[PATCH bpf-next v9 3/9] bpf: Refactor reporting log_true_size for prog_load
From: Leon Hwang <hidden>
Date: 2026-02-02 14:41:59
Also in:
bpf, linux-kselftest, lkml
Subsystem:
bpf [core], bpf [general] (safe dynamic programs and tools), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
The next commit will add support for reporting logs via extended common attributes, including 'log_true_size'. To prepare for that, refactor the 'log_true_size' reporting logic by introducing a new struct bpf_log_attr to encapsulate log-related behavior: * bpf_prog_load_log_attr_init(): initialize the log fields, which will support extended common attributes in the next commit. * bpf_log_attr_finalize(): handle log finalization and write back 'log_true_size' to userspace. Signed-off-by: Leon Hwang <redacted> --- include/linux/bpf.h | 4 +++- include/linux/bpf_verifier.h | 10 ++++++++++ kernel/bpf/log.c | 35 +++++++++++++++++++++++++++++++++++ kernel/bpf/syscall.c | 8 +++++--- kernel/bpf/verifier.c | 13 +++---------- 5 files changed, 56 insertions(+), 14 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index cd9b96434904..d4dbcc7ad156 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h@@ -2913,7 +2913,9 @@ int bpf_check_uarg_tail_zero(bpfptr_t uaddr, size_t expected_size, size_t actual_size); /* verify correctness of eBPF program */ -int bpf_check(struct bpf_prog **fp, union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size); +struct bpf_log_attr; +int bpf_check(struct bpf_prog **fp, union bpf_attr *attr, bpfptr_t uattr, + struct bpf_log_attr *attr_log); #ifndef CONFIG_BPF_JIT_ALWAYS_ON void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth);
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 8355b585cd18..c805b85b6f7a 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h@@ -631,6 +631,16 @@ static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log) return log && log->level; } +struct bpf_log_attr { + u32 offsetof_true_size; + u32 uattr_size; + bpfptr_t uattr; +}; + +int bpf_prog_load_log_attr_init(struct bpf_log_attr *attr_log, union bpf_attr *attr, + bpfptr_t uattr, u32 size); +int bpf_log_attr_finalize(struct bpf_log_attr *attr, struct bpf_verifier_log *log); + #define BPF_MAX_SUBPROGS 256 struct bpf_subprog_arg_info {
diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c
index a0c3b35de2ce..ff579fcba36f 100644
--- a/kernel/bpf/log.c
+++ b/kernel/bpf/log.c@@ -863,3 +863,38 @@ void print_insn_state(struct bpf_verifier_env *env, const struct bpf_verifier_st } print_verifier_state(env, vstate, frameno, false); } + +static void bpf_log_attr_init(struct bpf_log_attr *attr_log, int offsetof_true_size, bpfptr_t uattr, + u32 uattr_size) +{ + memset(attr_log, 0, sizeof(*attr_log)); + attr_log->offsetof_true_size = offsetof_true_size; + attr_log->uattr_size = uattr_size; + attr_log->uattr = uattr; +} + +int bpf_prog_load_log_attr_init(struct bpf_log_attr *attr_log, union bpf_attr *attr, + bpfptr_t uattr, u32 size) +{ + bpf_log_attr_init(attr_log, offsetof(union bpf_attr, log_true_size), uattr, size); + return 0; +} + +int bpf_log_attr_finalize(struct bpf_log_attr *attr, struct bpf_verifier_log *log) +{ + u32 log_true_size; + size_t size; + int err; + + if (!log) + return 0; + + err = bpf_vlog_finalize(log, &log_true_size); + + size = sizeof(log_true_size); + if (attr->uattr_size >= attr->offsetof_true_size + size && + copy_to_bpfptr_offset(attr->uattr, attr->offsetof_true_size, &log_true_size, size)) + err = -EFAULT; + + return err; +}
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index a58b16735e86..e81199361241 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c@@ -2860,7 +2860,7 @@ static int bpf_prog_mark_insn_arrays_ready(struct bpf_prog *prog) /* last field in 'union bpf_attr' used by this command */ #define BPF_PROG_LOAD_LAST_FIELD keyring_id -static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) +static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, struct bpf_log_attr *attr_log) { enum bpf_prog_type type = attr->prog_type; struct bpf_prog *prog, *dst_prog = NULL;
@@ -3078,7 +3078,7 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) goto free_prog_sec; /* run eBPF verifier */ - err = bpf_check(&prog, attr, uattr, uattr_size); + err = bpf_check(&prog, attr, uattr, attr_log); if (err < 0) goto free_used_maps;
@@ -6180,6 +6180,7 @@ static int __sys_bpf(enum bpf_cmd cmd, bpfptr_t uattr, unsigned int size, bpfptr_t uattr_common, unsigned int size_common) { struct bpf_common_attr attr_common; + struct bpf_log_attr attr_log; union bpf_attr attr; int err;
@@ -6231,7 +6232,8 @@ static int __sys_bpf(enum bpf_cmd cmd, bpfptr_t uattr, unsigned int size, err = map_freeze(&attr); break; case BPF_PROG_LOAD: - err = bpf_prog_load(&attr, uattr, size); + err = bpf_prog_load_log_attr_init(&attr_log, &attr, uattr, size); + err = err ?: bpf_prog_load(&attr, uattr, &attr_log); break; case BPF_OBJ_PIN: err = bpf_obj_pin(&attr);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 6b62b6d57175..1489867671e0 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c@@ -25604,12 +25604,12 @@ static int compute_scc(struct bpf_verifier_env *env) return err; } -int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u32 uattr_size) +int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, + struct bpf_log_attr *attr_log) { u64 start_time = ktime_get_ns(); struct bpf_verifier_env *env; int i, len, ret = -EINVAL, err; - u32 log_true_size; bool is_priv; BTF_TYPE_EMIT(enum bpf_features);
@@ -25808,17 +25808,10 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3 env->prog->aux->verified_insns = env->insn_processed; /* preserve original error even if log finalization is successful */ - err = bpf_vlog_finalize(&env->log, &log_true_size); + err = bpf_log_attr_finalize(attr_log, &env->log); if (err) ret = err; - if (uattr_size >= offsetofend(union bpf_attr, log_true_size) && - copy_to_bpfptr_offset(uattr, offsetof(union bpf_attr, log_true_size), - &log_true_size, sizeof(log_true_size))) { - ret = -EFAULT; - goto err_release_maps; - } - if (ret) goto err_release_maps;
--
2.52.0