| /* bpf.h |
| * Copyright (c) 2012 The Chromium OS Authors. All rights reserved. |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| * |
| * Berkeley Packet Filter functions. |
| */ |
| |
| #ifndef BPF_H |
| #define BPF_H |
| |
| #include <asm/bitsperlong.h> /* for __BITS_PER_LONG */ |
| #include <linux/audit.h> |
| #include <linux/filter.h> |
| #include <stddef.h> |
| #include <sys/user.h> |
| |
| #include "arch.h" |
| |
| #if __BITS_PER_LONG == 32 || defined(__ILP32__) |
| #define BITS32 |
| #elif __BITS_PER_LONG == 64 |
| #define BITS64 |
| #endif |
| |
| /* Constants for comparison operators. */ |
| #define MIN_OPERATOR 128 |
| enum operator { |
| EQ = MIN_OPERATOR, |
| NE, |
| LT, |
| LE, |
| GT, |
| GE, |
| SET |
| }; |
| |
| /* |
| * BPF return values and data structures, |
| * since they're not yet in the kernel. |
| */ |
| #define SECCOMP_RET_KILL 0x00000000U /* kill the task immediately */ |
| #define SECCOMP_RET_TRAP 0x00030000U /* return SIGSYS */ |
| #define SECCOMP_RET_ERRNO 0x00050000U /* return -1 and set errno */ |
| #define SECCOMP_RET_ALLOW 0x7fff0000U /* allow */ |
| |
| #define SECCOMP_RET_DATA 0x0000ffffU /* mask for return value */ |
| |
| struct seccomp_data { |
| int nr; |
| __u32 arch; |
| __u64 instruction_pointer; |
| __u64 args[6]; |
| }; |
| |
| #define syscall_nr (offsetof(struct seccomp_data, nr)) |
| #define arch_nr (offsetof(struct seccomp_data, arch)) |
| |
| /* Size-dependent defines. */ |
| #if defined(BITS32) |
| /* |
| * On 32 bits, comparisons take 2 instructions: 1 for loading the argument, |
| * 1 for the actual comparison. |
| */ |
| #define BPF_LOAD_ARG_LEN 1U |
| #define BPF_COMP_LEN 1U |
| #define BPF_ARG_COMP_LEN (BPF_LOAD_ARG_LEN + BPF_COMP_LEN) |
| |
| #define bpf_comp_jeq bpf_comp_jeq32 |
| #define bpf_comp_jset bpf_comp_jset32 |
| |
| #define LO_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) |
| |
| #elif defined(BITS64) |
| /* |
| * On 64 bits, comparisons take 7 instructions: 4 for loading the argument, |
| * and 3 for the actual comparison. |
| */ |
| #define BPF_LOAD_ARG_LEN 4U |
| #define BPF_COMP_LEN 3U |
| #define BPF_ARG_COMP_LEN (BPF_LOAD_ARG_LEN + BPF_COMP_LEN) |
| |
| #define bpf_comp_jeq bpf_comp_jeq64 |
| #define bpf_comp_jset bpf_comp_jset64 |
| |
| /* Ensure that we load the logically correct offset. */ |
| #if defined(__LITTLE_ENDIAN) |
| #define LO_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) |
| #define HI_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) + sizeof(__u32) |
| #elif defined(__BIG_ENDIAN) |
| #define LO_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) + sizeof(__u32) |
| #define HI_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) |
| #else |
| #error "Unknown endianness" |
| #endif |
| |
| #else |
| #error "Unknown bit width" |
| |
| #endif |
| |
| /* Common jump targets. */ |
| #define NEXT 0 |
| #define SKIP 1 |
| #define SKIPN(_n) (_n) |
| |
| /* Support for labels in BPF programs. */ |
| #define JUMP_JT 0xff |
| #define JUMP_JF 0xff |
| #define LABEL_JT 0xfe |
| #define LABEL_JF 0xfe |
| |
| #define MAX_BPF_LABEL_LEN 32 |
| |
| #define BPF_LABELS_MAX 256 |
| struct bpf_labels { |
| int count; |
| struct __bpf_label { |
| const char *label; |
| unsigned int location; |
| } labels[BPF_LABELS_MAX]; |
| }; |
| |
| /* BPF instruction manipulation functions and macros. */ |
| static inline size_t set_bpf_instr(struct sock_filter *instr, |
| unsigned short code, unsigned int k, |
| unsigned char jt, unsigned char jf) |
| { |
| instr->code = code; |
| instr->k = k; |
| instr->jt = jt; |
| instr->jf = jf; |
| return 1U; |
| } |
| |
| #define set_bpf_stmt(_block, _code, _k) \ |
| set_bpf_instr((_block), (_code), (_k), 0, 0) |
| |
| #define set_bpf_jump(_block, _code, _k, _jt, _jf) \ |
| set_bpf_instr((_block), (_code), (_k), (_jt), (_jf)) |
| |
| #define set_bpf_lbl(_block, _lbl_id) \ |
| set_bpf_jump((_block), BPF_JMP+BPF_JA, (_lbl_id), \ |
| LABEL_JT, LABEL_JF) |
| |
| #define set_bpf_jump_lbl(_block, _lbl_id) \ |
| set_bpf_jump((_block), BPF_JMP+BPF_JA, (_lbl_id), \ |
| JUMP_JT, JUMP_JF) |
| |
| #define set_bpf_ret_kill(_block) \ |
| set_bpf_stmt((_block), BPF_RET+BPF_K, SECCOMP_RET_KILL) |
| |
| #define set_bpf_ret_trap(_block) \ |
| set_bpf_stmt((_block), BPF_RET+BPF_K, SECCOMP_RET_TRAP) |
| |
| #define set_bpf_ret_errno(_block, _errno) \ |
| set_bpf_stmt((_block), BPF_RET+BPF_K, \ |
| SECCOMP_RET_ERRNO | ((_errno) & SECCOMP_RET_DATA)) |
| |
| #define set_bpf_ret_allow(_block) \ |
| set_bpf_stmt((_block), BPF_RET+BPF_K, SECCOMP_RET_ALLOW) |
| |
| #define bpf_load_syscall_nr(_filter) \ |
| set_bpf_stmt((_filter), BPF_LD+BPF_W+BPF_ABS, syscall_nr) |
| |
| /* BPF label functions. */ |
| int bpf_resolve_jumps(struct bpf_labels *labels, |
| struct sock_filter *filter, size_t count); |
| int bpf_label_id(struct bpf_labels *labels, const char *label); |
| void free_label_strings(struct bpf_labels *labels); |
| |
| /* BPF helper functions. */ |
| size_t bpf_load_arg(struct sock_filter *filter, int argidx); |
| size_t bpf_comp_jeq(struct sock_filter *filter, unsigned long c, |
| unsigned char jt, unsigned char jf); |
| size_t bpf_comp_jset(struct sock_filter *filter, unsigned long mask, |
| unsigned char jt, unsigned char jf); |
| |
| /* Functions called by syscall_filter.c */ |
| #define ARCH_VALIDATION_LEN 3U |
| #define ALLOW_SYSCALL_LEN 2U |
| |
| size_t bpf_arg_comp(struct sock_filter **pfilter, |
| int op, int argidx, unsigned long c, unsigned int label_id); |
| size_t bpf_validate_arch(struct sock_filter *filter); |
| size_t bpf_allow_syscall(struct sock_filter *filter, int nr); |
| size_t bpf_allow_syscall_args(struct sock_filter *filter, |
| int nr, unsigned int id); |
| |
| /* Debug functions. */ |
| void dump_bpf_prog(struct sock_fprog *fprog); |
| void dump_bpf_filter(struct sock_filter *filter, unsigned short len); |
| |
| #endif /* BPF_H */ |