diff options
| -rw-r--r-- | Documentation/filesystems/vfat.txt | 15 | ||||
| -rw-r--r-- | fs/fat/file.c | 24 | ||||
| -rw-r--r-- | fs/fat/inode.c | 18 | ||||
| -rw-r--r-- | include/linux/msdos_fs.h | 1 |
4 files changed, 55 insertions, 3 deletions
diff --git a/Documentation/filesystems/vfat.txt b/Documentation/filesystems/vfat.txt index fcc123ffa25..2d5e1e582e1 100644 --- a/Documentation/filesystems/vfat.txt +++ b/Documentation/filesystems/vfat.txt @@ -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. diff --git a/fs/fat/file.c b/fs/fat/file.c index e73f13a1379..d604bb13242 100644 --- a/fs/fat/file.c +++ b/fs/fat/file.c @@ -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; diff --git a/fs/fat/inode.c b/fs/fat/inode.c index f22f287e507..886f6095a37 100644 --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -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; diff --git a/include/linux/msdos_fs.h b/include/linux/msdos_fs.h index c4bed98bc00..81fb9bc5322 100644 --- a/include/linux/msdos_fs.h +++ b/include/linux/msdos_fs.h @@ -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 */ |