fat: Add allow_utime option
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 as
on disk info, so normal check is too unflexible.
With this option you can relax it.
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>
diff --git a/fs/fat/file.c b/fs/fat/file.c
index e73f13a..d604bb1 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -280,11 +280,27 @@
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 @@
}
}
+ /* 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;
