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![Sargun Dhillon](/assets/img/avatar_default.png)
This adds a bpf helper that's similar to the skb_in_cgroup helper to check whether the probe is currently executing in the context of a specific subset of the cgroupsv2 hierarchy. It does this based on membership test for a cgroup arraymap. It is invalid to call this in an interrupt, and it'll return an error. The helper is primarily to be used in debugging activities for containers, where you may have multiple programs running in a given top-level "container". Signed-off-by: Sargun Dhillon <sargun@sargun.me> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Tejun Heo <tj@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
582 lines
14 KiB
C
582 lines
14 KiB
C
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/bpf.h>
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#include <linux/err.h>
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#include <linux/vmalloc.h>
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#include <linux/slab.h>
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#include <linux/mm.h>
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#include <linux/filter.h>
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#include <linux/perf_event.h>
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static void bpf_array_free_percpu(struct bpf_array *array)
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{
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int i;
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for (i = 0; i < array->map.max_entries; i++)
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free_percpu(array->pptrs[i]);
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}
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static int bpf_array_alloc_percpu(struct bpf_array *array)
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{
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void __percpu *ptr;
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int i;
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for (i = 0; i < array->map.max_entries; i++) {
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ptr = __alloc_percpu_gfp(array->elem_size, 8,
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GFP_USER | __GFP_NOWARN);
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if (!ptr) {
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bpf_array_free_percpu(array);
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return -ENOMEM;
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}
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array->pptrs[i] = ptr;
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}
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return 0;
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}
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/* Called from syscall */
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static struct bpf_map *array_map_alloc(union bpf_attr *attr)
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{
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bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
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struct bpf_array *array;
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u64 array_size;
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u32 elem_size;
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/* check sanity of attributes */
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if (attr->max_entries == 0 || attr->key_size != 4 ||
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attr->value_size == 0 || attr->map_flags)
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return ERR_PTR(-EINVAL);
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if (attr->value_size >= 1 << (KMALLOC_SHIFT_MAX - 1))
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/* if value_size is bigger, the user space won't be able to
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* access the elements.
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*/
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return ERR_PTR(-E2BIG);
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elem_size = round_up(attr->value_size, 8);
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array_size = sizeof(*array);
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if (percpu)
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array_size += (u64) attr->max_entries * sizeof(void *);
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else
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array_size += (u64) attr->max_entries * elem_size;
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/* make sure there is no u32 overflow later in round_up() */
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if (array_size >= U32_MAX - PAGE_SIZE)
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return ERR_PTR(-ENOMEM);
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/* allocate all map elements and zero-initialize them */
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array = kzalloc(array_size, GFP_USER | __GFP_NOWARN);
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if (!array) {
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array = vzalloc(array_size);
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if (!array)
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return ERR_PTR(-ENOMEM);
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}
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/* copy mandatory map attributes */
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array->map.map_type = attr->map_type;
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array->map.key_size = attr->key_size;
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array->map.value_size = attr->value_size;
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array->map.max_entries = attr->max_entries;
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array->elem_size = elem_size;
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if (!percpu)
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goto out;
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array_size += (u64) attr->max_entries * elem_size * num_possible_cpus();
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if (array_size >= U32_MAX - PAGE_SIZE ||
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elem_size > PCPU_MIN_UNIT_SIZE || bpf_array_alloc_percpu(array)) {
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kvfree(array);
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return ERR_PTR(-ENOMEM);
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}
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out:
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array->map.pages = round_up(array_size, PAGE_SIZE) >> PAGE_SHIFT;
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return &array->map;
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}
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/* Called from syscall or from eBPF program */
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static void *array_map_lookup_elem(struct bpf_map *map, void *key)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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u32 index = *(u32 *)key;
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if (unlikely(index >= array->map.max_entries))
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return NULL;
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return array->value + array->elem_size * index;
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}
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/* Called from eBPF program */
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static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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u32 index = *(u32 *)key;
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if (unlikely(index >= array->map.max_entries))
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return NULL;
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return this_cpu_ptr(array->pptrs[index]);
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}
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int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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u32 index = *(u32 *)key;
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void __percpu *pptr;
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int cpu, off = 0;
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u32 size;
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if (unlikely(index >= array->map.max_entries))
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return -ENOENT;
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/* per_cpu areas are zero-filled and bpf programs can only
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* access 'value_size' of them, so copying rounded areas
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* will not leak any kernel data
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*/
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size = round_up(map->value_size, 8);
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rcu_read_lock();
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pptr = array->pptrs[index];
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for_each_possible_cpu(cpu) {
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bpf_long_memcpy(value + off, per_cpu_ptr(pptr, cpu), size);
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off += size;
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}
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rcu_read_unlock();
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return 0;
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}
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/* Called from syscall */
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static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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u32 index = *(u32 *)key;
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u32 *next = (u32 *)next_key;
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if (index >= array->map.max_entries) {
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*next = 0;
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return 0;
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}
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if (index == array->map.max_entries - 1)
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return -ENOENT;
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*next = index + 1;
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return 0;
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}
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/* Called from syscall or from eBPF program */
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static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
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u64 map_flags)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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u32 index = *(u32 *)key;
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if (unlikely(map_flags > BPF_EXIST))
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/* unknown flags */
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return -EINVAL;
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if (unlikely(index >= array->map.max_entries))
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/* all elements were pre-allocated, cannot insert a new one */
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return -E2BIG;
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if (unlikely(map_flags == BPF_NOEXIST))
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/* all elements already exist */
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return -EEXIST;
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if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
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memcpy(this_cpu_ptr(array->pptrs[index]),
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value, map->value_size);
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else
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memcpy(array->value + array->elem_size * index,
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value, map->value_size);
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return 0;
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}
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int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
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u64 map_flags)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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u32 index = *(u32 *)key;
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void __percpu *pptr;
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int cpu, off = 0;
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u32 size;
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if (unlikely(map_flags > BPF_EXIST))
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/* unknown flags */
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return -EINVAL;
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if (unlikely(index >= array->map.max_entries))
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/* all elements were pre-allocated, cannot insert a new one */
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return -E2BIG;
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if (unlikely(map_flags == BPF_NOEXIST))
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/* all elements already exist */
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return -EEXIST;
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/* the user space will provide round_up(value_size, 8) bytes that
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* will be copied into per-cpu area. bpf programs can only access
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* value_size of it. During lookup the same extra bytes will be
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* returned or zeros which were zero-filled by percpu_alloc,
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* so no kernel data leaks possible
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*/
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size = round_up(map->value_size, 8);
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rcu_read_lock();
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pptr = array->pptrs[index];
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for_each_possible_cpu(cpu) {
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bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value + off, size);
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off += size;
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}
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rcu_read_unlock();
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return 0;
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}
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/* Called from syscall or from eBPF program */
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static int array_map_delete_elem(struct bpf_map *map, void *key)
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{
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return -EINVAL;
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}
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/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
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static void array_map_free(struct bpf_map *map)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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/* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
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* so the programs (can be more than one that used this map) were
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* disconnected from events. Wait for outstanding programs to complete
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* and free the array
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*/
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synchronize_rcu();
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if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
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bpf_array_free_percpu(array);
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kvfree(array);
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}
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static const struct bpf_map_ops array_ops = {
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.map_alloc = array_map_alloc,
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.map_free = array_map_free,
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.map_get_next_key = array_map_get_next_key,
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.map_lookup_elem = array_map_lookup_elem,
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.map_update_elem = array_map_update_elem,
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.map_delete_elem = array_map_delete_elem,
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};
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static struct bpf_map_type_list array_type __read_mostly = {
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.ops = &array_ops,
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.type = BPF_MAP_TYPE_ARRAY,
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};
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static const struct bpf_map_ops percpu_array_ops = {
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.map_alloc = array_map_alloc,
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.map_free = array_map_free,
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.map_get_next_key = array_map_get_next_key,
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.map_lookup_elem = percpu_array_map_lookup_elem,
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.map_update_elem = array_map_update_elem,
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.map_delete_elem = array_map_delete_elem,
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};
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static struct bpf_map_type_list percpu_array_type __read_mostly = {
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.ops = &percpu_array_ops,
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.type = BPF_MAP_TYPE_PERCPU_ARRAY,
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};
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static int __init register_array_map(void)
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{
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bpf_register_map_type(&array_type);
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bpf_register_map_type(&percpu_array_type);
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return 0;
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}
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late_initcall(register_array_map);
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static struct bpf_map *fd_array_map_alloc(union bpf_attr *attr)
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{
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/* only file descriptors can be stored in this type of map */
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if (attr->value_size != sizeof(u32))
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return ERR_PTR(-EINVAL);
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return array_map_alloc(attr);
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}
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static void fd_array_map_free(struct bpf_map *map)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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int i;
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synchronize_rcu();
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/* make sure it's empty */
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for (i = 0; i < array->map.max_entries; i++)
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BUG_ON(array->ptrs[i] != NULL);
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kvfree(array);
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}
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static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)
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{
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return NULL;
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}
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/* only called from syscall */
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int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file,
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void *key, void *value, u64 map_flags)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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void *new_ptr, *old_ptr;
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u32 index = *(u32 *)key, ufd;
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if (map_flags != BPF_ANY)
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return -EINVAL;
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if (index >= array->map.max_entries)
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return -E2BIG;
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ufd = *(u32 *)value;
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new_ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
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if (IS_ERR(new_ptr))
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return PTR_ERR(new_ptr);
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old_ptr = xchg(array->ptrs + index, new_ptr);
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if (old_ptr)
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map->ops->map_fd_put_ptr(old_ptr);
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return 0;
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}
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static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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void *old_ptr;
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u32 index = *(u32 *)key;
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if (index >= array->map.max_entries)
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return -E2BIG;
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old_ptr = xchg(array->ptrs + index, NULL);
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if (old_ptr) {
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map->ops->map_fd_put_ptr(old_ptr);
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return 0;
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} else {
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return -ENOENT;
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}
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}
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static void *prog_fd_array_get_ptr(struct bpf_map *map,
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struct file *map_file, int fd)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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struct bpf_prog *prog = bpf_prog_get(fd);
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if (IS_ERR(prog))
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return prog;
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if (!bpf_prog_array_compatible(array, prog)) {
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bpf_prog_put(prog);
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return ERR_PTR(-EINVAL);
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}
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return prog;
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}
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static void prog_fd_array_put_ptr(void *ptr)
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{
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bpf_prog_put(ptr);
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}
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/* decrement refcnt of all bpf_progs that are stored in this map */
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void bpf_fd_array_map_clear(struct bpf_map *map)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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int i;
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for (i = 0; i < array->map.max_entries; i++)
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fd_array_map_delete_elem(map, &i);
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}
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static const struct bpf_map_ops prog_array_ops = {
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.map_alloc = fd_array_map_alloc,
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.map_free = fd_array_map_free,
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.map_get_next_key = array_map_get_next_key,
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.map_lookup_elem = fd_array_map_lookup_elem,
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.map_delete_elem = fd_array_map_delete_elem,
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.map_fd_get_ptr = prog_fd_array_get_ptr,
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.map_fd_put_ptr = prog_fd_array_put_ptr,
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};
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static struct bpf_map_type_list prog_array_type __read_mostly = {
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.ops = &prog_array_ops,
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.type = BPF_MAP_TYPE_PROG_ARRAY,
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};
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static int __init register_prog_array_map(void)
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{
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bpf_register_map_type(&prog_array_type);
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return 0;
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}
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late_initcall(register_prog_array_map);
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static struct bpf_event_entry *bpf_event_entry_gen(struct file *perf_file,
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struct file *map_file)
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{
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struct bpf_event_entry *ee;
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ee = kzalloc(sizeof(*ee), GFP_ATOMIC);
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if (ee) {
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ee->event = perf_file->private_data;
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ee->perf_file = perf_file;
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ee->map_file = map_file;
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}
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return ee;
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}
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static void __bpf_event_entry_free(struct rcu_head *rcu)
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{
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struct bpf_event_entry *ee;
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ee = container_of(rcu, struct bpf_event_entry, rcu);
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fput(ee->perf_file);
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kfree(ee);
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}
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static void bpf_event_entry_free_rcu(struct bpf_event_entry *ee)
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{
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call_rcu(&ee->rcu, __bpf_event_entry_free);
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}
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static void *perf_event_fd_array_get_ptr(struct bpf_map *map,
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struct file *map_file, int fd)
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{
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const struct perf_event_attr *attr;
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struct bpf_event_entry *ee;
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struct perf_event *event;
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struct file *perf_file;
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perf_file = perf_event_get(fd);
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if (IS_ERR(perf_file))
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return perf_file;
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event = perf_file->private_data;
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ee = ERR_PTR(-EINVAL);
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attr = perf_event_attrs(event);
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if (IS_ERR(attr) || attr->inherit)
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goto err_out;
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switch (attr->type) {
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case PERF_TYPE_SOFTWARE:
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if (attr->config != PERF_COUNT_SW_BPF_OUTPUT)
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goto err_out;
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/* fall-through */
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case PERF_TYPE_RAW:
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case PERF_TYPE_HARDWARE:
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ee = bpf_event_entry_gen(perf_file, map_file);
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if (ee)
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return ee;
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ee = ERR_PTR(-ENOMEM);
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/* fall-through */
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default:
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break;
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}
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err_out:
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fput(perf_file);
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return ee;
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}
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|
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static void perf_event_fd_array_put_ptr(void *ptr)
|
|
{
|
|
bpf_event_entry_free_rcu(ptr);
|
|
}
|
|
|
|
static void perf_event_fd_array_release(struct bpf_map *map,
|
|
struct file *map_file)
|
|
{
|
|
struct bpf_array *array = container_of(map, struct bpf_array, map);
|
|
struct bpf_event_entry *ee;
|
|
int i;
|
|
|
|
rcu_read_lock();
|
|
for (i = 0; i < array->map.max_entries; i++) {
|
|
ee = READ_ONCE(array->ptrs[i]);
|
|
if (ee && ee->map_file == map_file)
|
|
fd_array_map_delete_elem(map, &i);
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
static const struct bpf_map_ops perf_event_array_ops = {
|
|
.map_alloc = fd_array_map_alloc,
|
|
.map_free = fd_array_map_free,
|
|
.map_get_next_key = array_map_get_next_key,
|
|
.map_lookup_elem = fd_array_map_lookup_elem,
|
|
.map_delete_elem = fd_array_map_delete_elem,
|
|
.map_fd_get_ptr = perf_event_fd_array_get_ptr,
|
|
.map_fd_put_ptr = perf_event_fd_array_put_ptr,
|
|
.map_release = perf_event_fd_array_release,
|
|
};
|
|
|
|
static struct bpf_map_type_list perf_event_array_type __read_mostly = {
|
|
.ops = &perf_event_array_ops,
|
|
.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
|
|
};
|
|
|
|
static int __init register_perf_event_array_map(void)
|
|
{
|
|
bpf_register_map_type(&perf_event_array_type);
|
|
return 0;
|
|
}
|
|
late_initcall(register_perf_event_array_map);
|
|
|
|
#ifdef CONFIG_CGROUPS
|
|
static void *cgroup_fd_array_get_ptr(struct bpf_map *map,
|
|
struct file *map_file /* not used */,
|
|
int fd)
|
|
{
|
|
return cgroup_get_from_fd(fd);
|
|
}
|
|
|
|
static void cgroup_fd_array_put_ptr(void *ptr)
|
|
{
|
|
/* cgroup_put free cgrp after a rcu grace period */
|
|
cgroup_put(ptr);
|
|
}
|
|
|
|
static void cgroup_fd_array_free(struct bpf_map *map)
|
|
{
|
|
bpf_fd_array_map_clear(map);
|
|
fd_array_map_free(map);
|
|
}
|
|
|
|
static const struct bpf_map_ops cgroup_array_ops = {
|
|
.map_alloc = fd_array_map_alloc,
|
|
.map_free = cgroup_fd_array_free,
|
|
.map_get_next_key = array_map_get_next_key,
|
|
.map_lookup_elem = fd_array_map_lookup_elem,
|
|
.map_delete_elem = fd_array_map_delete_elem,
|
|
.map_fd_get_ptr = cgroup_fd_array_get_ptr,
|
|
.map_fd_put_ptr = cgroup_fd_array_put_ptr,
|
|
};
|
|
|
|
static struct bpf_map_type_list cgroup_array_type __read_mostly = {
|
|
.ops = &cgroup_array_ops,
|
|
.type = BPF_MAP_TYPE_CGROUP_ARRAY,
|
|
};
|
|
|
|
static int __init register_cgroup_array_map(void)
|
|
{
|
|
bpf_register_map_type(&cgroup_array_type);
|
|
return 0;
|
|
}
|
|
late_initcall(register_cgroup_array_map);
|
|
#endif
|