On Sun, Aug 27, 2023 at 12:42:07PM +0200, Jan Cincera wrote:
> Add GET and SET attributes ioctls to enable attribute modification.
> We already do this in FAT and a few userspace utils made for it would
> benefit from this also working on exFAT, namely fatattr.
>
> Signed-off-by: Jan Cincera <hcincera@xxxxxxxxx>
> ---
> Changes in v2:
> - Removed irrelevant comments.
> - Now masking reserved fields.
>
> fs/exfat/exfat_fs.h | 6 +++
> fs/exfat/file.c | 93 +++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 99 insertions(+)
>
> diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
> index 729ada9e26e8..ebe8c4b928f4 100644
> --- a/fs/exfat/exfat_fs.h
> +++ b/fs/exfat/exfat_fs.h
> @@ -149,6 +149,12 @@ enum {
> #define DIR_CACHE_SIZE \
> (DIV_ROUND_UP(EXFAT_DEN_TO_B(ES_MAX_ENTRY_NUM), SECTOR_SIZE) + 1)
>
> +/*
> + * attribute ioctls, same as their FAT equivalents.
> + */
> +#define EXFAT_IOCTL_GET_ATTRIBUTES _IOR('r', 0x10, __u32)
> +#define EXFAT_IOCTL_SET_ATTRIBUTES _IOW('r', 0x11, __u32)
Can you reuse the definitions from include/uapi/linux/msdos_fs.h instead
of redefining them here?
Otherwise this looks like a mostly straight port of the fs/fat/
versions of these functions.
--D
> +
> struct exfat_dentry_namebuf {
> char *lfn;
> int lfnbuf_len; /* usually MAX_UNINAME_BUF_SIZE */
> diff --git a/fs/exfat/file.c b/fs/exfat/file.c
> index 3cbd270e0cba..b31ce0868ddd 100644
> --- a/fs/exfat/file.c
> +++ b/fs/exfat/file.c
> @@ -8,6 +8,8 @@
> #include <linux/cred.h>
> #include <linux/buffer_head.h>
> #include <linux/blkdev.h>
> +#include <linux/fsnotify.h>
> +#include <linux/security.h>
>
> #include "exfat_raw.h"
> #include "exfat_fs.h"
> @@ -316,6 +318,92 @@ int exfat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
> return error;
> }
>
> +/*
> + * modified ioctls from fat/file.c by Welmer Almesberger
> + */
> +static int exfat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
> +{
> + u32 attr;
> +
> + inode_lock_shared(inode);
> + attr = exfat_make_attr(inode);
> + inode_unlock_shared(inode);
> +
> + return put_user(attr, user_attr);
> +}
> +
> +static int exfat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
> +{
> + struct inode *inode = file_inode(file);
> + struct exfat_sb_info *sbi = EXFAT_SB(inode->i_sb);
> + int is_dir = S_ISDIR(inode->i_mode);
> + u32 attr, oldattr;
> + struct iattr ia;
> + int err;
> +
> + err = get_user(attr, user_attr);
> + if (err)
> + goto out;
> +
> + err = mnt_want_write_file(file);
> + if (err)
> + goto out;
> + inode_lock(inode);
> +
> + oldattr = exfat_make_attr(inode);
> +
> + /*
> + * Mask attributes so we don't set reserved fields.
> + */
> + attr &= (ATTR_READONLY | ATTR_HIDDEN | ATTR_SYSTEM | ATTR_ARCHIVE);
> + attr |= (is_dir ? ATTR_SUBDIR : 0);
> +
> + /* Equivalent to a chmod() */
> + ia.ia_valid = ATTR_MODE | ATTR_CTIME;
> + ia.ia_ctime = current_time(inode);
> + if (is_dir)
> + ia.ia_mode = exfat_make_mode(sbi, attr, 0777);
> + else
> + ia.ia_mode = exfat_make_mode(sbi, attr, 0666 | (inode->i_mode & 0111));
> +
> + /* The root directory has no attributes */
> + if (inode->i_ino == EXFAT_ROOT_INO && attr != ATTR_SUBDIR) {
> + err = -EINVAL;
> + goto out_unlock_inode;
> + }
> +
> + if (((attr | oldattr) & ATTR_SYSTEM) &&
> + !capable(CAP_LINUX_IMMUTABLE)) {
> + err = -EPERM;
> + goto out_unlock_inode;
> + }
> +
> + /*
> + * The security check is questionable... We single
> + * out the RO attribute for checking by the security
> + * module, just because it maps to a file mode.
> + */
> + err = security_inode_setattr(file_mnt_idmap(file),
> + file->f_path.dentry, &ia);
> + if (err)
> + goto out_unlock_inode;
> +
> + /* This MUST be done before doing anything irreversible... */
> + err = exfat_setattr(file_mnt_idmap(file), file->f_path.dentry, &ia);
> + if (err)
> + goto out_unlock_inode;
> +
> + fsnotify_change(file->f_path.dentry, ia.ia_valid);
> +
> + exfat_save_attr(inode, attr);
> + mark_inode_dirty(inode);
> +out_unlock_inode:
> + inode_unlock(inode);
> + mnt_drop_write_file(file);
> +out:
> + return err;
> +}
> +
> static int exfat_ioctl_fitrim(struct inode *inode, unsigned long arg)
> {
> struct fstrim_range range;
> @@ -346,8 +434,13 @@ static int exfat_ioctl_fitrim(struct inode *inode, unsigned long arg)
> long exfat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> {
> struct inode *inode = file_inode(filp);
> + u32 __user *user_attr = (u32 __user *)arg;
>
> switch (cmd) {
> + case EXFAT_IOCTL_GET_ATTRIBUTES:
> + return exfat_ioctl_get_attributes(inode, user_attr);
> + case EXFAT_IOCTL_SET_ATTRIBUTES:
> + return exfat_ioctl_set_attributes(filp, user_attr);
> case FITRIM:
> return exfat_ioctl_fitrim(inode, arg);
> default:
> --
> 2.40.1
