vfs: Add setattr2 for filesystems with per mount permissions

This allows filesystems to use their mount private data to
influence the permssions they use in setattr2. It has
been separated into a new call to avoid disrupting current
setattr users.

Change-Id: I19959038309284448f1b7f232d579674ef546385
Signed-off-by: Daniel Rosenberg <drosen@google.com>

fs/attr.c

@@ -167,7 +167,7 @@ void setattr_copy(struct inode *inode, const struct iattr *attr)
 }
 EXPORT_SYMBOL(setattr_copy);
 
-int notify_change(struct dentry * dentry, struct iattr * attr)
+int notify_change2(struct vfsmount *mnt, struct dentry * dentry, struct iattr * attr)
 {
 	struct inode *inode = dentry->d_inode;
 	umode_t mode = inode->i_mode;
@@ -239,7 +239,9 @@ int notify_change(struct dentry * dentry, struct iattr * attr)
 	if (error)
 		return error;
 
-	if (inode->i_op->setattr)
+	if (mnt && inode->i_op->setattr2)
+		error = inode->i_op->setattr2(mnt, dentry, attr);
+	else if (inode->i_op->setattr)
 		error = inode->i_op->setattr(dentry, attr);
 	else
 		error = simple_setattr(dentry, attr);
@@ -252,4 +254,10 @@ int notify_change(struct dentry * dentry, struct iattr * attr)
 
 	return error;
 }
+EXPORT_SYMBOL(notify_change2);
+
+int notify_change(struct dentry * dentry, struct iattr * attr)
+{
+	return notify_change2(NULL, dentry, attr);
+}
 EXPORT_SYMBOL(notify_change);

fs/coredump.c

@@ -670,7 +670,7 @@ void do_coredump(siginfo_t *siginfo)
 			goto close_fail;
 		if (!cprm.file->f_op || !cprm.file->f_op->write)
 			goto close_fail;
-		if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
+		if (do_truncate2(cprm.file->f_path.mnt, cprm.file->f_path.dentry, 0, 0, cprm.file))
 			goto close_fail;
 	}
 

fs/inode.c

@@ -1637,12 +1637,12 @@ int should_remove_suid(struct dentry *dentry)
 }
 EXPORT_SYMBOL(should_remove_suid);
 
-static int __remove_suid(struct dentry *dentry, int kill)
+static int __remove_suid(struct vfsmount *mnt, struct dentry *dentry, int kill)
 {
 	struct iattr newattrs;
 
 	newattrs.ia_valid = ATTR_FORCE | kill;
-	return notify_change(dentry, &newattrs);
+	return notify_change2(mnt, dentry, &newattrs);
 }
 
 int file_remove_suid(struct file *file)
@@ -1665,7 +1665,7 @@ int file_remove_suid(struct file *file)
 	if (killpriv)
 		error = security_inode_killpriv(dentry);
 	if (!error && killsuid)
-		error = __remove_suid(dentry, killsuid);
+		error = __remove_suid(file->f_path.mnt, dentry, killsuid);
 	if (!error)
 		inode_has_no_xattr(inode);
 

fs/open.c

@@ -34,8 +34,8 @@
 
 #include "internal.h"
 
-int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
-	struct file *filp)
+int do_truncate2(struct vfsmount *mnt, struct dentry *dentry, loff_t length,
+		unsigned int time_attrs, struct file *filp)
 {
 	int ret;
 	struct iattr newattrs;
@@ -57,10 +57,15 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
 		newattrs.ia_valid |= ret | ATTR_FORCE;
 
 	mutex_lock(&dentry->d_inode->i_mutex);
-	ret = notify_change(dentry, &newattrs);
+	ret = notify_change2(mnt, dentry, &newattrs);
 	mutex_unlock(&dentry->d_inode->i_mutex);
 	return ret;
 }
+int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
+	struct file *filp)
+{
+	return do_truncate2(NULL, dentry, length, time_attrs, filp);
+}
 
 long vfs_truncate(struct path *path, loff_t length)
 {
@@ -105,7 +110,7 @@ long vfs_truncate(struct path *path, loff_t length)
 	if (!error)
 		error = security_path_truncate(path);
 	if (!error)
-		error = do_truncate(path->dentry, length, 0, NULL);
+		error = do_truncate2(mnt, path->dentry, length, 0, NULL);
 
 put_write_and_out:
 	put_write_access(inode);
@@ -154,6 +159,7 @@ static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
 {
 	struct inode *inode;
 	struct dentry *dentry;
+	struct vfsmount *mnt;
 	struct fd f;
 	int error;
 
@@ -170,6 +176,7 @@ static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
 		small = 0;
 
 	dentry = f.file->f_path.dentry;
+	mnt = f.file->f_path.mnt;
 	inode = dentry->d_inode;
 	error = -EINVAL;
 	if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
@@ -189,7 +196,7 @@ static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
 	if (!error)
 		error = security_path_truncate(&f.file->f_path);
 	if (!error)
-		error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, f.file);
+		error = do_truncate2(mnt, dentry, length, ATTR_MTIME|ATTR_CTIME, f.file);
 	sb_end_write(inode->i_sb);
 out_putf:
 	fdput(f);
@@ -482,7 +489,7 @@ static int chmod_common(struct path *path, umode_t mode)
 		goto out_unlock;
 	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
-	error = notify_change(path->dentry, &newattrs);
+	error = notify_change2(path->mnt, path->dentry, &newattrs);
 out_unlock:
 	mutex_unlock(&inode->i_mutex);
 	mnt_drop_write(path->mnt);
@@ -556,7 +563,7 @@ static int chown_common(struct path *path, uid_t user, gid_t group)
 	mutex_lock(&inode->i_mutex);
 	error = security_path_chown(path, uid, gid);
 	if (!error)
-		error = notify_change(path->dentry, &newattrs);
+		error = notify_change2(path->mnt, path->dentry, &newattrs);
 	mutex_unlock(&inode->i_mutex);
 
 	return error;

fs/utimes.c

@@ -102,7 +102,7 @@ static int utimes_common(struct path *path, struct timespec *times)
 		}
 	}
 	mutex_lock(&inode->i_mutex);
-	error = notify_change(path->dentry, &newattrs);
+	error = notify_change2(path->mnt, path->dentry, &newattrs);
 	mutex_unlock(&inode->i_mutex);
 
 mnt_drop_write_and_out:

include/linux/fs.h

@@ -1609,6 +1609,7 @@ struct inode_operations {
 	int (*rename) (struct inode *, struct dentry *,
 			struct inode *, struct dentry *);
 	int (*setattr) (struct dentry *, struct iattr *);
+	int (*setattr2) (struct vfsmount *, struct dentry *, struct iattr *);
 	int (*getattr) (struct vfsmount *mnt, struct dentry *, struct kstat *);
 	int (*setxattr) (struct dentry *, const char *,const void *,size_t,int);
 	ssize_t (*getxattr) (struct dentry *, const char *, void *, size_t);
@@ -2053,6 +2054,8 @@ struct filename {
 extern long vfs_truncate(struct path *, loff_t);
 extern int do_truncate(struct dentry *, loff_t start, unsigned int time_attrs,
 		       struct file *filp);
+extern int do_truncate2(struct vfsmount *, struct dentry *, loff_t start,
+			unsigned int time_attrs, struct file *filp);
 extern int do_fallocate(struct file *file, int mode, loff_t offset,
 			loff_t len);
 extern long do_sys_open(int dfd, const char __user *filename, int flags,
@@ -2262,6 +2265,7 @@ extern int intr_sync(int *);
 extern sector_t bmap(struct inode *, sector_t);
 #endif
 extern int notify_change(struct dentry *, struct iattr *);
+extern int notify_change2(struct vfsmount *, struct dentry *, struct iattr *);
 extern int inode_permission(struct inode *, int);
 extern int inode_permission2(struct vfsmount *, struct inode *, int);
 extern int generic_permission(struct inode *, int);