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Commit 9183482f authored by OGAWA Hirofumi's avatar OGAWA Hirofumi Committed by Linus Torvalds
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fat: Fix ATTR_RO in the case of (~umask & S_WUGO) == 0 



If inode->i_mode doesn't have S_WUGO, current code assumes it means
ATTR_RO.  However, if (~[ufd]mask & S_WUGO) == 0, inode->i_mode can't
hold S_WUGO. Therefore the updated directory entry will always have
ATTR_RO.

This adds fat_mode_can_hold_ro() to check it. And if inode->i_mode
can't hold, uses -i_attrs to hold ATTR_RO instead.

With this, we don't set ATTR_RO unless users change it via ioctl() if
(~[ufd]mask & S_WUGO) == 0.

And on FAT_IOCTL_GET_ATTRIBUTES path, this adds ->i_mutex to it for
not returning the partially updated attributes by FAT_IOCTL_SET_ATTRIBUTES
to userland.

Signed-off-by: default avatarOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9c0aa1b8

fs/fat/fat.h

+29 −4
Original line number Diff line number Diff line
@@ -117,6 +117,25 @@ static inline struct msdos_inode_info *MSDOS_I(struct inode *inode) 
	return container_of(inode, struct msdos_inode_info, vfs_inode);

}



/*

 * If ->i_mode can't hold S_IWUGO (i.e. ATTR_RO), we use ->i_attrs to

 * save ATTR_RO instead of ->i_mode.

 */

static inline int fat_mode_can_hold_ro(struct inode *inode)

{

	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);

	mode_t mask;



	if (S_ISDIR(inode->i_mode))

		mask = ~sbi->options.fs_dmask;

	else

		mask = ~sbi->options.fs_fmask;



	if (!(mask & S_IWUGO))

		return 0;

	return 1;

}



/* Convert attribute bits and a mask to the UNIX mode. */

static inline mode_t fat_make_mode(struct msdos_sb_info *sbi,

				   u8 attrs, mode_t mode)
@@ -133,14 +152,20 @@ static inline mode_t fat_make_mode(struct msdos_sb_info *sbi, 
/* Return the FAT attribute byte for this inode */

static inline u8 fat_make_attrs(struct inode *inode)

{

	return ((inode->i_mode & S_IWUGO) ? ATTR_NONE : ATTR_RO) |

		(S_ISDIR(inode->i_mode) ? ATTR_DIR : ATTR_NONE) |

		MSDOS_I(inode)->i_attrs;

	u8 attrs = MSDOS_I(inode)->i_attrs;

	if (S_ISDIR(inode->i_mode))

		attrs |= ATTR_DIR;

	if (fat_mode_can_hold_ro(inode) && !(inode->i_mode & S_IWUGO))

		attrs |= ATTR_RO;

	return attrs;

}



static inline void fat_save_attrs(struct inode *inode, u8 attrs)

{

	if (fat_mode_can_hold_ro(inode))

		MSDOS_I(inode)->i_attrs = attrs & ATTR_UNUSED;

	else

		MSDOS_I(inode)->i_attrs = attrs & (ATTR_UNUSED | ATTR_RO);

}



static inline unsigned char fat_checksum(const __u8 *name)

fs/fat/file.c

+6 −1
Original line number Diff line number Diff line
@@ -27,7 +27,12 @@ int fat_generic_ioctl(struct inode *inode, struct file *filp, 
	switch (cmd) {

	case FAT_IOCTL_GET_ATTRIBUTES:

	{

		u32 attr = fat_make_attrs(inode);

		u32 attr;



		mutex_lock(&inode->i_mutex);

		attr = fat_make_attrs(inode);

		mutex_unlock(&inode->i_mutex);



		return put_user(attr, user_attr);

	}

	case FAT_IOCTL_SET_ATTRIBUTES: