Add support for BPF monitors via the struct_ops mechanism, which allows BPF monitors to be loaded and appear almost like in-kernel modules.
Signed-off-by: Gabriele Monaco <[email protected]> --- kernel/trace/rv/Kconfig | 10 ++++ kernel/trace/rv/Makefile | 1 + kernel/trace/rv/rv_bpf.c | 118 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 129 insertions(+) create mode 100644 kernel/trace/rv/rv_bpf.c diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig index efa930f94ea4..be11e5c85a60 100644 --- a/kernel/trace/rv/Kconfig +++ b/kernel/trace/rv/Kconfig @@ -126,3 +126,13 @@ config RV_MONITORS_KUNIT_TEST unrelated KUnit test is running. If unsure, say N. + +config RV_MON_BPF_STRUCT_OPS + bool "BPF struct_ops support for RV monitors" + depends on RV && BPF_SYSCALL && BPF_JIT + help + Enable BPF programs to register as Runtime Verification monitors + using the BPF struct_ops mechanism. This allows BPF monitors to + be managed through the standard RV interface in sysfs alongside + kernel monitors. + It has no performance impact if not used. diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile index cdbf68c84f5a..635461395cba 100644 --- a/kernel/trace/rv/Makefile +++ b/kernel/trace/rv/Makefile @@ -26,3 +26,4 @@ obj-$(CONFIG_RV_REACTORS) += rv_reactors.o obj-$(CONFIG_RV_REACT_PRINTK) += reactor_printk.o obj-$(CONFIG_RV_REACT_PANIC) += reactor_panic.o obj-$(CONFIG_RV_MONITORS_KUNIT_TEST) += rv_monitors_test.o +obj-$(CONFIG_RV_MON_BPF_STRUCT_OPS) += rv_bpf.o diff --git a/kernel/trace/rv/rv_bpf.c b/kernel/trace/rv/rv_bpf.c new file mode 100644 index 000000000000..0450bcaf1b79 --- /dev/null +++ b/kernel/trace/rv/rv_bpf.c @@ -0,0 +1,118 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * BPF struct_ops support for Runtime Verification monitors + * + * Allows BPF programs to register as RV monitors via struct_ops. + * BPF monitors appear in /sys/kernel/tracing/rv/ alongside kernel monitors. + * + * Copyright (C) 2026-2029 Red Hat, Inc. Gabriele Monaco <[email protected]> + */ + +#include <linux/bpf.h> +#include <linux/bpf_verifier.h> +#include <linux/btf.h> +#include <linux/btf_ids.h> +#include <linux/filter.h> +#include <linux/rv.h> + +static int bpf_rv_monitor_init(struct btf *btf) +{ + return 0; +} + +static int bpf_rv_monitor_init_member(const struct btf_type *t, + const struct btf_member *member, + void *kdata, const void *udata) +{ + const struct rv_monitor *umon = udata; + struct rv_monitor *kmon = kdata; + u32 moff = __btf_member_bit_offset(t, member) / 8; + int ret; + + switch (moff) { + case offsetof(struct rv_monitor, name): + ret = bpf_obj_name_cpy(kmon->name, umon->name, + sizeof(kmon->name)); + if (ret < 0) + return ret; + if (ret == 0) + return -EINVAL; + return 1; + case offsetof(struct rv_monitor, description): + ret = strscpy(kmon->description, umon->description); + if (ret < 0) + return ret; + if (ret == 0) + return -EINVAL; + return 1; + } + + return 0; +} + +static int bpf_rv_monitor_reg(void *kdata, struct bpf_link *link) +{ + struct rv_monitor *mon = kdata; + + pr_info("rv: Registering BPF monitor %s\n", mon->name); + return rv_register_monitor(mon, NULL); +} + +static void bpf_rv_monitor_unreg(void *kdata, struct bpf_link *link) +{ + struct rv_monitor *mon = kdata; + + pr_info("rv: Unregistering BPF monitor %s\n", mon->name); + rv_unregister_monitor(mon); +} + +static int bpf_rv_monitor_validate(void *kdata) +{ + struct rv_monitor *mon = kdata; + + if (!mon->enable) + return -EINVAL; + + return 0; +} + +static const struct bpf_verifier_ops bpf_rv_monitor_verifier_ops = { + .get_func_proto = bpf_base_func_proto, + .is_valid_access = NULL, +}; + +static int rv_ops__mon_enable(void) +{ + return 0; +} + +static void rv_ops__mon_disable(void) { } + +static void rv_ops__mon_reset(void) { } + +static struct rv_monitor __bpf_ops_rv_monitor = { + .name = "rv_monitor", + .description = "stub BPF monitor.", + .enable = rv_ops__mon_enable, + .disable = rv_ops__mon_disable, + .reset = rv_ops__mon_reset, + .enabled = 0, +}; + +static struct bpf_struct_ops bpf_rv_monitor_ops = { + .verifier_ops = &bpf_rv_monitor_verifier_ops, + .init = bpf_rv_monitor_init, + .init_member = bpf_rv_monitor_init_member, + .reg = bpf_rv_monitor_reg, + .unreg = bpf_rv_monitor_unreg, + .validate = bpf_rv_monitor_validate, + .name = "rv_monitor", + .cfi_stubs = &__bpf_ops_rv_monitor, + .owner = THIS_MODULE, +}; + +static int __init bpf_rv_monitor_init_ops(void) +{ + return register_bpf_struct_ops(&bpf_rv_monitor_ops, rv_monitor); +} +late_initcall(bpf_rv_monitor_init_ops); -- 2.55.0
