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authorAmir Goldstein <amir73il@gmail.com>2017-04-08 14:49:07 +0300
committerMiklos Szeredi <mszeredi@redhat.com>2017-04-20 16:37:26 +0200
commitb0990fbbbd147da2096b24f2d462abe02ca251fd (patch)
treecf376e535baa2a18c3f8a63e393b2f1c54e1b366 /fs/overlayfs
parent78757af6518a35bdc22b4e7f660ff9dbbeba35d7 (diff)
ovl: check IS_APPEND() on real upper inode
For overlay file open, check IS_APPEND() on the real upper inode inside d_real(), because the overlay inode does not have the S_APPEND flag and IS_APPEND() can only be checked at open time. Note that because overlayfs does not copy up the chattr inode flags (i.e. S_APPEND, S_IMMUTABLE), the IS_APPEND() check is only relevant for upper inodes that were set with chattr +a and not to lower inodes that had chattr +a before copy up. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs')
-rw-r--r--fs/overlayfs/super.c28
1 files changed, 25 insertions, 3 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 07c8793efb1d..6faefa54cb5e 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -49,11 +49,28 @@ static void ovl_dentry_release(struct dentry *dentry)
}
}
+static int ovl_check_append_only(struct inode *inode, int flag)
+{
+ /*
+ * This test was moot in vfs may_open() because overlay inode does
+ * not have the S_APPEND flag, so re-check on real upper inode
+ */
+ if (IS_APPEND(inode)) {
+ if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
+ return -EPERM;
+ if (flag & O_TRUNC)
+ return -EPERM;
+ }
+
+ return 0;
+}
+
static struct dentry *ovl_d_real(struct dentry *dentry,
const struct inode *inode,
unsigned int open_flags)
{
struct dentry *real;
+ int err;
if (!d_is_reg(dentry)) {
if (!inode || inode == d_inode(dentry))
@@ -65,15 +82,20 @@ static struct dentry *ovl_d_real(struct dentry *dentry,
return dentry;
if (open_flags) {
- int err = ovl_open_maybe_copy_up(dentry, open_flags);
-
+ err = ovl_open_maybe_copy_up(dentry, open_flags);
if (err)
return ERR_PTR(err);
}
real = ovl_dentry_upper(dentry);
- if (real && (!inode || inode == d_inode(real)))
+ if (real && (!inode || inode == d_inode(real))) {
+ if (!inode) {
+ err = ovl_check_append_only(d_inode(real), open_flags);
+ if (err)
+ return ERR_PTR(err);
+ }
return real;
+ }
real = ovl_dentry_lower(dentry);
if (!real)