samples/seccomp/bpf-helper.c

Source file repositories/reference/linux-study-clean/samples/seccomp/bpf-helper.c

File Facts

System
Linux kernel
Corpus path
samples/seccomp/bpf-helper.c
Extension
.c
Size
2449 bytes
Lines
97
Domain
Support Tooling And Documentation
Bucket
samples
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

switch ((instr->jt<<8)|instr->jf) {
		case (JUMP_JT<<8)|JUMP_JF:
			if (labels->labels[instr->k].location == 0xffffffff) {
				fprintf(stderr, "Unresolved label: '%s'\n",
					labels->labels[instr->k].label);
				return 1;
			}
			instr->k = labels->labels[instr->k].location -
				    (offset + 1);
			instr->jt = 0;
			instr->jf = 0;
			continue;
		case (LABEL_JT<<8)|LABEL_JF:
			if (labels->labels[instr->k].location != 0xffffffff) {
				fprintf(stderr, "Duplicate label use: '%s'\n",
					labels->labels[instr->k].label);
				return 1;
			}
			labels->labels[instr->k].location = offset;
			instr->k = 0; /* fall through */
			instr->jt = 0;
			instr->jf = 0;
			continue;
		}
	}
	return 0;
}

/* Simple lookup table for labels. */
__u32 seccomp_bpf_label(struct bpf_labels *labels, const char *label)
{
	struct __bpf_label *begin = labels->labels, *end;
	int id;

	if (labels->count == BPF_LABELS_MAX) {
		fprintf(stderr, "Too many labels\n");
		exit(1);
	}
	if (labels->count == 0) {
		begin->label = label;
		begin->location = 0xffffffff;
		labels->count++;
		return 0;
	}
	end = begin + labels->count;
	for (id = 0; begin < end; ++begin, ++id) {
		if (!strcmp(label, begin->label))
			return id;
	}
	begin->label = label;
	begin->location = 0xffffffff;
	labels->count++;
	return id;
}

void seccomp_bpf_print(struct sock_filter *filter, size_t count)
{
	struct sock_filter *end = filter + count;
	for ( ; filter < end; ++filter)
		printf("{ code=%u,jt=%u,jf=%u,k=%u },\n",
			filter->code, filter->jt, filter->jf, filter->k);
}

Annotation

Implementation Notes