bpf: prevent out-of-bounds speculation

[mirror_ubuntu-bionic-kernel.git] / include / linux / bpf.h

/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 */
#ifndef _LINUX_BPF_H
#define _LINUX_BPF_H 1

#include <uapi/linux/bpf.h>

#include <linux/workqueue.h>
#include <linux/file.h>
#include <linux/percpu.h>
#include <linux/err.h>
#include <linux/rbtree_latch.h>
#include <linux/numa.h>
#include <linux/wait.h>

struct perf_event;
struct bpf_prog;
struct bpf_map;

/* map is generic key/value storage optionally accesible by eBPF programs */
struct bpf_map_ops {
	/* funcs callable from userspace (via syscall) */
	struct bpf_map *(*map_alloc)(union bpf_attr *attr);
	void (*map_release)(struct bpf_map *map, struct file *map_file);
	void (*map_free)(struct bpf_map *map);
	int (*map_get_next_key)(struct bpf_map *map, void *key, void *next_key);

	/* funcs callable from userspace and from eBPF programs */
	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);

	/* funcs called by prog_array and perf_event_array map */
	void *(*map_fd_get_ptr)(struct bpf_map *map, struct file *map_file,
				int fd);
	void (*map_fd_put_ptr)(void *ptr);
	u32 (*map_gen_lookup)(struct bpf_map *map, struct bpf_insn *insn_buf);
	u32 (*map_fd_sys_lookup_elem)(void *ptr);
};

struct bpf_map {
	atomic_t refcnt;
	enum bpf_map_type map_type;
	u32 key_size;
	u32 value_size;
	u32 max_entries;
	u32 map_flags;
	u32 pages;
	u32 id;
	int numa_node;
	bool unpriv_array;
	struct user_struct *user;
	const struct bpf_map_ops *ops;
	struct work_struct work;
	atomic_t usercnt;
	struct bpf_map *inner_map_meta;
	char name[BPF_OBJ_NAME_LEN];
#ifdef CONFIG_SECURITY
	void *security;
#endif
};

/* function argument constraints */
enum bpf_arg_type {
	ARG_DONTCARE = 0,	/* unused argument in helper function */

	/* the following constraints used to prototype
	 * bpf_map_lookup/update/delete_elem() functions
	 */
	ARG_CONST_MAP_PTR,	/* const argument used as pointer to bpf_map */
	ARG_PTR_TO_MAP_KEY,	/* pointer to stack used as map key */
	ARG_PTR_TO_MAP_VALUE,	/* pointer to stack used as map value */

	/* the following constraints used to prototype bpf_memcmp() and other
	 * functions that access data on eBPF program stack
	 */
	ARG_PTR_TO_MEM,		/* pointer to valid memory (stack, packet, map value) */
	ARG_PTR_TO_MEM_OR_NULL, /* pointer to valid memory or NULL */
	ARG_PTR_TO_UNINIT_MEM,	/* pointer to memory does not need to be initialized,
				 * helper function must fill all bytes or clear
				 * them in error case.
				 */

	ARG_CONST_SIZE,		/* number of bytes accessed from memory */
	ARG_CONST_SIZE_OR_ZERO,	/* number of bytes accessed from memory or 0 */

	ARG_PTR_TO_CTX,		/* pointer to context */
	ARG_ANYTHING,		/* any (initialized) argument is ok */
};

/* type of values returned from helper functions */
enum bpf_return_type {
	RET_INTEGER,			/* function returns integer */
	RET_VOID,			/* function doesn't return anything */
	RET_PTR_TO_MAP_VALUE_OR_NULL,	/* returns a pointer to map elem value or NULL */
};

/* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs
 * to in-kernel helper functions and for adjusting imm32 field in BPF_CALL
 * instructions after verifying
 */
struct bpf_func_proto {
	u64 (*func)(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
	bool gpl_only;
	bool pkt_access;
	enum bpf_return_type ret_type;
	enum bpf_arg_type arg1_type;
	enum bpf_arg_type arg2_type;
	enum bpf_arg_type arg3_type;
	enum bpf_arg_type arg4_type;
	enum bpf_arg_type arg5_type;
};

/* bpf_context is intentionally undefined structure. Pointer to bpf_context is
 * the first argument to eBPF programs.
 * For socket filters: 'struct bpf_context *' == 'struct sk_buff *'
 */
struct bpf_context;

enum bpf_access_type {
	BPF_READ = 1,
	BPF_WRITE = 2
};

/* types of values stored in eBPF registers */
/* Pointer types represent:
 * pointer
 * pointer + imm
 * pointer + (u16) var
 * pointer + (u16) var + imm
 * if (range > 0) then [ptr, ptr + range - off) is safe to access
 * if (id > 0) means that some 'var' was added
 * if (off > 0) means that 'imm' was added
 */
enum bpf_reg_type {
	NOT_INIT = 0,		 /* nothing was written into register */
	SCALAR_VALUE,		 /* reg doesn't contain a valid pointer */
	PTR_TO_CTX,		 /* reg points to bpf_context */
	CONST_PTR_TO_MAP,	 /* reg points to struct bpf_map */
	PTR_TO_MAP_VALUE,	 /* reg points to map element value */
	PTR_TO_MAP_VALUE_OR_NULL,/* points to map elem value or NULL */
	PTR_TO_STACK,		 /* reg == frame_pointer + offset */
	PTR_TO_PACKET_META,	 /* skb->data - meta_len */
	PTR_TO_PACKET,		 /* reg points to skb->data */
	PTR_TO_PACKET_END,	 /* skb->data + headlen */
};

/* The information passed from prog-specific *_is_valid_access
 * back to the verifier.
 */
struct bpf_insn_access_aux {
	enum bpf_reg_type reg_type;
	int ctx_field_size;
};

static inline void
bpf_ctx_record_field_size(struct bpf_insn_access_aux *aux, u32 size)
{
	aux->ctx_field_size = size;
}

struct bpf_prog_ops {
	int (*test_run)(struct bpf_prog *prog, const union bpf_attr *kattr,
			union bpf_attr __user *uattr);
};

struct bpf_verifier_ops {
	/* return eBPF function prototype for verification */
	const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id);

	/* return true if 'size' wide access at offset 'off' within bpf_context
	 * with 'type' (read or write) is allowed
	 */
	bool (*is_valid_access)(int off, int size, enum bpf_access_type type,
				struct bpf_insn_access_aux *info);
	int (*gen_prologue)(struct bpf_insn *insn, bool direct_write,
			    const struct bpf_prog *prog);
	u32 (*convert_ctx_access)(enum bpf_access_type type,
				  const struct bpf_insn *src,
				  struct bpf_insn *dst,
				  struct bpf_prog *prog, u32 *target_size);
};

struct bpf_dev_offload {
	struct bpf_prog		*prog;
	struct net_device	*netdev;
	void			*dev_priv;
	struct list_head	offloads;
	bool			dev_state;
	bool			verifier_running;
	wait_queue_head_t	verifier_done;
};

struct bpf_prog_aux {
	atomic_t refcnt;
	u32 used_map_cnt;
	u32 max_ctx_offset;
	u32 stack_depth;
	u32 id;
	struct latch_tree_node ksym_tnode;
	struct list_head ksym_lnode;
	const struct bpf_prog_ops *ops;
	struct bpf_map **used_maps;
	struct bpf_prog *prog;
	struct user_struct *user;
	u64 load_time; /* ns since boottime */
	char name[BPF_OBJ_NAME_LEN];
#ifdef CONFIG_SECURITY
	void *security;
#endif
	struct bpf_dev_offload *offload;
	union {
		struct work_struct work;
		struct rcu_head	rcu;
	};
};

struct bpf_array {
	struct bpf_map map;
	u32 elem_size;
	u32 index_mask;
	/* 'ownership' of prog_array is claimed by the first program that
	 * is going to use this map or by the first program which FD is stored
	 * in the map to make sure that all callers and callees have the same
	 * prog_type and JITed flag
	 */
	enum bpf_prog_type owner_prog_type;
	bool owner_jited;
	union {
		char value[0] __aligned(8);
		void *ptrs[0] __aligned(8);
		void __percpu *pptrs[0] __aligned(8);
	};
};

#define MAX_TAIL_CALL_CNT 32

struct bpf_event_entry {
	struct perf_event *event;
	struct file *perf_file;
	struct file *map_file;
	struct rcu_head rcu;
};

bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp);
int bpf_prog_calc_tag(struct bpf_prog *fp);

const struct bpf_func_proto *bpf_get_trace_printk_proto(void);

typedef unsigned long (*bpf_ctx_copy_t)(void *dst, const void *src,
					unsigned long off, unsigned long len);

u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
		     void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy);

int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
			  union bpf_attr __user *uattr);
int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
			  union bpf_attr __user *uattr);

/* an array of programs to be executed under rcu_lock.
 *
 * Typical usage:
 * ret = BPF_PROG_RUN_ARRAY(&bpf_prog_array, ctx, BPF_PROG_RUN);
 *
 * the structure returned by bpf_prog_array_alloc() should be populated
 * with program pointers and the last pointer must be NULL.
 * The user has to keep refcnt on the program and make sure the program
 * is removed from the array before bpf_prog_put().
 * The 'struct bpf_prog_array *' should only be replaced with xchg()
 * since other cpus are walking the array of pointers in parallel.
 */
struct bpf_prog_array {
	struct rcu_head rcu;
	struct bpf_prog *progs[0];
};

struct bpf_prog_array __rcu *bpf_prog_array_alloc(u32 prog_cnt, gfp_t flags);
void bpf_prog_array_free(struct bpf_prog_array __rcu *progs);
int bpf_prog_array_length(struct bpf_prog_array __rcu *progs);
int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *progs,
				__u32 __user *prog_ids, u32 cnt);

void bpf_prog_array_delete_safe(struct bpf_prog_array __rcu *progs,
				struct bpf_prog *old_prog);
int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array,
			struct bpf_prog *exclude_prog,
			struct bpf_prog *include_prog,
			struct bpf_prog_array **new_array);

#define __BPF_PROG_RUN_ARRAY(array, ctx, func, check_non_null)	\
	({						\
		struct bpf_prog **_prog, *__prog;	\
		struct bpf_prog_array *_array;		\
		u32 _ret = 1;				\
		rcu_read_lock();			\
		_array = rcu_dereference(array);	\
		if (unlikely(check_non_null && !_array))\
			goto _out;			\
		_prog = _array->progs;			\
		while ((__prog = READ_ONCE(*_prog))) {	\
			_ret &= func(__prog, ctx);	\
			_prog++;			\
		}					\
_out:							\
		rcu_read_unlock();			\
		_ret;					\
	 })

#define BPF_PROG_RUN_ARRAY(array, ctx, func)		\
	__BPF_PROG_RUN_ARRAY(array, ctx, func, false)

#define BPF_PROG_RUN_ARRAY_CHECK(array, ctx, func)	\
	__BPF_PROG_RUN_ARRAY(array, ctx, func, true)

#ifdef CONFIG_BPF_SYSCALL
DECLARE_PER_CPU(int, bpf_prog_active);

extern const struct file_operations bpf_map_fops;
extern const struct file_operations bpf_prog_fops;

#define BPF_PROG_TYPE(_id, _name) \
	extern const struct bpf_prog_ops _name ## _prog_ops; \
	extern const struct bpf_verifier_ops _name ## _verifier_ops;
#define BPF_MAP_TYPE(_id, _ops) \
	extern const struct bpf_map_ops _ops;
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
#undef BPF_MAP_TYPE

extern const struct bpf_prog_ops bpf_offload_prog_ops;
extern const struct bpf_verifier_ops tc_cls_act_analyzer_ops;
extern const struct bpf_verifier_ops xdp_analyzer_ops;

struct bpf_prog *bpf_prog_get(u32 ufd);
struct bpf_prog *bpf_prog_get_type_dev(u32 ufd, enum bpf_prog_type type,
				       bool attach_drv);
struct bpf_prog * __must_check bpf_prog_add(struct bpf_prog *prog, int i);
void bpf_prog_sub(struct bpf_prog *prog, int i);
struct bpf_prog * __must_check bpf_prog_inc(struct bpf_prog *prog);
struct bpf_prog * __must_check bpf_prog_inc_not_zero(struct bpf_prog *prog);
void bpf_prog_put(struct bpf_prog *prog);
int __bpf_prog_charge(struct user_struct *user, u32 pages);
void __bpf_prog_uncharge(struct user_struct *user, u32 pages);

struct bpf_map *bpf_map_get_with_uref(u32 ufd);
struct bpf_map *__bpf_map_get(struct fd f);
struct bpf_map * __must_check bpf_map_inc(struct bpf_map *map, bool uref);
void bpf_map_put_with_uref(struct bpf_map *map);
void bpf_map_put(struct bpf_map *map);
int bpf_map_precharge_memlock(u32 pages);
void *bpf_map_area_alloc(size_t size, int numa_node);
void bpf_map_area_free(void *base);

extern int sysctl_unprivileged_bpf_disabled;

int bpf_map_new_fd(struct bpf_map *map, int flags);
int bpf_prog_new_fd(struct bpf_prog *prog);

int bpf_obj_pin_user(u32 ufd, const char __user *pathname);
int bpf_obj_get_user(const char __user *pathname, int flags);

int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value);
int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value);
int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
			   u64 flags);
int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
			    u64 flags);

int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value);

int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file,
				 void *key, void *value, u64 map_flags);
int bpf_fd_array_map_lookup_elem(struct bpf_map *map, void *key, u32 *value);
void bpf_fd_array_map_clear(struct bpf_map *map);
int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
				void *key, void *value, u64 map_flags);
int bpf_fd_htab_map_lookup_elem(struct bpf_map *map, void *key, u32 *value);

int bpf_get_file_flag(int flags);

/* memcpy that is used with 8-byte aligned pointers, power-of-8 size and
 * forced to use 'long' read/writes to try to atomically copy long counters.
 * Best-effort only.  No barriers here, since it _will_ race with concurrent
 * updates from BPF programs. Called from bpf syscall and mostly used with
 * size 8 or 16 bytes, so ask compiler to inline it.
 */
static inline void bpf_long_memcpy(void *dst, const void *src, u32 size)
{
	const long *lsrc = src;
	long *ldst = dst;

	size /= sizeof(long);
	while (size--)
		*ldst++ = *lsrc++;
}

/* verify correctness of eBPF program */
int bpf_check(struct bpf_prog **fp, union bpf_attr *attr);

/* Map specifics */
struct net_device  *__dev_map_lookup_elem(struct bpf_map *map, u32 key);
void __dev_map_insert_ctx(struct bpf_map *map, u32 index);
void __dev_map_flush(struct bpf_map *map);

struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key);
void __cpu_map_insert_ctx(struct bpf_map *map, u32 index);
void __cpu_map_flush(struct bpf_map *map);
struct xdp_buff;
int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_buff *xdp,
		    struct net_device *dev_rx);

/* Return map's numa specified by userspace */
static inline int bpf_map_attr_numa_node(const union bpf_attr *attr)
{
	return (attr->map_flags & BPF_F_NUMA_NODE) ?
		attr->numa_node : NUMA_NO_NODE;
}

#else /* !CONFIG_BPF_SYSCALL */
static inline struct bpf_prog *bpf_prog_get(u32 ufd)
{
	return ERR_PTR(-EOPNOTSUPP);
}

static inline struct bpf_prog *bpf_prog_get_type_dev(u32 ufd,
						     enum bpf_prog_type type,
						     bool attach_drv)
{
	return ERR_PTR(-EOPNOTSUPP);
}

static inline struct bpf_prog * __must_check bpf_prog_add(struct bpf_prog *prog,
							  int i)
{
	return ERR_PTR(-EOPNOTSUPP);
}

static inline void bpf_prog_sub(struct bpf_prog *prog, int i)
{
}

static inline void bpf_prog_put(struct bpf_prog *prog)
{
}

static inline struct bpf_prog * __must_check bpf_prog_inc(struct bpf_prog *prog)
{
	return ERR_PTR(-EOPNOTSUPP);
}

static inline struct bpf_prog *__must_check
bpf_prog_inc_not_zero(struct bpf_prog *prog)
{
	return ERR_PTR(-EOPNOTSUPP);
}

static inline int __bpf_prog_charge(struct user_struct *user, u32 pages)
{
	return 0;
}

static inline void __bpf_prog_uncharge(struct user_struct *user, u32 pages)
{
}

static inline int bpf_obj_get_user(const char __user *pathname, int flags)
{
	return -EOPNOTSUPP;
}

static inline struct net_device  *__dev_map_lookup_elem(struct bpf_map *map,
						       u32 key)
{
	return NULL;
}

static inline void __dev_map_insert_ctx(struct bpf_map *map, u32 index)
{
}

static inline void __dev_map_flush(struct bpf_map *map)
{
}

static inline
struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key)
{
	return NULL;
}

static inline void __cpu_map_insert_ctx(struct bpf_map *map, u32 index)
{
}

static inline void __cpu_map_flush(struct bpf_map *map)
{
}

struct xdp_buff;
static inline int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu,
				  struct xdp_buff *xdp,
				  struct net_device *dev_rx)
{
	return 0;
}
#endif /* CONFIG_BPF_SYSCALL */

static inline struct bpf_prog *bpf_prog_get_type(u32 ufd,
						 enum bpf_prog_type type)
{
	return bpf_prog_get_type_dev(ufd, type, false);
}

int bpf_prog_offload_compile(struct bpf_prog *prog);
void bpf_prog_offload_destroy(struct bpf_prog *prog);

#if defined(CONFIG_NET) && defined(CONFIG_BPF_SYSCALL)
int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr);

static inline bool bpf_prog_is_dev_bound(struct bpf_prog_aux *aux)
{
	return aux->offload;
}
#else
static inline int bpf_prog_offload_init(struct bpf_prog *prog,
					union bpf_attr *attr)
{
	return -EOPNOTSUPP;
}

static inline bool bpf_prog_is_dev_bound(struct bpf_prog_aux *aux)
{
	return false;
}
#endif /* CONFIG_NET && CONFIG_BPF_SYSCALL */

#if defined(CONFIG_STREAM_PARSER) && defined(CONFIG_BPF_SYSCALL)
struct sock  *__sock_map_lookup_elem(struct bpf_map *map, u32 key);
int sock_map_prog(struct bpf_map *map, struct bpf_prog *prog, u32 type);
#else
static inline struct sock  *__sock_map_lookup_elem(struct bpf_map *map, u32 key)
{
	return NULL;
}

static inline int sock_map_prog(struct bpf_map *map,
				struct bpf_prog *prog,
				u32 type)
{
	return -EOPNOTSUPP;
}
#endif

/* verifier prototypes for helper functions called from eBPF programs */
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_get_prandom_u32_proto;
extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
extern const struct bpf_func_proto bpf_get_numa_node_id_proto;
extern const struct bpf_func_proto bpf_tail_call_proto;
extern const struct bpf_func_proto bpf_ktime_get_ns_proto;
extern const struct bpf_func_proto bpf_get_current_pid_tgid_proto;
extern const struct bpf_func_proto bpf_get_current_uid_gid_proto;
extern const struct bpf_func_proto bpf_get_current_comm_proto;
extern const struct bpf_func_proto bpf_skb_vlan_push_proto;
extern const struct bpf_func_proto bpf_skb_vlan_pop_proto;
extern const struct bpf_func_proto bpf_get_stackid_proto;
extern const struct bpf_func_proto bpf_sock_map_update_proto;

/* Shared helpers among cBPF and eBPF. */
void bpf_user_rnd_init_once(void);
u64 bpf_user_rnd_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);

#endif /* _LINUX_BPF_H */