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Commit 2af482a7 authored by Dave Hansen's avatar Dave Hansen Committed by Al Viro
Browse files

[PATCH] r/o bind mounts: elevate write count for chmod/chown callers 



chown/chmod,etc...  don't call permission in the same way that the normal
"open for write" calls do.  They still write to the filesystem, so bump the
write count during these operations.

Acked-by: default avatarAl Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarDave Hansen <haveblue@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 4a3fd211

fs/open.c

+30 −9
Original line number Diff line number Diff line
@@ -567,12 +567,12 @@ asmlinkage long sys_fchmod(unsigned int fd, mode_t mode) 


	audit_inode(NULL, dentry);



	err = -EROFS;

	if (IS_RDONLY(inode))

	err = mnt_want_write(file->f_path.mnt);

	if (err)

		goto out_putf;

	err = -EPERM;

	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))

		goto out_putf;

		goto out_drop_write;

	mutex_lock(&inode->i_mutex);

	if (mode == (mode_t) -1)

		mode = inode->i_mode;
@@ -581,6 +581,8 @@ asmlinkage long sys_fchmod(unsigned int fd, mode_t mode) 
	err = notify_change(dentry, &newattrs);

	mutex_unlock(&inode->i_mutex);



out_drop_write:

	mnt_drop_write(file->f_path.mnt);

out_putf:

	fput(file);

out:
@@ -600,13 +602,13 @@ asmlinkage long sys_fchmodat(int dfd, const char __user *filename, 
		goto out;

	inode = nd.path.dentry->d_inode;



	error = -EROFS;

	if (IS_RDONLY(inode))

	error = mnt_want_write(nd.path.mnt);

	if (error)

		goto dput_and_out;



	error = -EPERM;

	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))

		goto dput_and_out;

		goto out_drop_write;



	mutex_lock(&inode->i_mutex);

	if (mode == (mode_t) -1)
@@ -616,6 +618,8 @@ asmlinkage long sys_fchmodat(int dfd, const char __user *filename, 
	error = notify_change(nd.path.dentry, &newattrs);

	mutex_unlock(&inode->i_mutex);



out_drop_write:

	mnt_drop_write(nd.path.mnt);

dput_and_out:

	path_put(&nd.path);

out:
@@ -638,9 +642,6 @@ static int chown_common(struct dentry * dentry, uid_t user, gid_t group) 
		printk(KERN_ERR "chown_common: NULL inode\n");

		goto out;

	}

	error = -EROFS;

	if (IS_RDONLY(inode))

		goto out;

	error = -EPERM;

	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))

		goto out;
@@ -671,7 +672,12 @@ asmlinkage long sys_chown(const char __user * filename, uid_t user, gid_t group) 
	error = user_path_walk(filename, &nd);

	if (error)

		goto out;

	error = mnt_want_write(nd.path.mnt);

	if (error)

		goto out_release;

	error = chown_common(nd.path.dentry, user, group);

	mnt_drop_write(nd.path.mnt);

out_release:

	path_put(&nd.path);

out:

	return error;
@@ -691,7 +697,12 @@ asmlinkage long sys_fchownat(int dfd, const char __user *filename, uid_t user, 
	error = __user_walk_fd(dfd, filename, follow, &nd);

	if (error)

		goto out;

	error = mnt_want_write(nd.path.mnt);

	if (error)

		goto out_release;

	error = chown_common(nd.path.dentry, user, group);

	mnt_drop_write(nd.path.mnt);

out_release:

	path_put(&nd.path);

out:

	return error;
@@ -705,7 +716,12 @@ asmlinkage long sys_lchown(const char __user * filename, uid_t user, gid_t group 
	error = user_path_walk_link(filename, &nd);

	if (error)

		goto out;

	error = mnt_want_write(nd.path.mnt);

	if (error)

		goto out_release;

	error = chown_common(nd.path.dentry, user, group);

	mnt_drop_write(nd.path.mnt);

out_release:

	path_put(&nd.path);

out:

	return error;
@@ -722,9 +738,14 @@ asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group) 
	if (!file)

		goto out;



	error = mnt_want_write(file->f_path.mnt);

	if (error)

		goto out_fput;

	dentry = file->f_path.dentry;

	audit_inode(NULL, dentry);

	error = chown_common(dentry, user, group);

	mnt_drop_write(file->f_path.mnt);

out_fput:

	fput(file);

out:

	return error;