From f9d041271cf44ca02eed0cc82e1a6d8c814c53ed Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 28 Apr 2020 17:16:05 -0700 Subject: [PATCH] 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 --- include/linux/bpf-cgroup.h | 12 ------------ include/linux/bpf.h | 3 ++- kernel/bpf/cgroup.c | 30 ++++++++++++++++++++++++++++-- kernel/bpf/syscall.c | 11 ++++------- kernel/cgroup/cgroup.c | 27 --------------------------- 5 files changed, 34 insertions(+), 49 deletions(-) diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h index 0b41fd5fc96b..a9cb9a5bf8e9 100644 --- a/include/linux/bpf-cgroup.h +++ b/include/linux/bpf-cgroup.h @@ -100,8 +100,6 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog, struct bpf_cgroup_link *link, enum bpf_attach_type type); -int __cgroup_bpf_replace(struct cgroup *cgrp, struct bpf_cgroup_link *link, - struct bpf_prog *new_prog); int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr, union bpf_attr __user *uattr); @@ -112,8 +110,6 @@ int cgroup_bpf_attach(struct cgroup *cgrp, u32 flags); int cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog, enum bpf_attach_type type); -int cgroup_bpf_replace(struct bpf_link *link, struct bpf_prog *old_prog, - struct bpf_prog *new_prog); int cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr, union bpf_attr __user *uattr); @@ -353,7 +349,6 @@ int cgroup_bpf_prog_query(const union bpf_attr *attr, #else struct bpf_prog; -struct bpf_link; struct cgroup_bpf {}; static inline int cgroup_bpf_inherit(struct cgroup *cgrp) { return 0; } static inline void cgroup_bpf_offline(struct cgroup *cgrp) {} @@ -377,13 +372,6 @@ static inline int cgroup_bpf_link_attach(const union bpf_attr *attr, return -EINVAL; } -static inline int cgroup_bpf_replace(struct bpf_link *link, - struct bpf_prog *old_prog, - struct bpf_prog *new_prog) -{ - return -EINVAL; -} - static inline int cgroup_bpf_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr) { diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 10960cfabea4..81c8620cb4c4 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1093,7 +1093,8 @@ struct bpf_link { struct bpf_link_ops { void (*release)(struct bpf_link *link); void (*dealloc)(struct bpf_link *link); - + int (*update_prog)(struct bpf_link *link, struct bpf_prog *new_prog, + struct bpf_prog *old_prog); }; void bpf_link_init(struct bpf_link *link, const struct bpf_link_ops *ops, 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 @@ static void replace_effective_prog(struct cgroup *cgrp, * * 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) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 7626b8024471..f5358e1462eb 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3645,13 +3645,10 @@ static int link_update(union bpf_attr *attr) goto out_put_progs; } -#ifdef CONFIG_CGROUP_BPF - if (link->ops == &bpf_cgroup_link_lops) { - ret = cgroup_bpf_replace(link, old_prog, new_prog); - goto out_put_progs; - } -#endif - ret = -EINVAL; + if (link->ops->update_prog) + ret = link->ops->update_prog(link, new_prog, old_prog); + else + ret = EINVAL; out_put_progs: if (old_prog) diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 06b5ea9d899d..557a9b9d2244 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -6508,33 +6508,6 @@ int cgroup_bpf_attach(struct cgroup *cgrp, return ret; } -int cgroup_bpf_replace(struct bpf_link *link, struct bpf_prog *old_prog, - struct bpf_prog *new_prog) -{ - struct bpf_cgroup_link *cg_link; - int ret; - - if (link->ops != &bpf_cgroup_link_lops) - return -EINVAL; - - 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; -} - int cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog, enum bpf_attach_type type) {