commit 9d80678fd2ad97e6899b98e3282400c93c86c67e
author Daniel Rosenberg <drosen@google.com> Wed Oct 26 16:27:45 2016 -0700
committer Amit Pundir <amit.pundir@linaro.org> Tue Aug 28 17:10:42 2018 +0530
tree 839ba0899e20fe8ec6062bd2b77acece7f5cc479
parent 45c410859e3dde9052bd203a717be46c11504331

RFC: ANDROID: vfs: Add permission2 for filesystems with per mount permissions

This allows filesystems to use their mount private data to
influence the permssions they return in permission2. It has
been separated into a new call to avoid disrupting current
permission users.

Change-Id: I9d416e3b8b6eca84ef3e336bd2af89ddd51df6ca
Signed-off-by: Daniel Rosenberg <drosen@google.com>

[AmitP: Minor refactoring of original patch to align with
        changes from the following upstream commit
        4bfd054ae11e ("fs: fold __inode_permission() into inode_permission()").

        Also introduce vfs_mkobj2(), because do_create()
        moved from using vfs_create() to vfs_mkobj()
        eecec19d9e70 ("mqueue: switch to vfs_mkobj(), quit abusing ->d_fsdata")

        do_create() is dropped/cleaned up upstream so a
        minor refactoring there as well.
        066cc813e94a ("do_mq_open(): move all work prior to dentry_open() into a helper")]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>

fs/open.c

diff --git a/fs/open.c b/fs/open.c
index a642ec1..f862e1c 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -73,9 +73,11 @@
 long vfs_truncate(const struct path *path, loff_t length)
 {
 	struct inode *inode;
+	struct vfsmount *mnt;
 	long error;
 
 	inode = path->dentry->d_inode;
+	mnt = path->mnt;
 
 	/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
 	if (S_ISDIR(inode->i_mode))
@@ -87,7 +89,7 @@
 	if (error)
 		goto out;
 
-	error = inode_permission(inode, MAY_WRITE);
+	error = inode_permission2(mnt, inode, MAY_WRITE);
 	if (error)
 		goto mnt_drop_write_and_out;
 
@@ -357,6 +359,7 @@
 	struct cred *override_cred;
 	struct path path;
 	struct inode *inode;
+	struct vfsmount *mnt;
 	int res;
 	unsigned int lookup_flags = LOOKUP_FOLLOW;
 
@@ -387,6 +390,7 @@
 		goto out;
 
 	inode = d_backing_inode(path.dentry);
+	mnt = path.mnt;
 
 	if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
 		/*
@@ -398,7 +402,7 @@
 			goto out_path_release;
 	}
 
-	res = inode_permission(inode, mode | MAY_ACCESS);
+	res = inode_permission2(mnt, inode, mode | MAY_ACCESS);
 	/* SuS v2 requires we report a read only fs too */
 	if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
 		goto out_path_release;
@@ -447,7 +451,7 @@
 	if (error)
 		goto out;
 
-	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
+	error = inode_permission2(path.mnt, path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
 	if (error)
 		goto dput_and_out;
 
@@ -481,7 +485,8 @@
 	if (!d_can_lookup(f.file->f_path.dentry))
 		goto out_putf;
 
-	error = inode_permission(file_inode(f.file), MAY_EXEC | MAY_CHDIR);
+	error = inode_permission2(f.file->f_path.mnt, file_inode(f.file),
+				MAY_EXEC | MAY_CHDIR);
 	if (!error)
 		set_fs_pwd(current->fs, &f.file->f_path);
 out_putf:
@@ -500,7 +505,7 @@
 	if (error)
 		goto out;
 
-	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
+	error = inode_permission2(path.mnt, path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
 	if (error)
 		goto dput_and_out;