1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
2 *
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of version 2 of the GNU General Public
5 * License as published by the Free Software Foundation.
6 */
7 #ifndef _LINUX_BPF_H
8 #define _LINUX_BPF_H 1
9
10 #include <uapi/linux/bpf.h>
11 #include <linux/workqueue.h>
12 #include <linux/file.h>
13
14 struct bpf_map;
15
16 /* map is generic key/value storage optionally accesible by eBPF programs */
17 struct bpf_map_ops {
18 /* funcs callable from userspace (via syscall) */
19 struct bpf_map *(*map_alloc)(union bpf_attr *attr);
20 void (*map_free)(struct bpf_map *);
21 int (*map_get_next_key)(struct bpf_map *map, void *key, void *next_key);
22
23 /* funcs callable from userspace and from eBPF programs */
24 void *(*map_lookup_elem)(struct bpf_map *map, void *key);
25 int (*map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags);
26 int (*map_delete_elem)(struct bpf_map *map, void *key);
27 };
28
29 struct bpf_map {
30 atomic_t refcnt;
31 enum bpf_map_type map_type;
32 u32 key_size;
33 u32 value_size;
34 u32 max_entries;
35 const struct bpf_map_ops *ops;
36 struct work_struct work;
37 };
38
39 struct bpf_map_type_list {
40 struct list_head list_node;
41 const struct bpf_map_ops *ops;
42 enum bpf_map_type type;
43 };
44
45 /* function argument constraints */
46 enum bpf_arg_type {
47 ARG_DONTCARE = 0, /* unused argument in helper function */
48
49 /* the following constraints used to prototype
50 * bpf_map_lookup/update/delete_elem() functions
51 */
52 ARG_CONST_MAP_PTR, /* const argument used as pointer to bpf_map */
53 ARG_PTR_TO_MAP_KEY, /* pointer to stack used as map key */
54 ARG_PTR_TO_MAP_VALUE, /* pointer to stack used as map value */
55
56 /* the following constraints used to prototype bpf_memcmp() and other
57 * functions that access data on eBPF program stack
58 */
59 ARG_PTR_TO_STACK, /* any pointer to eBPF program stack */
60 ARG_CONST_STACK_SIZE, /* number of bytes accessed from stack */
61
62 ARG_PTR_TO_CTX, /* pointer to context */
63 ARG_ANYTHING, /* any (initialized) argument is ok */
64 };
65
66 /* type of values returned from helper functions */
67 enum bpf_return_type {
68 RET_INTEGER, /* function returns integer */
69 RET_VOID, /* function doesn't return anything */
70 RET_PTR_TO_MAP_VALUE_OR_NULL, /* returns a pointer to map elem value or NULL */
71 };
72
73 /* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs
74 * to in-kernel helper functions and for adjusting imm32 field in BPF_CALL
75 * instructions after verifying
76 */
77 struct bpf_func_proto {
78 u64 (*func)(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
79 bool gpl_only;
80 enum bpf_return_type ret_type;
81 enum bpf_arg_type arg1_type;
82 enum bpf_arg_type arg2_type;
83 enum bpf_arg_type arg3_type;
84 enum bpf_arg_type arg4_type;
85 enum bpf_arg_type arg5_type;
86 };
87
88 /* bpf_context is intentionally undefined structure. Pointer to bpf_context is
89 * the first argument to eBPF programs.
90 * For socket filters: 'struct bpf_context *' == 'struct sk_buff *'
91 */
92 struct bpf_context;
93
94 enum bpf_access_type {
95 BPF_READ = 1,
96 BPF_WRITE = 2
97 };
98
99 struct bpf_verifier_ops {
100 /* return eBPF function prototype for verification */
101 const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id);
102
103 /* return true if 'size' wide access at offset 'off' within bpf_context
104 * with 'type' (read or write) is allowed
105 */
106 bool (*is_valid_access)(int off, int size, enum bpf_access_type type);
107
108 u32 (*convert_ctx_access)(int dst_reg, int src_reg, int ctx_off,
109 struct bpf_insn *insn);
110 };
111
112 struct bpf_prog_type_list {
113 struct list_head list_node;
114 const struct bpf_verifier_ops *ops;
115 enum bpf_prog_type type;
116 };
117
118 struct bpf_prog;
119
120 struct bpf_prog_aux {
121 atomic_t refcnt;
122 u32 used_map_cnt;
123 const struct bpf_verifier_ops *ops;
124 struct bpf_map **used_maps;
125 struct bpf_prog *prog;
126 struct work_struct work;
127 };
128
129 #ifdef CONFIG_BPF_SYSCALL
130 void bpf_register_prog_type(struct bpf_prog_type_list *tl);
131 void bpf_register_map_type(struct bpf_map_type_list *tl);
132
133 struct bpf_prog *bpf_prog_get(u32 ufd);
134 void bpf_prog_put(struct bpf_prog *prog);
135
136 struct bpf_map *bpf_map_get(struct fd f);
137 void bpf_map_put(struct bpf_map *map);
138
139 /* verify correctness of eBPF program */
140 int bpf_check(struct bpf_prog **fp, union bpf_attr *attr);
141 #else
bpf_register_prog_type(struct bpf_prog_type_list * tl)142 static inline void bpf_register_prog_type(struct bpf_prog_type_list *tl)
143 {
144 }
145
bpf_prog_get(u32 ufd)146 static inline struct bpf_prog *bpf_prog_get(u32 ufd)
147 {
148 return ERR_PTR(-EOPNOTSUPP);
149 }
150
bpf_prog_put(struct bpf_prog * prog)151 static inline void bpf_prog_put(struct bpf_prog *prog)
152 {
153 }
154 #endif /* CONFIG_BPF_SYSCALL */
155
156 /* verifier prototypes for helper functions called from eBPF programs */
157 extern const struct bpf_func_proto bpf_map_lookup_elem_proto;
158 extern const struct bpf_func_proto bpf_map_update_elem_proto;
159 extern const struct bpf_func_proto bpf_map_delete_elem_proto;
160
161 extern const struct bpf_func_proto bpf_get_prandom_u32_proto;
162 extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
163
164 #endif /* _LINUX_BPF_H */
165