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Message-ID: <20190827133908.GA10098@quack2.suse.cz>
Date: Tue, 27 Aug 2019 15:39:08 +0200
From: Jan Kara <jack@...e.cz>
To: " Steven J. Magnani " <steve.magnani@...idescorp.com>
Cc: Jan Kara <jack@...e.com>,
"Steven J . Magnani" <steve@...idescorp.com>,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] udf: augment UDF permissions on new inodes
On Tue 27-08-19 07:13:59, Steven J. Magnani wrote:
> 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>
Thanks for the patch! I've added it to my tree.
Honza
> ---
>
> 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;
>
--
Jan Kara <jack@...e.com>
SUSE Labs, CR
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