diff options
| -rw-r--r-- | fs/overlayfs/super.c | 28 |
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) |