fat: Fix ATTR_RO for directory

FAT has the ATTR_RO (read-only) attribute. But on Windows, the ATTR_RO of the directory will be just ignored actually, and is used by only applications as flag. E.g. it's setted for the customized folder by Explorer. http://msdn2.microsoft.com/en-us/library/aa969337.aspx This adds "rodir" option. If user specified it, ATTR_RO is used as read-only flag even if it's the directory. Otherwise, inode->i_mode is not used to hold ATTR_RO (i.e. fat_mode_can_save_ro() returns 0). Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fat: Fix ATTR_RO for directory
FAT has the ATTR_RO (read-only) attribute. But on Windows, the ATTR_RO of the directory will be just ignored actually, and is used by only applications as flag. E.g. it's setted for the customized folder by Explorer. http://msdn2.microsoft.com/en-us/library/aa969337.aspx This adds "rodir" option. If user specified it, ATTR_RO is used as read-only flag even if it's the directory. Otherwise, inode->i_mode is not used to hold ATTR_RO (i.e. fat_mode_can_save_ro() returns 0). Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
OGAWA Hirofumi · Linus Torvalds
1 parent 9183482f5d
Showing 4 changed files with 43 additions and 12 deletions Side-by-side Diff
Documentation/filesystems/vfat.txt
fs/fat/fat.h
fs/fat/file.c
fs/fat/inode.c
@@ -124,6 +124,14 @@
 flush         -- If set, the filesystem will try to flush to disk more
 		 early than normal. Not set by default.
  
+rodir	      -- FAT has the ATTR_RO (read-only) attribute. But on Windows,
+		 the ATTR_RO of the directory will be just ignored actually,
+		 and is used by only applications as flag. E.g. it's setted
+		 for the customized folder.
+
+		 If you want to use ATTR_RO as read-only flag even for
+		 the directory, set this option.
+
 <bool>: 0,1,yes,no,true,false
  
 TODO
@@ -38,7 +38,8 @@
 		 flush:1,	  /* write things quickly */
 		 nocase:1,	  /* Does this need case conversion? 0=need case conversion*/
 		 usefree:1,	  /* Use free_clusters for FAT32 */
-		 tz_utc:1;	  /* Filesystem timestamps are in UTC */
+		 tz_utc:1,	  /* Filesystem timestamps are in UTC */
+		 rodir:1;	  /* allow ATTR_RO for directory */
 };
  
 #define FAT_HASH_BITS	8
  
  
@@ -120,15 +121,20 @@
 /*
  * If ->i_mode can't hold S_IWUGO (i.e. ATTR_RO), we use ->i_attrs to
  * save ATTR_RO instead of ->i_mode.
+ *
+ * If it's directory and !sbi->options.rodir, ATTR_RO isn't read-only
+ * bit, it's just used as flag for app.
  */
 static inline int fat_mode_can_hold_ro(struct inode *inode)
 {
 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 	mode_t mask;
  
-	if (S_ISDIR(inode->i_mode))
+	if (S_ISDIR(inode->i_mode)) {
+		if (!sbi->options.rodir)
+			return 0;
 		mask = ~sbi->options.fs_dmask;
-	else
+	} else
 		mask = ~sbi->options.fs_fmask;
  
 	if (!(mask & S_IWUGO))
@@ -140,7 +146,7 @@
 static inline mode_t fat_make_mode(struct msdos_sb_info *sbi,
 				   u8 attrs, mode_t mode)
 {
-	if (attrs & ATTR_RO)
+	if (attrs & ATTR_RO && !((attrs & ATTR_DIR) && !sbi->options.rodir))
 		mode &= ~S_IWUGO;
  
 	if (attrs & ATTR_DIR)
@@ -282,11 +282,18 @@
 	/*
 	 * Of the r and x bits, all (subject to umask) must be present. Of the
 	 * w bits, either all (subject to umask) or none must be present.
+	 *
+	 * If fat_mode_can_hold_ro(inode) is false, can't change w bits.
 	 */
 	if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
 		return -EPERM;
-	if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
-		return -EPERM;
+	if (fat_mode_can_hold_ro(inode)) {
+		if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
+			return -EPERM;
+	} else {
+		if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
+			return -EPERM;
+	}
  
 	*mode_ptr &= S_IFMT | perm;
  
  
@@ -316,8 +323,8 @@
 {
 	struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
 	struct inode *inode = dentry->d_inode;
-	int error = 0;
 	unsigned int ia_valid;
+	int error;
  
 	/*
 	 * Expand the file. Since inode_setattr() updates ->i_size
@@ -371,7 +378,8 @@
 			attr->ia_valid &= ~ATTR_MODE;
 	}
  
-	error = inode_setattr(inode, attr);
+	if (attr->ia_valid)
+		error = inode_setattr(inode, attr);
 out:
 	return error;
 }
@@ -797,8 +797,10 @@
 			seq_puts(m, ",uni_xlate");
 		if (!opts->numtail)
 			seq_puts(m, ",nonumtail");
+		if (opts->rodir)
+			seq_puts(m, ",rodir");
 	}
-	if (sbi->options.flush)
+	if (opts->flush)
 		seq_puts(m, ",flush");
 	if (opts->tz_utc)
 		seq_puts(m, ",tz=UTC");
@@ -814,7 +816,7 @@
 	Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
 	Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
 	Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
-	Opt_obsolate, Opt_flush, Opt_tz_utc, Opt_err,
+	Opt_obsolate, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err,
 };
  
 static const match_table_t fat_tokens = {
@@ -886,6 +888,7 @@
 	{Opt_nonumtail_yes, "nonumtail=yes"},
 	{Opt_nonumtail_yes, "nonumtail=true"},
 	{Opt_nonumtail_yes, "nonumtail"},
+	{Opt_rodir, "rodir"},
 	{Opt_err, NULL}
 };
  
  
  
@@ -905,10 +908,13 @@
 	opts->allow_utime = -1;
 	opts->codepage = fat_default_codepage;
 	opts->iocharset = fat_default_iocharset;
-	if (is_vfat)
+	if (is_vfat) {
 		opts->shortname = VFAT_SFN_DISPLAY_LOWER|VFAT_SFN_CREATE_WIN95;
-	else
+		opts->rodir = 0;
+	} else {
 		opts->shortname = 0;
+		opts->rodir = 1;
+	}
 	opts->name_check = 'n';
 	opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
 	opts->utf8 = opts->unicode_xlate = 0;
@@ -1058,6 +1064,9 @@
 			break;
 		case Opt_nonumtail_yes:		/* empty or 1 or yes or true */
 			opts->numtail = 0;	/* negated option */
+			break;
+		case Opt_rodir:
+			opts->rodir = 1;
 			break;
  
 		/* obsolete mount options */
...	...	@@ -124,6 +124,14 @@
124	124	flush -- If set, the filesystem will try to flush to disk more
125	125	early than normal. Not set by default.
126	126
	127	+rodir -- FAT has the ATTR_RO (read-only) attribute. But on Windows,
	128	+ the ATTR_RO of the directory will be just ignored actually,
	129	+ and is used by only applications as flag. E.g. it's setted
	130	+ for the customized folder.
	131	+
	132	+ If you want to use ATTR_RO as read-only flag even for
	133	+ the directory, set this option.
	134	+
127	135	<bool>: 0,1,yes,no,true,false
128	136
129	137	TODO
...	...	@@ -38,7 +38,8 @@
38	38	flush:1, /* write things quickly */
39	39	nocase:1, /* Does this need case conversion? 0=need case conversion*/
40	40	usefree:1, /* Use free_clusters for FAT32 */
41		- tz_utc:1; /* Filesystem timestamps are in UTC */
	41	+ tz_utc:1, /* Filesystem timestamps are in UTC */
	42	+ rodir:1; /* allow ATTR_RO for directory */
42	43	};
43	44
44	45	#define FAT_HASH_BITS 8
45	46
46	47
...	...	@@ -120,15 +121,20 @@
120	121	/*
121	122	* If ->i_mode can't hold S_IWUGO (i.e. ATTR_RO), we use ->i_attrs to
122	123	* save ATTR_RO instead of ->i_mode.
	124	+ *
	125	+ * If it's directory and !sbi->options.rodir, ATTR_RO isn't read-only
	126	+ * bit, it's just used as flag for app.
123	127	*/
124	128	static inline int fat_mode_can_hold_ro(struct inode *inode)
125	129	{
126	130	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
127	131	mode_t mask;
128	132
129		- if (S_ISDIR(inode->i_mode))
	133	+ if (S_ISDIR(inode->i_mode)) {
	134	+ if (!sbi->options.rodir)
	135	+ return 0;
130	136	mask = ~sbi->options.fs_dmask;
131		- else
	137	+ } else
132	138	mask = ~sbi->options.fs_fmask;
133	139
134	140	if (!(mask & S_IWUGO))
...	...	@@ -140,7 +146,7 @@
140	146	static inline mode_t fat_make_mode(struct msdos_sb_info *sbi,
141	147	u8 attrs, mode_t mode)
142	148	{
143		- if (attrs & ATTR_RO)
	149	+ if (attrs & ATTR_RO && !((attrs & ATTR_DIR) && !sbi->options.rodir))
144	150	mode &= ~S_IWUGO;
145	151
146	152	if (attrs & ATTR_DIR)
...	...	@@ -282,11 +282,18 @@
282	282	/*
283	283	* Of the r and x bits, all (subject to umask) must be present. Of the
284	284	* w bits, either all (subject to umask) or none must be present.
	285	+ *
	286	+ * If fat_mode_can_hold_ro(inode) is false, can't change w bits.
285	287	*/
286	288	if ((perm & (S_IRUGO \| S_IXUGO)) != (inode->i_mode & (S_IRUGO\|S_IXUGO)))
287	289	return -EPERM;
288		- if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
289		- return -EPERM;
	290	+ if (fat_mode_can_hold_ro(inode)) {
	291	+ if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
	292	+ return -EPERM;
	293	+ } else {
	294	+ if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
	295	+ return -EPERM;
	296	+ }
290	297
291	298	*mode_ptr &= S_IFMT \| perm;
292	299
293	300
...	...	@@ -316,8 +323,8 @@
316	323	{
317	324	struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
318	325	struct inode *inode = dentry->d_inode;
319		- int error = 0;
320	326	unsigned int ia_valid;
	327	+ int error;
321	328
322	329	/*
323	330	* Expand the file. Since inode_setattr() updates ->i_size
...	...	@@ -371,7 +378,8 @@
371	378	attr->ia_valid &= ~ATTR_MODE;
372	379	}
373	380
374		- error = inode_setattr(inode, attr);
	381	+ if (attr->ia_valid)
	382	+ error = inode_setattr(inode, attr);
375	383	out:
376	384	return error;
377	385	}
...	...	@@ -797,8 +797,10 @@
797	797	seq_puts(m, ",uni_xlate");
798	798	if (!opts->numtail)
799	799	seq_puts(m, ",nonumtail");
	800	+ if (opts->rodir)
	801	+ seq_puts(m, ",rodir");
800	802	}
801		- if (sbi->options.flush)
	803	+ if (opts->flush)
802	804	seq_puts(m, ",flush");
803	805	if (opts->tz_utc)
804	806	seq_puts(m, ",tz=UTC");
...	...	@@ -814,7 +816,7 @@
814	816	Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
815	817	Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
816	818	Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
817		- Opt_obsolate, Opt_flush, Opt_tz_utc, Opt_err,
	819	+ Opt_obsolate, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err,
818	820	};
819	821
820	822	static const match_table_t fat_tokens = {
...	...	@@ -886,6 +888,7 @@
886	888	{Opt_nonumtail_yes, "nonumtail=yes"},
887	889	{Opt_nonumtail_yes, "nonumtail=true"},
888	890	{Opt_nonumtail_yes, "nonumtail"},
	891	+ {Opt_rodir, "rodir"},
889	892	{Opt_err, NULL}
890	893	};
891	894
892	895
893	896
...	...	@@ -905,10 +908,13 @@
905	908	opts->allow_utime = -1;
906	909	opts->codepage = fat_default_codepage;
907	910	opts->iocharset = fat_default_iocharset;
908		- if (is_vfat)
	911	+ if (is_vfat) {
909	912	opts->shortname = VFAT_SFN_DISPLAY_LOWER\|VFAT_SFN_CREATE_WIN95;
910		- else
	913	+ opts->rodir = 0;
	914	+ } else {
911	915	opts->shortname = 0;
	916	+ opts->rodir = 1;
	917	+ }
912	918	opts->name_check = 'n';
913	919	opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK = 0;
914	920	opts->utf8 = opts->unicode_xlate = 0;
...	...	@@ -1058,6 +1064,9 @@
1058	1064	break;
1059	1065	case Opt_nonumtail_yes: /* empty or 1 or yes or true */
1060	1066	opts->numtail = 0; /* negated option */
	1067	+ break;
	1068	+ case Opt_rodir:
	1069	+ opts->rodir = 1;
1061	1070	break;
1062	1071
1063	1072	/* obsolete mount options */