Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 9c8105bd authored by Jiong Wang's avatar Jiong Wang Committed by Daniel Borkmann
Browse files

bpf: centre subprog information fields 



It is better to centre all subprog information fields into one structure.
This structure could later serve as function node in call graph.

Signed-off-by: default avatarJiong Wang <jiong.wang@netronome.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent f910cefa

include/linux/bpf_verifier.h

+6 −3
Original line number Diff line number Diff line
@@ -173,6 +173,11 @@ static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log) 


#define BPF_MAX_SUBPROGS 256



struct bpf_subprog_info {

	u32 start; /* insn idx of function entry point */

	u16 stack_depth; /* max. stack depth used by this function */

};



/* single container for all structs

 * one verifier_env per bpf_check() call

 */
@@ -191,9 +196,7 @@ struct bpf_verifier_env { 
	bool seen_direct_write;

	struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */

	struct bpf_verifier_log log;

	u32 subprog_starts[BPF_MAX_SUBPROGS + 1];

	/* computes the stack depth of each bpf function */

	u16 subprog_stack_depth[BPF_MAX_SUBPROGS + 1];

	struct bpf_subprog_info subprog_info[BPF_MAX_SUBPROGS + 1];

	u32 subprog_cnt;

};

kernel/bpf/verifier.c

+32 −30
Original line number Diff line number Diff line
@@ -741,18 +741,19 @@ enum reg_arg_type { 


static int cmp_subprogs(const void *a, const void *b)

{

	return *(int *)a - *(int *)b;

	return ((struct bpf_subprog_info *)a)->start -

	       ((struct bpf_subprog_info *)b)->start;

}



static int find_subprog(struct bpf_verifier_env *env, int off)

{

	u32 *p;

	struct bpf_subprog_info *p;



	p = bsearch(&off, env->subprog_starts, env->subprog_cnt,

		    sizeof(env->subprog_starts[0]), cmp_subprogs);

	p = bsearch(&off, env->subprog_info, env->subprog_cnt,

		    sizeof(env->subprog_info[0]), cmp_subprogs);

	if (!p)

		return -ENOENT;

	return p - env->subprog_starts;

	return p - env->subprog_info;



}
@@ -772,15 +773,16 @@ static int add_subprog(struct bpf_verifier_env *env, int off) 
		verbose(env, "too many subprograms\n");

		return -E2BIG;

	}

	env->subprog_starts[env->subprog_cnt++] = off;

	sort(env->subprog_starts, env->subprog_cnt,

	     sizeof(env->subprog_starts[0]), cmp_subprogs, NULL);

	env->subprog_info[env->subprog_cnt++].start = off;

	sort(env->subprog_info, env->subprog_cnt,

	     sizeof(env->subprog_info[0]), cmp_subprogs, NULL);

	return 0;

}



static int check_subprogs(struct bpf_verifier_env *env)

{

	int i, ret, subprog_start, subprog_end, off, cur_subprog = 0;

	struct bpf_subprog_info *subprog = env->subprog_info;

	struct bpf_insn *insn = env->prog->insnsi;

	int insn_cnt = env->prog->len;
@@ -810,14 +812,14 @@ static int check_subprogs(struct bpf_verifier_env *env) 


	if (env->log.level > 1)

		for (i = 0; i < env->subprog_cnt; i++)

			verbose(env, "func#%d @%d\n", i, env->subprog_starts[i]);

			verbose(env, "func#%d @%d\n", i, subprog[i].start);



	/* now check that all jumps are within the same subprog */

	subprog_start = 0;

	if (env->subprog_cnt == cur_subprog + 1)

		subprog_end = insn_cnt;

	else

		subprog_end = env->subprog_starts[cur_subprog + 1];

		subprog_end = subprog[cur_subprog + 1].start;

	for (i = 0; i < insn_cnt; i++) {

		u8 code = insn[i].code;
@@ -846,8 +848,7 @@ static int check_subprogs(struct bpf_verifier_env *env) 
			if (env->subprog_cnt == cur_subprog + 1)

				subprog_end = insn_cnt;

			else

				subprog_end =

					env->subprog_starts[cur_subprog + 1];

				subprog_end = subprog[cur_subprog + 1].start;

		}

	}

	return 0;
@@ -1480,13 +1481,13 @@ static int update_stack_depth(struct bpf_verifier_env *env, 
			      const struct bpf_func_state *func,

			      int off)

{

	u16 stack = env->subprog_stack_depth[func->subprogno];

	u16 stack = env->subprog_info[func->subprogno].stack_depth;



	if (stack >= -off)

		return 0;



	/* update known max for given subprogram */

	env->subprog_stack_depth[func->subprogno] = -off;

	env->subprog_info[func->subprogno].stack_depth = -off;

	return 0;

}
@@ -1498,7 +1499,8 @@ static int update_stack_depth(struct bpf_verifier_env *env, 
 */

static int check_max_stack_depth(struct bpf_verifier_env *env)

{

	int depth = 0, frame = 0, subprog = 0, i = 0, subprog_end;

	int depth = 0, frame = 0, idx = 0, i = 0, subprog_end;

	struct bpf_subprog_info *subprog = env->subprog_info;

	struct bpf_insn *insn = env->prog->insnsi;

	int insn_cnt = env->prog->len;

	int ret_insn[MAX_CALL_FRAMES];
@@ -1508,17 +1510,17 @@ static int check_max_stack_depth(struct bpf_verifier_env *env) 
	/* round up to 32-bytes, since this is granularity

	 * of interpreter stack size

	 */

	depth += round_up(max_t(u32, env->subprog_stack_depth[subprog], 1), 32);

	depth += round_up(max_t(u32, subprog[idx].stack_depth, 1), 32);

	if (depth > MAX_BPF_STACK) {

		verbose(env, "combined stack size of %d calls is %d. Too large\n",

			frame + 1, depth);

		return -EACCES;

	}

continue_func:

	if (env->subprog_cnt == subprog + 1)

	if (env->subprog_cnt == idx + 1)

		subprog_end = insn_cnt;

	else

		subprog_end = env->subprog_starts[subprog + 1];

		subprog_end = subprog[idx + 1].start;

	for (; i < subprog_end; i++) {

		if (insn[i].code != (BPF_JMP | BPF_CALL))

			continue;
@@ -1526,12 +1528,12 @@ static int check_max_stack_depth(struct bpf_verifier_env *env) 
			continue;

		/* remember insn and function to return to */

		ret_insn[frame] = i + 1;

		ret_prog[frame] = subprog;

		ret_prog[frame] = idx;



		/* find the callee */

		i = i + insn[i].imm + 1;

		subprog = find_subprog(env, i);

		if (subprog < 0) {

		idx = find_subprog(env, i);

		if (idx < 0) {

			WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",

				  i);

			return -EFAULT;
@@ -1548,10 +1550,10 @@ static int check_max_stack_depth(struct bpf_verifier_env *env) 
	 */

	if (frame == 0)

		return 0;

	depth -= round_up(max_t(u32, env->subprog_stack_depth[subprog], 1), 32);

	depth -= round_up(max_t(u32, subprog[idx].stack_depth, 1), 32);

	frame--;

	i = ret_insn[frame];

	subprog = ret_prog[frame];

	idx = ret_prog[frame];

	goto continue_func;

}
@@ -1567,7 +1569,7 @@ static int get_callee_stack_depth(struct bpf_verifier_env *env, 
			  start);

		return -EFAULT;

	}

	return env->subprog_stack_depth[subprog];

	return env->subprog_info[subprog].stack_depth;

}

#endif
@@ -4926,14 +4928,14 @@ static int do_check(struct bpf_verifier_env *env) 
	verbose(env, "processed %d insns (limit %d), stack depth ",

		insn_processed, BPF_COMPLEXITY_LIMIT_INSNS);

	for (i = 0; i < env->subprog_cnt; i++) {

		u32 depth = env->subprog_stack_depth[i];

		u32 depth = env->subprog_info[i].stack_depth;



		verbose(env, "%d", depth);

		if (i + 1 < env->subprog_cnt)

			verbose(env, "+");

	}

	verbose(env, "\n");

	env->prog->aux->stack_depth = env->subprog_stack_depth[0];

	env->prog->aux->stack_depth = env->subprog_info[0].stack_depth;

	return 0;

}
@@ -5140,9 +5142,9 @@ static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len 
	if (len == 1)

		return;

	for (i = 0; i < env->subprog_cnt; i++) {

		if (env->subprog_starts[i] < off)

		if (env->subprog_info[i].start < off)

			continue;

		env->subprog_starts[i] += len - 1;

		env->subprog_info[i].start += len - 1;

	}

}
@@ -5340,7 +5342,7 @@ static int jit_subprogs(struct bpf_verifier_env *env) 
		if (env->subprog_cnt == i + 1)

			subprog_end = prog->len;

		else

			subprog_end = env->subprog_starts[i + 1];

			subprog_end = env->subprog_info[i + 1].start;



		len = subprog_end - subprog_start;

		func[i] = bpf_prog_alloc(bpf_prog_size(len), GFP_USER);
@@ -5357,7 +5359,7 @@ static int jit_subprogs(struct bpf_verifier_env *env) 
		 * Long term would need debug info to populate names

		 */

		func[i]->aux->name[0] = 'F';

		func[i]->aux->stack_depth = env->subprog_stack_depth[i];

		func[i]->aux->stack_depth = env->subprog_info[i].stack_depth;

		func[i]->jit_requested = 1;

		func[i] = bpf_int_jit_compile(func[i]);

		if (!func[i]->jited) {