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/coda/coda_linux.h | 95 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 95 insertions(+) create mode 100644 fs/coda/coda_linux.h (limited to 'fs/coda/coda_linux.h') diff --git a/fs/coda/coda_linux.h b/fs/coda/coda_linux.h new file mode 100644 index 000000000..dd6277d87 --- /dev/null +++ b/fs/coda/coda_linux.h @@ -0,0 +1,95 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Coda File System, Linux Kernel module + * + * Original version, adapted from cfs_mach.c, (C) Carnegie Mellon University + * Linux modifications (C) 1996, Peter J. Braam + * Rewritten for Linux 2.1 (C) 1997 Carnegie Mellon University + * + * Carnegie Mellon University encourages users of this software to + * contribute improvements to the Coda project. + */ + +#ifndef _LINUX_CODA_FS +#define _LINUX_CODA_FS + +#ifdef pr_fmt +#undef pr_fmt +#endif + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include +#include +#include +#include +#include "coda_fs_i.h" + +/* operations */ +extern const struct inode_operations coda_dir_inode_operations; +extern const struct inode_operations coda_file_inode_operations; +extern const struct inode_operations coda_ioctl_inode_operations; + +extern const struct dentry_operations coda_dentry_operations; + +extern const struct address_space_operations coda_file_aops; +extern const struct address_space_operations coda_symlink_aops; + +extern const struct file_operations coda_dir_operations; +extern const struct file_operations coda_file_operations; +extern const struct file_operations coda_ioctl_operations; + +/* operations shared over more than one file */ +int coda_open(struct inode *i, struct file *f); +int coda_release(struct inode *i, struct file *f); +int coda_permission(struct mnt_idmap *idmap, struct inode *inode, + int mask); +int coda_revalidate_inode(struct inode *); +int coda_getattr(struct mnt_idmap *, const struct path *, struct kstat *, + u32, unsigned int); +int coda_setattr(struct mnt_idmap *, struct dentry *, struct iattr *); + +/* this file: helpers */ +char *coda_f2s(struct CodaFid *f); +int coda_iscontrol(const char *name, size_t length); + +umode_t coda_inode_type(struct coda_vattr *attr); +void coda_vattr_to_iattr(struct inode *, struct coda_vattr *); +void coda_iattr_to_vattr(struct iattr *, struct coda_vattr *); +unsigned short coda_flags_to_cflags(unsigned short); + +/* inode to cnode access functions */ + +static inline struct coda_inode_info *ITOC(struct inode *inode) +{ + return container_of(inode, struct coda_inode_info, vfs_inode); +} + +static __inline__ struct CodaFid *coda_i2f(struct inode *inode) +{ + return &(ITOC(inode)->c_fid); +} + +static __inline__ char *coda_i2s(struct inode *inode) +{ + return coda_f2s(&(ITOC(inode)->c_fid)); +} + +/* this will not zap the inode away */ +static __inline__ void coda_flag_inode(struct inode *inode, int flag) +{ + struct coda_inode_info *cii = ITOC(inode); + + if (!inode) + return; + + spin_lock(&cii->c_lock); + cii->c_flags |= flag; + spin_unlock(&cii->c_lock); +} + +#endif -- cgit v1.3.1