#include <linux/bpf.h>#include <linux/btf.h>#include <linux/err.h>#include <linux/irq_work.h>#include <linux/slab.h>#include <linux/filter.h>#include <linux/mm.h>#include <linux/vmalloc.h>#include <linux/wait.h>#include <linux/poll.h>#include <linux/kmemleak.h>#include <uapi/linux/btf.h> #define RINGBUF_CREATE_FLAG_MASK (BPF_F_NUMA_NODE) /* non-mmap()'able part of bpf_ringbuf (everything up to consumer page) */#define RINGBUF_PGOFF \	(offsetof(struct bpf_ringbuf, consumer_pos) >> PAGE_SHIFT)/* consumer page and producer page */#define RINGBUF_POS_PAGES 2 #define RINGBUF_MAX_RECORD_SZ (UINT_MAX/4) /* Maximum size of ring buffer area is limited by 32-bit page offset within * record header, counted in pages. Reserve 8 bits for extensibility, and take * into account few extra pages for consumer/producer pages and * non-mmap()'able parts. This gives 64GB limit, which seems plenty for single * ring buffer. */#define RINGBUF_MAX_DATA_SZ \	(((1ULL << 24) - RINGBUF_POS_PAGES - RINGBUF_PGOFF) * PAGE_SIZE) struct bpf_ringbuf {	wait_queue_head_t waitq;	struct irq_work work;	u64 mask;	struct page **pages;	int nr_pages;	spinlock_t spinlock ____cacheline_aligned_in_smp;	/* Consumer and producer counters are put into separate pages to allow	 * mapping consumer page as r/w, but restrict producer page to r/o.	 * This protects producer position from being modified by user-space	 * application and ruining in-kernel position tracking.	 */	unsigned long consumer_pos __aligned(PAGE_SIZE);	unsigned long producer_pos __aligned(PAGE_SIZE);	char data[] __aligned(PAGE_SIZE);}; struct bpf_ringbuf_map {	struct bpf_map map;	struct bpf_ringbuf *rb;}; /* 8-byte ring buffer record header structure */struct bpf_ringbuf_hdr {	u32 len;	u32 pg_off;}; static struct bpf_ringbuf *bpf_ringbuf_area_alloc(size_t data_sz, int numa_node){	const gfp_t flags = GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL |			    __GFP_NOWARN | __GFP_ZERO;	int nr_meta_pages = RINGBUF_PGOFF + RINGBUF_POS_PAGES;	int nr_data_pages = data_sz >> PAGE_SHIFT;	int nr_pages = nr_meta_pages + nr_data_pages;	struct page **pages, *page;	struct bpf_ringbuf *rb;	size_t array_size;	int i; 	/* Each data page is mapped twice to allow "virtual"	 * continuous read of samples wrapping around the end of ring	 * buffer area:	 * ------------------------------------------------------	 * | meta pages |  real data pages  |  same data pages  |	 * ------------------------------------------------------	 * |            | 1 2 3 4 5 6 7 8 9 | 1 2 3 4 5 6 7 8 9 |	 * ------------------------------------------------------	 * |            | TA             DA | TA             DA |	 * ------------------------------------------------------	 *                               ^^^^^^^	 *                                  |	 * Here, no need to worry about special handling of wrapped-around	 * data due to double-mapped data pages. This works both in kernel and	 * when mmap()'ed in user-space, simplifying both kernel and	 * user-space implementations significantly.	 */	array_size = (nr_meta_pages + 2 * nr_data_pages) * sizeof(*pages);	pages = bpf_map_area_alloc(array_size, numa_node);	if (!pages)		return NULL; 	for (i = 0; i < nr_pages; i++) {		page = alloc_pages_node(numa_node, flags, 0);		if (!page) {			nr_pages = i;			goto err_free_pages;		}		pages[i] = page;		if (i >= nr_meta_pages)			pages[nr_data_pages + i] = page;	} 	rb = vmap(pages, nr_meta_pages + 2 * nr_data_pages,		  VM_MAP | VM_USERMAP, PAGE_KERNEL);	if (rb) {		kmemleak_not_leak(pages);		rb->pages = pages;		rb->nr_pages = nr_pages;		return rb;	} err_free_pages:	for (i = 0; i < nr_pages; i++)		__free_page(pages[i]);	kvfree(pages);	return NULL;} static void bpf_ringbuf_notify(struct irq_work *work){	struct bpf_ringbuf *rb = container_of(work, struct bpf_ringbuf, work); 	wake_up_all(&rb->waitq);} static struct bpf_ringbuf *bpf_ringbuf_alloc(size_t data_sz, int numa_node){	struct bpf_ringbuf *rb; 	rb = bpf_ringbuf_area_alloc(data_sz, numa_node);	if (!rb)		return NULL; 	spin_lock_init(&rb->spinlock);	init_waitqueue_head(&rb->waitq);	init_irq_work(&rb->work, bpf_ringbuf_notify); 	rb->mask = data_sz - 1;	rb->consumer_pos = 0;	rb->producer_pos = 0; 	return rb;} static struct bpf_map *ringbuf_map_alloc(union bpf_attr *attr){	struct bpf_ringbuf_map *rb_map; 	if (attr->map_flags & ~RINGBUF_CREATE_FLAG_MASK)		return ERR_PTR(-EINVAL); 	if (attr->key_size || attr->value_size ||	    !is_power_of_2(attr->max_entries) ||	    !PAGE_ALIGNED(attr->max_entries))		return ERR_PTR(-EINVAL); #ifdef CONFIG_64BIT	/* on 32-bit arch, it's impossible to overflow record's hdr->pgoff */	if (attr->max_entries > RINGBUF_MAX_DATA_SZ)		return ERR_PTR(-E2BIG);#endif 	rb_map = kzalloc(sizeof(*rb_map), GFP_USER | __GFP_ACCOUNT);	if (!rb_map)		return ERR_PTR(-ENOMEM); 	bpf_map_init_from_attr(&rb_map->map, attr); 	rb_map->rb = bpf_ringbuf_alloc(attr->max_entries, rb_map->map.numa_node);	if (!rb_map->rb) {		kfree(rb_map);		return ERR_PTR(-ENOMEM);	} 	return &rb_map->map;} static void bpf_ringbuf_free(struct bpf_ringbuf *rb){	/* copy pages pointer and nr_pages to local variable, as we are going	 * to unmap rb itself with vunmap() below	 */	struct page **pages = rb->pages;	int i, nr_pages = rb->nr_pages; 	vunmap(rb);	for (i = 0; i < nr_pages; i++)		__free_page(pages[i]);	kvfree(pages);} static void ringbuf_map_free(struct bpf_map *map){	struct bpf_ringbuf_map *rb_map; 	rb_map = container_of(map, struct bpf_ringbuf_map, map);	bpf_ringbuf_free(rb_map->rb);	kfree(rb_map);} static void *ringbuf_map_lookup_elem(struct bpf_map *map, void *key){	return ERR_PTR(-ENOTSUPP);} static int ringbuf_map_update_elem(struct bpf_map *map, void *key, void *value,				   u64 flags){	return -ENOTSUPP;} static int ringbuf_map_delete_elem(struct bpf_map *map, void *key){	return -ENOTSUPP;} static int ringbuf_map_get_next_key(struct bpf_map *map, void *key,				    void *next_key){	return -ENOTSUPP;} static int ringbuf_map_mmap(struct bpf_map *map, struct vm_area_struct *vma){	struct bpf_ringbuf_map *rb_map; 	rb_map = container_of(map, struct bpf_ringbuf_map, map); 	if (vma->vm_flags & VM_WRITE) {		/* allow writable mapping for the consumer_pos only */		if (vma->vm_pgoff != 0 || vma->vm_end - vma->vm_start != PAGE_SIZE)			return -EPERM;	} else {		vma->vm_flags &= ~VM_MAYWRITE;	}	/* remap_vmalloc_range() checks size and offset constraints */	return remap_vmalloc_range(vma, rb_map->rb,				   vma->vm_pgoff + RINGBUF_PGOFF);} static unsigned long ringbuf_avail_data_sz(struct bpf_ringbuf *rb){	unsigned long cons_pos, prod_pos; 	cons_pos = smp_load_acquire(&rb->consumer_pos);	prod_pos = smp_load_acquire(&rb->producer_pos);	return prod_pos - cons_pos;} static __poll_t ringbuf_map_poll(struct bpf_map *map, struct file *filp,				 struct poll_table_struct *pts){	struct bpf_ringbuf_map *rb_map; 	rb_map = container_of(map, struct bpf_ringbuf_map, map);	poll_wait(filp, &rb_map->rb->waitq, pts); 	if (ringbuf_avail_data_sz(rb_map->rb))		return EPOLLIN | EPOLLRDNORM;	return 0;} static int ringbuf_map_btf_id;const struct bpf_map_ops ringbuf_map_ops = {	.map_meta_equal = bpf_map_meta_equal,	.map_alloc = ringbuf_map_alloc,	.map_free = ringbuf_map_free,	.map_mmap = ringbuf_map_mmap,	.map_poll = ringbuf_map_poll,	.map_lookup_elem = ringbuf_map_lookup_elem,	.map_update_elem = ringbuf_map_update_elem,	.map_delete_elem = ringbuf_map_delete_elem,	.map_get_next_key = ringbuf_map_get_next_key,	.map_btf_name = "bpf_ringbuf_map",	.map_btf_id = &ringbuf_map_btf_id,}; /* Given pointer to ring buffer record metadata and struct bpf_ringbuf itself, * calculate offset from record metadata to ring buffer in pages, rounded * down. This page offset is stored as part of record metadata and allows to * restore struct bpf_ringbuf * from record pointer. This page offset is * stored at offset 4 of record metadata header. */static size_t bpf_ringbuf_rec_pg_off(struct bpf_ringbuf *rb,				     struct bpf_ringbuf_hdr *hdr){	return ((void *)hdr - (void *)rb) >> PAGE_SHIFT;} /* Given pointer to ring buffer record header, restore pointer to struct * bpf_ringbuf itself by using page offset stored at offset 4 */static struct bpf_ringbuf *bpf_ringbuf_restore_from_rec(struct bpf_ringbuf_hdr *hdr){	unsigned long addr = (unsigned long)(void *)hdr;	unsigned long off = (unsigned long)hdr->pg_off << PAGE_SHIFT; 	return (void*)((addr & PAGE_MASK) - off);} static void *__bpf_ringbuf_reserve(struct bpf_ringbuf *rb, u64 size){	unsigned long cons_pos, prod_pos, new_prod_pos, flags;	u32 len, pg_off;	struct bpf_ringbuf_hdr *hdr; 	if (unlikely(size > RINGBUF_MAX_RECORD_SZ))		return NULL; 	len = round_up(size + BPF_RINGBUF_HDR_SZ, 8);	if (len > rb->mask + 1)		return NULL; 	cons_pos = smp_load_acquire(&rb->consumer_pos); 	if (in_nmi()) {		if (!spin_trylock_irqsave(&rb->spinlock, flags))			return NULL;	} else {		spin_lock_irqsave(&rb->spinlock, flags);	} 	prod_pos = rb->producer_pos;	new_prod_pos = prod_pos + len; 	/* check for out of ringbuf space by ensuring producer position	 * doesn't advance more than (ringbuf_size - 1) ahead	 */	if (new_prod_pos - cons_pos > rb->mask) {		spin_unlock_irqrestore(&rb->spinlock, flags);		return NULL;	} 	hdr = (void *)rb->data + (prod_pos & rb->mask);	pg_off = bpf_ringbuf_rec_pg_off(rb, hdr);	hdr->len = size | BPF_RINGBUF_BUSY_BIT;	hdr->pg_off = pg_off; 	/* pairs with consumer's smp_load_acquire() */	smp_store_release(&rb->producer_pos, new_prod_pos); 	spin_unlock_irqrestore(&rb->spinlock, flags); 	return (void *)hdr + BPF_RINGBUF_HDR_SZ;} BPF_CALL_3(bpf_ringbuf_reserve, struct bpf_map *, map, u64, size, u64, flags){	struct bpf_ringbuf_map *rb_map; 	if (unlikely(flags))		return 0; 	rb_map = container_of(map, struct bpf_ringbuf_map, map);	return (unsigned long)__bpf_ringbuf_reserve(rb_map->rb, size);} const struct bpf_func_proto bpf_ringbuf_reserve_proto = {	.func		= bpf_ringbuf_reserve,	.ret_type	= RET_PTR_TO_ALLOC_MEM_OR_NULL,	.arg1_type	= ARG_CONST_MAP_PTR,	.arg2_type	= ARG_CONST_ALLOC_SIZE_OR_ZERO,	.arg3_type	= ARG_ANYTHING,}; static void bpf_ringbuf_commit(void *sample, u64 flags, bool discard){	unsigned long rec_pos, cons_pos;	struct bpf_ringbuf_hdr *hdr;	struct bpf_ringbuf *rb;	u32 new_len; 	hdr = sample - BPF_RINGBUF_HDR_SZ;	rb = bpf_ringbuf_restore_from_rec(hdr);	new_len = hdr->len ^ BPF_RINGBUF_BUSY_BIT;	if (discard)		new_len |= BPF_RINGBUF_DISCARD_BIT; 	/* update record header with correct final size prefix */	xchg(&hdr->len, new_len); 	/* if consumer caught up and is waiting for our record, notify about	 * new data availability	 */	rec_pos = (void *)hdr - (void *)rb->data;	cons_pos = smp_load_acquire(&rb->consumer_pos) & rb->mask; 	if (flags & BPF_RB_FORCE_WAKEUP)		irq_work_queue(&rb->work);	else if (cons_pos == rec_pos && !(flags & BPF_RB_NO_WAKEUP))		irq_work_queue(&rb->work);} BPF_CALL_2(bpf_ringbuf_submit, void *, sample, u64, flags){	bpf_ringbuf_commit(sample, flags, false /* discard */);	return 0;} const struct bpf_func_proto bpf_ringbuf_submit_proto = {	.func		= bpf_ringbuf_submit,	.ret_type	= RET_VOID,	.arg1_type	= ARG_PTR_TO_ALLOC_MEM,	.arg2_type	= ARG_ANYTHING,}; BPF_CALL_2(bpf_ringbuf_discard, void *, sample, u64, flags){	bpf_ringbuf_commit(sample, flags, true /* discard */);	return 0;} const struct bpf_func_proto bpf_ringbuf_discard_proto = {	.func		= bpf_ringbuf_discard,	.ret_type	= RET_VOID,	.arg1_type	= ARG_PTR_TO_ALLOC_MEM,	.arg2_type	= ARG_ANYTHING,}; BPF_CALL_4(bpf_ringbuf_output, struct bpf_map *, map, void *, data, u64, size,	   u64, flags){	struct bpf_ringbuf_map *rb_map;	void *rec; 	if (unlikely(flags & ~(BPF_RB_NO_WAKEUP | BPF_RB_FORCE_WAKEUP)))		return -EINVAL; 	rb_map = container_of(map, struct bpf_ringbuf_map, map);	rec = __bpf_ringbuf_reserve(rb_map->rb, size);	if (!rec)		return -EAGAIN; 	memcpy(rec, data, size);	bpf_ringbuf_commit(rec, flags, false /* discard */);	return 0;} const struct bpf_func_proto bpf_ringbuf_output_proto = {	.func		= bpf_ringbuf_output,	.ret_type	= RET_INTEGER,	.arg1_type	= ARG_CONST_MAP_PTR,	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,	.arg4_type	= ARG_ANYTHING,}; BPF_CALL_2(bpf_ringbuf_query, struct bpf_map *, map, u64, flags){	struct bpf_ringbuf *rb; 	rb = container_of(map, struct bpf_ringbuf_map, map)->rb; 	switch (flags) {	case BPF_RB_AVAIL_DATA:		return ringbuf_avail_data_sz(rb);	case BPF_RB_RING_SIZE:		return rb->mask + 1;	case BPF_RB_CONS_POS:		return smp_load_acquire(&rb->consumer_pos);	case BPF_RB_PROD_POS:		return smp_load_acquire(&rb->producer_pos);	default:		return 0;	}} const struct bpf_func_proto bpf_ringbuf_query_proto = {	.func		= bpf_ringbuf_query,	.ret_type	= RET_INTEGER,	.arg1_type	= ARG_CONST_MAP_PTR,	.arg2_type	= ARG_ANYTHING,};