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Commit c3367a1b authored by Steven J. Magnani's avatar Steven J. Magnani Committed by Jan Kara
Browse files

udf: augment UDF permissions on new inodes 



Windows presents files created within Linux as read-only, even when
permissions in Linux indicate the file should be writable.

UDF defines a slightly different set of basic file permissions than Linux.
Specifically, UDF has "delete" and "change attribute" permissions for each
access class (user/group/other). Linux has no equivalents for these.

When the Linux UDF driver creates a file (or directory), no UDF delete or
change attribute permissions are granted. The lack of delete permission
appears to cause Windows to mark an item read-only when its permissions
otherwise indicate that it should be read-write.

Fix this by having UDF delete permissions track Linux write permissions.
Also grant UDF change attribute permission to the owner when creating a
new inode.

Reported by: Ty Young
Signed-off-by: default avatarSteven J. Magnani <steve@digidescorp.com>
Link: https://lore.kernel.org/r/20190827121359.9954-1-steve@digidescorp.com


Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 8cbd9af9

fs/udf/file.c

+3 −0
Original line number Diff line number Diff line
@@ -280,6 +280,9 @@ static int udf_setattr(struct dentry *dentry, struct iattr *attr) 
			return error;

	}



	if (attr->ia_valid & ATTR_MODE)

		udf_update_extra_perms(inode, attr->ia_mode);



	setattr_copy(inode, attr);

	mark_inode_dirty(inode);

	return 0;

fs/udf/ialloc.c

+3 −0
Original line number Diff line number Diff line
@@ -118,6 +118,9 @@ struct inode *udf_new_inode(struct inode *dir, umode_t mode) 
	iinfo->i_lenAlloc = 0;

	iinfo->i_use = 0;

	iinfo->i_checkpoint = 1;

	iinfo->i_extraPerms = FE_PERM_U_CHATTR;

	udf_update_extra_perms(inode, mode);



	if (UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_USE_AD_IN_ICB))

		iinfo->i_alloc_type = ICBTAG_FLAG_AD_IN_ICB;

	else if (UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_USE_SHORT_AD))

fs/udf/inode.c

+27 −4
Original line number Diff line number Diff line
@@ -45,6 +45,13 @@ 


#define EXTENT_MERGE_SIZE 5



#define FE_MAPPED_PERMS	(FE_PERM_U_READ | FE_PERM_U_WRITE | FE_PERM_U_EXEC | \

			 FE_PERM_G_READ | FE_PERM_G_WRITE | FE_PERM_G_EXEC | \

			 FE_PERM_O_READ | FE_PERM_O_WRITE | FE_PERM_O_EXEC)



#define FE_DELETE_PERMS	(FE_PERM_U_DELETE | FE_PERM_G_DELETE | \

			 FE_PERM_O_DELETE)



static umode_t udf_convert_permissions(struct fileEntry *);

static int udf_update_inode(struct inode *, int);

static int udf_sync_inode(struct inode *inode);
@@ -1458,6 +1465,8 @@ static int udf_read_inode(struct inode *inode, bool hidden_inode) 
	else

		inode->i_mode = udf_convert_permissions(fe);

	inode->i_mode &= ~sbi->s_umask;

	iinfo->i_extraPerms = le32_to_cpu(fe->permissions) & ~FE_MAPPED_PERMS;



	read_unlock(&sbi->s_cred_lock);



	link_count = le16_to_cpu(fe->fileLinkCount);
@@ -1631,6 +1640,23 @@ static umode_t udf_convert_permissions(struct fileEntry *fe) 
	return mode;

}



void udf_update_extra_perms(struct inode *inode, umode_t mode)

{

	struct udf_inode_info *iinfo = UDF_I(inode);



	/*

	 * UDF 2.01 sec. 3.3.3.3 Note 2:

	 * In Unix, delete permission tracks write

	 */

	iinfo->i_extraPerms &= ~FE_DELETE_PERMS;

	if (mode & 0200)

		iinfo->i_extraPerms |= FE_PERM_U_DELETE;

	if (mode & 0020)

		iinfo->i_extraPerms |= FE_PERM_G_DELETE;

	if (mode & 0002)

		iinfo->i_extraPerms |= FE_PERM_O_DELETE;

}



int udf_write_inode(struct inode *inode, struct writeback_control *wbc)

{

	return udf_update_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
@@ -1703,10 +1729,7 @@ static int udf_update_inode(struct inode *inode, int do_sync) 
		   ((inode->i_mode & 0070) << 2) |

		   ((inode->i_mode & 0700) << 4);



	udfperms |= (le32_to_cpu(fe->permissions) &

		    (FE_PERM_O_DELETE | FE_PERM_O_CHATTR |

		     FE_PERM_G_DELETE | FE_PERM_G_CHATTR |

		     FE_PERM_U_DELETE | FE_PERM_U_CHATTR));

	udfperms |= iinfo->i_extraPerms;

	fe->permissions = cpu_to_le32(udfperms);



	if (S_ISDIR(inode->i_mode) && inode->i_nlink > 0)

fs/udf/udf_i.h

+1 −0
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ struct udf_inode_info { 
	__u32			i_next_alloc_block;

	__u32			i_next_alloc_goal;

	__u32			i_checkpoint;

	__u32			i_extraPerms;

	unsigned		i_alloc_type : 3;

	unsigned		i_efe : 1;	/* extendedFileEntry */

	unsigned		i_use : 1;	/* unallocSpaceEntry */

fs/udf/udfdecl.h

+1 −0
Original line number Diff line number Diff line
@@ -170,6 +170,7 @@ extern int8_t udf_next_aext(struct inode *, struct extent_position *, 
			    struct kernel_lb_addr *, uint32_t *, int);

extern int8_t udf_current_aext(struct inode *, struct extent_position *,

			       struct kernel_lb_addr *, uint32_t *, int);

extern void udf_update_extra_perms(struct inode *inode, umode_t mode);



/* misc.c */

extern struct buffer_head *udf_tgetblk(struct super_block *sb,