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Message-ID: <1a1af1dd-fb30-1af6-ab2a-d146ff230989@gmail.com>
Date: Tue, 15 Aug 2023 20:29:03 +0200
From: Jan Cincera <hcincera@...il.com>
To: Namjae Jeon <linkinjeon@...nel.org>,
Sungjong Seo <sj1557.seo@...sung.com>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] exfat: add ioctls for accessing attributes
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@...il.com>
---
fs/exfat/exfat_fs.h | 6 +++
fs/exfat/file.c | 97 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 103 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)
+
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..b358acbead27 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 +318,96 @@ 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);
+
+ /*
+ * ATTR_VOLUME and ATTR_SUBDIR cannot be changed; this also
+ * prevents the user from turning us into a VFAT
+ * longname entry. Also, we obviously can't set
+ * any of the NTFS attributes in the high 24 bits.
+ */
+ attr &= 0xff & ~(ATTR_VOLUME | ATTR_SUBDIR);
+ /* Merge in ATTR_VOLUME and ATTR_DIR */
+ attr |= (EXFAT_I(inode)->attr & ATTR_VOLUME) |
+ (is_dir ? ATTR_SUBDIR : 0);
+ oldattr = exfat_make_attr(inode);
+
+ /* 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 +438,13 @@ 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
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