On Mon, Jan 12, 2026 at 6:59 AM Leon Hwang <[email protected]> wrote: > > The log buffer of common attributes would be confusing with the one in > 'union bpf_attr' for BPF_PROG_LOAD. > > In order to clarify the usage of these two log buffers, they both can be > used for logging if: > > * They are same, including 'log_buf', 'log_level' and 'log_size'. > * One of them is missing, then another one will be used for logging. > > If they both have 'log_buf' but they are not same totally, return -EUSERS.
why use this special error code that we don't seem to use in BPF subsystem at all? What's wrong with -EINVAL. This shouldn't be an easy mistake to do, tbh. > > Signed-off-by: Leon Hwang <[email protected]> > --- > include/linux/bpf_verifier.h | 4 +++- > kernel/bpf/log.c | 29 ++++++++++++++++++++++++++--- > kernel/bpf/syscall.c | 9 ++++++--- > 3 files changed, 35 insertions(+), 7 deletions(-) > > diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h > index 4c9632c40059..da2d37ca60e7 100644 > --- a/include/linux/bpf_verifier.h > +++ b/include/linux/bpf_verifier.h > @@ -637,9 +637,11 @@ struct bpf_log_attr { > u32 log_level; > struct bpf_attrs *attrs; > u32 offsetof_log_true_size; > + struct bpf_attrs *attrs_common; > }; > > -int bpf_prog_load_log_attr_init(struct bpf_log_attr *log_attr, struct > bpf_attrs *attrs); > +int bpf_prog_load_log_attr_init(struct bpf_log_attr *log_attr, struct > bpf_attrs *attrs, > + struct bpf_attrs *attrs_common); > int bpf_log_attr_finalize(struct bpf_log_attr *log_attr, struct > bpf_verifier_log *log); > > #define BPF_MAX_SUBPROGS 256 > diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c > index 457b724c4176..eba60a13e244 100644 > --- a/kernel/bpf/log.c > +++ b/kernel/bpf/log.c > @@ -865,23 +865,41 @@ void print_insn_state(struct bpf_verifier_env *env, > const struct bpf_verifier_st > } > > static int bpf_log_attr_init(struct bpf_log_attr *log_attr, struct bpf_attrs > *attrs, u64 log_buf, > - u32 log_size, u32 log_level, int > offsetof_log_true_size) > + u32 log_size, u32 log_level, int > offsetof_log_true_size, > + struct bpf_attrs *attrs_common) > { > + const struct bpf_common_attr *common_attr = attrs_common ? > attrs_common->attr : NULL; > + There is something to be said about naming choices here :) it's easy to get lost in attrs_common being actually bpf_attrs, which contains attr field, which is actually of bpf_common_attr type... It's a bit disorienting. :) > memset(log_attr, 0, sizeof(*log_attr)); > log_attr->log_buf = log_buf; > log_attr->log_size = log_size; > log_attr->log_level = log_level; > log_attr->attrs = attrs; > log_attr->offsetof_log_true_size = offsetof_log_true_size; > + log_attr->attrs_common = attrs_common; > + > + if (log_buf && common_attr && common_attr->log_buf && > + (log_buf != common_attr->log_buf || > + log_size != common_attr->log_size || > + log_level != common_attr->log_level)) > + return -EUSERS; > + > + if (!log_buf && common_attr && common_attr->log_buf) { > + log_attr->log_buf = common_attr->log_buf; > + log_attr->log_size = common_attr->log_size; > + log_attr->log_level = common_attr->log_level; > + } > + > return 0; > } > [...]
