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Date: Tue, 27 Aug 2019 07:13:59 -0500
From: "Steven J. Magnani" <steve.magnani@...idescorp.com>
To: Jan Kara <jack@...e.com>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
"Steven J . Magnani" <steve@...idescorp.com>
Subject: [PATCH v2] 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: Steven J. Magnani <steve@...idescorp.com>
---
Changes since rev 1:
UDF delete permission tracks with Linux write permission instead
of being unconditionally granted to the owner at inode creation
--- a/fs/udf/udf_i.h 2019-08-14 07:24:05.029508342 -0500
+++ b/fs/udf/udf_i.h 2019-08-26 21:33:05.064410067 -0500
@@ -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 */
--- a/fs/udf/udfdecl.h 2019-08-26 21:38:12.138562583 -0500
+++ b/fs/udf/udfdecl.h 2019-08-26 21:09:19.465000110 -0500
@@ -178,6 +178,7 @@ extern int8_t udf_next_aext(struct inode
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,
--- a/fs/udf/ialloc.c 2019-08-14 07:24:05.029508342 -0500
+++ b/fs/udf/ialloc.c 2019-08-26 21:16:43.379449924 -0500
@@ -125,6 +125,9 @@ struct inode *udf_new_inode(struct inode
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))
--- a/fs/udf/inode.c 2019-08-14 07:24:05.029508342 -0500
+++ b/fs/udf/inode.c 2019-08-26 21:40:17.865649383 -0500
@@ -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 @@ reread:
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(s
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->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)
--- a/fs/udf/file.c 2019-08-26 21:38:12.138562583 -0500
+++ b/fs/udf/file.c 2019-08-26 21:12:44.664536308 -0500
@@ -280,6 +280,9 @@ static int udf_setattr(struct dentry *de
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;
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