1127 lines
29 KiB
C
1127 lines
29 KiB
C
/*
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* Functions to manage eBPF programs attached to cgroups
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*
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* Copyright (c) 2016 Daniel Mack
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*
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* This file is subject to the terms and conditions of version 2 of the GNU
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* General Public License. See the file COPYING in the main directory of the
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* Linux distribution for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/atomic.h>
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#include <linux/cgroup.h>
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#include <linux/filter.h>
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#include <linux/slab.h>
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#include <linux/sysctl.h>
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#include <linux/string.h>
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#include <linux/bpf.h>
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#include <linux/bpf-cgroup.h>
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#include <net/sock.h>
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DEFINE_STATIC_KEY_FALSE(cgroup_bpf_enabled_key);
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EXPORT_SYMBOL(cgroup_bpf_enabled_key);
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/**
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* cgroup_bpf_put() - put references of all bpf programs
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* @cgrp: the cgroup to modify
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*/
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void cgroup_bpf_put(struct cgroup *cgrp)
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{
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enum bpf_cgroup_storage_type stype;
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unsigned int type;
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for (type = 0; type < ARRAY_SIZE(cgrp->bpf.progs); type++) {
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struct list_head *progs = &cgrp->bpf.progs[type];
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struct bpf_prog_list *pl, *tmp;
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list_for_each_entry_safe(pl, tmp, progs, node) {
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list_del(&pl->node);
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bpf_prog_put(pl->prog);
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for_each_cgroup_storage_type(stype) {
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bpf_cgroup_storage_unlink(pl->storage[stype]);
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bpf_cgroup_storage_free(pl->storage[stype]);
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}
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kfree(pl);
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static_branch_dec(&cgroup_bpf_enabled_key);
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}
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bpf_prog_array_free(cgrp->bpf.effective[type]);
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}
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}
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/* count number of elements in the list.
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* it's slow but the list cannot be long
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*/
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static u32 prog_list_length(struct list_head *head)
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{
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struct bpf_prog_list *pl;
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u32 cnt = 0;
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list_for_each_entry(pl, head, node) {
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if (!pl->prog)
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continue;
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cnt++;
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}
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return cnt;
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}
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/* if parent has non-overridable prog attached,
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* disallow attaching new programs to the descendent cgroup.
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* if parent has overridable or multi-prog, allow attaching
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*/
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static bool hierarchy_allows_attach(struct cgroup *cgrp,
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enum bpf_attach_type type,
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u32 new_flags)
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{
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struct cgroup *p;
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p = cgroup_parent(cgrp);
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if (!p)
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return true;
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do {
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u32 flags = p->bpf.flags[type];
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u32 cnt;
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if (flags & BPF_F_ALLOW_MULTI)
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return true;
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cnt = prog_list_length(&p->bpf.progs[type]);
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WARN_ON_ONCE(cnt > 1);
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if (cnt == 1)
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return !!(flags & BPF_F_ALLOW_OVERRIDE);
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p = cgroup_parent(p);
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} while (p);
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return true;
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}
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/* compute a chain of effective programs for a given cgroup:
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* start from the list of programs in this cgroup and add
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* all parent programs.
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* Note that parent's F_ALLOW_OVERRIDE-type program is yielding
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* to programs in this cgroup
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*/
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static int compute_effective_progs(struct cgroup *cgrp,
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enum bpf_attach_type type,
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struct bpf_prog_array __rcu **array)
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{
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enum bpf_cgroup_storage_type stype;
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struct bpf_prog_array *progs;
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struct bpf_prog_list *pl;
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struct cgroup *p = cgrp;
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int cnt = 0;
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/* count number of effective programs by walking parents */
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do {
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if (cnt == 0 || (p->bpf.flags[type] & BPF_F_ALLOW_MULTI))
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cnt += prog_list_length(&p->bpf.progs[type]);
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p = cgroup_parent(p);
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} while (p);
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progs = bpf_prog_array_alloc(cnt, GFP_KERNEL);
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if (!progs)
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return -ENOMEM;
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/* populate the array with effective progs */
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cnt = 0;
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p = cgrp;
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do {
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if (cnt > 0 && !(p->bpf.flags[type] & BPF_F_ALLOW_MULTI))
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continue;
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list_for_each_entry(pl, &p->bpf.progs[type], node) {
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if (!pl->prog)
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continue;
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progs->items[cnt].prog = pl->prog;
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for_each_cgroup_storage_type(stype)
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progs->items[cnt].cgroup_storage[stype] =
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pl->storage[stype];
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cnt++;
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}
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} while ((p = cgroup_parent(p)));
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rcu_assign_pointer(*array, progs);
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return 0;
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}
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static void activate_effective_progs(struct cgroup *cgrp,
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enum bpf_attach_type type,
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struct bpf_prog_array __rcu *array)
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{
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struct bpf_prog_array __rcu *old_array;
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old_array = xchg(&cgrp->bpf.effective[type], array);
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/* free prog array after grace period, since __cgroup_bpf_run_*()
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* might be still walking the array
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*/
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bpf_prog_array_free(old_array);
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}
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/**
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* cgroup_bpf_inherit() - inherit effective programs from parent
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* @cgrp: the cgroup to modify
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*/
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int cgroup_bpf_inherit(struct cgroup *cgrp)
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{
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/* has to use marco instead of const int, since compiler thinks
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* that array below is variable length
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*/
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#define NR ARRAY_SIZE(cgrp->bpf.effective)
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struct bpf_prog_array __rcu *arrays[NR] = {};
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int i;
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for (i = 0; i < NR; i++)
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INIT_LIST_HEAD(&cgrp->bpf.progs[i]);
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for (i = 0; i < NR; i++)
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if (compute_effective_progs(cgrp, i, &arrays[i]))
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goto cleanup;
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for (i = 0; i < NR; i++)
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activate_effective_progs(cgrp, i, arrays[i]);
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return 0;
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cleanup:
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for (i = 0; i < NR; i++)
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bpf_prog_array_free(arrays[i]);
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return -ENOMEM;
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}
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static int update_effective_progs(struct cgroup *cgrp,
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enum bpf_attach_type type)
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{
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struct cgroup_subsys_state *css;
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int err;
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/* allocate and recompute effective prog arrays */
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css_for_each_descendant_pre(css, &cgrp->self) {
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struct cgroup *desc = container_of(css, struct cgroup, self);
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err = compute_effective_progs(desc, type, &desc->bpf.inactive);
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if (err)
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goto cleanup;
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}
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/* all allocations were successful. Activate all prog arrays */
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css_for_each_descendant_pre(css, &cgrp->self) {
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struct cgroup *desc = container_of(css, struct cgroup, self);
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activate_effective_progs(desc, type, desc->bpf.inactive);
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desc->bpf.inactive = NULL;
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}
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return 0;
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cleanup:
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/* oom while computing effective. Free all computed effective arrays
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* since they were not activated
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*/
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css_for_each_descendant_pre(css, &cgrp->self) {
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struct cgroup *desc = container_of(css, struct cgroup, self);
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bpf_prog_array_free(desc->bpf.inactive);
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desc->bpf.inactive = NULL;
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}
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return err;
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}
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#define BPF_CGROUP_MAX_PROGS 64
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/**
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* __cgroup_bpf_attach() - Attach the program to a cgroup, and
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* propagate the change to descendants
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* @cgrp: The cgroup which descendants to traverse
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* @prog: A program to attach
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* @type: Type of attach operation
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* @flags: Option flags
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*
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* Must be called with cgroup_mutex held.
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*/
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int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
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enum bpf_attach_type type, u32 flags)
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{
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struct list_head *progs = &cgrp->bpf.progs[type];
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struct bpf_prog *old_prog = NULL;
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struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE],
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*old_storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {NULL};
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enum bpf_cgroup_storage_type stype;
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struct bpf_prog_list *pl;
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bool pl_was_allocated;
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int err;
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if ((flags & BPF_F_ALLOW_OVERRIDE) && (flags & BPF_F_ALLOW_MULTI))
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/* invalid combination */
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return -EINVAL;
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if (!hierarchy_allows_attach(cgrp, type, flags))
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return -EPERM;
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if (!list_empty(progs) && cgrp->bpf.flags[type] != flags)
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/* Disallow attaching non-overridable on top
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* of existing overridable in this cgroup.
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* Disallow attaching multi-prog if overridable or none
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*/
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return -EPERM;
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if (prog_list_length(progs) >= BPF_CGROUP_MAX_PROGS)
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return -E2BIG;
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for_each_cgroup_storage_type(stype) {
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storage[stype] = bpf_cgroup_storage_alloc(prog, stype);
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if (IS_ERR(storage[stype])) {
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storage[stype] = NULL;
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for_each_cgroup_storage_type(stype)
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bpf_cgroup_storage_free(storage[stype]);
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return -ENOMEM;
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}
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}
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if (flags & BPF_F_ALLOW_MULTI) {
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list_for_each_entry(pl, progs, node) {
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if (pl->prog == prog) {
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/* disallow attaching the same prog twice */
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for_each_cgroup_storage_type(stype)
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bpf_cgroup_storage_free(storage[stype]);
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return -EINVAL;
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}
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}
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pl = kmalloc(sizeof(*pl), GFP_KERNEL);
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if (!pl) {
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for_each_cgroup_storage_type(stype)
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bpf_cgroup_storage_free(storage[stype]);
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return -ENOMEM;
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}
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pl_was_allocated = true;
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pl->prog = prog;
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for_each_cgroup_storage_type(stype)
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pl->storage[stype] = storage[stype];
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list_add_tail(&pl->node, progs);
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} else {
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if (list_empty(progs)) {
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pl = kmalloc(sizeof(*pl), GFP_KERNEL);
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if (!pl) {
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for_each_cgroup_storage_type(stype)
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bpf_cgroup_storage_free(storage[stype]);
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return -ENOMEM;
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}
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pl_was_allocated = true;
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list_add_tail(&pl->node, progs);
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} else {
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pl = list_first_entry(progs, typeof(*pl), node);
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old_prog = pl->prog;
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for_each_cgroup_storage_type(stype) {
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old_storage[stype] = pl->storage[stype];
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bpf_cgroup_storage_unlink(old_storage[stype]);
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}
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pl_was_allocated = false;
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}
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pl->prog = prog;
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for_each_cgroup_storage_type(stype)
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pl->storage[stype] = storage[stype];
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}
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cgrp->bpf.flags[type] = flags;
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err = update_effective_progs(cgrp, type);
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if (err)
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goto cleanup;
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static_branch_inc(&cgroup_bpf_enabled_key);
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for_each_cgroup_storage_type(stype) {
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if (!old_storage[stype])
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continue;
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bpf_cgroup_storage_free(old_storage[stype]);
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}
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if (old_prog) {
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bpf_prog_put(old_prog);
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static_branch_dec(&cgroup_bpf_enabled_key);
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}
|
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for_each_cgroup_storage_type(stype)
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bpf_cgroup_storage_link(storage[stype], cgrp, type);
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return 0;
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cleanup:
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/* and cleanup the prog list */
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pl->prog = old_prog;
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for_each_cgroup_storage_type(stype) {
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bpf_cgroup_storage_free(pl->storage[stype]);
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pl->storage[stype] = old_storage[stype];
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bpf_cgroup_storage_link(old_storage[stype], cgrp, type);
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}
|
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if (pl_was_allocated) {
|
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list_del(&pl->node);
|
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kfree(pl);
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}
|
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return err;
|
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}
|
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|
|
/**
|
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* __cgroup_bpf_detach() - Detach the program from a cgroup, and
|
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* propagate the change to descendants
|
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* @cgrp: The cgroup which descendants to traverse
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* @prog: A program to detach or NULL
|
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* @type: Type of detach operation
|
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*
|
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* Must be called with cgroup_mutex held.
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*/
|
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int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
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enum bpf_attach_type type)
|
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{
|
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struct list_head *progs = &cgrp->bpf.progs[type];
|
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enum bpf_cgroup_storage_type stype;
|
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u32 flags = cgrp->bpf.flags[type];
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struct bpf_prog *old_prog = NULL;
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struct bpf_prog_list *pl;
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int err;
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|
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if (flags & BPF_F_ALLOW_MULTI) {
|
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if (!prog)
|
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/* to detach MULTI prog the user has to specify valid FD
|
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* of the program to be detached
|
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*/
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return -EINVAL;
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} else {
|
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if (list_empty(progs))
|
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/* report error when trying to detach and nothing is attached */
|
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return -ENOENT;
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}
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|
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if (flags & BPF_F_ALLOW_MULTI) {
|
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/* find the prog and detach it */
|
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list_for_each_entry(pl, progs, node) {
|
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if (pl->prog != prog)
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continue;
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old_prog = prog;
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/* mark it deleted, so it's ignored while
|
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* recomputing effective
|
|
*/
|
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pl->prog = NULL;
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break;
|
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}
|
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if (!old_prog)
|
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return -ENOENT;
|
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} else {
|
|
/* to maintain backward compatibility NONE and OVERRIDE cgroups
|
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* allow detaching with invalid FD (prog==NULL)
|
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*/
|
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pl = list_first_entry(progs, typeof(*pl), node);
|
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old_prog = pl->prog;
|
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pl->prog = NULL;
|
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}
|
|
|
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err = update_effective_progs(cgrp, type);
|
|
if (err)
|
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goto cleanup;
|
|
|
|
/* now can actually delete it from this cgroup list */
|
|
list_del(&pl->node);
|
|
for_each_cgroup_storage_type(stype) {
|
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bpf_cgroup_storage_unlink(pl->storage[stype]);
|
|
bpf_cgroup_storage_free(pl->storage[stype]);
|
|
}
|
|
kfree(pl);
|
|
if (list_empty(progs))
|
|
/* last program was detached, reset flags to zero */
|
|
cgrp->bpf.flags[type] = 0;
|
|
|
|
bpf_prog_put(old_prog);
|
|
static_branch_dec(&cgroup_bpf_enabled_key);
|
|
return 0;
|
|
|
|
cleanup:
|
|
/* and restore back old_prog */
|
|
pl->prog = old_prog;
|
|
return err;
|
|
}
|
|
|
|
/* Must be called with cgroup_mutex held to avoid races. */
|
|
int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
|
|
union bpf_attr __user *uattr)
|
|
{
|
|
__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
|
|
enum bpf_attach_type type = attr->query.attach_type;
|
|
struct list_head *progs = &cgrp->bpf.progs[type];
|
|
u32 flags = cgrp->bpf.flags[type];
|
|
int cnt, ret = 0, i;
|
|
|
|
if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE)
|
|
cnt = bpf_prog_array_length(cgrp->bpf.effective[type]);
|
|
else
|
|
cnt = prog_list_length(progs);
|
|
|
|
if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
|
|
return -EFAULT;
|
|
if (copy_to_user(&uattr->query.prog_cnt, &cnt, sizeof(cnt)))
|
|
return -EFAULT;
|
|
if (attr->query.prog_cnt == 0 || !prog_ids || !cnt)
|
|
/* return early if user requested only program count + flags */
|
|
return 0;
|
|
if (attr->query.prog_cnt < cnt) {
|
|
cnt = attr->query.prog_cnt;
|
|
ret = -ENOSPC;
|
|
}
|
|
|
|
if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE) {
|
|
return bpf_prog_array_copy_to_user(cgrp->bpf.effective[type],
|
|
prog_ids, cnt);
|
|
} else {
|
|
struct bpf_prog_list *pl;
|
|
u32 id;
|
|
|
|
i = 0;
|
|
list_for_each_entry(pl, progs, node) {
|
|
id = pl->prog->aux->id;
|
|
if (copy_to_user(prog_ids + i, &id, sizeof(id)))
|
|
return -EFAULT;
|
|
if (++i == cnt)
|
|
break;
|
|
}
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
int cgroup_bpf_prog_attach(const union bpf_attr *attr,
|
|
enum bpf_prog_type ptype, struct bpf_prog *prog)
|
|
{
|
|
struct cgroup *cgrp;
|
|
int ret;
|
|
|
|
cgrp = cgroup_get_from_fd(attr->target_fd);
|
|
if (IS_ERR(cgrp))
|
|
return PTR_ERR(cgrp);
|
|
|
|
ret = cgroup_bpf_attach(cgrp, prog, attr->attach_type,
|
|
attr->attach_flags);
|
|
cgroup_put(cgrp);
|
|
return ret;
|
|
}
|
|
|
|
int cgroup_bpf_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype)
|
|
{
|
|
struct bpf_prog *prog;
|
|
struct cgroup *cgrp;
|
|
int ret;
|
|
|
|
cgrp = cgroup_get_from_fd(attr->target_fd);
|
|
if (IS_ERR(cgrp))
|
|
return PTR_ERR(cgrp);
|
|
|
|
prog = bpf_prog_get_type(attr->attach_bpf_fd, ptype);
|
|
if (IS_ERR(prog))
|
|
prog = NULL;
|
|
|
|
ret = cgroup_bpf_detach(cgrp, prog, attr->attach_type, 0);
|
|
if (prog)
|
|
bpf_prog_put(prog);
|
|
|
|
cgroup_put(cgrp);
|
|
return ret;
|
|
}
|
|
|
|
int cgroup_bpf_prog_query(const union bpf_attr *attr,
|
|
union bpf_attr __user *uattr)
|
|
{
|
|
struct cgroup *cgrp;
|
|
int ret;
|
|
|
|
cgrp = cgroup_get_from_fd(attr->query.target_fd);
|
|
if (IS_ERR(cgrp))
|
|
return PTR_ERR(cgrp);
|
|
|
|
ret = cgroup_bpf_query(cgrp, attr, uattr);
|
|
|
|
cgroup_put(cgrp);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* __cgroup_bpf_run_filter_skb() - Run a program for packet filtering
|
|
* @sk: The socket sending or receiving traffic
|
|
* @skb: The skb that is being sent or received
|
|
* @type: The type of program to be exectuted
|
|
*
|
|
* If no socket is passed, or the socket is not of type INET or INET6,
|
|
* this function does nothing and returns 0.
|
|
*
|
|
* The program type passed in via @type must be suitable for network
|
|
* filtering. No further check is performed to assert that.
|
|
*
|
|
* This function will return %-EPERM if any if an attached program was found
|
|
* and if it returned != 1 during execution. In all other cases, 0 is returned.
|
|
*/
|
|
int __cgroup_bpf_run_filter_skb(struct sock *sk,
|
|
struct sk_buff *skb,
|
|
enum bpf_attach_type type)
|
|
{
|
|
unsigned int offset = skb->data - skb_network_header(skb);
|
|
struct sock *save_sk;
|
|
void *saved_data_end;
|
|
struct cgroup *cgrp;
|
|
int ret;
|
|
|
|
if (!sk || !sk_fullsock(sk))
|
|
return 0;
|
|
|
|
if (sk->sk_family != AF_INET && sk->sk_family != AF_INET6)
|
|
return 0;
|
|
|
|
cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
|
|
save_sk = skb->sk;
|
|
skb->sk = sk;
|
|
__skb_push(skb, offset);
|
|
|
|
/* compute pointers for the bpf prog */
|
|
bpf_compute_and_save_data_end(skb, &saved_data_end);
|
|
|
|
ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], skb,
|
|
__bpf_prog_run_save_cb);
|
|
bpf_restore_data_end(skb, saved_data_end);
|
|
__skb_pull(skb, offset);
|
|
skb->sk = save_sk;
|
|
return ret == 1 ? 0 : -EPERM;
|
|
}
|
|
EXPORT_SYMBOL(__cgroup_bpf_run_filter_skb);
|
|
|
|
/**
|
|
* __cgroup_bpf_run_filter_sk() - Run a program on a sock
|
|
* @sk: sock structure to manipulate
|
|
* @type: The type of program to be exectuted
|
|
*
|
|
* socket is passed is expected to be of type INET or INET6.
|
|
*
|
|
* The program type passed in via @type must be suitable for sock
|
|
* filtering. No further check is performed to assert that.
|
|
*
|
|
* This function will return %-EPERM if any if an attached program was found
|
|
* and if it returned != 1 during execution. In all other cases, 0 is returned.
|
|
*/
|
|
int __cgroup_bpf_run_filter_sk(struct sock *sk,
|
|
enum bpf_attach_type type)
|
|
{
|
|
struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
|
|
int ret;
|
|
|
|
ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], sk, BPF_PROG_RUN);
|
|
return ret == 1 ? 0 : -EPERM;
|
|
}
|
|
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sk);
|
|
|
|
/**
|
|
* __cgroup_bpf_run_filter_sock_addr() - Run a program on a sock and
|
|
* provided by user sockaddr
|
|
* @sk: sock struct that will use sockaddr
|
|
* @uaddr: sockaddr struct provided by user
|
|
* @type: The type of program to be exectuted
|
|
* @t_ctx: Pointer to attach type specific context
|
|
*
|
|
* socket is expected to be of type INET or INET6.
|
|
*
|
|
* This function will return %-EPERM if an attached program is found and
|
|
* returned value != 1 during execution. In all other cases, 0 is returned.
|
|
*/
|
|
int __cgroup_bpf_run_filter_sock_addr(struct sock *sk,
|
|
struct sockaddr *uaddr,
|
|
enum bpf_attach_type type,
|
|
void *t_ctx)
|
|
{
|
|
struct bpf_sock_addr_kern ctx = {
|
|
.sk = sk,
|
|
.uaddr = uaddr,
|
|
.t_ctx = t_ctx,
|
|
};
|
|
struct sockaddr_storage unspec;
|
|
struct cgroup *cgrp;
|
|
int ret;
|
|
|
|
/* Check socket family since not all sockets represent network
|
|
* endpoint (e.g. AF_UNIX).
|
|
*/
|
|
if (sk->sk_family != AF_INET && sk->sk_family != AF_INET6)
|
|
return 0;
|
|
|
|
if (!ctx.uaddr) {
|
|
memset(&unspec, 0, sizeof(unspec));
|
|
ctx.uaddr = (struct sockaddr *)&unspec;
|
|
}
|
|
|
|
cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
|
|
ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], &ctx, BPF_PROG_RUN);
|
|
|
|
return ret == 1 ? 0 : -EPERM;
|
|
}
|
|
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_addr);
|
|
|
|
/**
|
|
* __cgroup_bpf_run_filter_sock_ops() - Run a program on a sock
|
|
* @sk: socket to get cgroup from
|
|
* @sock_ops: bpf_sock_ops_kern struct to pass to program. Contains
|
|
* sk with connection information (IP addresses, etc.) May not contain
|
|
* cgroup info if it is a req sock.
|
|
* @type: The type of program to be exectuted
|
|
*
|
|
* socket passed is expected to be of type INET or INET6.
|
|
*
|
|
* The program type passed in via @type must be suitable for sock_ops
|
|
* filtering. No further check is performed to assert that.
|
|
*
|
|
* This function will return %-EPERM if any if an attached program was found
|
|
* and if it returned != 1 during execution. In all other cases, 0 is returned.
|
|
*/
|
|
int __cgroup_bpf_run_filter_sock_ops(struct sock *sk,
|
|
struct bpf_sock_ops_kern *sock_ops,
|
|
enum bpf_attach_type type)
|
|
{
|
|
struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
|
|
int ret;
|
|
|
|
ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], sock_ops,
|
|
BPF_PROG_RUN);
|
|
return ret == 1 ? 0 : -EPERM;
|
|
}
|
|
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_ops);
|
|
|
|
int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
|
|
short access, enum bpf_attach_type type)
|
|
{
|
|
struct cgroup *cgrp;
|
|
struct bpf_cgroup_dev_ctx ctx = {
|
|
.access_type = (access << 16) | dev_type,
|
|
.major = major,
|
|
.minor = minor,
|
|
};
|
|
int allow = 1;
|
|
|
|
rcu_read_lock();
|
|
cgrp = task_dfl_cgroup(current);
|
|
allow = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], &ctx,
|
|
BPF_PROG_RUN);
|
|
rcu_read_unlock();
|
|
|
|
return !allow;
|
|
}
|
|
EXPORT_SYMBOL(__cgroup_bpf_check_dev_permission);
|
|
|
|
static const struct bpf_func_proto *
|
|
cgroup_base_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
|
|
{
|
|
switch (func_id) {
|
|
case BPF_FUNC_map_lookup_elem:
|
|
return &bpf_map_lookup_elem_proto;
|
|
case BPF_FUNC_map_update_elem:
|
|
return &bpf_map_update_elem_proto;
|
|
case BPF_FUNC_map_delete_elem:
|
|
return &bpf_map_delete_elem_proto;
|
|
case BPF_FUNC_get_current_uid_gid:
|
|
return &bpf_get_current_uid_gid_proto;
|
|
case BPF_FUNC_get_local_storage:
|
|
return &bpf_get_local_storage_proto;
|
|
case BPF_FUNC_get_current_cgroup_id:
|
|
return &bpf_get_current_cgroup_id_proto;
|
|
case BPF_FUNC_trace_printk:
|
|
if (capable(CAP_SYS_ADMIN))
|
|
return bpf_get_trace_printk_proto();
|
|
/* fall through */
|
|
default:
|
|
return NULL;
|
|
}
|
|
}
|
|
|
|
static const struct bpf_func_proto *
|
|
cgroup_dev_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
|
|
{
|
|
return cgroup_base_func_proto(func_id, prog);
|
|
}
|
|
|
|
static bool cgroup_dev_is_valid_access(int off, int size,
|
|
enum bpf_access_type type,
|
|
const struct bpf_prog *prog,
|
|
struct bpf_insn_access_aux *info)
|
|
{
|
|
const int size_default = sizeof(__u32);
|
|
|
|
if (type == BPF_WRITE)
|
|
return false;
|
|
|
|
if (off < 0 || off + size > sizeof(struct bpf_cgroup_dev_ctx))
|
|
return false;
|
|
/* The verifier guarantees that size > 0. */
|
|
if (off % size != 0)
|
|
return false;
|
|
|
|
switch (off) {
|
|
case bpf_ctx_range(struct bpf_cgroup_dev_ctx, access_type):
|
|
bpf_ctx_record_field_size(info, size_default);
|
|
if (!bpf_ctx_narrow_access_ok(off, size, size_default))
|
|
return false;
|
|
break;
|
|
default:
|
|
if (size != size_default)
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
const struct bpf_prog_ops cg_dev_prog_ops = {
|
|
};
|
|
|
|
const struct bpf_verifier_ops cg_dev_verifier_ops = {
|
|
.get_func_proto = cgroup_dev_func_proto,
|
|
.is_valid_access = cgroup_dev_is_valid_access,
|
|
};
|
|
|
|
/**
|
|
* __cgroup_bpf_run_filter_sysctl - Run a program on sysctl
|
|
*
|
|
* @head: sysctl table header
|
|
* @table: sysctl table
|
|
* @write: sysctl is being read (= 0) or written (= 1)
|
|
* @buf: pointer to buffer passed by user space
|
|
* @pcount: value-result argument: value is size of buffer pointed to by @buf,
|
|
* result is size of @new_buf if program set new value, initial value
|
|
* otherwise
|
|
* @ppos: value-result argument: value is position at which read from or write
|
|
* to sysctl is happening, result is new position if program overrode it,
|
|
* initial value otherwise
|
|
* @new_buf: pointer to pointer to new buffer that will be allocated if program
|
|
* overrides new value provided by user space on sysctl write
|
|
* NOTE: it's caller responsibility to free *new_buf if it was set
|
|
* @type: type of program to be executed
|
|
*
|
|
* Program is run when sysctl is being accessed, either read or written, and
|
|
* can allow or deny such access.
|
|
*
|
|
* This function will return %-EPERM if an attached program is found and
|
|
* returned value != 1 during execution. In all other cases 0 is returned.
|
|
*/
|
|
int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
|
|
struct ctl_table *table, int write,
|
|
void __user *buf, size_t *pcount,
|
|
loff_t *ppos, void **new_buf,
|
|
enum bpf_attach_type type)
|
|
{
|
|
struct bpf_sysctl_kern ctx = {
|
|
.head = head,
|
|
.table = table,
|
|
.write = write,
|
|
.ppos = ppos,
|
|
.cur_val = NULL,
|
|
.cur_len = PAGE_SIZE,
|
|
.new_val = NULL,
|
|
.new_len = 0,
|
|
.new_updated = 0,
|
|
};
|
|
struct cgroup *cgrp;
|
|
int ret;
|
|
|
|
ctx.cur_val = kmalloc_track_caller(ctx.cur_len, GFP_KERNEL);
|
|
if (ctx.cur_val) {
|
|
mm_segment_t old_fs;
|
|
loff_t pos = 0;
|
|
|
|
old_fs = get_fs();
|
|
set_fs(KERNEL_DS);
|
|
if (table->proc_handler(table, 0, (void __user *)ctx.cur_val,
|
|
&ctx.cur_len, &pos)) {
|
|
/* Let BPF program decide how to proceed. */
|
|
ctx.cur_len = 0;
|
|
}
|
|
set_fs(old_fs);
|
|
} else {
|
|
/* Let BPF program decide how to proceed. */
|
|
ctx.cur_len = 0;
|
|
}
|
|
|
|
if (write && buf && *pcount) {
|
|
/* BPF program should be able to override new value with a
|
|
* buffer bigger than provided by user.
|
|
*/
|
|
ctx.new_val = kmalloc_track_caller(PAGE_SIZE, GFP_KERNEL);
|
|
ctx.new_len = min(PAGE_SIZE, *pcount);
|
|
if (!ctx.new_val ||
|
|
copy_from_user(ctx.new_val, buf, ctx.new_len))
|
|
/* Let BPF program decide how to proceed. */
|
|
ctx.new_len = 0;
|
|
}
|
|
|
|
rcu_read_lock();
|
|
cgrp = task_dfl_cgroup(current);
|
|
ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], &ctx, BPF_PROG_RUN);
|
|
rcu_read_unlock();
|
|
|
|
kfree(ctx.cur_val);
|
|
|
|
if (ret == 1 && ctx.new_updated) {
|
|
*new_buf = ctx.new_val;
|
|
*pcount = ctx.new_len;
|
|
} else {
|
|
kfree(ctx.new_val);
|
|
}
|
|
|
|
return ret == 1 ? 0 : -EPERM;
|
|
}
|
|
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sysctl);
|
|
|
|
static ssize_t sysctl_cpy_dir(const struct ctl_dir *dir, char **bufp,
|
|
size_t *lenp)
|
|
{
|
|
ssize_t tmp_ret = 0, ret;
|
|
|
|
if (dir->header.parent) {
|
|
tmp_ret = sysctl_cpy_dir(dir->header.parent, bufp, lenp);
|
|
if (tmp_ret < 0)
|
|
return tmp_ret;
|
|
}
|
|
|
|
ret = strscpy(*bufp, dir->header.ctl_table[0].procname, *lenp);
|
|
if (ret < 0)
|
|
return ret;
|
|
*bufp += ret;
|
|
*lenp -= ret;
|
|
ret += tmp_ret;
|
|
|
|
/* Avoid leading slash. */
|
|
if (!ret)
|
|
return ret;
|
|
|
|
tmp_ret = strscpy(*bufp, "/", *lenp);
|
|
if (tmp_ret < 0)
|
|
return tmp_ret;
|
|
*bufp += tmp_ret;
|
|
*lenp -= tmp_ret;
|
|
|
|
return ret + tmp_ret;
|
|
}
|
|
|
|
BPF_CALL_4(bpf_sysctl_get_name, struct bpf_sysctl_kern *, ctx, char *, buf,
|
|
size_t, buf_len, u64, flags)
|
|
{
|
|
ssize_t tmp_ret = 0, ret;
|
|
|
|
if (!buf)
|
|
return -EINVAL;
|
|
|
|
if (!(flags & BPF_F_SYSCTL_BASE_NAME)) {
|
|
if (!ctx->head)
|
|
return -EINVAL;
|
|
tmp_ret = sysctl_cpy_dir(ctx->head->parent, &buf, &buf_len);
|
|
if (tmp_ret < 0)
|
|
return tmp_ret;
|
|
}
|
|
|
|
ret = strscpy(buf, ctx->table->procname, buf_len);
|
|
|
|
return ret < 0 ? ret : tmp_ret + ret;
|
|
}
|
|
|
|
static const struct bpf_func_proto bpf_sysctl_get_name_proto = {
|
|
.func = bpf_sysctl_get_name,
|
|
.gpl_only = false,
|
|
.ret_type = RET_INTEGER,
|
|
.arg1_type = ARG_PTR_TO_CTX,
|
|
.arg2_type = ARG_PTR_TO_MEM,
|
|
.arg3_type = ARG_CONST_SIZE,
|
|
.arg4_type = ARG_ANYTHING,
|
|
};
|
|
|
|
static int copy_sysctl_value(char *dst, size_t dst_len, char *src,
|
|
size_t src_len)
|
|
{
|
|
if (!dst)
|
|
return -EINVAL;
|
|
|
|
if (!dst_len)
|
|
return -E2BIG;
|
|
|
|
if (!src || !src_len) {
|
|
memset(dst, 0, dst_len);
|
|
return -EINVAL;
|
|
}
|
|
|
|
memcpy(dst, src, min(dst_len, src_len));
|
|
|
|
if (dst_len > src_len) {
|
|
memset(dst + src_len, '\0', dst_len - src_len);
|
|
return src_len;
|
|
}
|
|
|
|
dst[dst_len - 1] = '\0';
|
|
|
|
return -E2BIG;
|
|
}
|
|
|
|
BPF_CALL_3(bpf_sysctl_get_current_value, struct bpf_sysctl_kern *, ctx,
|
|
char *, buf, size_t, buf_len)
|
|
{
|
|
return copy_sysctl_value(buf, buf_len, ctx->cur_val, ctx->cur_len);
|
|
}
|
|
|
|
static const struct bpf_func_proto bpf_sysctl_get_current_value_proto = {
|
|
.func = bpf_sysctl_get_current_value,
|
|
.gpl_only = false,
|
|
.ret_type = RET_INTEGER,
|
|
.arg1_type = ARG_PTR_TO_CTX,
|
|
.arg2_type = ARG_PTR_TO_UNINIT_MEM,
|
|
.arg3_type = ARG_CONST_SIZE,
|
|
};
|
|
|
|
BPF_CALL_3(bpf_sysctl_get_new_value, struct bpf_sysctl_kern *, ctx, char *, buf,
|
|
size_t, buf_len)
|
|
{
|
|
if (!ctx->write) {
|
|
if (buf && buf_len)
|
|
memset(buf, '\0', buf_len);
|
|
return -EINVAL;
|
|
}
|
|
return copy_sysctl_value(buf, buf_len, ctx->new_val, ctx->new_len);
|
|
}
|
|
|
|
static const struct bpf_func_proto bpf_sysctl_get_new_value_proto = {
|
|
.func = bpf_sysctl_get_new_value,
|
|
.gpl_only = false,
|
|
.ret_type = RET_INTEGER,
|
|
.arg1_type = ARG_PTR_TO_CTX,
|
|
.arg2_type = ARG_PTR_TO_UNINIT_MEM,
|
|
.arg3_type = ARG_CONST_SIZE,
|
|
};
|
|
|
|
BPF_CALL_3(bpf_sysctl_set_new_value, struct bpf_sysctl_kern *, ctx,
|
|
const char *, buf, size_t, buf_len)
|
|
{
|
|
if (!ctx->write || !ctx->new_val || !ctx->new_len || !buf || !buf_len)
|
|
return -EINVAL;
|
|
|
|
if (buf_len > PAGE_SIZE - 1)
|
|
return -E2BIG;
|
|
|
|
memcpy(ctx->new_val, buf, buf_len);
|
|
ctx->new_len = buf_len;
|
|
ctx->new_updated = 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct bpf_func_proto bpf_sysctl_set_new_value_proto = {
|
|
.func = bpf_sysctl_set_new_value,
|
|
.gpl_only = false,
|
|
.ret_type = RET_INTEGER,
|
|
.arg1_type = ARG_PTR_TO_CTX,
|
|
.arg2_type = ARG_PTR_TO_MEM,
|
|
.arg3_type = ARG_CONST_SIZE,
|
|
};
|
|
|
|
static const struct bpf_func_proto *
|
|
sysctl_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
|
|
{
|
|
switch (func_id) {
|
|
case BPF_FUNC_strtol:
|
|
return &bpf_strtol_proto;
|
|
case BPF_FUNC_strtoul:
|
|
return &bpf_strtoul_proto;
|
|
case BPF_FUNC_sysctl_get_name:
|
|
return &bpf_sysctl_get_name_proto;
|
|
case BPF_FUNC_sysctl_get_current_value:
|
|
return &bpf_sysctl_get_current_value_proto;
|
|
case BPF_FUNC_sysctl_get_new_value:
|
|
return &bpf_sysctl_get_new_value_proto;
|
|
case BPF_FUNC_sysctl_set_new_value:
|
|
return &bpf_sysctl_set_new_value_proto;
|
|
default:
|
|
return cgroup_base_func_proto(func_id, prog);
|
|
}
|
|
}
|
|
|
|
static bool sysctl_is_valid_access(int off, int size, enum bpf_access_type type,
|
|
const struct bpf_prog *prog,
|
|
struct bpf_insn_access_aux *info)
|
|
{
|
|
const int size_default = sizeof(__u32);
|
|
|
|
if (off < 0 || off + size > sizeof(struct bpf_sysctl) || off % size)
|
|
return false;
|
|
|
|
switch (off) {
|
|
case offsetof(struct bpf_sysctl, write):
|
|
if (type != BPF_READ)
|
|
return false;
|
|
bpf_ctx_record_field_size(info, size_default);
|
|
return bpf_ctx_narrow_access_ok(off, size, size_default);
|
|
case offsetof(struct bpf_sysctl, file_pos):
|
|
if (type == BPF_READ) {
|
|
bpf_ctx_record_field_size(info, size_default);
|
|
return bpf_ctx_narrow_access_ok(off, size, size_default);
|
|
} else {
|
|
return size == size_default;
|
|
}
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
static u32 sysctl_convert_ctx_access(enum bpf_access_type type,
|
|
const struct bpf_insn *si,
|
|
struct bpf_insn *insn_buf,
|
|
struct bpf_prog *prog, u32 *target_size)
|
|
{
|
|
struct bpf_insn *insn = insn_buf;
|
|
|
|
switch (si->off) {
|
|
case offsetof(struct bpf_sysctl, write):
|
|
*insn++ = BPF_LDX_MEM(
|
|
BPF_SIZE(si->code), si->dst_reg, si->src_reg,
|
|
bpf_target_off(struct bpf_sysctl_kern, write,
|
|
FIELD_SIZEOF(struct bpf_sysctl_kern,
|
|
write),
|
|
target_size));
|
|
break;
|
|
case offsetof(struct bpf_sysctl, file_pos):
|
|
/* ppos is a pointer so it should be accessed via indirect
|
|
* loads and stores. Also for stores additional temporary
|
|
* register is used since neither src_reg nor dst_reg can be
|
|
* overridden.
|
|
*/
|
|
if (type == BPF_WRITE) {
|
|
int treg = BPF_REG_9;
|
|
|
|
if (si->src_reg == treg || si->dst_reg == treg)
|
|
--treg;
|
|
if (si->src_reg == treg || si->dst_reg == treg)
|
|
--treg;
|
|
*insn++ = BPF_STX_MEM(
|
|
BPF_DW, si->dst_reg, treg,
|
|
offsetof(struct bpf_sysctl_kern, tmp_reg));
|
|
*insn++ = BPF_LDX_MEM(
|
|
BPF_FIELD_SIZEOF(struct bpf_sysctl_kern, ppos),
|
|
treg, si->dst_reg,
|
|
offsetof(struct bpf_sysctl_kern, ppos));
|
|
*insn++ = BPF_STX_MEM(
|
|
BPF_SIZEOF(u32), treg, si->src_reg, 0);
|
|
*insn++ = BPF_LDX_MEM(
|
|
BPF_DW, treg, si->dst_reg,
|
|
offsetof(struct bpf_sysctl_kern, tmp_reg));
|
|
} else {
|
|
*insn++ = BPF_LDX_MEM(
|
|
BPF_FIELD_SIZEOF(struct bpf_sysctl_kern, ppos),
|
|
si->dst_reg, si->src_reg,
|
|
offsetof(struct bpf_sysctl_kern, ppos));
|
|
*insn++ = BPF_LDX_MEM(
|
|
BPF_SIZE(si->code), si->dst_reg, si->dst_reg, 0);
|
|
}
|
|
*target_size = sizeof(u32);
|
|
break;
|
|
}
|
|
|
|
return insn - insn_buf;
|
|
}
|
|
|
|
const struct bpf_verifier_ops cg_sysctl_verifier_ops = {
|
|
.get_func_proto = sysctl_func_proto,
|
|
.is_valid_access = sysctl_is_valid_access,
|
|
.convert_ctx_access = sysctl_convert_ctx_access,
|
|
};
|
|
|
|
const struct bpf_prog_ops cg_sysctl_prog_ops = {
|
|
};
|