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authorLinus Torvalds <torvalds@linux-foundation.org>2016-01-21 12:20:46 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-01-21 12:20:46 -0800
commite9f57ebcba563e0cd532926cab83c92bb4d79360 (patch)
tree6cf11baa7851129145cc35f9218583287f41dd64 /fs/overlayfs/inode.c
parent5c89e9ea7ef1feaa147325b2ab47a89a147fb903 (diff)
parent84889d49335627bc770b32787c1ef9ebad1da232 (diff)
downloadlinux-e9f57ebcba563e0cd532926cab83c92bb4d79360.tar.bz2
Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs updates from Miklos Szeredi: "This contains several bug fixes and a new mount option 'default_permissions' that allows read-only exported NFS filesystems to be used as lower layer" * 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: ovl: check dentry positiveness in ovl_cleanup_whiteouts() ovl: setattr: check permissions before copy-up ovl: root: copy attr ovl: move super block magic number to magic.h ovl: use a minimal buffer in ovl_copy_xattr ovl: allow zero size xattr ovl: default permissions
Diffstat (limited to 'fs/overlayfs/inode.c')
-rw-r--r--fs/overlayfs/inode.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 964a60fa7afc..bf996e574f3d 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -42,6 +42,19 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
int err;
struct dentry *upperdentry;
+ /*
+ * Check for permissions before trying to copy-up. This is redundant
+ * since it will be rechecked later by ->setattr() on upper dentry. But
+ * without this, copy-up can be triggered by just about anybody.
+ *
+ * We don't initialize inode->size, which just means that
+ * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not
+ * check for a swapfile (which this won't be anyway).
+ */
+ err = inode_change_ok(dentry->d_inode, attr);
+ if (err)
+ return err;
+
err = ovl_want_write(dentry);
if (err)
goto out;
@@ -95,6 +108,29 @@ int ovl_permission(struct inode *inode, int mask)
realdentry = ovl_entry_real(oe, &is_upper);
+ if (ovl_is_default_permissions(inode)) {
+ struct kstat stat;
+ struct path realpath = { .dentry = realdentry };
+
+ if (mask & MAY_NOT_BLOCK)
+ return -ECHILD;
+
+ realpath.mnt = ovl_entry_mnt_real(oe, inode, is_upper);
+
+ err = vfs_getattr(&realpath, &stat);
+ if (err)
+ return err;
+
+ if ((stat.mode ^ inode->i_mode) & S_IFMT)
+ return -ESTALE;
+
+ inode->i_mode = stat.mode;
+ inode->i_uid = stat.uid;
+ inode->i_gid = stat.gid;
+
+ return generic_permission(inode, mask);
+ }
+
/* Careful in RCU walk mode */
realinode = ACCESS_ONCE(realdentry->d_inode);
if (!realinode) {