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Commit e9f57ebc authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs 

Pull overlayfs updates from Miklos Szeredi:
 "This contains several bug fixes and a new mount option
  'default_permissions' that allows read-only exported NFS
  filesystems to be used as lower layer"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: check dentry positiveness in ovl_cleanup_whiteouts()
  ovl: setattr: check permissions before copy-up
  ovl: root: copy attr
  ovl: move super block magic number to magic.h
  ovl: use a minimal buffer in ovl_copy_xattr
  ovl: allow zero size xattr
  ovl: default permissions
parents 5c89e9ea 84889d49

fs/overlayfs/copy_up.c

+26 −15
Original line number Diff line number Diff line
@@ -22,9 +22,9 @@ 


int ovl_copy_xattr(struct dentry *old, struct dentry *new)

{

	ssize_t list_size, size;

	char *buf, *name, *value;

	int error;

	ssize_t list_size, size, value_size = 0;

	char *buf, *name, *value = NULL;

	int uninitialized_var(error);



	if (!old->d_inode->i_op->getxattr ||

	    !new->d_inode->i_op->getxattr)
@@ -41,29 +41,40 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new) 
	if (!buf)

		return -ENOMEM;



	error = -ENOMEM;

	value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL);

	if (!value)

		goto out;



	list_size = vfs_listxattr(old, buf, list_size);

	if (list_size <= 0) {

		error = list_size;

		goto out_free_value;

		goto out;

	}



	for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {

		size = vfs_getxattr(old, name, value, XATTR_SIZE_MAX);

		if (size <= 0) {

retry:

		size = vfs_getxattr(old, name, value, value_size);

		if (size == -ERANGE)

			size = vfs_getxattr(old, name, NULL, 0);



		if (size < 0) {

			error = size;

			goto out_free_value;

			break;

		}



		if (size > value_size) {

			void *new;



			new = krealloc(value, size, GFP_KERNEL);

			if (!new) {

				error = -ENOMEM;

				break;

			}

			value = new;

			value_size = size;

			goto retry;

		}



		error = vfs_setxattr(new, name, value, size, 0);

		if (error)

			goto out_free_value;

			break;

	}



out_free_value:

	kfree(value);

out:

	kfree(buf);

fs/overlayfs/inode.c

+36 −0
Original line number Diff line number Diff line
@@ -42,6 +42,19 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr) 
	int err;

	struct dentry *upperdentry;



	/*

	 * Check for permissions before trying to copy-up.  This is redundant

	 * since it will be rechecked later by ->setattr() on upper dentry.  But

	 * without this, copy-up can be triggered by just about anybody.

	 *

	 * We don't initialize inode->size, which just means that

	 * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not

	 * check for a swapfile (which this won't be anyway).

	 */

	err = inode_change_ok(dentry->d_inode, attr);

	if (err)

		return err;



	err = ovl_want_write(dentry);

	if (err)

		goto out;
@@ -95,6 +108,29 @@ int ovl_permission(struct inode *inode, int mask) 


	realdentry = ovl_entry_real(oe, &is_upper);



	if (ovl_is_default_permissions(inode)) {

		struct kstat stat;

		struct path realpath = { .dentry = realdentry };



		if (mask & MAY_NOT_BLOCK)

			return -ECHILD;



		realpath.mnt = ovl_entry_mnt_real(oe, inode, is_upper);



		err = vfs_getattr(&realpath, &stat);

		if (err)

			return err;



		if ((stat.mode ^ inode->i_mode) & S_IFMT)

			return -ESTALE;



		inode->i_mode = stat.mode;

		inode->i_uid = stat.uid;

		inode->i_gid = stat.gid;



		return generic_permission(inode, mask);

	}



	/* Careful in RCU walk mode */

	realinode = ACCESS_ONCE(realdentry->d_inode);

	if (!realinode) {

fs/overlayfs/overlayfs.h

+3 −0
Original line number Diff line number Diff line
@@ -142,7 +142,10 @@ struct dentry *ovl_dentry_upper(struct dentry *dentry); 
struct dentry *ovl_dentry_lower(struct dentry *dentry);

struct dentry *ovl_dentry_real(struct dentry *dentry);

struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper);

struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode,

				    bool is_upper);

struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry);

bool ovl_is_default_permissions(struct inode *inode);

void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache);

struct dentry *ovl_workdir(struct dentry *dentry);

int ovl_want_write(struct dentry *dentry);

fs/overlayfs/readdir.c

+2 −1
Original line number Diff line number Diff line
@@ -571,6 +571,7 @@ void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list) 
			       (int) PTR_ERR(dentry));

			continue;

		}

		if (dentry->d_inode)

			ovl_cleanup(upper->d_inode, dentry);

		dput(dentry);

	}

fs/overlayfs/super.c

+33 −2
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 


#include <linux/fs.h>

#include <linux/namei.h>

#include <linux/pagemap.h>

#include <linux/xattr.h>

#include <linux/security.h>

#include <linux/mount.h>
@@ -24,12 +25,11 @@ MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); 
MODULE_DESCRIPTION("Overlay filesystem");

MODULE_LICENSE("GPL");



#define OVERLAYFS_SUPER_MAGIC 0x794c7630



struct ovl_config {

	char *lowerdir;

	char *upperdir;

	char *workdir;

	bool default_permissions;

};



/* private information held for overlayfs's superblock */
@@ -154,6 +154,18 @@ struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper) 
	return realdentry;

}



struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode,

				    bool is_upper)

{

	if (is_upper) {

		struct ovl_fs *ofs = inode->i_sb->s_fs_info;



		return ofs->upper_mnt;

	} else {

		return oe->numlower ? oe->lowerstack[0].mnt : NULL;

	}

}



struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)

{

	struct ovl_entry *oe = dentry->d_fsdata;
@@ -161,6 +173,13 @@ struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry) 
	return oe->cache;

}



bool ovl_is_default_permissions(struct inode *inode)

{

	struct ovl_fs *ofs = inode->i_sb->s_fs_info;



	return ofs->config.default_permissions;

}



void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)

{

	struct ovl_entry *oe = dentry->d_fsdata;
@@ -594,6 +613,8 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) 
		seq_show_option(m, "upperdir", ufs->config.upperdir);

		seq_show_option(m, "workdir", ufs->config.workdir);

	}

	if (ufs->config.default_permissions)

		seq_puts(m, ",default_permissions");

	return 0;

}
@@ -618,6 +639,7 @@ enum { 
	OPT_LOWERDIR,

	OPT_UPPERDIR,

	OPT_WORKDIR,

	OPT_DEFAULT_PERMISSIONS,

	OPT_ERR,

};
@@ -625,6 +647,7 @@ static const match_table_t ovl_tokens = { 
	{OPT_LOWERDIR,			"lowerdir=%s"},

	{OPT_UPPERDIR,			"upperdir=%s"},

	{OPT_WORKDIR,			"workdir=%s"},

	{OPT_DEFAULT_PERMISSIONS,	"default_permissions"},

	{OPT_ERR,			NULL}

};
@@ -685,6 +708,10 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) 
				return -ENOMEM;

			break;



		case OPT_DEFAULT_PERMISSIONS:

			config->default_permissions = true;

			break;



		default:

			pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);

			return -EINVAL;
@@ -910,6 +937,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 
	}



	sb->s_stack_depth = 0;

	sb->s_maxbytes = MAX_LFS_FILESIZE;

	if (ufs->config.upperdir) {

		if (!ufs->config.workdir) {

			pr_err("overlayfs: missing 'workdir'\n");
@@ -1053,6 +1081,9 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 


	root_dentry->d_fsdata = oe;



	ovl_copyattr(ovl_dentry_real(root_dentry)->d_inode,

		     root_dentry->d_inode);



	sb->s_magic = OVERLAYFS_SUPER_MAGIC;

	sb->s_op = &ovl_super_operations;

	sb->s_root = root_dentry;