From f9d041271cf44ca02eed0cc82e1a6d8c814c53ed Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 28 Apr 2020 17:16:05 -0700 Subject: bpf: Refactor bpf_link update handling Make bpf_link update support more generic by making it into another bpf_link_ops methods. This allows generic syscall handling code to be agnostic to various conditionally compiled features (e.g., the case of CONFIG_CGROUP_BPF). This also allows to keep link type-specific code to remain static within respective code base. Refactor existing bpf_cgroup_link code and take advantage of this. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200429001614.1544-2-andriin@fb.com --- kernel/bpf/cgroup.c | 30 ++++++++++++++++++++++++++++-- 1 file changed, 28 insertions(+), 2 deletions(-) (limited to 'kernel/bpf/cgroup.c') diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c index bf634959885c..da6e48e802b2 100644 --- a/kernel/bpf/cgroup.c +++ b/kernel/bpf/cgroup.c @@ -557,8 +557,9 @@ found: * * Must be called with cgroup_mutex held. */ -int __cgroup_bpf_replace(struct cgroup *cgrp, struct bpf_cgroup_link *link, - struct bpf_prog *new_prog) +static int __cgroup_bpf_replace(struct cgroup *cgrp, + struct bpf_cgroup_link *link, + struct bpf_prog *new_prog) { struct list_head *progs = &cgrp->bpf.progs[link->type]; struct bpf_prog *old_prog; @@ -583,6 +584,30 @@ int __cgroup_bpf_replace(struct cgroup *cgrp, struct bpf_cgroup_link *link, return 0; } +static int cgroup_bpf_replace(struct bpf_link *link, struct bpf_prog *new_prog, + struct bpf_prog *old_prog) +{ + struct bpf_cgroup_link *cg_link; + int ret; + + cg_link = container_of(link, struct bpf_cgroup_link, link); + + mutex_lock(&cgroup_mutex); + /* link might have been auto-released by dying cgroup, so fail */ + if (!cg_link->cgroup) { + ret = -EINVAL; + goto out_unlock; + } + if (old_prog && link->prog != old_prog) { + ret = -EPERM; + goto out_unlock; + } + ret = __cgroup_bpf_replace(cg_link->cgroup, cg_link, new_prog); +out_unlock: + mutex_unlock(&cgroup_mutex); + return ret; +} + static struct bpf_prog_list *find_detach_entry(struct list_head *progs, struct bpf_prog *prog, struct bpf_cgroup_link *link, @@ -811,6 +836,7 @@ static void bpf_cgroup_link_dealloc(struct bpf_link *link) const struct bpf_link_ops bpf_cgroup_link_lops = { .release = bpf_cgroup_link_release, .dealloc = bpf_cgroup_link_dealloc, + .update_prog = cgroup_bpf_replace, }; int cgroup_bpf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) -- cgit v1.2.3-59-g8ed1b