL)
+			rc = cifs_do_set_acl(xid, pTcon, full_path, acl,
+					     ACL_TYPE_ACCESS,
+					     cifs_sb->local_nls,
+					     cifs_remap(cifs_sb));
+#endif  /* CONFIG_CIFS_POSIX */
+		break;
+
+	case ACL_TYPE_DEFAULT:
+#ifdef CONFIG_CIFS_POSIX
+		if (!acl)
+			goto out;
+		if (sb->s_flags & SB_POSIXACL)
+			rc = cifs_do_set_acl(xid, pTcon, full_path, acl,
+					     ACL_TYPE_DEFAULT,
+					     cifs_sb->local_nls,
+					     cifs_remap(cifs_sb));
+#endif  /* CONFIG_CIFS_POSIX */
+		break;
+#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
+	}
+
+out:
+	free_dentry_path(page);
+	free_xid(xid);
+	cifs_put_tlink(tlink);
+	return rc;
+}
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 5c00d79fda99..c8d46c1b10e4 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -1129,6 +1129,7 @@ const struct inode_operations cifs_dir_inode_ops = {
 	.mknod   = cifs_mknod,
 	.listxattr = cifs_listxattr,
 	.get_acl = cifs_get_acl,
+	.set_acl = cifs_set_acl,
 };
 
 const struct inode_operations cifs_file_inode_ops = {
@@ -1138,6 +1139,7 @@ const struct inode_operations cifs_file_inode_ops = {
 	.listxattr = cifs_listxattr,
 	.fiemap = cifs_fiemap,
 	.get_acl = cifs_get_acl,
+	.set_acl = cifs_set_acl,
 };
 
 const struct inode_operations cifs_symlink_inode_ops = {
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 953fd910da70..279e867dee2e 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -227,6 +227,8 @@ extern struct cifs_ntsd *get_cifs_acl_by_fid(struct cifs_sb_info *,
 				const struct cifs_fid *, u32 *, u32);
 extern struct posix_acl *cifs_get_acl(struct user_namespace *mnt_userns,
 				      struct dentry *dentry, int type);
+extern int cifs_set_acl(struct user_namespace *mnt_userns,
+			struct dentry *dentry, struct posix_acl *acl, int type);
 extern int set_cifs_acl(struct cifs_ntsd *, __u32, struct inode *,
 				const char *, int);
 extern unsigned int setup_authusers_ACE(struct cifs_ace *pace);
@@ -552,6 +554,10 @@ extern int CIFSSMBSetPosixACL(const unsigned int xid, struct cifs_tcon *tcon,
 		const unsigned char *fileName,
 		const char *local_acl, const int buflen, const int acl_type,
 		const struct nls_table *nls_codepage, int remap_special_chars);
+extern int cifs_do_set_acl(const unsigned int xid, struct cifs_tcon *tcon,
+			   const unsigned char *fileName,
+			   const struct posix_acl *acl, const int acl_type,
+			   const struct nls_table *nls_codepage, int remap);
 extern int CIFSGetExtAttr(const unsigned int xid, struct cifs_tcon *tcon,
 			const int netfid, __u64 *pExtAttrBits, __u64 *pMask);
 #endif /* CIFS_ALLOW_INSECURE_LEGACY */
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 4c0871771c76..7b47d0def5d2 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -3308,6 +3308,83 @@ static int cifs_to_posix_acl(struct posix_acl **acl, char *src,
 	return 0;
 }
 
+/**
+ * cifs_init_ace - convert ACL entry from POSIX ACL to cifs format
+ * @cifs_ace: the cifs ACL entry to store into
+ * @local_ace: the POSIX ACL entry to convert
+ */
+static void cifs_init_ace(struct cifs_posix_ace *cifs_ace,
+			  const struct posix_acl_entry *local_ace)
+{
+	cifs_ace->cifs_e_perm = local_ace->e_perm;
+	cifs_ace->cifs_e_tag =  local_ace->e_tag;
+
+	switch (local_ace->e_tag) {
+	case ACL_USER:
+		cifs_ace->cifs_uid =
+			cpu_to_le64(from_kuid(&init_user_ns, local_ace->e_uid));
+		break;
+	case ACL_GROUP:
+		cifs_ace->cifs_uid =
+			cpu_to_le64(from_kgid(&init_user_ns, local_ace->e_gid));
+		break;
+	default:
+		cifs_ace->cifs_uid = cpu_to_le64(-1);
+	}
+}
+
+/**
+ * posix_acl_to_cifs - convert ACLs from POSIX ACL to cifs format
+ * @parm_data: ACLs in cifs format to conver to
+ * @acl: ACLs in POSIX ACL format to convert from
+ * @acl_type: the type of POSIX ACLs stored in @acl
+ *
+ * Return: the number cifs ACL entries after conversion
+ */
+static __u16 posix_acl_to_cifs(char *parm_data, const struct posix_acl *acl,
+			       const int acl_type)
+{
+	__u16 rc = 0;
+	struct cifs_posix_acl *cifs_acl = (struct cifs_posix_acl *)parm_data;
+	const struct posix_acl_entry *pa, *pe;
+	int count;
+	int i = 0;
+
+	if ((acl == NULL) || (cifs_acl == NULL))
+		return 0;
+
+	count = acl->a_count;
+	cifs_dbg(FYI, "setting acl with %d entries\n", count);
+
+	/*
+	 * Note that the uapi POSIX ACL version is verified by the VFS and is
+	 * independent of the cifs ACL version. Changing the POSIX ACL version
+	 * is a uapi change and if it's changed we will pass down the POSIX ACL
+	 * version in struct posix_acl from the VFS. For now there's really
+	 * only one that all filesystems know how to deal with.
+	 */
+	cifs_acl->version = cpu_to_le16(1);
+	if (acl_type == ACL_TYPE_ACCESS) {
+		cifs_acl->access_entry_count = cpu_to_le16(count);
+		cifs_acl->default_entry_count = cpu_to_le16(0xFFFF);
+	} else if (acl_type == ACL_TYPE_DEFAULT) {
+		cifs_acl->default_entry_count = cpu_to_le16(count);
+		cifs_acl->access_entry_count = cpu_to_le16(0xFFFF);
+	} else {
+		cifs_dbg(FYI, "unknown ACL type %d\n", acl_type);
+		return 0;
+	}
+	FOREACH_ACL_ENTRY(pa, acl, pe) {
+		cifs_init_ace(&cifs_acl->ace_array[i++], pa);
+	}
+	if (rc == 0) {
+		rc = (__u16)(count * sizeof(struct cifs_posix_ace));
+		rc += sizeof(struct cifs_posix_acl);
+		/* BB add check to make sure ACL does not overflow SMB */
+	}
+	return rc;
+}
+
 int cifs_do_get_acl(const unsigned int xid, struct cifs_tcon *tcon,
 		    const unsigned char *searchName, struct posix_acl **acl,
 		    const int acl_type, const struct nls_table *nls_codepage,
@@ -3398,6 +3475,81 @@ int cifs_do_get_acl(const unsigned int xid, struct cifs_tcon *tcon,
 		goto queryAclRetry;
 	return rc;
 }
+
+int cifs_do_set_acl(const unsigned int xid, struct cifs_tcon *tcon,
+		    const unsigned char *fileName, const struct posix_acl *acl,
+		    const int acl_type, const struct nls_table *nls_codepage,
+		    int remap)
+{
+	struct smb_com_transaction2_spi_req *pSMB = NULL;
+	struct smb_com_transaction2_spi_rsp *pSMBr = NULL;
+	char *parm_data;
+	int name_len;
+	int rc = 0;
+	int bytes_returned = 0;
+	__u16 params, byte_count, data_count, param_offset, offset;
+
+	cifs_dbg(FYI, "In SetPosixACL (Unix) for path %s\n", fileName);
+setAclRetry:
+	rc = smb_init(SMB_COM_TRANSACTION2, 15, tcon, (void **) &pSMB,
+		      (void **) &pSMBr);
+	if (rc)
+		return rc;
+	if (pSMB->hdr.Flags2 & SMBFLG2_UNICODE) {
+		name_len =
+			cifsConvertToUTF16((__le16 *) pSMB->FileName, fileName,
+					   PATH_MAX, nls_codepage, remap);
+		name_len++;     /* trailing null */
+		name_len *= 2;
+	} else {
+		name_len = copy_path_name(pSMB->FileName, fileName);
+	}
+	params = 6 + name_len;
+	pSMB->MaxParameterCount = cpu_to_le16(2);
+	/* BB find max SMB size from sess */
+	pSMB->MaxDataCount = cpu_to_le16(1000);
+	pSMB->MaxSetupCount = 0;
+	pSMB->Reserved = 0;
+	pSMB->Flags = 0;
+	pSMB->Timeout = 0;
+	pSMB->Reserved2 = 0;
+	param_offset = offsetof(struct smb_com_transaction2_spi_req,
+				InformationLevel) - 4;
+	offset = param_offset + params;
+	parm_data = ((char *) &pSMB->hdr.Protocol) + offset;
+	pSMB->ParameterOffset = cpu_to_le16(param_offset);
+
+	/* convert to on the wire format for POSIX ACL */
+	data_count = posix_acl_to_cifs(parm_data, acl, acl_type);
+
+	if (data_count == 0) {
+		rc = -EOPNOTSUPP;
+		goto setACLerrorExit;
+	}
+	pSMB->DataOffset = cpu_to_le16(offset);
+	pSMB->SetupCount = 1;
+	pSMB->Reserved3 = 0;
+	pSMB->SubCommand = cpu_to_le16(TRANS2_SET_PATH_INFORMATION);
+	pSMB->InformationLevel = cpu_to_le16(SMB_SET_POSIX_ACL);
+	byte_count = 3 /* pad */  + params + data_count;
+	pSMB->DataCount = cpu_to_le16(data_count);
+	pSMB->TotalDataCount = pSMB->DataCount;
+	pSMB->ParameterCount = cpu_to_le16(params);
+	pSMB->TotalParameterCount = pSMB->ParameterCount;
+	pSMB->Reserved4 = 0;
+	inc_rfc1001_len(pSMB, byte_count);
+	pSMB->ByteCount = cpu_to_le16(byte_count);
+	rc = SendReceive(xid, tcon->ses, (struct smb_hdr *) pSMB,
+			 (struct smb_hdr *) pSMBr, &bytes_returned, 0);
+	if (rc)
+		cifs_dbg(FYI, "Set POSIX ACL returned %d\n", rc);
+
+setACLerrorExit:
+	cifs_buf_release(pSMB);
+	if (rc == -EAGAIN)
+		goto setAclRetry;
+	return rc;
+}
 #else
 int cifs_do_get_acl(const unsigned int xid, struct cifs_tcon *tcon,
 		    const unsigned char *searchName, struct posix_acl **acl,
@@ -3406,6 +3558,14 @@ int cifs_do_get_acl(const unsigned int xid, struct cifs_tcon *tcon,
 {
 	return -EOPNOTSUPP;
 }
+
+int cifs_do_set_acl(const unsigned int xid, struct cifs_tcon *tcon,
+		    const unsigned char *fileName, const struct posix_acl *acl,
+		    const int acl_type, const struct nls_table *nls_codepage,
+		    int remap)
+{
+	return -EOPNOTSUPP;
+}
 #endif /* CONFIG_FS_POSIX_ACL */
 
 int
-- 
2.34.1

[PATCH v2 19/30] ksmbd: use vfs_remove_acl()

[Christian Brauner]

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].

Now that we've switched all filesystems that can serve as the lower
filesystem for ksmbd we can switch ksmbd over to rely on
the posix acl api. Note that this is orthogonal to switching the vfs
itself over.

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

Notes:
    /* v2 */
    unchanged

 fs/ksmbd/vfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ksmbd/vfs.c b/fs/ksmbd/vfs.c
index 430962dd2efa..482bd0911127 100644
--- a/fs/ksmbd/vfs.c
+++ b/fs/ksmbd/vfs.c
@@ -1311,7 +1311,7 @@ int ksmbd_vfs_remove_acl_xattrs(struct user_namespace *user_ns,
 			     sizeof(XATTR_NAME_POSIX_ACL_ACCESS) - 1) ||
 		    !strncmp(name, XATTR_NAME_POSIX_ACL_DEFAULT,
 			     sizeof(XATTR_NAME_POSIX_ACL_DEFAULT) - 1)) {
-			err = ksmbd_vfs_remove_xattr(user_ns, dentry, name);
+			err = vfs_remove_acl(user_ns, dentry, name);
 			if (err)
 				ksmbd_debug(SMB,
 					    "remove acl xattr failed : %s\n", name);
-- 
2.34.1

[PATCH v2 28/30] cifs: use stub posix acl handlers

[Christian Brauner]

Now that cifs supports the get and set acl inode operations and the vfs
has been switched to the new posi api, cifs can simply rely on the stub
posix acl handlers. The custom xattr handlers and associated unused
helpers can be removed.

Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
---

Notes:
    /* v2 */
    unchanged

 fs/cifs/cifsproto.h |   8 --
 fs/cifs/cifssmb.c   | 298 --------------------------------------------
 fs/cifs/xattr.c     |  68 +---------
 3 files changed, 4 insertions(+), 370 deletions(-)

diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 279e867dee2e..9259da1b885d 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -542,18 +542,10 @@ extern int CIFSSMBGetCIFSACL(const unsigned int xid, struct cifs_tcon *tcon,
 			__u16 fid, struct cifs_ntsd **acl_inf, __u32 *buflen);
 extern int CIFSSMBSetCIFSACL(const unsigned int, struct cifs_tcon *, __u16,
 			struct cifs_ntsd *, __u32, int);
-extern int CIFSSMBGetPosixACL(const unsigned int xid, struct cifs_tcon *tcon,
-		const unsigned char *searchName,
-		char *acl_inf, const int buflen, const int acl_type,
-		const struct nls_table *nls_codepage, int remap_special_chars);
 extern int cifs_do_get_acl(const unsigned int xid, struct cifs_tcon *tcon,
 			   const unsigned char *searchName,
 			   struct posix_acl **acl, const int acl_type,
 			   const struct nls_table *nls_codepage, int remap);
-extern int CIFSSMBSetPosixACL(const unsigned int xid, struct cifs_tcon *tcon,
-		const unsigned char *fileName,
-		const char *local_acl, const int buflen, const int acl_type,
-		const struct nls_table *nls_codepage, int remap_special_chars);
 extern int cifs_do_set_acl(const unsigned int xid, struct cifs_tcon *tcon,
 			   const unsigned char *fileName,
 			   const struct posix_acl *acl, const int acl_type,
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 7b47d0def5d2..ddef789a6fcb 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -2914,304 +2914,6 @@ CIFSSMB_set_compression(const unsigned int xid, struct cifs_tcon *tcon,
 
 #ifdef CONFIG_CIFS_POSIX
 
-/*Convert an Access Control Entry from wire format to local POSIX xattr format*/
-static void cifs_convert_ace(struct posix_acl_xattr_entry *ace,
-			     struct cifs_posix_ace *cifs_ace)
-{
-	/* u8 cifs fields do not need le conversion */
-	ace->e_perm = cpu_to_le16(cifs_ace->cifs_e_perm);
-	ace->e_tag  = cpu_to_le16(cifs_ace->cifs_e_tag);
-	ace->e_id   = cpu_to_le32(le64_to_cpu(cifs_ace->cifs_uid));
-/*
-	cifs_dbg(FYI, "perm %d tag %d id %d\n",
-		 ace->e_perm, ace->e_tag, ace->e_id);
-*/
-
-	return;
-}
-
-/* Convert ACL from CIFS POSIX wire format to local Linux POSIX ACL xattr */
-static int cifs_copy_posix_acl(char *trgt, char *src, const int buflen,
-			       const int acl_type, const int size_of_data_area)
-{
-	int size =  0;
-	int i;
-	__u16 count;
-	struct cifs_posix_ace *pACE;
-	struct cifs_posix_acl *cifs_acl = (struct cifs_posix_acl *)src;
-	struct posix_acl_xattr_header *local_acl = (void *)trgt;
-
-	if (le16_to_cpu(cifs_acl->version) != CIFS_ACL_VERSION)
-		return -EOPNOTSUPP;
-
-	if (acl_type == ACL_TYPE_ACCESS) {
-		count = le16_to_cpu(cifs_acl->access_entry_count);
-		pACE = &cifs_acl->ace_array[0];
-		size = sizeof(struct cifs_posix_acl);
-		size += sizeof(struct cifs_posix_ace) * count;
-		/* check if we would go beyond end of SMB */
-		if (size_of_data_area < size) {
-			cifs_dbg(FYI, "bad CIFS POSIX ACL size %d vs. %d\n",
-				 size_of_data_area, size);
-			return -EINVAL;
-		}
-	} else if (acl_type == ACL_TYPE_DEFAULT) {
-		count = le16_to_cpu(cifs_acl->access_entry_count);
-		size = sizeof(struct cifs_posix_acl);
-		size += sizeof(struct cifs_posix_ace) * count;
-/* skip past access ACEs to get to default ACEs */
-		pACE = &cifs_acl->ace_array[count];
-		count = le16_to_cpu(cifs_acl->default_entry_count);
-		size += sizeof(struct cifs_posix_ace) * count;
-		/* check if we would go beyond end of SMB */
-		if (size_of_data_area < size)
-			return -EINVAL;
-	} else {
-		/* illegal type */
-		return -EINVAL;
-	}
-
-	size = posix_acl_xattr_size(count);
-	if ((buflen == 0) || (local_acl == NULL)) {
-		/* used to query ACL EA size */
-	} else if (size > buflen) {
-		return -ERANGE;
-	} else /* buffer big enough */ {
-		struct posix_acl_xattr_entry *ace = (void *)(local_acl + 1);
-
-		local_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
-		for (i = 0; i < count ; i++) {
-			cifs_convert_ace(&ace[i], pACE);
-			pACE++;
-		}
-	}
-	return size;
-}
-
-static void convert_ace_to_cifs_ace(struct cifs_posix_ace *cifs_ace,
-				     const struct posix_acl_xattr_entry *local_ace)
-{
-	cifs_ace->cifs_e_perm = le16_to_cpu(local_ace->e_perm);
-	cifs_ace->cifs_e_tag =  le16_to_cpu(local_ace->e_tag);
-	/* BB is there a better way to handle the large uid? */
-	if (local_ace->e_id == cpu_to_le32(-1)) {
-	/* Probably no need to le convert -1 on any arch but can not hurt */
-		cifs_ace->cifs_uid = cpu_to_le64(-1);
-	} else
-		cifs_ace->cifs_uid = cpu_to_le64(le32_to_cpu(local_ace->e_id));
-/*
-	cifs_dbg(FYI, "perm %d tag %d id %d\n",
-		 ace->e_perm, ace->e_tag, ace->e_id);
-*/
-}
-
-/* Convert ACL from local Linux POSIX xattr to CIFS POSIX ACL wire format */
-static __u16 ACL_to_cifs_posix(char *parm_data, const char *pACL,
-			       const int buflen, const int acl_type)
-{
-	__u16 rc = 0;
-	struct cifs_posix_acl *cifs_acl = (struct cifs_posix_acl *)parm_data;
-	struct posix_acl_xattr_header *local_acl = (void *)pACL;
-	struct posix_acl_xattr_entry *ace = (void *)(local_acl + 1);
-	int count;
-	int i;
-
-	if ((buflen == 0) || (pACL == NULL) || (cifs_acl == NULL))
-		return 0;
-
-	count = posix_acl_xattr_count((size_t)buflen);
-	cifs_dbg(FYI, "setting acl with %d entries from buf of length %d and version of %d\n",
-		 count, buflen, le32_to_cpu(local_acl->a_version));
-	if (le32_to_cpu(local_acl->a_version) != 2) {
-		cifs_dbg(FYI, "unknown POSIX ACL version %d\n",
-			 le32_to_cpu(local_acl->a_version));
-		return 0;
-	}
-	cifs_acl->version = cpu_to_le16(1);
-	if (acl_type == ACL_TYPE_ACCESS) {
-		cifs_acl->access_entry_count = cpu_to_le16(count);
-		cifs_acl->default_entry_count = cpu_to_le16(0xFFFF);
-	} else if (acl_type == ACL_TYPE_DEFAULT) {
-		cifs_acl->default_entry_count = cpu_to_le16(count);
-		cifs_acl->access_entry_count = cpu_to_le16(0xFFFF);
-	} else {
-		cifs_dbg(FYI, "unknown ACL type %d\n", acl_type);
-		return 0;
-	}
-	for (i = 0; i < count; i++)
-		convert_ace_to_cifs_ace(&cifs_acl->ace_array[i], &ace[i]);
-	if (rc == 0) {
-		rc = (__u16)(count * sizeof(struct cifs_posix_ace));
-		rc += sizeof(struct cifs_posix_acl);
-		/* BB add check to make sure ACL does not overflow SMB */
-	}
-	return rc;
-}
-
-int
-CIFSSMBGetPosixACL(const unsigned int xid, struct cifs_tcon *tcon,
-		   const unsigned char *searchName,
-		   char *acl_inf, const int buflen, const int acl_type,
-		   const struct nls_table *nls_codepage, int remap)
-{
-/* SMB_QUERY_POSIX_ACL */
-	TRANSACTION2_QPI_REQ *pSMB = NULL;
-	TRANSACTION2_QPI_RSP *pSMBr = NULL;
-	int rc = 0;
-	int bytes_returned;
-	int name_len;
-	__u16 params, byte_count;
-
-	cifs_dbg(FYI, "In GetPosixACL (Unix) for path %s\n", searchName);
-
-queryAclRetry:
-	rc = smb_init(SMB_COM_TRANSACTION2, 15, tcon, (void **) &pSMB,
-		(void **) &pSMBr);
-	if (rc)
-		return rc;
-
-	if (pSMB->hdr.Flags2 & SMBFLG2_UNICODE) {
-		name_len =
-			cifsConvertToUTF16((__le16 *) pSMB->FileName,
-					   searchName, PATH_MAX, nls_codepage,
-					   remap);
-		name_len++;     /* trailing null */
-		name_len *= 2;
-		pSMB->FileName[name_len] = 0;
-		pSMB->FileName[name_len+1] = 0;
-	} else {
-		name_len = copy_path_name(pSMB->FileName, searchName);
-	}
-
-	params = 2 /* level */  + 4 /* rsrvd */  + name_len /* incl null */ ;
-	pSMB->TotalDataCount = 0;
-	pSMB->MaxParameterCount = cpu_to_le16(2);
-	/* BB find exact max data count below from sess structure BB */
-	pSMB->MaxDataCount = cpu_to_le16(4000);
-	pSMB->MaxSetupCount = 0;
-	pSMB->Reserved = 0;
-	pSMB->Flags = 0;
-	pSMB->Timeout = 0;
-	pSMB->Reserved2 = 0;
-	pSMB->ParameterOffset = cpu_to_le16(
-		offsetof(struct smb_com_transaction2_qpi_req,
-			 InformationLevel) - 4);
-	pSMB->DataCount = 0;
-	pSMB->DataOffset = 0;
-	pSMB->SetupCount = 1;
-	pSMB->Reserved3 = 0;
-	pSMB->SubCommand = cpu_to_le16(TRANS2_QUERY_PATH_INFORMATION);
-	byte_count = params + 1 /* pad */ ;
-	pSMB->TotalParameterCount = cpu_to_le16(params);
-	pSMB->ParameterCount = pSMB->TotalParameterCount;
-	pSMB->InformationLevel = cpu_to_le16(SMB_QUERY_POSIX_ACL);
-	pSMB->Reserved4 = 0;
-	inc_rfc1001_len(pSMB, byte_count);
-	pSMB->ByteCount = cpu_to_le16(byte_count);
-
-	rc = SendReceive(xid, tcon->ses, (struct smb_hdr *) pSMB,
-		(struct smb_hdr *) pSMBr, &bytes_returned, 0);
-	cifs_stats_inc(&tcon->stats.cifs_stats.num_acl_get);
-	if (rc) {
-		cifs_dbg(FYI, "Send error in Query POSIX ACL = %d\n", rc);
-	} else {
-		/* decode response */
-
-		rc = validate_t2((struct smb_t2_rsp *)pSMBr);
-		/* BB also check enough total bytes returned */
-		if (rc || get_bcc(&pSMBr->hdr) < 2)
-			rc = -EIO;      /* bad smb */
-		else {
-			__u16 data_offset = le16_to_cpu(pSMBr->t2.DataOffset);
-			__u16 count = le16_to_cpu(pSMBr->t2.DataCount);
-			rc = cifs_copy_posix_acl(acl_inf,
-				(char *)&pSMBr->hdr.Protocol+data_offset,
-				buflen, acl_type, count);
-		}
-	}
-	cifs_buf_release(pSMB);
-	if (rc == -EAGAIN)
-		goto queryAclRetry;
-	return rc;
-}
-
-int
-CIFSSMBSetPosixACL(const unsigned int xid, struct cifs_tcon *tcon,
-		   const unsigned char *fileName,
-		   const char *local_acl, const int buflen,
-		   const int acl_type,
-		   const struct nls_table *nls_codepage, int remap)
-{
-	struct smb_com_transaction2_spi_req *pSMB = NULL;
-	struct smb_com_transaction2_spi_rsp *pSMBr = NULL;
-	char *parm_data;
-	int name_len;
-	int rc = 0;
-	int bytes_returned = 0;
-	__u16 params, byte_count, data_count, param_offset, offset;
-
-	cifs_dbg(FYI, "In SetPosixACL (Unix) for path %s\n", fileName);
-setAclRetry:
-	rc = smb_init(SMB_COM_TRANSACTION2, 15, tcon, (void **) &pSMB,
-		      (void **) &pSMBr);
-	if (rc)
-		return rc;
-	if (pSMB->hdr.Flags2 & SMBFLG2_UNICODE) {
-		name_len =
-			cifsConvertToUTF16((__le16 *) pSMB->FileName, fileName,
-					   PATH_MAX, nls_codepage, remap);
-		name_len++;     /* trailing null */
-		name_len *= 2;
-	} else {
-		name_len = copy_path_name(pSMB->FileName, fileName);
-	}
-	params = 6 + name_len;
-	pSMB->MaxParameterCount = cpu_to_le16(2);
-	/* BB find max SMB size from sess */
-	pSMB->MaxDataCount = cpu_to_le16(1000);
-	pSMB->MaxSetupCount = 0;
-	pSMB->Reserved = 0;
-	pSMB->Flags = 0;
-	pSMB->Timeout = 0;
-	pSMB->Reserved2 = 0;
-	param_offset = offsetof(struct smb_com_transaction2_spi_req,
-				InformationLevel) - 4;
-	offset = param_offset + params;
-	parm_data = ((char *) &pSMB->hdr.Protocol) + offset;
-	pSMB->ParameterOffset = cpu_to_le16(param_offset);
-
-	/* convert to on the wire format for POSIX ACL */
-	data_count = ACL_to_cifs_posix(parm_data, local_acl, buflen, acl_type);
-
-	if (data_count == 0) {
-		rc = -EOPNOTSUPP;
-		goto setACLerrorExit;
-	}
-	pSMB->DataOffset = cpu_to_le16(offset);
-	pSMB->SetupCount = 1;
-	pSMB->Reserved3 = 0;
-	pSMB->SubCommand = cpu_to_le16(TRANS2_SET_PATH_INFORMATION);
-	pSMB->InformationLevel = cpu_to_le16(SMB_SET_POSIX_ACL);
-	byte_count = 3 /* pad */  + params + data_count;
-	pSMB->DataCount = cpu_to_le16(data_count);
-	pSMB->TotalDataCount = pSMB->DataCount;
-	pSMB->ParameterCount = cpu_to_le16(params);
-	pSMB->TotalParameterCount = pSMB->ParameterCount;
-	pSMB->Reserved4 = 0;
-	inc_rfc1001_len(pSMB, byte_count);
-	pSMB->ByteCount = cpu_to_le16(byte_count);
-	rc = SendReceive(xid, tcon->ses, (struct smb_hdr *) pSMB,
-			 (struct smb_hdr *) pSMBr, &bytes_returned, 0);
-	if (rc)
-		cifs_dbg(FYI, "Set POSIX ACL returned %d\n", rc);
-
-setACLerrorExit:
-	cifs_buf_release(pSMB);
-	if (rc == -EAGAIN)
-		goto setAclRetry;
-	return rc;
-}
-
 #ifdef CONFIG_FS_POSIX_ACL
 /**
  * cifs_init_posix_acl - convert ACL from cifs to POSIX ACL format
diff --git a/fs/cifs/xattr.c b/fs/cifs/xattr.c
index 998fa51f9b68..293ffe89d6b2 100644
--- a/fs/cifs/xattr.c
+++ b/fs/cifs/xattr.c
@@ -200,32 +200,6 @@ static int cifs_xattr_set(const struct xattr_handler *handler,
 		}
 		break;
 	}
-
-#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
-	case XATTR_ACL_ACCESS:
-#ifdef CONFIG_CIFS_POSIX
-		if (!value)
-			goto out;
-		if (sb->s_flags & SB_POSIXACL)
-			rc = CIFSSMBSetPosixACL(xid, pTcon, full_path,
-				value, (const int)size,
-				ACL_TYPE_ACCESS, cifs_sb->local_nls,
-				cifs_remap(cifs_sb));
-#endif  /* CONFIG_CIFS_POSIX */
-		break;
-
-	case XATTR_ACL_DEFAULT:
-#ifdef CONFIG_CIFS_POSIX
-		if (!value)
-			goto out;
-		if (sb->s_flags & SB_POSIXACL)
-			rc = CIFSSMBSetPosixACL(xid, pTcon, full_path,
-				value, (const int)size,
-				ACL_TYPE_DEFAULT, cifs_sb->local_nls,
-				cifs_remap(cifs_sb));
-#endif  /* CONFIG_CIFS_POSIX */
-		break;
-#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
 	}
 
 out:
@@ -366,27 +340,6 @@ static int cifs_xattr_get(const struct xattr_handler *handler,
 		}
 		break;
 	}
-#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
-	case XATTR_ACL_ACCESS:
-#ifdef CONFIG_CIFS_POSIX
-		if (sb->s_flags & SB_POSIXACL)
-			rc = CIFSSMBGetPosixACL(xid, pTcon, full_path,
-				value, size, ACL_TYPE_ACCESS,
-				cifs_sb->local_nls,
-				cifs_remap(cifs_sb));
-#endif  /* CONFIG_CIFS_POSIX */
-		break;
-
-	case XATTR_ACL_DEFAULT:
-#ifdef CONFIG_CIFS_POSIX
-		if (sb->s_flags & SB_POSIXACL)
-			rc = CIFSSMBGetPosixACL(xid, pTcon, full_path,
-				value, size, ACL_TYPE_DEFAULT,
-				cifs_sb->local_nls,
-				cifs_remap(cifs_sb));
-#endif  /* CONFIG_CIFS_POSIX */
-		break;
-#endif /* ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
 	}
 
 	/* We could add an additional check for streams ie
@@ -525,21 +478,6 @@ static const struct xattr_handler smb3_ntsd_full_xattr_handler = {
 	.set = cifs_xattr_set,
 };
 
-
-static const struct xattr_handler cifs_posix_acl_access_xattr_handler = {
-	.name = XATTR_NAME_POSIX_ACL_ACCESS,
-	.flags = XATTR_ACL_ACCESS,
-	.get = cifs_xattr_get,
-	.set = cifs_xattr_set,
-};
-
-static const struct xattr_handler cifs_posix_acl_default_xattr_handler = {
-	.name = XATTR_NAME_POSIX_ACL_DEFAULT,
-	.flags = XATTR_ACL_DEFAULT,
-	.get = cifs_xattr_get,
-	.set = cifs_xattr_set,
-};
-
 const struct xattr_handler *cifs_xattr_handlers[] = {
 	&cifs_user_xattr_handler,
 	&cifs_os2_xattr_handler,
@@ -549,7 +487,9 @@ const struct xattr_handler *cifs_xattr_handlers[] = {
 	&smb3_ntsd_xattr_handler, /* alias for above since avoiding "cifs" */
 	&cifs_cifs_ntsd_full_xattr_handler,
 	&smb3_ntsd_full_xattr_handler, /* alias for above since avoiding "cifs" */
-	&cifs_posix_acl_access_xattr_handler,
-	&cifs_posix_acl_default_xattr_handler,
+#ifdef CONFIG_XFS_POSIX_ACL
+	&posix_acl_access_xattr_handler,
+	&posix_acl_default_xattr_handler,
+#endif
 	NULL
 };
-- 
2.34.1

Re: [PATCH v2 00/30] acl: add vfs posix acl api

[Casey Schaufler]

On 9/26/2022 7:07 AM, Christian Brauner wrote:
> From: "Christian Brauner (Microsoft)" <brauner@kernel.org>
>
> Hey everyone,
>
> /* v2 */
> This fixes various things pointed out during review. The individual
> commits contain more details were appropriate.
>
> As we discussed and seen multiple times the current state of how posix
> acls are handled isn't nice and comes with a lot of problems. For a long
> and detailed explanation for just some of the issues [1] provides a good
> summary.
>
> The current way of handling posix acls via the generic xattr api is
> error prone, hard to maintain, and type unsafe for the vfs until we call
> into the filesystem's dedicated get and set inode operations.
>
> It is already the case that posix acls are special-cased to death all
> the way through the vfs. There are an uncounted number of hacks that
> operate on the uapi posix acl struct instead of the dedicated vfs struct
> posix_acl. And the vfs must be involved in order to interpret and fixup
> posix acls before storing them to the backing store, caching them,
> reporting them to userspace, or for permission checking.
>
> Currently a range of hacks and duct tape exist to make this work. As
> with most things this is really no ones fault it's just something that
> happened over time. But the code is hard to understand and difficult
> to maintain and one is constantly at risk of introducing bugs and
> regressions when having to touch it.
>
> Instead of continuing to hack posix acls through the xattr handlers this
> series builds a dedicated posix acl api solely around the get and set
> inode operations. Going forward, the vfs_get_acl(), vfs_remove_acl(),
> and vfs_set_acl() helpers must be used in order to interact with posix
> acls. They operate directly on the vfs internal struct posix_acl instead
> of abusing the uapi posix acl struct as we currently do. In the end this
> removes all of the hackiness, makes the codepaths easier to maintain,
> and gets us type safety.

I may have missed something obvious, but from the LSM side the only place
where the ACL handling differs from general xattr handling in in EVM. This
seems like a lot of "clean-up" to address that one special case. Especially
since EVM isn't (currently) an LSM. I'll admit that a future LSM might look
into the posix acl, although looking at another security feature's data is
hardly encouraged. EVM, which is all about protecting the content of other
security data is kind of exceptional in that.

I suggest that you might focus on the acl/evm interface rather than the entire
LSM interface. Unless there's a serious plan to make ima/evm into a proper LSM
I don't see how the breadth of this patch set is appropriate.

>
> This series passes the LTP and xfstests suites without any regressions.
> For xfstests the following combinations were tested:
>
> * xfs
> * ext4
> * btrfs
> * overlayfs
> * overlayfs on top of idmapped mounts
>
> For people wanting to run their own xfstests I'd recommend to shorten
> their test runs via:
>
> ./check -g acl,attr,cap,idmapped,io_uring,perms,subvol,unlink
>
> I would appreciate if the 9p and cifs folks could run any posix acl
> related tests as I have no setup to really do this without causing me a
> lot of pain.
>
> Very likely there's a lot more simplifications for posix acls that we
> can make in the future if the basic api has made it.
>
> A few implementation details:
>
> * The series makes sure to retain exactly the same security and
>   integrity module permission checks. See [2] for annotated callchains.
>   Especially for the integrity modules this api is a win because right
>   now they convert the uapi posix acl struct passed to them via a void
>   pointer into the vfs struct posix_acl format to perform permission
>   checking on the mode.
>
>   There's a new dedicated security hook for setting posix acls which
>   passes the vfs struct posix_acl not a void pointer. Basing checking on
>   the posix acl stored in the uapi format is really unreliable. The vfs
>   currently hacks around directly in the uapi struct storing values that
>   frankly the security and integrity modules can't correctly interpret
>   as evidenced by bugs we reported and fixed in this area. It's not
>   necessarily even their fault it's just that the format we provide to
>   them is sub optimal.
>
> * Some filesystems like 9p and cifs need access to the dentry in order
>   to get and set posix acls which is why they either only partially or
>   not even at all implement get and set inode operations. For example,
>   cifs allows setxattr() and getxattr() operations but doesn't allow
>   permission checking based on posix acls because it can't implement a
>   get acl inode operation.
>
>   Thus, this patch series updates the set acl inode operation to take a
>   dentry instead of an inode argument. However, for the get acl inode
>   operation we can't do this as the old get acl method is called in
>   e.g., generic_permission() and inode_permission(). These helpers in
>   turn are called in various filesystem's permission inode operation. So
>   passing a dentry argument to the old get acl inode operation would
>   amount to passing a dentry to the permission inode operation which we
>   shouldn't and probably can't do.
>
>   So instead of extending the existing inode operation Christoph
>   suggested to add a new one. He also requested to ensure that the get
>   and set acl inode operation taking a dentry are consistently named. So
>   for this version the old get acl operation is renamed to
>   ->get_inode_acl() and a new ->get_acl() inode operation taking a
>   dentry is added. With this we can give both 9p and cifs get and set
>   acl inode operations and in turn remove their complex custom posix
>   xattr handlers.
>
> * I've done a full audit of every codepaths using variant of the
>   current generic xattr api to get and set posix acls and surprisingly
>   it isn't that many places. There's of course always a chance that I
>   might have missed some and I'm sure we'll find them soon enough.
>
>   The crucial codepaths to be converted are obviously stacking
>   filesystems such as ecryptfs and overlayfs.
>
>   For a list of all callers currently using generic xattr api helpers
>   see [2] including comments whether they support posix acls or not.
>
> * The old vfs generic posix acl infrastructure doesn't obey
>   the create and replace semantics promised on the setxattr(2) manpage.
>   This patch series doesn't address this. It really is something we
>   should revisit later though.
>
> The patch series is roughly organized as follows:
>
> // intended to be a non-functional change
> 1. Change existing set acl inode operation to take a dentry argument.
>
> // intended to be a non-functional change
> 2. Rename existing get acl method.
>
> // intended to be a non-functional change
> 3. Implement get and set acl inode operations for filesystems that
>    couldn't implement one before because of the missing dentry. That's
>    mostly 9p and cifs.
>
> // intended to be a non-functional change
> 4. Build posix acl api, i.e., add vfs_get_acl(), vfs_remove_acl(), and
>    vfs_set_acl() including security and integrity hooks.
>
> // intended to be a non-functional change
> 5. Implement get and set acl inode operations for stacking filesystems.
>
> // semantical change
> 6. Switch posix acl handling in stacking filesystems to new posix acl
>    api now that all filesystems it can stack upon support it.
>
> // semantical change
> 7. Switch vfs to new posix acl api
>
> 8. Remove all now unused helpers
>
> The series can be pulled from:
>
> https://gitlab.com/brauner/linux/-/commits/fs.acl.rework
> https://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping.git/log/?h=fs.acl.rework
>
> The series contains a few preliminary patches which are scheduled for
> the next merge window. It was just easier to base the series on top of
> them. But if you pull this branch you'll get them included.
>
> I've been working on this for a while and before going any further it'd
> be nice to get some reviews. I think that it should be fine to have get
> and set acl inode operations that operate on the dentry at least nothing
> stuck out immediately that would prevent this. But obviously having
> other people point out issues with that would be helpful.
>
> Thanks to Seth for a lot of good discussion around this and
> encouragement and input from Christoph.
>
> [1]: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org
> [2]: https://gist.github.com/brauner/12c795b93a05dc3b3056b1982549a633
>
> v1: https://lore.kernel.org/linux-cifs/20220922151728.1557914-1-brauner@kernel.org
>
> Thanks!
> Christian
>
> Christian Brauner (30):
>   orangefs: rework posix acl handling when creating new filesystem
>     objects
>   fs: pass dentry to set acl method
>   fs: rename current get acl method
>   fs: add new get acl method
>   cifs: implement get acl method
>   cifs: implement set acl method
>   9p: implement get acl method
>   9p: implement set acl method
>   acl: add vfs_set_acl()
>   security: add set acl hook
>   selinux: implement set acl hook
>   smack: implement set acl hook
>   evm: implement set acl hook
>   acl: use set acl hook
>   evm: add post set acl hook
>   acl: add vfs_get_acl()
>   acl: add vfs_remove_acl()
>   evm: simplify evm_xattr_acl_change()
>   ksmbd: use vfs_remove_acl()
>   ecryptfs: implement get acl method
>   ecryptfs: implement set acl method
>   ovl: implement get acl method
>   ovl: implement set acl method
>   ovl: use posix acl api
>   xattr: use posix acl api
>   ecryptfs: use stub posix acl handlers
>   ovl: use stub posix acl handlers
>   cifs: use stub posix acl handlers
>   9p: use stub posix acl handlers
>   acl: remove a slew of now unused helpers
>
>  Documentation/filesystems/locking.rst |   4 +-
>  Documentation/filesystems/porting.rst |   4 +-
>  Documentation/filesystems/vfs.rst     |   3 +-
>  fs/9p/acl.c                           | 295 +++++------
>  fs/9p/acl.h                           |   8 +-
>  fs/9p/vfs_inode_dotl.c                |   4 +
>  fs/9p/xattr.c                         |   7 +-
>  fs/9p/xattr.h                         |   2 -
>  fs/bad_inode.c                        |   4 +-
>  fs/btrfs/acl.c                        |   3 +-
>  fs/btrfs/ctree.h                      |   2 +-
>  fs/btrfs/inode.c                      |   8 +-
>  fs/ceph/acl.c                         |   3 +-
>  fs/ceph/dir.c                         |   2 +-
>  fs/ceph/inode.c                       |   4 +-
>  fs/ceph/super.h                       |   2 +-
>  fs/cifs/cifsacl.c                     | 141 ++++++
>  fs/cifs/cifsfs.c                      |   4 +
>  fs/cifs/cifsproto.h                   |  20 +-
>  fs/cifs/cifssmb.c                     | 206 +++++---
>  fs/cifs/xattr.c                       |  68 +--
>  fs/ecryptfs/inode.c                   |  32 ++
>  fs/erofs/inode.c                      |   6 +-
>  fs/erofs/namei.c                      |   2 +-
>  fs/ext2/acl.c                         |   3 +-
>  fs/ext2/acl.h                         |   2 +-
>  fs/ext2/file.c                        |   2 +-
>  fs/ext2/inode.c                       |   2 +-
>  fs/ext2/namei.c                       |   4 +-
>  fs/ext4/acl.c                         |   3 +-
>  fs/ext4/acl.h                         |   2 +-
>  fs/ext4/file.c                        |   2 +-
>  fs/ext4/inode.c                       |   2 +-
>  fs/ext4/namei.c                       |   4 +-
>  fs/f2fs/acl.c                         |   4 +-
>  fs/f2fs/acl.h                         |   2 +-
>  fs/f2fs/file.c                        |   4 +-
>  fs/f2fs/namei.c                       |   4 +-
>  fs/fuse/acl.c                         |   3 +-
>  fs/fuse/dir.c                         |   4 +-
>  fs/fuse/fuse_i.h                      |   2 +-
>  fs/gfs2/acl.c                         |   3 +-
>  fs/gfs2/acl.h                         |   2 +-
>  fs/gfs2/inode.c                       |   6 +-
>  fs/internal.h                         |   1 +
>  fs/jffs2/acl.c                        |   3 +-
>  fs/jffs2/acl.h                        |   2 +-
>  fs/jffs2/dir.c                        |   2 +-
>  fs/jffs2/file.c                       |   2 +-
>  fs/jffs2/fs.c                         |   2 +-
>  fs/jfs/acl.c                          |   3 +-
>  fs/jfs/file.c                         |   4 +-
>  fs/jfs/jfs_acl.h                      |   2 +-
>  fs/jfs/namei.c                        |   2 +-
>  fs/ksmbd/smb2pdu.c                    |   4 +-
>  fs/ksmbd/smbacl.c                     |   4 +-
>  fs/ksmbd/vfs.c                        |  17 +-
>  fs/ksmbd/vfs.h                        |   4 +-
>  fs/namei.c                            |   2 +-
>  fs/nfs/nfs3_fs.h                      |   2 +-
>  fs/nfs/nfs3acl.c                      |   3 +-
>  fs/nfs/nfs3proc.c                     |   4 +-
>  fs/nfsd/nfs2acl.c                     |   4 +-
>  fs/nfsd/nfs3acl.c                     |   4 +-
>  fs/nfsd/vfs.c                         |   4 +-
>  fs/ntfs3/file.c                       |   4 +-
>  fs/ntfs3/namei.c                      |   4 +-
>  fs/ntfs3/ntfs_fs.h                    |   4 +-
>  fs/ntfs3/xattr.c                      |   9 +-
>  fs/ocfs2/acl.c                        |   3 +-
>  fs/ocfs2/acl.h                        |   2 +-
>  fs/ocfs2/file.c                       |   4 +-
>  fs/ocfs2/namei.c                      |   2 +-
>  fs/orangefs/acl.c                     |  47 +-
>  fs/orangefs/inode.c                   |  47 +-
>  fs/orangefs/namei.c                   |   2 +-
>  fs/orangefs/orangefs-kernel.h         |   9 +-
>  fs/orangefs/orangefs-utils.c          |  12 +-
>  fs/overlayfs/copy_up.c                |  38 ++
>  fs/overlayfs/dir.c                    |  22 +-
>  fs/overlayfs/inode.c                  | 151 +++++-
>  fs/overlayfs/overlayfs.h              |  34 +-
>  fs/overlayfs/super.c                  | 107 +---
>  fs/posix_acl.c                        | 681 +++++++++++++-------------
>  fs/reiserfs/acl.h                     |   6 +-
>  fs/reiserfs/file.c                    |   2 +-
>  fs/reiserfs/inode.c                   |   2 +-
>  fs/reiserfs/namei.c                   |   4 +-
>  fs/reiserfs/xattr_acl.c               |   9 +-
>  fs/xattr.c                            |  78 ++-
>  fs/xfs/xfs_acl.c                      |   3 +-
>  fs/xfs/xfs_acl.h                      |   2 +-
>  fs/xfs/xfs_iops.c                     |  16 +-
>  include/linux/evm.h                   |  23 +
>  include/linux/fs.h                    |  10 +-
>  include/linux/lsm_hook_defs.h         |   2 +
>  include/linux/lsm_hooks.h             |   4 +
>  include/linux/posix_acl.h             |  39 +-
>  include/linux/posix_acl_xattr.h       |  43 +-
>  include/linux/security.h              |  11 +
>  include/linux/xattr.h                 |   8 +
>  io_uring/xattr.c                      |   2 +
>  mm/shmem.c                            |   2 +-
>  security/integrity/evm/evm_main.c     | 128 +++--
>  security/security.c                   |  16 +
>  security/selinux/hooks.c              |   8 +
>  security/smack/smack_lsm.c            |  24 +
>  107 files changed, 1550 insertions(+), 1043 deletions(-)
>
>
> base-commit: 38e316398e4e6338b80223fb5f74415c0513718f

Re: [PATCH v2 00/30] acl: add vfs posix acl api

[Christoph Hellwig]

On Mon, Sep 26, 2022 at 05:22:45PM -0700, Casey Schaufler wrote:
> I suggest that you might focus on the acl/evm interface rather than the entire
> LSM interface. Unless there's a serious plan to make ima/evm into a proper LSM
> I don't see how the breadth of this patch set is appropriate.

Umm. The problem is the historically the Linux xattr interface was
intended for unstructured data, while some of it is very much structured
and requires interpretation by the VFS and associated entities.  So
splitting these out and add proper interface is absolutely the right
thing to do and long overdue (also for other thing like capabilities).
It might make things a little more verbose for LSM, but it fixes a very
real problem.

Re: [PATCH v2 00/30] acl: add vfs posix acl api

[Christian Brauner]

On Tue, Sep 27, 2022 at 09:41:01AM +0200, Christoph Hellwig wrote:
> On Mon, Sep 26, 2022 at 05:22:45PM -0700, Casey Schaufler wrote:
> > I suggest that you might focus on the acl/evm interface rather than the entire
> > LSM interface. Unless there's a serious plan to make ima/evm into a proper LSM
> > I don't see how the breadth of this patch set is appropriate.
> 
> Umm. The problem is the historically the Linux xattr interface was
> intended for unstructured data, while some of it is very much structured
> and requires interpretation by the VFS and associated entities.  So
> splitting these out and add proper interface is absolutely the right
> thing to do and long overdue (also for other thing like capabilities).
> It might make things a little more verbose for LSM, but it fixes a very
> real problem.

Agreed.

Re: [PATCH v2 00/30] acl: add vfs posix acl api

[Casey Schaufler]

On 9/27/2022 12:41 AM, Christoph Hellwig wrote:
> On Mon, Sep 26, 2022 at 05:22:45PM -0700, Casey Schaufler wrote:
>> I suggest that you might focus on the acl/evm interface rather than the entire
>> LSM interface. Unless there's a serious plan to make ima/evm into a proper LSM
>> I don't see how the breadth of this patch set is appropriate.
> Umm. The problem is the historically the Linux xattr interface was
> intended for unstructured data, while some of it is very much structured
> and requires interpretation by the VFS and associated entities.  So
> splitting these out and add proper interface is absolutely the right
> thing to do and long overdue (also for other thing like capabilities).
> It might make things a little more verbose for LSM, but it fixes a very
> real problem.

Here's the problem I see. All of the LSMs see xattrs, except for their own,
as opaque objects. Introducing LSM hooks to address the data interpretation
issues between VFS and EVM, which is not an LSM, adds to an already overlarge
and interface. And the "real" users of the interface don't need the new hook.
I'm not saying that the ACL doesn't have problems. I'm not saying that the
solution you've proposed isn't better than what's there now. I am saying that
using LSM as a conduit between VFS and EVM at the expense of the rest of the
modules is dubious. A lot of change to LSM for no value to LSM.

I am not adamant about this. A whole lot worse has been done for worse reasons.
But as Paul says, we're overdue to make an effort to keep the LSM interface sane.

Re: [PATCH v2 00/30] acl: add vfs posix acl api

[Seth Forshee]

On Tue, Sep 27, 2022 at 07:11:17AM -0700, Casey Schaufler wrote:
> On 9/27/2022 12:41 AM, Christoph Hellwig wrote:
> > On Mon, Sep 26, 2022 at 05:22:45PM -0700, Casey Schaufler wrote:
> >> I suggest that you might focus on the acl/evm interface rather than the entire
> >> LSM interface. Unless there's a serious plan to make ima/evm into a proper LSM
> >> I don't see how the breadth of this patch set is appropriate.
> > Umm. The problem is the historically the Linux xattr interface was
> > intended for unstructured data, while some of it is very much structured
> > and requires interpretation by the VFS and associated entities.  So
> > splitting these out and add proper interface is absolutely the right
> > thing to do and long overdue (also for other thing like capabilities).
> > It might make things a little more verbose for LSM, but it fixes a very
> > real problem.
> 
> Here's the problem I see. All of the LSMs see xattrs, except for their own,
> as opaque objects. Introducing LSM hooks to address the data interpretation
> issues between VFS and EVM, which is not an LSM, adds to an already overlarge
> and interface. And the "real" users of the interface don't need the new hook.
> I'm not saying that the ACL doesn't have problems. I'm not saying that the
> solution you've proposed isn't better than what's there now. I am saying that
> using LSM as a conduit between VFS and EVM at the expense of the rest of the
> modules is dubious. A lot of change to LSM for no value to LSM.
> 
> I am not adamant about this. A whole lot worse has been done for worse reasons.
> But as Paul says, we're overdue to make an effort to keep the LSM interface sane.

So I assume the alternative you have in mind would be to use the
existing setxattr hook? I worry about type confusion if an LSM does
someday want to look inside the ACL data. Unless LSMs aren't supposed to
look inside of xattr data, but in that case why pass the data pointer on
to the LSMs?

Note that the caller of this new hook does not have access to the uapi
xattr data, and I think this is the right place for the new hook to be
called as it's the interface that stacked filesystems like overlayfs
will use to write ACLs to the lower filesystems.

Seth

Re: [PATCH v2 00/30] acl: add vfs posix acl api

[Casey Schaufler]

On 9/27/2022 8:16 AM, Seth Forshee wrote:
> On Tue, Sep 27, 2022 at 07:11:17AM -0700, Casey Schaufler wrote:
>> On 9/27/2022 12:41 AM, Christoph Hellwig wrote:
>>> On Mon, Sep 26, 2022 at 05:22:45PM -0700, Casey Schaufler wrote:
>>>> I suggest that you might focus on the acl/evm interface rather than the entire
>>>> LSM interface. Unless there's a serious plan to make ima/evm into a proper LSM
>>>> I don't see how the breadth of this patch set is appropriate.
>>> Umm. The problem is the historically the Linux xattr interface was
>>> intended for unstructured data, while some of it is very much structured
>>> and requires interpretation by the VFS and associated entities.  So
>>> splitting these out and add proper interface is absolutely the right
>>> thing to do and long overdue (also for other thing like capabilities).
>>> It might make things a little more verbose for LSM, but it fixes a very
>>> real problem.
>> Here's the problem I see. All of the LSMs see xattrs, except for their own,
>> as opaque objects. Introducing LSM hooks to address the data interpretation
>> issues between VFS and EVM, which is not an LSM, adds to an already overlarge
>> and interface. And the "real" users of the interface don't need the new hook.
>> I'm not saying that the ACL doesn't have problems. I'm not saying that the
>> solution you've proposed isn't better than what's there now. I am saying that
>> using LSM as a conduit between VFS and EVM at the expense of the rest of the
>> modules is dubious. A lot of change to LSM for no value to LSM.
>>
>> I am not adamant about this. A whole lot worse has been done for worse reasons.
>> But as Paul says, we're overdue to make an effort to keep the LSM interface sane.
> So I assume the alternative you have in mind would be to use the
> existing setxattr hook?

That is how it works today.

>  I worry about type confusion if an LSM does
> someday want to look inside the ACL data.

I suggest that changes to system behavior based on the content of
an ACL really belongs in the ACL code, not in an LSM. Can I imagine
someone wanting to add SELinux policy that controls what entries
are allowed to be set by a particular domain? Sure, but I can't see
how that would be popular with existing ACL fans.

>  Unless LSMs aren't supposed to
> look inside of xattr data, but in that case why pass the data pointer on
> to the LSMs?

So that the LSM can look at it's own xattr data.

> Note that the caller of this new hook does not have access to the uapi
> xattr data, and I think this is the right place for the new hook to be
> called as it's the interface that stacked filesystems like overlayfs
> will use to write ACLs to the lower filesystems.

I'm not saying anything about the organization of the calling code.
Why is it calling

	security_acl_hooha(...)

instead of

	evm_acl_hooha(...)


>
> Seth

Re: [PATCH v2 00/30] acl: add vfs posix acl api

[Paul Moore]

On Tue, Sep 27, 2022 at 10:13 AM Casey Schaufler <casey@schaufler-ca.com> wrote:
>
> On 9/27/2022 12:41 AM, Christoph Hellwig wrote:
> > On Mon, Sep 26, 2022 at 05:22:45PM -0700, Casey Schaufler wrote:
> >> I suggest that you might focus on the acl/evm interface rather than the entire
> >> LSM interface. Unless there's a serious plan to make ima/evm into a proper LSM
> >> I don't see how the breadth of this patch set is appropriate.
> > Umm. The problem is the historically the Linux xattr interface was
> > intended for unstructured data, while some of it is very much structured
> > and requires interpretation by the VFS and associated entities.  So
> > splitting these out and add proper interface is absolutely the right
> > thing to do and long overdue (also for other thing like capabilities).
> > It might make things a little more verbose for LSM, but it fixes a very
> > real problem.
>
> Here's the problem I see. All of the LSMs see xattrs, except for their own,
> as opaque objects. Introducing LSM hooks to address the data interpretation
> issues between VFS and EVM, which is not an LSM, adds to an already overlarge
> and interface. And the "real" users of the interface don't need the new hook.
> I'm not saying that the ACL doesn't have problems. I'm not saying that the
> solution you've proposed isn't better than what's there now. I am saying that
> using LSM as a conduit between VFS and EVM at the expense of the rest of the
> modules is dubious. A lot of change to LSM for no value to LSM.

Let's take a step back and look not just at the LSM changes, but the
patchset as a whole.  Forgive my paraphrasing, but what Christian is
trying to do here is introduce a proper ACL API in the kernel to
remove a lot of kludges, special-cases, etc. in the VFS layer,
enabling better type checking, code abstractions, and all the nice
things you get when you have nice APIs.  This is admirable work, even
if it does result in some duplication at the LSM layer (and below).

It is my opinion that the impact to the LSM, both at the LSM layer,
and in the individual affected LSMs is not significant enough to
outweigh the other advantages offered by this patchset.

-- 
paul-moore.com

Re: [PATCH v2 00/30] acl: add vfs posix acl api

[Casey Schaufler]

On 9/27/2022 4:24 PM, Paul Moore wrote:
> On Tue, Sep 27, 2022 at 10:13 AM Casey Schaufler <casey@schaufler-ca.com> wrote:
>> On 9/27/2022 12:41 AM, Christoph Hellwig wrote:
>>> On Mon, Sep 26, 2022 at 05:22:45PM -0700, Casey Schaufler wrote:
>>>> I suggest that you might focus on the acl/evm interface rather than the entire
>>>> LSM interface. Unless there's a serious plan to make ima/evm into a proper LSM
>>>> I don't see how the breadth of this patch set is appropriate.
>>> Umm. The problem is the historically the Linux xattr interface was
>>> intended for unstructured data, while some of it is very much structured
>>> and requires interpretation by the VFS and associated entities.  So
>>> splitting these out and add proper interface is absolutely the right
>>> thing to do and long overdue (also for other thing like capabilities).
>>> It might make things a little more verbose for LSM, but it fixes a very
>>> real problem.
>> Here's the problem I see. All of the LSMs see xattrs, except for their own,
>> as opaque objects. Introducing LSM hooks to address the data interpretation
>> issues between VFS and EVM, which is not an LSM, adds to an already overlarge
>> and interface. And the "real" users of the interface don't need the new hook.
>> I'm not saying that the ACL doesn't have problems. I'm not saying that the
>> solution you've proposed isn't better than what's there now. I am saying that
>> using LSM as a conduit between VFS and EVM at the expense of the rest of the
>> modules is dubious. A lot of change to LSM for no value to LSM.
> Let's take a step back and look not just at the LSM changes, but the
> patchset as a whole.  Forgive my paraphrasing, but what Christian is
> trying to do here is introduce a proper ACL API in the kernel to
> remove a lot of kludges, special-cases, etc. in the VFS layer,
> enabling better type checking, code abstractions, and all the nice
> things you get when you have nice APIs.  This is admirable work, even
> if it does result in some duplication at the LSM layer (and below).
>
> It is my opinion that the impact to the LSM, both at the LSM layer,
> and in the individual affected LSMs is not significant enough to
> outweigh the other advantages offered by this patchset.

Hey, in the end it's your call. I agree that cleaning up kludgy code
is inherently good. I'm willing to believe that putting further effort
into the patch set to make the LSM aspects cleaner isn't cost effective.
If everyone else thinks this is the right approach, I don't need to
question it further.