From: Amir Goldstein amir73il@gmail.com
[ Upstream commit 03fedf93593c82538b18476d8c4f0e8f8435ea70 ]
When inode has no listxattr op of its own (e.g. squashfs) vfs_listxattr calls the LSM inode_listsecurity hooks to list the xattrs that LSMs will intercept in inode_getxattr hooks.
When selinux LSM is installed but not initialized, it will list the security.selinux xattr in inode_listsecurity, but will not intercept it in inode_getxattr. This results in -ENODATA for a getxattr call for an xattr returned by listxattr.
This situation was manifested as overlayfs failure to copy up lower files from squashfs when selinux is built-in but not initialized, because ovl_copy_xattr() iterates the lower inode xattrs by vfs_listxattr() and vfs_getxattr().
ovl_copy_xattr() skips copy up of security labels that are indentified by inode_copy_up_xattr LSM hooks, but it does that after vfs_getxattr(). Since we are not going to copy them, skip vfs_getxattr() of the security labels.
Reported-by: Michael Labriola michael.d.labriola@gmail.com Tested-by: Michael Labriola michael.d.labriola@gmail.com Link: https://lore.kernel.org/linux-unionfs/2nv9d47zt7.fsf@aldarion.sourceruckus.o... Signed-off-by: Amir Goldstein amir73il@gmail.com Signed-off-by: Miklos Szeredi mszeredi@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/overlayfs/copy_up.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index 955ecd4030f04..89d5d59c7d7a4 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -84,6 +84,14 @@ int ovl_copy_xattr(struct super_block *sb, struct dentry *old,
if (ovl_is_private_xattr(sb, name)) continue; + + error = security_inode_copy_up_xattr(name); + if (error < 0 && error != -EOPNOTSUPP) + break; + if (error == 1) { + error = 0; + continue; /* Discard */ + } retry: size = vfs_getxattr(old, name, value, value_size); if (size == -ERANGE) @@ -107,13 +115,6 @@ retry: goto retry; }
- error = security_inode_copy_up_xattr(name); - if (error < 0 && error != -EOPNOTSUPP) - break; - if (error == 1) { - error = 0; - continue; /* Discard */ - } error = vfs_setxattr(new, name, value, size, 0); if (error) { if (error != -EOPNOTSUPP || ovl_must_copy_xattr(name))