fat: Add allow_utime option (1ae43f82) · Commits · 戴 / test

Documentation/filesystems/vfat.txt

+15 −0

Original line number	Diff line number	Diff line
		@@ -17,6 +17,21 @@ dmask=### -- The permission mask for the directory.
		fmask=### -- The permission mask for files.
		The default is the umask of current process.

		allow_utime=### -- This option controls the permission check of mtime/atime.

		20 - If current process is in group of file's group ID,
		you can change timestamp.
		2 - Other users can change timestamp.

		The default is set from `dmask' option. (If the directory is
		writable, utime(2) is also allowed. I.e. ~dmask & 022)

		Normally utime(2) checks current process is owner of
		the file, or it has CAP_FOWNER capability. But FAT
		filesystem doesn't have uid/gid on disk, so normal
		check is too unflexible. With this option you can
		relax it.

		codepage=### -- Sets the codepage number for converting to shortname
		characters on FAT filesystem.
		By default, FAT_DEFAULT_CODEPAGE setting is used.

fs/fat/file.c

+24 −0

Original line number	Diff line number	Diff line
		@@ -280,11 +280,27 @@ static int fat_check_mode(const struct msdos_sb_info sbi, struct inode inode,
		return 0;
		}

		static int fat_allow_set_time(struct msdos_sb_info sbi, struct inode inode)
		{
		mode_t allow_utime = sbi->options.allow_utime;

		if (current->fsuid != inode->i_uid) {
		if (in_group_p(inode->i_gid))
		allow_utime >>= 3;
		if (allow_utime & MAY_WRITE)
		return 1;
		}

		/* use a default check */
		return 0;
		}

		int fat_setattr(struct dentry dentry, struct iattr attr)
		{
		struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
		struct inode *inode = dentry->d_inode;
		int mask, error = 0;
		unsigned int ia_valid;

		lock_kernel();

		@@ -302,7 +318,15 @@ int fat_setattr(struct dentry dentry, struct iattr attr)
		}
		}

		/* Check for setting the inode time. */
		ia_valid = attr->ia_valid;
		if (ia_valid & (ATTR_MTIME_SET \| ATTR_ATIME_SET)) {
		if (fat_allow_set_time(sbi, inode))
		attr->ia_valid &= ~(ATTR_MTIME_SET \| ATTR_ATIME_SET);
		}

		error = inode_change_ok(inode, attr);
		attr->ia_valid = ia_valid;
		if (error) {
		if (sbi->options.quiet)
		error = 0;

fs/fat/inode.c

+15 −3

Original line number	Diff line number	Diff line
		@@ -785,6 +785,8 @@ static int fat_show_options(struct seq_file m, struct vfsmount mnt)
		seq_printf(m, ",gid=%u", opts->fs_gid);
		seq_printf(m, ",fmask=%04o", opts->fs_fmask);
		seq_printf(m, ",dmask=%04o", opts->fs_dmask);
		if (opts->allow_utime)
		seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
		if (sbi->nls_disk)
		seq_printf(m, ",codepage=%s", sbi->nls_disk->charset);
		if (isvfat) {
		@@ -840,9 +842,9 @@ static int fat_show_options(struct seq_file m, struct vfsmount mnt)

		enum {
		Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
		Opt_umask, Opt_dmask, Opt_fmask, Opt_codepage, Opt_usefree, Opt_nocase,
		Opt_quiet, Opt_showexec, Opt_debug, Opt_immutable,
		Opt_dots, Opt_nodots,
		Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
		Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
		Opt_immutable, Opt_dots, Opt_nodots,
		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,
		@@ -861,6 +863,7 @@ static match_table_t fat_tokens = {
		{Opt_umask, "umask=%o"},
		{Opt_dmask, "dmask=%o"},
		{Opt_fmask, "fmask=%o"},
		{Opt_allow_utime, "allow_utime=%o"},
		{Opt_codepage, "codepage=%u"},
		{Opt_usefree, "usefree"},
		{Opt_nocase, "nocase"},
		@@ -932,6 +935,7 @@ static int parse_options(char options, int is_vfat, int silent, int debug,
		opts->fs_uid = current->uid;
		opts->fs_gid = current->gid;
		opts->fs_fmask = opts->fs_dmask = current->fs->umask;
		opts->allow_utime = -1;
		opts->codepage = fat_default_codepage;
		opts->iocharset = fat_default_iocharset;
		if (is_vfat)
		@@ -1019,6 +1023,11 @@ static int parse_options(char options, int is_vfat, int silent, int debug,
		return 0;
		opts->fs_fmask = option;
		break;
		case Opt_allow_utime:
		if (match_octal(&args[0], &option))
		return 0;
		opts->allow_utime = option & (S_IWGRP \| S_IWOTH);
		break;
		case Opt_codepage:
		if (match_int(&args[0], &option))
		return 0;
		@@ -1101,6 +1110,9 @@ static int parse_options(char options, int is_vfat, int silent, int debug,
		" for FAT filesystems, filesystem will be case sensitive!\n");
		}

		/* If user doesn't specify allow_utime, it's initialized from dmask. */
		if (opts->allow_utime == (unsigned short)-1)
		opts->allow_utime = ~opts->fs_dmask & (S_IWGRP \| S_IWOTH);
		if (opts->unicode_xlate)
		opts->utf8 = 0;

include/linux/msdos_fs.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -195,6 +195,7 @@ struct fat_mount_options {
		char iocharset; / Charset used for filename input/display */
		unsigned short shortname; /* flags for shortname display/create rule */
		unsigned char name_check; /* r = relaxed, n = normal, s = strict */
		unsigned short allow_utime;/* permission for setting the [am]time */
		unsigned quiet:1, /* set = fake successful chmods and chowns */
		showexec:1, /* set = only set x bit for com/exe/bat */
		sys_immutable:1, /* set = system files are immutable */

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