[PATCH v2 20/30] ecryptfs: implement get acl method

[PATCH v2 20/30] ecryptfs: 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 ecryptfs didn't implement get and set acl inode operations
because it wanted easy 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 ecryptfs
implement get and set acl inode operations.

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/ecryptfs/inode.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 16d50dface59..740312986388 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -18,6 +18,8 @@
 #include <linux/fs_stack.h>
 #include <linux/slab.h>
 #include <linux/xattr.h>
+#include <linux/posix_acl.h>
+#include <linux/posix_acl_xattr.h>
 #include <linux/fileattr.h>
 #include <asm/unaligned.h>
 #include "ecryptfs_kernel.h"
@@ -1120,6 +1122,13 @@ static int ecryptfs_fileattr_set(struct user_namespace *mnt_userns,
 	return rc;
 }
 
+static struct posix_acl *ecryptfs_get_acl(struct user_namespace *mnt_userns,
+					  struct dentry *dentry, int type)
+{
+	return vfs_get_acl(mnt_userns, ecryptfs_dentry_to_lower(dentry),
+			   posix_acl_xattr_name(type));
+}
+
 const struct inode_operations ecryptfs_symlink_iops = {
 	.get_link = ecryptfs_get_link,
 	.permission = ecryptfs_permission,
@@ -1143,6 +1152,7 @@ const struct inode_operations ecryptfs_dir_iops = {
 	.listxattr = ecryptfs_listxattr,
 	.fileattr_get = ecryptfs_fileattr_get,
 	.fileattr_set = ecryptfs_fileattr_set,
+	.get_acl = ecryptfs_get_acl,
 };
 
 const struct inode_operations ecryptfs_main_iops = {
@@ -1152,6 +1162,7 @@ const struct inode_operations ecryptfs_main_iops = {
 	.listxattr = ecryptfs_listxattr,
 	.fileattr_get = ecryptfs_fileattr_get,
 	.fileattr_set = ecryptfs_fileattr_set,
+	.get_acl = ecryptfs_get_acl,
 };
 
 static int ecryptfs_xattr_get(const struct xattr_handler *handler,
-- 
2.34.1

[PATCH v2 21/30] ecryptfs: 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 ecryptfs didn't implement get and set acl inode operations
because it wanted easy 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 ecryptfs
implement get and set acl inode operations.

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/ecryptfs/inode.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 740312986388..c3d1ae688a19 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -1129,6 +1129,21 @@ static struct posix_acl *ecryptfs_get_acl(struct user_namespace *mnt_userns,
 			   posix_acl_xattr_name(type));
 }
 
+static int ecryptfs_set_acl(struct user_namespace *mnt_userns,
+			    struct dentry *dentry, struct posix_acl *acl,
+			    int type)
+{
+	int rc;
+	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	struct inode *lower_inode = d_inode(lower_dentry);
+
+	rc = vfs_set_acl(&init_user_ns, lower_dentry,
+			 posix_acl_xattr_name(type), acl);
+	if (!rc)
+		fsstack_copy_attr_all(d_inode(dentry), lower_inode);
+	return rc;
+}
+
 const struct inode_operations ecryptfs_symlink_iops = {
 	.get_link = ecryptfs_get_link,
 	.permission = ecryptfs_permission,
@@ -1153,6 +1168,7 @@ const struct inode_operations ecryptfs_dir_iops = {
 	.fileattr_get = ecryptfs_fileattr_get,
 	.fileattr_set = ecryptfs_fileattr_set,
 	.get_acl = ecryptfs_get_acl,
+	.set_acl = ecryptfs_set_acl,
 };
 
 const struct inode_operations ecryptfs_main_iops = {
@@ -1163,6 +1179,7 @@ const struct inode_operations ecryptfs_main_iops = {
 	.fileattr_get = ecryptfs_fileattr_get,
 	.fileattr_set = ecryptfs_fileattr_set,
 	.get_acl = ecryptfs_get_acl,
+	.set_acl = ecryptfs_set_acl,
 };
 
 static int ecryptfs_xattr_get(const struct xattr_handler *handler,
-- 
2.34.1

[PATCH v2 26/30] ecryptfs: use stub posix acl handlers

[Christian Brauner]

Now that ecryptfs supports the get and set acl inode operations and the
vfs has been switched to the new posi api, ecryptfs can simply rely on
the stub posix acl handlers.

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

Notes:
    /* v2 */
    unchanged

 fs/ecryptfs/inode.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index c3d1ae688a19..bd6ae2582cd6 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -1210,6 +1210,10 @@ static const struct xattr_handler ecryptfs_xattr_handler = {
 };
 
 const struct xattr_handler *ecryptfs_xattr_handlers[] = {
+#ifdef CONFIG_XFS_POSIX_ACL
+	&posix_acl_access_xattr_handler,
+	&posix_acl_default_xattr_handler,
+#endif
 	&ecryptfs_xattr_handler,
 	NULL
 };
-- 
2.34.1