Merge tag 'fs.idmapped.vfsuid.v5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

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

2 files changed, 10 insertions, 7 deletions

diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index cc88f02c7562..93e8bc047a73 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -755,13 +755,14 @@ void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)
 	evm_update_evmxattr(dentry, xattr_name, NULL, 0);
 }
 
-static int evm_attr_change(struct dentry *dentry, struct iattr *attr)
+static int evm_attr_change(struct user_namespace *mnt_userns,
+			   struct dentry *dentry, struct iattr *attr)
 {
 	struct inode *inode = d_backing_inode(dentry);
 	unsigned int ia_valid = attr->ia_valid;
 
-	if ((!(ia_valid & ATTR_UID) || uid_eq(attr->ia_uid, inode->i_uid)) &&
-	    (!(ia_valid & ATTR_GID) || gid_eq(attr->ia_gid, inode->i_gid)) &&
+	if (!i_uid_needs_update(mnt_userns, attr, inode) &&
+	    !i_gid_needs_update(mnt_userns, attr, inode) &&
 	    (!(ia_valid & ATTR_MODE) || attr->ia_mode == inode->i_mode))
 		return 0;
 
@@ -775,7 +776,8 @@ static int evm_attr_change(struct dentry *dentry, struct iattr *attr)
  * Permit update of file attributes when files have a valid EVM signature,
  * except in the case of them having an immutable portable signature.
  */
-int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
+int evm_inode_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+		      struct iattr *attr)
 {
 	unsigned int ia_valid = attr->ia_valid;
 	enum integrity_status evm_status;
@@ -801,7 +803,7 @@ int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
 		return 0;
 
 	if (evm_status == INTEGRITY_PASS_IMMUTABLE &&
-	    !evm_attr_change(dentry, attr))
+	    !evm_attr_change(mnt_userns, dentry, attr))
 		return 0;
 
 	integrity_audit_msg(AUDIT_INTEGRITY_METADATA, d_backing_inode(dentry),
diff --git a/security/security.c b/security/security.c
index 188b8f782220..f85afb02ea1c 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1324,7 +1324,8 @@ int security_inode_permission(struct inode *inode, int mask)
 	return call_int_hook(inode_permission, 0, inode, mask);
 }
 
-int security_inode_setattr(struct dentry *dentry, struct iattr *attr)
+int security_inode_setattr(struct user_namespace *mnt_userns,
+			   struct dentry *dentry, struct iattr *attr)
 {
 	int ret;
 
@@ -1333,7 +1334,7 @@ int security_inode_setattr(struct dentry *dentry, struct iattr *attr)
 	ret = call_int_hook(inode_setattr, 0, dentry, attr);
 	if (ret)
 		return ret;
-	return evm_inode_setattr(dentry, attr);
+	return evm_inode_setattr(mnt_userns, dentry, attr);
 }
 EXPORT_SYMBOL_GPL(security_inode_setattr);