Commit 5d6b501f authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'ovl-fixes-5.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs 

Pull overlayfs fixes from Miklos Szeredi:
 "Here's one fix for a class of bugs triggered by syzcaller, and one
  that makes xfstests fail less"

* tag 'ovl-fixes-5.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: doc: add non-standard corner cases
  ovl: detect overlapping layers
  ovl: support the FS_IOC_FS[SG]ETXATTR ioctls
parents 21175857 5d3211b6

Documentation/filesystems/overlayfs.txt

+14 −2
Original line number Diff line number Diff line
@@ -336,8 +336,20 @@ the copied layers will fail the verification of the lower root file handle. 
Non-standard behavior

---------------------



Overlayfs can now act as a POSIX compliant filesystem with the following

features turned on:

Current version of overlayfs can act as a mostly POSIX compliant

filesystem.



This is the list of cases that overlayfs doesn't currently handle:



a) POSIX mandates updating st_atime for reads.  This is currently not

done in the case when the file resides on a lower layer.



b) If a file residing on a lower layer is opened for read-only and then

memory mapped with MAP_SHARED, then subsequent changes to the file are not

reflected in the memory mapping.



The following options allow overlayfs to act more like a standards

compliant filesystem:



1) "redirect_dir"

fs/overlayfs/file.c

+6 −3
Original line number Diff line number Diff line
@@ -426,7 +426,8 @@ static unsigned int ovl_get_inode_flags(struct inode *inode) 
	return ovl_iflags;

}



static long ovl_ioctl_set_flags(struct file *file, unsigned long arg)

static long ovl_ioctl_set_flags(struct file *file, unsigned int cmd,

				unsigned long arg)

{

	long ret;

	struct inode *inode = file_inode(file);
@@ -456,7 +457,7 @@ static long ovl_ioctl_set_flags(struct file *file, unsigned long arg) 
	if (ret)

		goto unlock;



	ret = ovl_real_ioctl(file, FS_IOC_SETFLAGS, arg);

	ret = ovl_real_ioctl(file, cmd, arg);



	ovl_copyflags(ovl_inode_real(inode), inode);

unlock:
@@ -474,11 +475,13 @@ static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 


	switch (cmd) {

	case FS_IOC_GETFLAGS:

	case FS_IOC_FSGETXATTR:

		ret = ovl_real_ioctl(file, cmd, arg);

		break;



	case FS_IOC_SETFLAGS:

		ret = ovl_ioctl_set_flags(file, arg);

	case FS_IOC_FSSETXATTR:

		ret = ovl_ioctl_set_flags(file, cmd, arg);

		break;



	default:

fs/overlayfs/inode.c

+48 −0
Original line number Diff line number Diff line
@@ -777,6 +777,54 @@ struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real, 
	return inode;

}



bool ovl_lookup_trap_inode(struct super_block *sb, struct dentry *dir)

{

	struct inode *key = d_inode(dir);

	struct inode *trap;

	bool res;



	trap = ilookup5(sb, (unsigned long) key, ovl_inode_test, key);

	if (!trap)

		return false;



	res = IS_DEADDIR(trap) && !ovl_inode_upper(trap) &&

				  !ovl_inode_lower(trap);



	iput(trap);

	return res;

}



/*

 * Create an inode cache entry for layer root dir, that will intentionally

 * fail ovl_verify_inode(), so any lookup that will find some layer root

 * will fail.

 */

struct inode *ovl_get_trap_inode(struct super_block *sb, struct dentry *dir)

{

	struct inode *key = d_inode(dir);

	struct inode *trap;



	if (!d_is_dir(dir))

		return ERR_PTR(-ENOTDIR);



	trap = iget5_locked(sb, (unsigned long) key, ovl_inode_test,

			    ovl_inode_set, key);

	if (!trap)

		return ERR_PTR(-ENOMEM);



	if (!(trap->i_state & I_NEW)) {

		/* Conflicting layer roots? */

		iput(trap);

		return ERR_PTR(-ELOOP);

	}



	trap->i_mode = S_IFDIR;

	trap->i_flags = S_DEAD;

	unlock_new_inode(trap);



	return trap;

}



/*

 * Does overlay inode need to be hashed by lower inode?

 */

fs/overlayfs/namei.c

+8 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include "overlayfs.h"



struct ovl_lookup_data {

	struct super_block *sb;

	struct qstr name;

	bool is_dir;

	bool opaque;
@@ -244,6 +245,12 @@ static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d, 
		if (!d->metacopy || d->last)

			goto out;

	} else {

		if (ovl_lookup_trap_inode(d->sb, this)) {

			/* Caught in a trap of overlapping layers */

			err = -ELOOP;

			goto out_err;

		}



		if (last_element)

			d->is_dir = true;

		if (d->last)
@@ -819,6 +826,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
	int err;

	bool metacopy = false;

	struct ovl_lookup_data d = {

		.sb = dentry->d_sb,

		.name = dentry->d_name,

		.is_dir = false,

		.opaque = false,

fs/overlayfs/overlayfs.h

+3 −0
Original line number Diff line number Diff line
@@ -270,6 +270,7 @@ void ovl_clear_flag(unsigned long flag, struct inode *inode); 
bool ovl_test_flag(unsigned long flag, struct inode *inode);

bool ovl_inuse_trylock(struct dentry *dentry);

void ovl_inuse_unlock(struct dentry *dentry);

bool ovl_is_inuse(struct dentry *dentry);

bool ovl_need_index(struct dentry *dentry);

int ovl_nlink_start(struct dentry *dentry);

void ovl_nlink_end(struct dentry *dentry);
@@ -376,6 +377,8 @@ struct ovl_inode_params { 
struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev);

struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,

			       bool is_upper);

bool ovl_lookup_trap_inode(struct super_block *sb, struct dentry *dir);

struct inode *ovl_get_trap_inode(struct super_block *sb, struct dentry *dir);

struct inode *ovl_get_inode(struct super_block *sb,

			    struct ovl_inode_params *oip);

static inline void ovl_copyattr(struct inode *from, struct inode *to)

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