From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- fs/ext2/xattr_trusted.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 fs/ext2/xattr_trusted.c (limited to 'fs/ext2/xattr_trusted.c') diff --git a/fs/ext2/xattr_trusted.c b/fs/ext2/xattr_trusted.c new file mode 100644 index 000000000..995f93122 --- /dev/null +++ b/fs/ext2/xattr_trusted.c @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/fs/ext2/xattr_trusted.c + * Handler for trusted extended attributes. + * + * Copyright (C) 2003 by Andreas Gruenbacher, + */ + +#include "ext2.h" +#include "xattr.h" + +static bool +ext2_xattr_trusted_list(struct dentry *dentry) +{ + return capable(CAP_SYS_ADMIN); +} + +static int +ext2_xattr_trusted_get(const struct xattr_handler *handler, + struct dentry *unused, struct inode *inode, + const char *name, void *buffer, size_t size) +{ + return ext2_xattr_get(inode, EXT2_XATTR_INDEX_TRUSTED, name, + buffer, size); +} + +static int +ext2_xattr_trusted_set(const struct xattr_handler *handler, + struct mnt_idmap *idmap, + struct dentry *unused, struct inode *inode, + const char *name, const void *value, + size_t size, int flags) +{ + return ext2_xattr_set(inode, EXT2_XATTR_INDEX_TRUSTED, name, + value, size, flags); +} + +const struct xattr_handler ext2_xattr_trusted_handler = { + .prefix = XATTR_TRUSTED_PREFIX, + .list = ext2_xattr_trusted_list, + .get = ext2_xattr_trusted_get, + .set = ext2_xattr_trusted_set, +}; -- cgit v1.3.1