diff --git a/include/linux/bpf.h b/include/linux/bpf.h index a010c5c40649..f52c74774e9d 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -793,6 +793,7 @@ struct bpf_link { struct bpf_link_ops { void (*release)(struct bpf_link *link); void (*dealloc)(struct bpf_link *link); + int (*detach)(struct bpf_link *link); int (*update_prog)(struct bpf_link *link, struct bpf_prog *new_prog, struct bpf_prog *old_prog); void (*show_fdinfo)(const struct bpf_link *link, struct seq_file *seq); diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 4045de9e3156..c4f0ff9e03b8 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -117,6 +117,7 @@ enum bpf_cmd { BPF_LINK_GET_NEXT_ID, BPF_ENABLE_STATS, BPF_ITER_CREATE, + BPF_LINK_DETACH, }; enum bpf_map_type { @@ -634,6 +635,10 @@ union bpf_attr { __u32 old_prog_fd; } link_update; + struct { + __u32 link_fd; + } link_detach; + struct { /* struct used by BPF_ENABLE_STATS command */ __u32 type; } enable_stats; diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c index 23720fff8107..46884aed3ae0 100644 --- a/kernel/bpf/cgroup.c +++ b/kernel/bpf/cgroup.c @@ -814,6 +814,7 @@ static void bpf_cgroup_link_release(struct bpf_link *link) { struct bpf_cgroup_link *cg_link = container_of(link, struct bpf_cgroup_link, link); + struct cgroup *cg; /* link might have been auto-detached by dying cgroup already, * in that case our work is done here @@ -832,8 +833,12 @@ static void bpf_cgroup_link_release(struct bpf_link *link) WARN_ON(__cgroup_bpf_detach(cg_link->cgroup, NULL, cg_link, cg_link->type)); + cg = cg_link->cgroup; + cg_link->cgroup = NULL; + mutex_unlock(&cgroup_mutex); - cgroup_put(cg_link->cgroup); + + cgroup_put(cg); } static void bpf_cgroup_link_dealloc(struct bpf_link *link) @@ -844,6 +849,13 @@ static void bpf_cgroup_link_dealloc(struct bpf_link *link) kfree(cg_link); } +static int bpf_cgroup_link_detach(struct bpf_link *link) +{ + bpf_cgroup_link_release(link); + + return 0; +} + static void bpf_cgroup_link_show_fdinfo(const struct bpf_link *link, struct seq_file *seq) { @@ -883,6 +895,7 @@ static int bpf_cgroup_link_fill_link_info(const struct bpf_link *link, static const struct bpf_link_ops bpf_cgroup_link_lops = { .release = bpf_cgroup_link_release, .dealloc = bpf_cgroup_link_dealloc, + .detach = bpf_cgroup_link_detach, .update_prog = cgroup_bpf_replace, .show_fdinfo = bpf_cgroup_link_show_fdinfo, .fill_link_info = bpf_cgroup_link_fill_link_info, diff --git a/kernel/bpf/net_namespace.c b/kernel/bpf/net_namespace.c index 38b368bccda2..27b82ac3be82 100644 --- a/kernel/bpf/net_namespace.c +++ b/kernel/bpf/net_namespace.c @@ -113,9 +113,16 @@ static void bpf_netns_link_release(struct bpf_link *link) bpf_prog_array_free(old_array); out_unlock: + net_link->net = NULL; mutex_unlock(&netns_bpf_mutex); } +static int bpf_netns_link_detach(struct bpf_link *link) +{ + bpf_netns_link_release(link); + return 0; +} + static void bpf_netns_link_dealloc(struct bpf_link *link) { struct bpf_netns_link *net_link = @@ -199,6 +206,7 @@ static void bpf_netns_link_show_fdinfo(const struct bpf_link *link, static const struct bpf_link_ops bpf_netns_link_ops = { .release = bpf_netns_link_release, .dealloc = bpf_netns_link_dealloc, + .detach = bpf_netns_link_detach, .update_prog = bpf_netns_link_update_prog, .fill_link_info = bpf_netns_link_fill_info, .show_fdinfo = bpf_netns_link_show_fdinfo, diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index e12a5608a450..acfc3ced1e4b 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3989,6 +3989,29 @@ out_put_link: return ret; } +#define BPF_LINK_DETACH_LAST_FIELD link_detach.link_fd + +static int link_detach(union bpf_attr *attr) +{ + struct bpf_link *link; + int ret; + + if (CHECK_ATTR(BPF_LINK_DETACH)) + return -EINVAL; + + link = bpf_link_get_from_fd(attr->link_detach.link_fd); + if (IS_ERR(link)) + return PTR_ERR(link); + + if (link->ops->detach) + ret = link->ops->detach(link); + else + ret = -EOPNOTSUPP; + + bpf_link_put(link); + return ret; +} + static int bpf_link_inc_not_zero(struct bpf_link *link) { return atomic64_fetch_add_unless(&link->refcnt, 1, 0) ? 0 : -ENOENT; @@ -4238,6 +4261,9 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz case BPF_ITER_CREATE: err = bpf_iter_create(&attr); break; + case BPF_LINK_DETACH: + err = link_detach(&attr); + break; default: err = -EINVAL; break; diff --git a/net/core/dev.c b/net/core/dev.c index 07658f51afe5..56110c1328d4 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -8937,12 +8937,20 @@ static void bpf_xdp_link_release(struct bpf_link *link) /* if racing with net_device's tear down, xdp_link->dev might be * already NULL, in which case link was already auto-detached */ - if (xdp_link->dev) + if (xdp_link->dev) { WARN_ON(dev_xdp_detach_link(xdp_link->dev, NULL, xdp_link)); + xdp_link->dev = NULL; + } rtnl_unlock(); } +static int bpf_xdp_link_detach(struct bpf_link *link) +{ + bpf_xdp_link_release(link); + return 0; +} + static void bpf_xdp_link_dealloc(struct bpf_link *link) { struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link); @@ -9024,6 +9032,7 @@ out_unlock: static const struct bpf_link_ops bpf_xdp_link_lops = { .release = bpf_xdp_link_release, .dealloc = bpf_xdp_link_dealloc, + .detach = bpf_xdp_link_detach, .show_fdinfo = bpf_xdp_link_show_fdinfo, .fill_link_info = bpf_xdp_link_fill_link_info, .update_prog = bpf_xdp_link_update,