On Fri, Jun 3, 2022 at 11:59 PM Martin KaFai Lau <kafai@xxxxxx> wrote:
>
> On Wed, Jun 01, 2022 at 12:02:12PM -0700, Stanislav Fomichev wrote:
> > diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
> > index a27a6a7bd852..cb3338ef01e0 100644
> > --- a/kernel/bpf/cgroup.c
> > +++ b/kernel/bpf/cgroup.c
> > @@ -1035,6 +1035,7 @@ static int cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
> > static int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
> > union bpf_attr __user *uattr)
> > {
> > + __u32 __user *prog_attach_flags = u64_to_user_ptr(attr->query.prog_attach_flags);
> > __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
> > enum bpf_attach_type type = attr->query.attach_type;
> > enum cgroup_bpf_attach_type atype;
> > @@ -1042,50 +1043,92 @@ static int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
> > struct hlist_head *progs;
> > struct bpf_prog *prog;
> > int cnt, ret = 0, i;
> > + int total_cnt = 0;
> > u32 flags;
> >
> > - atype = to_cgroup_bpf_attach_type(type);
> > - if (atype < 0)
> > - return -EINVAL;
> > + enum cgroup_bpf_attach_type from_atype, to_atype;
> >
> > - progs = &cgrp->bpf.progs[atype];
> > - flags = cgrp->bpf.flags[atype];
> > + if (type == BPF_LSM_CGROUP) {
> > + from_atype = CGROUP_LSM_START;
> > + to_atype = CGROUP_LSM_END;
> Enforce prog_attach_flags for BPF_LSM_CGROUP:
>
> if (total_cnt && !prog_attach_flags)
> return -EINVAL;
All the comments make sense, will apply. The only thing that I'll
probably keep as is is the copy_to_user(flags) part. We can't move it
above because it hasn't been properly initialized there.
What I think I'll do is:
if (atype != to_atype) /* exported via prog_attach_flags */
flags = 0;
copy_to_user(.., flags,..);
That seems to better describe why we're not doing it?
> > + } else {
> > + from_atype = to_cgroup_bpf_attach_type(type);
> > + if (from_atype < 0)
> > + return -EINVAL;
> > + to_atype = from_atype;
> > + }
> >
> > - effective = rcu_dereference_protected(cgrp->bpf.effective[atype],
> > - lockdep_is_held(&cgroup_mutex));
> > + for (atype = from_atype; atype <= to_atype; atype++) {
> > + progs = &cgrp->bpf.progs[atype];
> > + flags = cgrp->bpf.flags[atype];
> >
> > - if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE)
> > - cnt = bpf_prog_array_length(effective);
> > - else
> > - cnt = prog_list_length(progs);
> > + effective = rcu_dereference_protected(cgrp->bpf.effective[atype],
> > + lockdep_is_held(&cgroup_mutex));
> nit. This can be done under the BPF_F_QUERY_EFFECTIVE case below.
>
> >
> > - if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
> > - return -EFAULT;
> > - if (copy_to_user(&uattr->query.prog_cnt, &cnt, sizeof(cnt)))
> > + if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE)
> > + total_cnt += bpf_prog_array_length(effective);
> > + else
> > + total_cnt += prog_list_length(progs);
> > + }
> > +
> > + if (type != BPF_LSM_CGROUP)
> > + if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
> > + return -EFAULT;
> nit. Move this copy_to_user(&uattr->query.attach_flags,...) to the
> 'if (type == BPF_LSM_CGROUP) { from_atype = .... } else { ... }' above.
> That will save a BPF_LSM_CGROUP test.
>
> I think the '== BPF_LSM_CGROUP' case needs to copy a 0 to user also.
>
> > + if (copy_to_user(&uattr->query.prog_cnt, &total_cnt, sizeof(total_cnt)))
> > return -EFAULT;
> > - if (attr->query.prog_cnt == 0 || !prog_ids || !cnt)
> > + if (attr->query.prog_cnt == 0 || !prog_ids || !total_cnt)
> > /* return early if user requested only program count + flags */
> > return 0;
> > - if (attr->query.prog_cnt < cnt) {
> > - cnt = attr->query.prog_cnt;
> > +
> > + if (attr->query.prog_cnt < total_cnt) {
> > + total_cnt = attr->query.prog_cnt;
> > ret = -ENOSPC;
> > }
> >
> > - if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE) {
> > - return bpf_prog_array_copy_to_user(effective, prog_ids, cnt);
> > - } else {
> > - struct bpf_prog_list *pl;
> > - u32 id;
> > + for (atype = from_atype; atype <= to_atype; atype++) {
> > + if (total_cnt <= 0)
> nit. total_cnt cannot be -ve ?
> !total_cnt instead ?
> and may be do it in the for-loop test.
>
> > + break;
> >
> > - i = 0;
> > - hlist_for_each_entry(pl, progs, node) {
> > - prog = prog_list_prog(pl);
> > - id = prog->aux->id;
> > - if (copy_to_user(prog_ids + i, &id, sizeof(id)))
> > - return -EFAULT;
> > - if (++i == cnt)
> > - break;
> > + progs = &cgrp->bpf.progs[atype];
> > + flags = cgrp->bpf.flags[atype];
> > +
> > + effective = rcu_dereference_protected(cgrp->bpf.effective[atype],
> > + lockdep_is_held(&cgroup_mutex));
> nit. This can be done under the BPF_F_QUERY_EFFECTIVE case below.
>
> > +
> > + if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE)
> > + cnt = bpf_prog_array_length(effective);
> > + else
> > + cnt = prog_list_length(progs);
> > +
> > + if (cnt >= total_cnt)
> > + cnt = total_cnt;
> nit. This seems to be the only reason that
> the "if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE)"
> need to be broken up into two halves. One above and one below.
> It does not save much code. How about repeating this one line
> 'cnt = min_t(int, cnt, total_cnt);' instead ?
>
> > +
> > + if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE) {
> > + ret = bpf_prog_array_copy_to_user(effective, prog_ids, cnt);
> > + } else {
> > + struct bpf_prog_list *pl;
> > + u32 id;
> > +
> > + i = 0;
> > + hlist_for_each_entry(pl, progs, node) {
> > + prog = prog_list_prog(pl);
> > + id = prog->aux->id;
> > + if (copy_to_user(prog_ids + i, &id, sizeof(id)))
> > + return -EFAULT;
> > + if (++i == cnt)
> > + break;
> > + }
> > }
> > +
> > + if (prog_attach_flags)
> > + for (i = 0; i < cnt; i++)
> > + if (copy_to_user(prog_attach_flags + i, &flags, sizeof(flags)))
> > + return -EFAULT;
> > +
> > + prog_ids += cnt;
> > + total_cnt -= cnt;
> > + if (prog_attach_flags)
> > + prog_attach_flags += cnt;
> nit. Merge this into the above "if (prog_attach_flags)" case.
>
> > }
> > return ret;
> > }
> > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> > index a237be4f8bb3..27492d44133f 100644
> > --- a/kernel/bpf/syscall.c
> > +++ b/kernel/bpf/syscall.c
> > @@ -3520,7 +3520,7 @@ static int bpf_prog_detach(const union bpf_attr *attr)
> > }
> > }
> >
> > -#define BPF_PROG_QUERY_LAST_FIELD query.prog_cnt
> > +#define BPF_PROG_QUERY_LAST_FIELD query.prog_attach_flags
> >
> > static int bpf_prog_query(const union bpf_attr *attr,
> > union bpf_attr __user *uattr)
> > @@ -3556,6 +3556,7 @@ static int bpf_prog_query(const union bpf_attr *attr,
> > case BPF_CGROUP_SYSCTL:
> > case BPF_CGROUP_GETSOCKOPT:
> > case BPF_CGROUP_SETSOCKOPT:
> > + case BPF_LSM_CGROUP:
> > return cgroup_bpf_prog_query(attr, uattr);
> > case BPF_LIRC_MODE2:
> > return lirc_prog_query(attr, uattr);
> > @@ -4066,6 +4067,9 @@ static int bpf_prog_get_info_by_fd(struct file *file,
> >
> > if (prog->aux->btf)
> > info.btf_id = btf_obj_id(prog->aux->btf);
> > + info.attach_btf_id = prog->aux->attach_btf_id;
> > + if (prog->aux->attach_btf)
> > + info.attach_btf_obj_id = btf_obj_id(prog->aux->attach_btf);
> Need this also:
>
> else if (prog->aux->dst_prog)
> info.attach_btf_obj_id = btf_obj_id(prog->aux->dst_prog->aux->attach_btf);
>
> >
> > ulen = info.nr_func_info;
> > info.nr_func_info = prog->aux->func_info_cnt;
> > --
> > 2.36.1.255.ge46751e96f-goog
> >
