Message ID | 153986858555.9127.14517764371945179514.stgit@kernel |
---|---|
State | Accepted, archived |
Delegated to: | BPF Maintainers |
Headers | show |
Series | Implement queue/stack maps | expand |
On Thu, Oct 18, 2018 at 6:16 AM Mauricio Vasquez B <mauricio.vasquez@polito.it> wrote: > > Queue/stack maps implement a FIFO/LIFO data storage for ebpf programs. > These maps support peek, pop and push operations that are exposed to eBPF > programs through the new bpf_map[peek/pop/push] helpers. Those operations > are exposed to userspace applications through the already existing > syscalls in the following way: > > BPF_MAP_LOOKUP_ELEM -> peek > BPF_MAP_LOOKUP_AND_DELETE_ELEM -> pop > BPF_MAP_UPDATE_ELEM -> push > > Queue/stack maps are implemented using a buffer, tail and head indexes, > hence BPF_F_NO_PREALLOC is not supported. > > As opposite to other maps, queue and stack do not use RCU for protecting > maps values, the bpf_map[peek/pop] have a ARG_PTR_TO_UNINIT_MAP_VALUE > argument that is a pointer to a memory zone where to save the value of a > map. Basically the same as ARG_PTR_TO_UNINIT_MEM, but the size has not > be passed as an extra argument. > > Our main motivation for implementing queue/stack maps was to keep track > of a pool of elements, like network ports in a SNAT, however we forsee > other use cases, like for exampling saving last N kernel events in a map > and then analysing from userspace. > > Signed-off-by: Mauricio Vasquez B <mauricio.vasquez@polito.it> Acked-by: Song Liu <songliubraving@fb.com> > --- > include/linux/bpf.h | 6 + > include/linux/bpf_types.h | 2 > include/uapi/linux/bpf.h | 29 ++++ > kernel/bpf/Makefile | 2 > kernel/bpf/core.c | 3 > kernel/bpf/helpers.c | 43 ++++++ > kernel/bpf/queue_stack_maps.c | 288 +++++++++++++++++++++++++++++++++++++++++ > kernel/bpf/syscall.c | 6 + > kernel/bpf/verifier.c | 19 +++ > net/core/filter.c | 6 + > 10 files changed, 401 insertions(+), 3 deletions(-) > create mode 100644 kernel/bpf/queue_stack_maps.c > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index 0f8b863e0229..33014ae73103 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -39,6 +39,9 @@ struct bpf_map_ops { > void *(*map_lookup_elem)(struct bpf_map *map, void *key); > int (*map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags); > int (*map_delete_elem)(struct bpf_map *map, void *key); > + int (*map_push_elem)(struct bpf_map *map, void *value, u64 flags); > + int (*map_pop_elem)(struct bpf_map *map, void *value); > + int (*map_peek_elem)(struct bpf_map *map, void *value); > > /* funcs called by prog_array and perf_event_array map */ > void *(*map_fd_get_ptr)(struct bpf_map *map, struct file *map_file, > @@ -811,6 +814,9 @@ static inline int bpf_fd_reuseport_array_update_elem(struct bpf_map *map, > extern const struct bpf_func_proto bpf_map_lookup_elem_proto; > extern const struct bpf_func_proto bpf_map_update_elem_proto; > extern const struct bpf_func_proto bpf_map_delete_elem_proto; > +extern const struct bpf_func_proto bpf_map_push_elem_proto; > +extern const struct bpf_func_proto bpf_map_pop_elem_proto; > +extern const struct bpf_func_proto bpf_map_peek_elem_proto; > > extern const struct bpf_func_proto bpf_get_prandom_u32_proto; > extern const struct bpf_func_proto bpf_get_smp_processor_id_proto; > diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h > index 7bad4e1947ed..44d9ab4809bd 100644 > --- a/include/linux/bpf_types.h > +++ b/include/linux/bpf_types.h > @@ -69,3 +69,5 @@ BPF_MAP_TYPE(BPF_MAP_TYPE_XSKMAP, xsk_map_ops) > BPF_MAP_TYPE(BPF_MAP_TYPE_REUSEPORT_SOCKARRAY, reuseport_array_ops) > #endif > #endif > +BPF_MAP_TYPE(BPF_MAP_TYPE_QUEUE, queue_map_ops) > +BPF_MAP_TYPE(BPF_MAP_TYPE_STACK, stack_map_ops) > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > index f9187b41dff6..b8fc161c5b78 100644 > --- a/include/uapi/linux/bpf.h > +++ b/include/uapi/linux/bpf.h > @@ -128,6 +128,8 @@ enum bpf_map_type { > BPF_MAP_TYPE_CGROUP_STORAGE, > BPF_MAP_TYPE_REUSEPORT_SOCKARRAY, > BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE, > + BPF_MAP_TYPE_QUEUE, > + BPF_MAP_TYPE_STACK, > }; > > enum bpf_prog_type { > @@ -462,6 +464,28 @@ union bpf_attr { > * Return > * 0 on success, or a negative error in case of failure. > * > + * int bpf_map_push_elem(struct bpf_map *map, const void *value, u64 flags) > + * Description > + * Push an element *value* in *map*. *flags* is one of: > + * > + * **BPF_EXIST** > + * If the queue/stack is full, the oldest element is removed to > + * make room for this. > + * Return > + * 0 on success, or a negative error in case of failure. > + * > + * int bpf_map_pop_elem(struct bpf_map *map, void *value) > + * Description > + * Pop an element from *map*. > + * Return > + * 0 on success, or a negative error in case of failure. > + * > + * int bpf_map_peek_elem(struct bpf_map *map, void *value) > + * Description > + * Get an element from *map* without removing it. > + * Return > + * 0 on success, or a negative error in case of failure. > + * > * int bpf_probe_read(void *dst, u32 size, const void *src) > * Description > * For tracing programs, safely attempt to read *size* bytes from > @@ -2303,7 +2327,10 @@ union bpf_attr { > FN(skb_ancestor_cgroup_id), \ > FN(sk_lookup_tcp), \ > FN(sk_lookup_udp), \ > - FN(sk_release), > + FN(sk_release), \ > + FN(map_push_elem), \ > + FN(map_pop_elem), \ > + FN(map_peek_elem), > > /* integer value in 'imm' field of BPF_CALL instruction selects which helper > * function eBPF program intends to call > diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile > index ff8262626b8f..4c2fa3ac56f6 100644 > --- a/kernel/bpf/Makefile > +++ b/kernel/bpf/Makefile > @@ -3,7 +3,7 @@ obj-y := core.o > > obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o > obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o > -obj-$(CONFIG_BPF_SYSCALL) += local_storage.o > +obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o > obj-$(CONFIG_BPF_SYSCALL) += disasm.o > obj-$(CONFIG_BPF_SYSCALL) += btf.o > ifeq ($(CONFIG_NET),y) > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c > index defcf4df6d91..7c7eeea8cffc 100644 > --- a/kernel/bpf/core.c > +++ b/kernel/bpf/core.c > @@ -1783,6 +1783,9 @@ BPF_CALL_0(bpf_user_rnd_u32) > const struct bpf_func_proto bpf_map_lookup_elem_proto __weak; > const struct bpf_func_proto bpf_map_update_elem_proto __weak; > const struct bpf_func_proto bpf_map_delete_elem_proto __weak; > +const struct bpf_func_proto bpf_map_push_elem_proto __weak; > +const struct bpf_func_proto bpf_map_pop_elem_proto __weak; > +const struct bpf_func_proto bpf_map_peek_elem_proto __weak; > > const struct bpf_func_proto bpf_get_prandom_u32_proto __weak; > const struct bpf_func_proto bpf_get_smp_processor_id_proto __weak; > diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c > index 6502115e8f55..ab0d5e3f9892 100644 > --- a/kernel/bpf/helpers.c > +++ b/kernel/bpf/helpers.c > @@ -76,6 +76,49 @@ const struct bpf_func_proto bpf_map_delete_elem_proto = { > .arg2_type = ARG_PTR_TO_MAP_KEY, > }; > > +BPF_CALL_3(bpf_map_push_elem, struct bpf_map *, map, void *, value, u64, flags) > +{ > + return map->ops->map_push_elem(map, value, flags); > +} > + > +const struct bpf_func_proto bpf_map_push_elem_proto = { > + .func = bpf_map_push_elem, > + .gpl_only = false, > + .pkt_access = true, > + .ret_type = RET_INTEGER, > + .arg1_type = ARG_CONST_MAP_PTR, > + .arg2_type = ARG_PTR_TO_MAP_VALUE, > + .arg3_type = ARG_ANYTHING, > +}; > + > +BPF_CALL_2(bpf_map_pop_elem, struct bpf_map *, map, void *, value) > +{ > + return map->ops->map_pop_elem(map, value); > +} > + > +const struct bpf_func_proto bpf_map_pop_elem_proto = { > + .func = bpf_map_pop_elem, > + .gpl_only = false, > + .pkt_access = true, > + .ret_type = RET_INTEGER, > + .arg1_type = ARG_CONST_MAP_PTR, > + .arg2_type = ARG_PTR_TO_UNINIT_MAP_VALUE, > +}; > + > +BPF_CALL_2(bpf_map_peek_elem, struct bpf_map *, map, void *, value) > +{ > + return map->ops->map_peek_elem(map, value); > +} > + > +const struct bpf_func_proto bpf_map_peek_elem_proto = { > + .func = bpf_map_pop_elem, > + .gpl_only = false, > + .pkt_access = true, > + .ret_type = RET_INTEGER, > + .arg1_type = ARG_CONST_MAP_PTR, > + .arg2_type = ARG_PTR_TO_UNINIT_MAP_VALUE, > +}; > + > const struct bpf_func_proto bpf_get_prandom_u32_proto = { > .func = bpf_user_rnd_u32, > .gpl_only = false, > diff --git a/kernel/bpf/queue_stack_maps.c b/kernel/bpf/queue_stack_maps.c > new file mode 100644 > index 000000000000..12a93fb37449 > --- /dev/null > +++ b/kernel/bpf/queue_stack_maps.c > @@ -0,0 +1,288 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * queue_stack_maps.c: BPF queue and stack maps > + * > + * Copyright (c) 2018 Politecnico di Torino > + */ > +#include <linux/bpf.h> > +#include <linux/list.h> > +#include <linux/slab.h> > +#include "percpu_freelist.h" > + > +#define QUEUE_STACK_CREATE_FLAG_MASK \ > + (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY) > + > + > +struct bpf_queue_stack { > + struct bpf_map map; > + raw_spinlock_t lock; > + u32 head, tail; > + u32 size; /* max_entries + 1 */ > + > + char elements[0] __aligned(8); > +}; > + > +static struct bpf_queue_stack *bpf_queue_stack(struct bpf_map *map) > +{ > + return container_of(map, struct bpf_queue_stack, map); > +} > + > +static bool queue_stack_map_is_empty(struct bpf_queue_stack *qs) > +{ > + return qs->head == qs->tail; > +} > + > +static bool queue_stack_map_is_full(struct bpf_queue_stack *qs) > +{ > + u32 head = qs->head + 1; > + > + if (unlikely(head >= qs->size)) > + head = 0; > + > + return head == qs->tail; > +} > + > +/* Called from syscall */ > +static int queue_stack_map_alloc_check(union bpf_attr *attr) > +{ > + /* check sanity of attributes */ > + if (attr->max_entries == 0 || attr->key_size != 0 || > + attr->map_flags & ~QUEUE_STACK_CREATE_FLAG_MASK) > + return -EINVAL; > + > + if (attr->value_size > KMALLOC_MAX_SIZE) > + /* if value_size is bigger, the user space won't be able to > + * access the elements. > + */ > + return -E2BIG; > + > + return 0; > +} > + > +static struct bpf_map *queue_stack_map_alloc(union bpf_attr *attr) > +{ > + int ret, numa_node = bpf_map_attr_numa_node(attr); > + struct bpf_queue_stack *qs; > + u32 size, value_size; > + u64 queue_size, cost; > + > + size = attr->max_entries + 1; > + value_size = attr->value_size; > + > + queue_size = sizeof(*qs) + (u64) value_size * size; > + > + cost = queue_size; > + if (cost >= U32_MAX - PAGE_SIZE) > + return ERR_PTR(-E2BIG); > + > + cost = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT; > + > + ret = bpf_map_precharge_memlock(cost); > + if (ret < 0) > + return ERR_PTR(ret); > + > + qs = bpf_map_area_alloc(queue_size, numa_node); > + if (!qs) > + return ERR_PTR(-ENOMEM); > + > + memset(qs, 0, sizeof(*qs)); > + > + bpf_map_init_from_attr(&qs->map, attr); > + > + qs->map.pages = cost; > + qs->size = size; > + > + raw_spin_lock_init(&qs->lock); > + > + return &qs->map; > +} > + > +/* Called when map->refcnt goes to zero, either from workqueue or from syscall */ > +static void queue_stack_map_free(struct bpf_map *map) > +{ > + struct bpf_queue_stack *qs = bpf_queue_stack(map); > + > + /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0, > + * so the programs (can be more than one that used this map) were > + * disconnected from events. Wait for outstanding critical sections in > + * these programs to complete > + */ > + synchronize_rcu(); > + > + bpf_map_area_free(qs); > +} > + > +static int __queue_map_get(struct bpf_map *map, void *value, bool delete) > +{ > + struct bpf_queue_stack *qs = bpf_queue_stack(map); > + unsigned long flags; > + int err = 0; > + void *ptr; > + > + raw_spin_lock_irqsave(&qs->lock, flags); > + > + if (queue_stack_map_is_empty(qs)) { > + err = -ENOENT; > + goto out; > + } > + > + ptr = &qs->elements[qs->tail * qs->map.value_size]; > + memcpy(value, ptr, qs->map.value_size); > + > + if (delete) { > + if (unlikely(++qs->tail >= qs->size)) > + qs->tail = 0; > + } > + > +out: > + raw_spin_unlock_irqrestore(&qs->lock, flags); > + return err; > +} > + > + > +static int __stack_map_get(struct bpf_map *map, void *value, bool delete) > +{ > + struct bpf_queue_stack *qs = bpf_queue_stack(map); > + unsigned long flags; > + int err = 0; > + void *ptr; > + u32 index; > + > + raw_spin_lock_irqsave(&qs->lock, flags); > + > + if (queue_stack_map_is_empty(qs)) { > + err = -ENOENT; > + goto out; > + } > + > + index = qs->head - 1; > + if (unlikely(index >= qs->size)) > + index = qs->size - 1; > + > + ptr = &qs->elements[index * qs->map.value_size]; > + memcpy(value, ptr, qs->map.value_size); > + > + if (delete) > + qs->head = index; > + > +out: > + raw_spin_unlock_irqrestore(&qs->lock, flags); > + return err; > +} > + > +/* Called from syscall or from eBPF program */ > +static int queue_map_peek_elem(struct bpf_map *map, void *value) > +{ > + return __queue_map_get(map, value, false); > +} > + > +/* Called from syscall or from eBPF program */ > +static int stack_map_peek_elem(struct bpf_map *map, void *value) > +{ > + return __stack_map_get(map, value, false); > +} > + > +/* Called from syscall or from eBPF program */ > +static int queue_map_pop_elem(struct bpf_map *map, void *value) > +{ > + return __queue_map_get(map, value, true); > +} > + > +/* Called from syscall or from eBPF program */ > +static int stack_map_pop_elem(struct bpf_map *map, void *value) > +{ > + return __stack_map_get(map, value, true); > +} > + > +/* Called from syscall or from eBPF program */ > +static int queue_stack_map_push_elem(struct bpf_map *map, void *value, > + u64 flags) > +{ > + struct bpf_queue_stack *qs = bpf_queue_stack(map); > + unsigned long irq_flags; > + int err = 0; > + void *dst; > + > + /* BPF_EXIST is used to force making room for a new element in case the > + * map is full > + */ > + bool replace = (flags & BPF_EXIST); > + > + /* Check supported flags for queue and stack maps */ > + if (flags & BPF_NOEXIST || flags > BPF_EXIST) > + return -EINVAL; > + > + raw_spin_lock_irqsave(&qs->lock, irq_flags); > + > + if (queue_stack_map_is_full(qs)) { > + if (!replace) { > + err = -E2BIG; > + goto out; > + } > + /* advance tail pointer to overwrite oldest element */ > + if (unlikely(++qs->tail >= qs->size)) > + qs->tail = 0; > + } > + > + dst = &qs->elements[qs->head * qs->map.value_size]; > + memcpy(dst, value, qs->map.value_size); > + > + if (unlikely(++qs->head >= qs->size)) > + qs->head = 0; > + > +out: > + raw_spin_unlock_irqrestore(&qs->lock, irq_flags); > + return err; > +} > + > +/* Called from syscall or from eBPF program */ > +static void *queue_stack_map_lookup_elem(struct bpf_map *map, void *key) > +{ > + return NULL; > +} > + > +/* Called from syscall or from eBPF program */ > +static int queue_stack_map_update_elem(struct bpf_map *map, void *key, > + void *value, u64 flags) > +{ > + return -EINVAL; > +} > + > +/* Called from syscall or from eBPF program */ > +static int queue_stack_map_delete_elem(struct bpf_map *map, void *key) > +{ > + return -EINVAL; > +} > + > +/* Called from syscall */ > +static int queue_stack_map_get_next_key(struct bpf_map *map, void *key, > + void *next_key) > +{ > + return -EINVAL; > +} > + > +const struct bpf_map_ops queue_map_ops = { > + .map_alloc_check = queue_stack_map_alloc_check, > + .map_alloc = queue_stack_map_alloc, > + .map_free = queue_stack_map_free, > + .map_lookup_elem = queue_stack_map_lookup_elem, > + .map_update_elem = queue_stack_map_update_elem, > + .map_delete_elem = queue_stack_map_delete_elem, > + .map_push_elem = queue_stack_map_push_elem, > + .map_pop_elem = queue_map_pop_elem, > + .map_peek_elem = queue_map_peek_elem, > + .map_get_next_key = queue_stack_map_get_next_key, > +}; > + > +const struct bpf_map_ops stack_map_ops = { > + .map_alloc_check = queue_stack_map_alloc_check, > + .map_alloc = queue_stack_map_alloc, > + .map_free = queue_stack_map_free, > + .map_lookup_elem = queue_stack_map_lookup_elem, > + .map_update_elem = queue_stack_map_update_elem, > + .map_delete_elem = queue_stack_map_delete_elem, > + .map_push_elem = queue_stack_map_push_elem, > + .map_pop_elem = stack_map_pop_elem, > + .map_peek_elem = stack_map_peek_elem, > + .map_get_next_key = queue_stack_map_get_next_key, > +}; > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > index 78d9dd95e25f..1617407f9ee5 100644 > --- a/kernel/bpf/syscall.c > +++ b/kernel/bpf/syscall.c > @@ -727,6 +727,9 @@ static int map_lookup_elem(union bpf_attr *attr) > err = bpf_fd_htab_map_lookup_elem(map, key, value); > } else if (map->map_type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY) { > err = bpf_fd_reuseport_array_lookup_elem(map, key, value); > + } else if (map->map_type == BPF_MAP_TYPE_QUEUE || > + map->map_type == BPF_MAP_TYPE_STACK) { > + err = map->ops->map_peek_elem(map, value); > } else { > rcu_read_lock(); > ptr = map->ops->map_lookup_elem(map, key); > @@ -857,6 +860,9 @@ static int map_update_elem(union bpf_attr *attr) > /* rcu_read_lock() is not needed */ > err = bpf_fd_reuseport_array_update_elem(map, key, value, > attr->flags); > + } else if (map->map_type == BPF_MAP_TYPE_QUEUE || > + map->map_type == BPF_MAP_TYPE_STACK) { > + err = map->ops->map_push_elem(map, value, attr->flags); > } else { > rcu_read_lock(); > err = map->ops->map_update_elem(map, key, value, attr->flags); > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index d84c91ac3b70..7d6d9cf9ebd5 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -2324,6 +2324,13 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, > if (func_id != BPF_FUNC_sk_select_reuseport) > goto error; > break; > + case BPF_MAP_TYPE_QUEUE: > + case BPF_MAP_TYPE_STACK: > + if (func_id != BPF_FUNC_map_peek_elem && > + func_id != BPF_FUNC_map_pop_elem && > + func_id != BPF_FUNC_map_push_elem) > + goto error; > + break; > default: > break; > } > @@ -2380,6 +2387,13 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, > if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY) > goto error; > break; > + case BPF_FUNC_map_peek_elem: > + case BPF_FUNC_map_pop_elem: > + case BPF_FUNC_map_push_elem: > + if (map->map_type != BPF_MAP_TYPE_QUEUE && > + map->map_type != BPF_MAP_TYPE_STACK) > + goto error; > + break; > default: > break; > } > @@ -2675,7 +2689,10 @@ record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, > if (func_id != BPF_FUNC_tail_call && > func_id != BPF_FUNC_map_lookup_elem && > func_id != BPF_FUNC_map_update_elem && > - func_id != BPF_FUNC_map_delete_elem) > + func_id != BPF_FUNC_map_delete_elem && > + func_id != BPF_FUNC_map_push_elem && > + func_id != BPF_FUNC_map_pop_elem && > + func_id != BPF_FUNC_map_peek_elem) > return 0; > > if (meta->map_ptr == NULL) { > diff --git a/net/core/filter.c b/net/core/filter.c > index 1a3ac6c46873..ea48ec789b5c 100644 > --- a/net/core/filter.c > +++ b/net/core/filter.c > @@ -4876,6 +4876,12 @@ bpf_base_func_proto(enum bpf_func_id func_id) > return &bpf_map_update_elem_proto; > case BPF_FUNC_map_delete_elem: > return &bpf_map_delete_elem_proto; > + case BPF_FUNC_map_push_elem: > + return &bpf_map_push_elem_proto; > + case BPF_FUNC_map_pop_elem: > + return &bpf_map_pop_elem_proto; > + case BPF_FUNC_map_peek_elem: > + return &bpf_map_peek_elem_proto; > case BPF_FUNC_get_prandom_u32: > return &bpf_get_prandom_u32_proto; > case BPF_FUNC_get_smp_processor_id: >
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 0f8b863e0229..33014ae73103 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -39,6 +39,9 @@ struct bpf_map_ops { void *(*map_lookup_elem)(struct bpf_map *map, void *key); int (*map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags); int (*map_delete_elem)(struct bpf_map *map, void *key); + int (*map_push_elem)(struct bpf_map *map, void *value, u64 flags); + int (*map_pop_elem)(struct bpf_map *map, void *value); + int (*map_peek_elem)(struct bpf_map *map, void *value); /* funcs called by prog_array and perf_event_array map */ void *(*map_fd_get_ptr)(struct bpf_map *map, struct file *map_file, @@ -811,6 +814,9 @@ static inline int bpf_fd_reuseport_array_update_elem(struct bpf_map *map, extern const struct bpf_func_proto bpf_map_lookup_elem_proto; extern const struct bpf_func_proto bpf_map_update_elem_proto; extern const struct bpf_func_proto bpf_map_delete_elem_proto; +extern const struct bpf_func_proto bpf_map_push_elem_proto; +extern const struct bpf_func_proto bpf_map_pop_elem_proto; +extern const struct bpf_func_proto bpf_map_peek_elem_proto; extern const struct bpf_func_proto bpf_get_prandom_u32_proto; extern const struct bpf_func_proto bpf_get_smp_processor_id_proto; diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h index 7bad4e1947ed..44d9ab4809bd 100644 --- a/include/linux/bpf_types.h +++ b/include/linux/bpf_types.h @@ -69,3 +69,5 @@ BPF_MAP_TYPE(BPF_MAP_TYPE_XSKMAP, xsk_map_ops) BPF_MAP_TYPE(BPF_MAP_TYPE_REUSEPORT_SOCKARRAY, reuseport_array_ops) #endif #endif +BPF_MAP_TYPE(BPF_MAP_TYPE_QUEUE, queue_map_ops) +BPF_MAP_TYPE(BPF_MAP_TYPE_STACK, stack_map_ops) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index f9187b41dff6..b8fc161c5b78 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -128,6 +128,8 @@ enum bpf_map_type { BPF_MAP_TYPE_CGROUP_STORAGE, BPF_MAP_TYPE_REUSEPORT_SOCKARRAY, BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE, + BPF_MAP_TYPE_QUEUE, + BPF_MAP_TYPE_STACK, }; enum bpf_prog_type { @@ -462,6 +464,28 @@ union bpf_attr { * Return * 0 on success, or a negative error in case of failure. * + * int bpf_map_push_elem(struct bpf_map *map, const void *value, u64 flags) + * Description + * Push an element *value* in *map*. *flags* is one of: + * + * **BPF_EXIST** + * If the queue/stack is full, the oldest element is removed to + * make room for this. + * Return + * 0 on success, or a negative error in case of failure. + * + * int bpf_map_pop_elem(struct bpf_map *map, void *value) + * Description + * Pop an element from *map*. + * Return + * 0 on success, or a negative error in case of failure. + * + * int bpf_map_peek_elem(struct bpf_map *map, void *value) + * Description + * Get an element from *map* without removing it. + * Return + * 0 on success, or a negative error in case of failure. + * * int bpf_probe_read(void *dst, u32 size, const void *src) * Description * For tracing programs, safely attempt to read *size* bytes from @@ -2303,7 +2327,10 @@ union bpf_attr { FN(skb_ancestor_cgroup_id), \ FN(sk_lookup_tcp), \ FN(sk_lookup_udp), \ - FN(sk_release), + FN(sk_release), \ + FN(map_push_elem), \ + FN(map_pop_elem), \ + FN(map_peek_elem), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile index ff8262626b8f..4c2fa3ac56f6 100644 --- a/kernel/bpf/Makefile +++ b/kernel/bpf/Makefile @@ -3,7 +3,7 @@ obj-y := core.o obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o -obj-$(CONFIG_BPF_SYSCALL) += local_storage.o +obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o obj-$(CONFIG_BPF_SYSCALL) += disasm.o obj-$(CONFIG_BPF_SYSCALL) += btf.o ifeq ($(CONFIG_NET),y) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index defcf4df6d91..7c7eeea8cffc 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1783,6 +1783,9 @@ BPF_CALL_0(bpf_user_rnd_u32) const struct bpf_func_proto bpf_map_lookup_elem_proto __weak; const struct bpf_func_proto bpf_map_update_elem_proto __weak; const struct bpf_func_proto bpf_map_delete_elem_proto __weak; +const struct bpf_func_proto bpf_map_push_elem_proto __weak; +const struct bpf_func_proto bpf_map_pop_elem_proto __weak; +const struct bpf_func_proto bpf_map_peek_elem_proto __weak; const struct bpf_func_proto bpf_get_prandom_u32_proto __weak; const struct bpf_func_proto bpf_get_smp_processor_id_proto __weak; diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 6502115e8f55..ab0d5e3f9892 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -76,6 +76,49 @@ const struct bpf_func_proto bpf_map_delete_elem_proto = { .arg2_type = ARG_PTR_TO_MAP_KEY, }; +BPF_CALL_3(bpf_map_push_elem, struct bpf_map *, map, void *, value, u64, flags) +{ + return map->ops->map_push_elem(map, value, flags); +} + +const struct bpf_func_proto bpf_map_push_elem_proto = { + .func = bpf_map_push_elem, + .gpl_only = false, + .pkt_access = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_CONST_MAP_PTR, + .arg2_type = ARG_PTR_TO_MAP_VALUE, + .arg3_type = ARG_ANYTHING, +}; + +BPF_CALL_2(bpf_map_pop_elem, struct bpf_map *, map, void *, value) +{ + return map->ops->map_pop_elem(map, value); +} + +const struct bpf_func_proto bpf_map_pop_elem_proto = { + .func = bpf_map_pop_elem, + .gpl_only = false, + .pkt_access = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_CONST_MAP_PTR, + .arg2_type = ARG_PTR_TO_UNINIT_MAP_VALUE, +}; + +BPF_CALL_2(bpf_map_peek_elem, struct bpf_map *, map, void *, value) +{ + return map->ops->map_peek_elem(map, value); +} + +const struct bpf_func_proto bpf_map_peek_elem_proto = { + .func = bpf_map_pop_elem, + .gpl_only = false, + .pkt_access = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_CONST_MAP_PTR, + .arg2_type = ARG_PTR_TO_UNINIT_MAP_VALUE, +}; + const struct bpf_func_proto bpf_get_prandom_u32_proto = { .func = bpf_user_rnd_u32, .gpl_only = false, diff --git a/kernel/bpf/queue_stack_maps.c b/kernel/bpf/queue_stack_maps.c new file mode 100644 index 000000000000..12a93fb37449 --- /dev/null +++ b/kernel/bpf/queue_stack_maps.c @@ -0,0 +1,288 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * queue_stack_maps.c: BPF queue and stack maps + * + * Copyright (c) 2018 Politecnico di Torino + */ +#include <linux/bpf.h> +#include <linux/list.h> +#include <linux/slab.h> +#include "percpu_freelist.h" + +#define QUEUE_STACK_CREATE_FLAG_MASK \ + (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY) + + +struct bpf_queue_stack { + struct bpf_map map; + raw_spinlock_t lock; + u32 head, tail; + u32 size; /* max_entries + 1 */ + + char elements[0] __aligned(8); +}; + +static struct bpf_queue_stack *bpf_queue_stack(struct bpf_map *map) +{ + return container_of(map, struct bpf_queue_stack, map); +} + +static bool queue_stack_map_is_empty(struct bpf_queue_stack *qs) +{ + return qs->head == qs->tail; +} + +static bool queue_stack_map_is_full(struct bpf_queue_stack *qs) +{ + u32 head = qs->head + 1; + + if (unlikely(head >= qs->size)) + head = 0; + + return head == qs->tail; +} + +/* Called from syscall */ +static int queue_stack_map_alloc_check(union bpf_attr *attr) +{ + /* check sanity of attributes */ + if (attr->max_entries == 0 || attr->key_size != 0 || + attr->map_flags & ~QUEUE_STACK_CREATE_FLAG_MASK) + return -EINVAL; + + if (attr->value_size > KMALLOC_MAX_SIZE) + /* if value_size is bigger, the user space won't be able to + * access the elements. + */ + return -E2BIG; + + return 0; +} + +static struct bpf_map *queue_stack_map_alloc(union bpf_attr *attr) +{ + int ret, numa_node = bpf_map_attr_numa_node(attr); + struct bpf_queue_stack *qs; + u32 size, value_size; + u64 queue_size, cost; + + size = attr->max_entries + 1; + value_size = attr->value_size; + + queue_size = sizeof(*qs) + (u64) value_size * size; + + cost = queue_size; + if (cost >= U32_MAX - PAGE_SIZE) + return ERR_PTR(-E2BIG); + + cost = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT; + + ret = bpf_map_precharge_memlock(cost); + if (ret < 0) + return ERR_PTR(ret); + + qs = bpf_map_area_alloc(queue_size, numa_node); + if (!qs) + return ERR_PTR(-ENOMEM); + + memset(qs, 0, sizeof(*qs)); + + bpf_map_init_from_attr(&qs->map, attr); + + qs->map.pages = cost; + qs->size = size; + + raw_spin_lock_init(&qs->lock); + + return &qs->map; +} + +/* Called when map->refcnt goes to zero, either from workqueue or from syscall */ +static void queue_stack_map_free(struct bpf_map *map) +{ + struct bpf_queue_stack *qs = bpf_queue_stack(map); + + /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0, + * so the programs (can be more than one that used this map) were + * disconnected from events. Wait for outstanding critical sections in + * these programs to complete + */ + synchronize_rcu(); + + bpf_map_area_free(qs); +} + +static int __queue_map_get(struct bpf_map *map, void *value, bool delete) +{ + struct bpf_queue_stack *qs = bpf_queue_stack(map); + unsigned long flags; + int err = 0; + void *ptr; + + raw_spin_lock_irqsave(&qs->lock, flags); + + if (queue_stack_map_is_empty(qs)) { + err = -ENOENT; + goto out; + } + + ptr = &qs->elements[qs->tail * qs->map.value_size]; + memcpy(value, ptr, qs->map.value_size); + + if (delete) { + if (unlikely(++qs->tail >= qs->size)) + qs->tail = 0; + } + +out: + raw_spin_unlock_irqrestore(&qs->lock, flags); + return err; +} + + +static int __stack_map_get(struct bpf_map *map, void *value, bool delete) +{ + struct bpf_queue_stack *qs = bpf_queue_stack(map); + unsigned long flags; + int err = 0; + void *ptr; + u32 index; + + raw_spin_lock_irqsave(&qs->lock, flags); + + if (queue_stack_map_is_empty(qs)) { + err = -ENOENT; + goto out; + } + + index = qs->head - 1; + if (unlikely(index >= qs->size)) + index = qs->size - 1; + + ptr = &qs->elements[index * qs->map.value_size]; + memcpy(value, ptr, qs->map.value_size); + + if (delete) + qs->head = index; + +out: + raw_spin_unlock_irqrestore(&qs->lock, flags); + return err; +} + +/* Called from syscall or from eBPF program */ +static int queue_map_peek_elem(struct bpf_map *map, void *value) +{ + return __queue_map_get(map, value, false); +} + +/* Called from syscall or from eBPF program */ +static int stack_map_peek_elem(struct bpf_map *map, void *value) +{ + return __stack_map_get(map, value, false); +} + +/* Called from syscall or from eBPF program */ +static int queue_map_pop_elem(struct bpf_map *map, void *value) +{ + return __queue_map_get(map, value, true); +} + +/* Called from syscall or from eBPF program */ +static int stack_map_pop_elem(struct bpf_map *map, void *value) +{ + return __stack_map_get(map, value, true); +} + +/* Called from syscall or from eBPF program */ +static int queue_stack_map_push_elem(struct bpf_map *map, void *value, + u64 flags) +{ + struct bpf_queue_stack *qs = bpf_queue_stack(map); + unsigned long irq_flags; + int err = 0; + void *dst; + + /* BPF_EXIST is used to force making room for a new element in case the + * map is full + */ + bool replace = (flags & BPF_EXIST); + + /* Check supported flags for queue and stack maps */ + if (flags & BPF_NOEXIST || flags > BPF_EXIST) + return -EINVAL; + + raw_spin_lock_irqsave(&qs->lock, irq_flags); + + if (queue_stack_map_is_full(qs)) { + if (!replace) { + err = -E2BIG; + goto out; + } + /* advance tail pointer to overwrite oldest element */ + if (unlikely(++qs->tail >= qs->size)) + qs->tail = 0; + } + + dst = &qs->elements[qs->head * qs->map.value_size]; + memcpy(dst, value, qs->map.value_size); + + if (unlikely(++qs->head >= qs->size)) + qs->head = 0; + +out: + raw_spin_unlock_irqrestore(&qs->lock, irq_flags); + return err; +} + +/* Called from syscall or from eBPF program */ +static void *queue_stack_map_lookup_elem(struct bpf_map *map, void *key) +{ + return NULL; +} + +/* Called from syscall or from eBPF program */ +static int queue_stack_map_update_elem(struct bpf_map *map, void *key, + void *value, u64 flags) +{ + return -EINVAL; +} + +/* Called from syscall or from eBPF program */ +static int queue_stack_map_delete_elem(struct bpf_map *map, void *key) +{ + return -EINVAL; +} + +/* Called from syscall */ +static int queue_stack_map_get_next_key(struct bpf_map *map, void *key, + void *next_key) +{ + return -EINVAL; +} + +const struct bpf_map_ops queue_map_ops = { + .map_alloc_check = queue_stack_map_alloc_check, + .map_alloc = queue_stack_map_alloc, + .map_free = queue_stack_map_free, + .map_lookup_elem = queue_stack_map_lookup_elem, + .map_update_elem = queue_stack_map_update_elem, + .map_delete_elem = queue_stack_map_delete_elem, + .map_push_elem = queue_stack_map_push_elem, + .map_pop_elem = queue_map_pop_elem, + .map_peek_elem = queue_map_peek_elem, + .map_get_next_key = queue_stack_map_get_next_key, +}; + +const struct bpf_map_ops stack_map_ops = { + .map_alloc_check = queue_stack_map_alloc_check, + .map_alloc = queue_stack_map_alloc, + .map_free = queue_stack_map_free, + .map_lookup_elem = queue_stack_map_lookup_elem, + .map_update_elem = queue_stack_map_update_elem, + .map_delete_elem = queue_stack_map_delete_elem, + .map_push_elem = queue_stack_map_push_elem, + .map_pop_elem = stack_map_pop_elem, + .map_peek_elem = stack_map_peek_elem, + .map_get_next_key = queue_stack_map_get_next_key, +}; diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 78d9dd95e25f..1617407f9ee5 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -727,6 +727,9 @@ static int map_lookup_elem(union bpf_attr *attr) err = bpf_fd_htab_map_lookup_elem(map, key, value); } else if (map->map_type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY) { err = bpf_fd_reuseport_array_lookup_elem(map, key, value); + } else if (map->map_type == BPF_MAP_TYPE_QUEUE || + map->map_type == BPF_MAP_TYPE_STACK) { + err = map->ops->map_peek_elem(map, value); } else { rcu_read_lock(); ptr = map->ops->map_lookup_elem(map, key); @@ -857,6 +860,9 @@ static int map_update_elem(union bpf_attr *attr) /* rcu_read_lock() is not needed */ err = bpf_fd_reuseport_array_update_elem(map, key, value, attr->flags); + } else if (map->map_type == BPF_MAP_TYPE_QUEUE || + map->map_type == BPF_MAP_TYPE_STACK) { + err = map->ops->map_push_elem(map, value, attr->flags); } else { rcu_read_lock(); err = map->ops->map_update_elem(map, key, value, attr->flags); diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d84c91ac3b70..7d6d9cf9ebd5 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2324,6 +2324,13 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, if (func_id != BPF_FUNC_sk_select_reuseport) goto error; break; + case BPF_MAP_TYPE_QUEUE: + case BPF_MAP_TYPE_STACK: + if (func_id != BPF_FUNC_map_peek_elem && + func_id != BPF_FUNC_map_pop_elem && + func_id != BPF_FUNC_map_push_elem) + goto error; + break; default: break; } @@ -2380,6 +2387,13 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY) goto error; break; + case BPF_FUNC_map_peek_elem: + case BPF_FUNC_map_pop_elem: + case BPF_FUNC_map_push_elem: + if (map->map_type != BPF_MAP_TYPE_QUEUE && + map->map_type != BPF_MAP_TYPE_STACK) + goto error; + break; default: break; } @@ -2675,7 +2689,10 @@ record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, if (func_id != BPF_FUNC_tail_call && func_id != BPF_FUNC_map_lookup_elem && func_id != BPF_FUNC_map_update_elem && - func_id != BPF_FUNC_map_delete_elem) + func_id != BPF_FUNC_map_delete_elem && + func_id != BPF_FUNC_map_push_elem && + func_id != BPF_FUNC_map_pop_elem && + func_id != BPF_FUNC_map_peek_elem) return 0; if (meta->map_ptr == NULL) { diff --git a/net/core/filter.c b/net/core/filter.c index 1a3ac6c46873..ea48ec789b5c 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -4876,6 +4876,12 @@ bpf_base_func_proto(enum bpf_func_id func_id) return &bpf_map_update_elem_proto; case BPF_FUNC_map_delete_elem: return &bpf_map_delete_elem_proto; + case BPF_FUNC_map_push_elem: + return &bpf_map_push_elem_proto; + case BPF_FUNC_map_pop_elem: + return &bpf_map_pop_elem_proto; + case BPF_FUNC_map_peek_elem: + return &bpf_map_peek_elem_proto; case BPF_FUNC_get_prandom_u32: return &bpf_get_prandom_u32_proto; case BPF_FUNC_get_smp_processor_id:
Queue/stack maps implement a FIFO/LIFO data storage for ebpf programs. These maps support peek, pop and push operations that are exposed to eBPF programs through the new bpf_map[peek/pop/push] helpers. Those operations are exposed to userspace applications through the already existing syscalls in the following way: BPF_MAP_LOOKUP_ELEM -> peek BPF_MAP_LOOKUP_AND_DELETE_ELEM -> pop BPF_MAP_UPDATE_ELEM -> push Queue/stack maps are implemented using a buffer, tail and head indexes, hence BPF_F_NO_PREALLOC is not supported. As opposite to other maps, queue and stack do not use RCU for protecting maps values, the bpf_map[peek/pop] have a ARG_PTR_TO_UNINIT_MAP_VALUE argument that is a pointer to a memory zone where to save the value of a map. Basically the same as ARG_PTR_TO_UNINIT_MEM, but the size has not be passed as an extra argument. Our main motivation for implementing queue/stack maps was to keep track of a pool of elements, like network ports in a SNAT, however we forsee other use cases, like for exampling saving last N kernel events in a map and then analysing from userspace. Signed-off-by: Mauricio Vasquez B <mauricio.vasquez@polito.it> --- include/linux/bpf.h | 6 + include/linux/bpf_types.h | 2 include/uapi/linux/bpf.h | 29 ++++ kernel/bpf/Makefile | 2 kernel/bpf/core.c | 3 kernel/bpf/helpers.c | 43 ++++++ kernel/bpf/queue_stack_maps.c | 288 +++++++++++++++++++++++++++++++++++++++++ kernel/bpf/syscall.c | 6 + kernel/bpf/verifier.c | 19 +++ net/core/filter.c | 6 + 10 files changed, 401 insertions(+), 3 deletions(-) create mode 100644 kernel/bpf/queue_stack_maps.c