/* * Seccomp BPF helper functions * * Copyright (c) 2012 The Chromium OS Authors * Author: Will Drewry * * The code may be used by anyone for any purpose, * and can serve as a starting point for developing * applications using prctl(PR_ATTACH_SECCOMP_FILTER). */ #include #include #include #include "bpf-helper.h" int bpf_resolve_jumps(struct bpf_labels *labels, struct sock_filter *filter, size_t count) { size_t i; if (count < 1 || count > BPF_MAXINSNS) return -1; /* * Walk it once, backwards, to build the label table and do fixups. * Since backward jumps are disallowed by BPF, this is easy. */ for (i = 0; i < count; ++i) { size_t offset = count - i - 1; struct sock_filter *instr = &filter[offset]; if (instr->code != (BPF_JMP+BPF_JA)) continue; 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); } value='0d7f1b993b2e8babf424f009f5984fa06a713919'/>
path: root/include/net/ax25.h
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