xref: /linux-6.15/include/linux/filter.h (revision 915de2ad) 
1 /*
2  * Linux Socket Filter Data Structures
3  */
4 #ifndef __LINUX_FILTER_H__
5 #define __LINUX_FILTER_H__
6 
7 #include <linux/atomic.h>
8 #include <linux/compat.h>
9 #include <linux/skbuff.h>
10 #include <linux/workqueue.h>
11 #include <uapi/linux/filter.h>
12 
13 /* Internally used and optimized filter representation with extended
14  * instruction set based on top of classic BPF.
15  */
16 
17 /* instruction classes */
18 #define BPF_ALU64	0x07	/* alu mode in double word width */
19 
20 /* ld/ldx fields */
21 #define BPF_DW		0x18	/* double word */
22 #define BPF_XADD	0xc0	/* exclusive add */
23 
24 /* alu/jmp fields */
25 #define BPF_MOV		0xb0	/* mov reg to reg */
26 #define BPF_ARSH	0xc0	/* sign extending arithmetic shift right */
27 
28 /* change endianness of a register */
29 #define BPF_END		0xd0	/* flags for endianness conversion: */
30 #define BPF_TO_LE	0x00	/* convert to little-endian */
31 #define BPF_TO_BE	0x08	/* convert to big-endian */
32 #define BPF_FROM_LE	BPF_TO_LE
33 #define BPF_FROM_BE	BPF_TO_BE
34 
35 #define BPF_JNE		0x50	/* jump != */
36 #define BPF_JSGT	0x60	/* SGT is signed '>', GT in x86 */
37 #define BPF_JSGE	0x70	/* SGE is signed '>=', GE in x86 */
38 #define BPF_CALL	0x80	/* function call */
39 #define BPF_EXIT	0x90	/* function return */
40 
41 /* Register numbers */
42 enum {
43 	BPF_REG_0 = 0,
44 	BPF_REG_1,
45 	BPF_REG_2,
46 	BPF_REG_3,
47 	BPF_REG_4,
48 	BPF_REG_5,
49 	BPF_REG_6,
50 	BPF_REG_7,
51 	BPF_REG_8,
52 	BPF_REG_9,
53 	BPF_REG_10,
54 	__MAX_BPF_REG,
55 };
56 
57 /* BPF has 10 general purpose 64-bit registers and stack frame. */
58 #define MAX_BPF_REG	__MAX_BPF_REG
59 
60 /* ArgX, context and stack frame pointer register positions. Note,
61  * Arg1, Arg2, Arg3, etc are used as argument mappings of function
62  * calls in BPF_CALL instruction.
63  */
64 #define BPF_REG_ARG1	BPF_REG_1
65 #define BPF_REG_ARG2	BPF_REG_2
66 #define BPF_REG_ARG3	BPF_REG_3
67 #define BPF_REG_ARG4	BPF_REG_4
68 #define BPF_REG_ARG5	BPF_REG_5
69 #define BPF_REG_CTX	BPF_REG_6
70 #define BPF_REG_FP	BPF_REG_10
71 
72 /* Additional register mappings for converted user programs. */
73 #define BPF_REG_A	BPF_REG_0
74 #define BPF_REG_X	BPF_REG_7
75 #define BPF_REG_TMP	BPF_REG_8
76 
77 /* BPF program can access up to 512 bytes of stack space. */
78 #define MAX_BPF_STACK	512
79 
80 /* Helper macros for filter block array initializers. */
81 
82 /* ALU ops on registers, bpf_add|sub|...: dst_reg += src_reg */
83 
84 #define BPF_ALU64_REG(OP, DST, SRC)				\
85 	((struct bpf_insn) {					\
86 		.code  = BPF_ALU64 | BPF_OP(OP) | BPF_X,	\
87 		.dst_reg = DST,					\
88 		.src_reg = SRC,					\
89 		.off   = 0,					\
90 		.imm   = 0 })
91 
92 #define BPF_ALU32_REG(OP, DST, SRC)				\
93 	((struct bpf_insn) {					\
94 		.code  = BPF_ALU | BPF_OP(OP) | BPF_X,		\
95 		.dst_reg = DST,					\
96 		.src_reg = SRC,					\
97 		.off   = 0,					\
98 		.imm   = 0 })
99 
100 /* ALU ops on immediates, bpf_add|sub|...: dst_reg += imm32 */
101 
102 #define BPF_ALU64_IMM(OP, DST, IMM)				\
103 	((struct bpf_insn) {					\
104 		.code  = BPF_ALU64 | BPF_OP(OP) | BPF_K,	\
105 		.dst_reg = DST,					\
106 		.src_reg = 0,					\
107 		.off   = 0,					\
108 		.imm   = IMM })
109 
110 #define BPF_ALU32_IMM(OP, DST, IMM)				\
111 	((struct bpf_insn) {					\
112 		.code  = BPF_ALU | BPF_OP(OP) | BPF_K,		\
113 		.dst_reg = DST,					\
114 		.src_reg = 0,					\
115 		.off   = 0,					\
116 		.imm   = IMM })
117 
118 /* Endianess conversion, cpu_to_{l,b}e(), {l,b}e_to_cpu() */
119 
120 #define BPF_ENDIAN(TYPE, DST, LEN)				\
121 	((struct bpf_insn) {					\
122 		.code  = BPF_ALU | BPF_END | BPF_SRC(TYPE),	\
123 		.dst_reg = DST,					\
124 		.src_reg = 0,					\
125 		.off   = 0,					\
126 		.imm   = LEN })
127 
128 /* Short form of mov, dst_reg = src_reg */
129 
130 #define BPF_MOV64_REG(DST, SRC)					\
131 	((struct bpf_insn) {					\
132 		.code  = BPF_ALU64 | BPF_MOV | BPF_X,		\
133 		.dst_reg = DST,					\
134 		.src_reg = SRC,					\
135 		.off   = 0,					\
136 		.imm   = 0 })
137 
138 #define BPF_MOV32_REG(DST, SRC)					\
139 	((struct bpf_insn) {					\
140 		.code  = BPF_ALU | BPF_MOV | BPF_X,		\
141 		.dst_reg = DST,					\
142 		.src_reg = SRC,					\
143 		.off   = 0,					\
144 		.imm   = 0 })
145 
146 /* Short form of mov, dst_reg = imm32 */
147 
148 #define BPF_MOV64_IMM(DST, IMM)					\
149 	((struct bpf_insn) {					\
150 		.code  = BPF_ALU64 | BPF_MOV | BPF_K,		\
151 		.dst_reg = DST,					\
152 		.src_reg = 0,					\
153 		.off   = 0,					\
154 		.imm   = IMM })
155 
156 #define BPF_MOV32_IMM(DST, IMM)					\
157 	((struct bpf_insn) {					\
158 		.code  = BPF_ALU | BPF_MOV | BPF_K,		\
159 		.dst_reg = DST,					\
160 		.src_reg = 0,					\
161 		.off   = 0,					\
162 		.imm   = IMM })
163 
164 /* Short form of mov based on type, BPF_X: dst_reg = src_reg, BPF_K: dst_reg = imm32 */
165 
166 #define BPF_MOV64_RAW(TYPE, DST, SRC, IMM)			\
167 	((struct bpf_insn) {					\
168 		.code  = BPF_ALU64 | BPF_MOV | BPF_SRC(TYPE),	\
169 		.dst_reg = DST,					\
170 		.src_reg = SRC,					\
171 		.off   = 0,					\
172 		.imm   = IMM })
173 
174 #define BPF_MOV32_RAW(TYPE, DST, SRC, IMM)			\
175 	((struct bpf_insn) {					\
176 		.code  = BPF_ALU | BPF_MOV | BPF_SRC(TYPE),	\
177 		.dst_reg = DST,					\
178 		.src_reg = SRC,					\
179 		.off   = 0,					\
180 		.imm   = IMM })
181 
182 /* Direct packet access, R0 = *(uint *) (skb->data + imm32) */
183 
184 #define BPF_LD_ABS(SIZE, IMM)					\
185 	((struct bpf_insn) {					\
186 		.code  = BPF_LD | BPF_SIZE(SIZE) | BPF_ABS,	\
187 		.dst_reg = 0,					\
188 		.src_reg = 0,					\
189 		.off   = 0,					\
190 		.imm   = IMM })
191 
192 /* Indirect packet access, R0 = *(uint *) (skb->data + src_reg + imm32) */
193 
194 #define BPF_LD_IND(SIZE, SRC, IMM)				\
195 	((struct bpf_insn) {					\
196 		.code  = BPF_LD | BPF_SIZE(SIZE) | BPF_IND,	\
197 		.dst_reg = 0,					\
198 		.src_reg = SRC,					\
199 		.off   = 0,					\
200 		.imm   = IMM })
201 
202 /* Memory load, dst_reg = *(uint *) (src_reg + off16) */
203 
204 #define BPF_LDX_MEM(SIZE, DST, SRC, OFF)			\
205 	((struct bpf_insn) {					\
206 		.code  = BPF_LDX | BPF_SIZE(SIZE) | BPF_MEM,	\
207 		.dst_reg = DST,					\
208 		.src_reg = SRC,					\
209 		.off   = OFF,					\
210 		.imm   = 0 })
211 
212 /* Memory store, *(uint *) (dst_reg + off16) = src_reg */
213 
214 #define BPF_STX_MEM(SIZE, DST, SRC, OFF)			\
215 	((struct bpf_insn) {					\
216 		.code  = BPF_STX | BPF_SIZE(SIZE) | BPF_MEM,	\
217 		.dst_reg = DST,					\
218 		.src_reg = SRC,					\
219 		.off   = OFF,					\
220 		.imm   = 0 })
221 
222 /* Memory store, *(uint *) (dst_reg + off16) = imm32 */
223 
224 #define BPF_ST_MEM(SIZE, DST, OFF, IMM)				\
225 	((struct bpf_insn) {					\
226 		.code  = BPF_ST | BPF_SIZE(SIZE) | BPF_MEM,	\
227 		.dst_reg = DST,					\
228 		.src_reg = 0,					\
229 		.off   = OFF,					\
230 		.imm   = IMM })
231 
232 /* Conditional jumps against registers, if (dst_reg 'op' src_reg) goto pc + off16 */
233 
234 #define BPF_JMP_REG(OP, DST, SRC, OFF)				\
235 	((struct bpf_insn) {					\
236 		.code  = BPF_JMP | BPF_OP(OP) | BPF_X,		\
237 		.dst_reg = DST,					\
238 		.src_reg = SRC,					\
239 		.off   = OFF,					\
240 		.imm   = 0 })
241 
242 /* Conditional jumps against immediates, if (dst_reg 'op' imm32) goto pc + off16 */
243 
244 #define BPF_JMP_IMM(OP, DST, IMM, OFF)				\
245 	((struct bpf_insn) {					\
246 		.code  = BPF_JMP | BPF_OP(OP) | BPF_K,		\
247 		.dst_reg = DST,					\
248 		.src_reg = 0,					\
249 		.off   = OFF,					\
250 		.imm   = IMM })
251 
252 /* Function call */
253 
254 #define BPF_EMIT_CALL(FUNC)					\
255 	((struct bpf_insn) {					\
256 		.code  = BPF_JMP | BPF_CALL,			\
257 		.dst_reg = 0,					\
258 		.src_reg = 0,					\
259 		.off   = 0,					\
260 		.imm   = ((FUNC) - __bpf_call_base) })
261 
262 /* Raw code statement block */
263 
264 #define BPF_RAW_INSN(CODE, DST, SRC, OFF, IMM)			\
265 	((struct bpf_insn) {					\
266 		.code  = CODE,					\
267 		.dst_reg = DST,					\
268 		.src_reg = SRC,					\
269 		.off   = OFF,					\
270 		.imm   = IMM })
271 
272 /* Program exit */
273 
274 #define BPF_EXIT_INSN()						\
275 	((struct bpf_insn) {					\
276 		.code  = BPF_JMP | BPF_EXIT,			\
277 		.dst_reg = 0,					\
278 		.src_reg = 0,					\
279 		.off   = 0,					\
280 		.imm   = 0 })
281 
282 #define bytes_to_bpf_size(bytes)				\
283 ({								\
284 	int bpf_size = -EINVAL;					\
285 								\
286 	if (bytes == sizeof(u8))				\
287 		bpf_size = BPF_B;				\
288 	else if (bytes == sizeof(u16))				\
289 		bpf_size = BPF_H;				\
290 	else if (bytes == sizeof(u32))				\
291 		bpf_size = BPF_W;				\
292 	else if (bytes == sizeof(u64))				\
293 		bpf_size = BPF_DW;				\
294 								\
295 	bpf_size;						\
296 })
297 
298 /* Macro to invoke filter function. */
299 #define SK_RUN_FILTER(filter, ctx) \
300 	(*filter->prog->bpf_func)(ctx, filter->prog->insnsi)
301 
302 struct bpf_insn {
303 	__u8	code;		/* opcode */
304 	__u8	dst_reg:4;	/* dest register */
305 	__u8	src_reg:4;	/* source register */
306 	__s16	off;		/* signed offset */
307 	__s32	imm;		/* signed immediate constant */
308 };
309 
310 #ifdef CONFIG_COMPAT
311 /* A struct sock_filter is architecture independent. */
312 struct compat_sock_fprog {
313 	u16		len;
314 	compat_uptr_t	filter;	/* struct sock_filter * */
315 };
316 #endif
317 
318 struct sock_fprog_kern {
319 	u16			len;
320 	struct sock_filter	*filter;
321 };
322 
323 struct sk_buff;
324 struct sock;
325 struct seccomp_data;
326 
327 struct bpf_prog {
328 	u32			jited:1,	/* Is our filter JIT'ed? */
329 				len:31;		/* Number of filter blocks */
330 	struct sock_fprog_kern	*orig_prog;	/* Original BPF program */
331 	unsigned int		(*bpf_func)(const struct sk_buff *skb,
332 					    const struct bpf_insn *filter);
333 	union {
334 		struct sock_filter	insns[0];
335 		struct bpf_insn		insnsi[0];
336 		struct work_struct	work;
337 	};
338 };
339 
340 struct sk_filter {
341 	atomic_t	refcnt;
342 	struct rcu_head	rcu;
343 	struct bpf_prog	*prog;
344 };
345 
346 #define BPF_PROG_RUN(filter, ctx)  (*filter->bpf_func)(ctx, filter->insnsi)
347 
348 static inline unsigned int bpf_prog_size(unsigned int proglen)
349 {
350 	return max(sizeof(struct bpf_prog),
351 		   offsetof(struct bpf_prog, insns[proglen]));
352 }
353 
354 #define bpf_classic_proglen(fprog) (fprog->len * sizeof(fprog->filter[0]))
355 
356 int sk_filter(struct sock *sk, struct sk_buff *skb);
357 
358 void bpf_prog_select_runtime(struct bpf_prog *fp);
359 void bpf_prog_free(struct bpf_prog *fp);
360 
361 int bpf_convert_filter(struct sock_filter *prog, int len,
362 		       struct bpf_insn *new_prog, int *new_len);
363 
364 int bpf_prog_create(struct bpf_prog **pfp, struct sock_fprog_kern *fprog);
365 void bpf_prog_destroy(struct bpf_prog *fp);
366 
367 int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
368 int sk_detach_filter(struct sock *sk);
369 
370 int bpf_check_classic(const struct sock_filter *filter, unsigned int flen);
371 int sk_get_filter(struct sock *sk, struct sock_filter __user *filter,
372 		  unsigned int len);
373 
374 bool sk_filter_charge(struct sock *sk, struct sk_filter *fp);
375 void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp);
376 
377 u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
378 void bpf_int_jit_compile(struct bpf_prog *fp);
379 
380 #define BPF_ANC		BIT(15)
381 
382 static inline u16 bpf_anc_helper(const struct sock_filter *ftest)
383 {
384 	BUG_ON(ftest->code & BPF_ANC);
385 
386 	switch (ftest->code) {
387 	case BPF_LD | BPF_W | BPF_ABS:
388 	case BPF_LD | BPF_H | BPF_ABS:
389 	case BPF_LD | BPF_B | BPF_ABS:
390 #define BPF_ANCILLARY(CODE)	case SKF_AD_OFF + SKF_AD_##CODE:	\
391 				return BPF_ANC | SKF_AD_##CODE
392 		switch (ftest->k) {
393 		BPF_ANCILLARY(PROTOCOL);
394 		BPF_ANCILLARY(PKTTYPE);
395 		BPF_ANCILLARY(IFINDEX);
396 		BPF_ANCILLARY(NLATTR);
397 		BPF_ANCILLARY(NLATTR_NEST);
398 		BPF_ANCILLARY(MARK);
399 		BPF_ANCILLARY(QUEUE);
400 		BPF_ANCILLARY(HATYPE);
401 		BPF_ANCILLARY(RXHASH);
402 		BPF_ANCILLARY(CPU);
403 		BPF_ANCILLARY(ALU_XOR_X);
404 		BPF_ANCILLARY(VLAN_TAG);
405 		BPF_ANCILLARY(VLAN_TAG_PRESENT);
406 		BPF_ANCILLARY(PAY_OFFSET);
407 		BPF_ANCILLARY(RANDOM);
408 		}
409 		/* Fallthrough. */
410 	default:
411 		return ftest->code;
412 	}
413 }
414 
415 void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb,
416 					   int k, unsigned int size);
417 
418 static inline void *bpf_load_pointer(const struct sk_buff *skb, int k,
419 				     unsigned int size, void *buffer)
420 {
421 	if (k >= 0)
422 		return skb_header_pointer(skb, k, size, buffer);
423 
424 	return bpf_internal_load_pointer_neg_helper(skb, k, size);
425 }
426 
427 #ifdef CONFIG_BPF_JIT
428 #include <stdarg.h>
429 #include <linux/linkage.h>
430 #include <linux/printk.h>
431 
432 void bpf_jit_compile(struct bpf_prog *fp);
433 void bpf_jit_free(struct bpf_prog *fp);
434 
435 static inline void bpf_jit_dump(unsigned int flen, unsigned int proglen,
436 				u32 pass, void *image)
437 {
438 	pr_err("flen=%u proglen=%u pass=%u image=%pK\n",
439 	       flen, proglen, pass, image);
440 	if (image)
441 		print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_OFFSET,
442 			       16, 1, image, proglen, false);
443 }
444 #else
445 #include <linux/slab.h>
446 
447 static inline void bpf_jit_compile(struct bpf_prog *fp)
448 {
449 }
450 
451 static inline void bpf_jit_free(struct bpf_prog *fp)
452 {
453 	kfree(fp);
454 }
455 #endif /* CONFIG_BPF_JIT */
456 
457 static inline int bpf_tell_extensions(void)
458 {
459 	return SKF_AD_MAX;
460 }
461 
462 #endif /* __LINUX_FILTER_H__ */
463