1 /* 2 * Copyright (c) 2015 Dmitry V. Levin <ldv (at) altlinux.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. The name of the author may not be used to endorse or promote products 14 * derived from this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include "defs.h" 29 30 #ifdef HAVE_LINUX_SECCOMP_H 31 # include <linux/seccomp.h> 32 #endif 33 #include "xlat/seccomp_ops.h" 34 #include "xlat/seccomp_filter_flags.h" 35 36 #ifdef HAVE_LINUX_FILTER_H 37 # include <linux/filter.h> 38 # include "xlat/bpf_class.h" 39 # include "xlat/bpf_miscop.h" 40 # include "xlat/bpf_mode.h" 41 # include "xlat/bpf_op_alu.h" 42 # include "xlat/bpf_op_jmp.h" 43 # include "xlat/bpf_rval.h" 44 # include "xlat/bpf_size.h" 45 # include "xlat/bpf_src.h" 46 47 # ifndef SECCOMP_RET_ACTION 48 # define SECCOMP_RET_ACTION 0x7fff0000U 49 # endif 50 # include "xlat/seccomp_ret_action.h" 51 #endif 52 53 struct bpf_filter { 54 uint16_t code; 55 uint8_t jt; 56 uint8_t jf; 57 uint32_t k; 58 }; 59 60 #ifdef HAVE_LINUX_FILTER_H 61 62 static void 63 decode_bpf_code(uint16_t code) 64 { 65 uint16_t i = code & ~BPF_CLASS(code); 66 67 printxval(bpf_class, BPF_CLASS(code), "BPF_???"); 68 switch (BPF_CLASS(code)) { 69 case BPF_LD: 70 case BPF_LDX: 71 tprints(" | "); 72 printxval(bpf_size, BPF_SIZE(code), "BPF_???"); 73 tprints(" | "); 74 printxval(bpf_mode, BPF_MODE(code), "BPF_???"); 75 break; 76 case BPF_ST: 77 case BPF_STX: 78 if (i) 79 tprintf(" | %#x /* %s */", i, "BPF_???"); 80 break; 81 case BPF_ALU: 82 tprints(" | "); 83 printxval(bpf_src, BPF_SRC(code), "BPF_???"); 84 tprints(" | "); 85 printxval(bpf_op_alu, BPF_OP(code), "BPF_???"); 86 break; 87 case BPF_JMP: 88 tprints(" | "); 89 printxval(bpf_src, BPF_SRC(code), "BPF_???"); 90 tprints(" | "); 91 printxval(bpf_op_jmp, BPF_OP(code), "BPF_???"); 92 break; 93 case BPF_RET: 94 tprints(" | "); 95 printxval(bpf_rval, BPF_RVAL(code), "BPF_???"); 96 i &= ~BPF_RVAL(code); 97 if (i) 98 tprintf(" | %#x /* %s */", i, "BPF_???"); 99 break; 100 case BPF_MISC: 101 tprints(" | "); 102 printxval(bpf_miscop, BPF_MISCOP(code), "BPF_???"); 103 i &= ~BPF_MISCOP(code); 104 if (i) 105 tprintf(" | %#x /* %s */", i, "BPF_???"); 106 break; 107 } 108 109 } 110 111 static void 112 decode_bpf_stmt(const struct bpf_filter *filter) 113 { 114 #ifdef HAVE_LINUX_FILTER_H 115 tprints("BPF_STMT("); 116 decode_bpf_code(filter->code); 117 tprints(", "); 118 if (BPF_CLASS(filter->code) == BPF_RET) { 119 unsigned int action = SECCOMP_RET_ACTION & filter->k; 120 unsigned int data = filter->k & ~action; 121 122 printxval(seccomp_ret_action, action, "SECCOMP_RET_???"); 123 if (data) 124 tprintf(" | %#x)", data); 125 else 126 tprints(")"); 127 } else { 128 tprintf("%#x)", filter->k); 129 } 130 #else 131 tprintf("BPF_STMT(%#x, %#x)", filter->code, filter->k); 132 #endif /* HAVE_LINUX_FILTER_H */ 133 } 134 135 static void 136 decode_bpf_jump(const struct bpf_filter *filter) 137 { 138 #ifdef HAVE_LINUX_FILTER_H 139 tprints("BPF_JUMP("); 140 decode_bpf_code(filter->code); 141 tprintf(", %#x, %#x, %#x)", 142 filter->k, filter->jt, filter->jf); 143 #else 144 tprintf("BPF_JUMP(%#x, %#x, %#x, %#x)", 145 filter->code, filter->k, filter->jt, filter->jf); 146 #endif /* HAVE_LINUX_FILTER_H */ 147 } 148 149 static void 150 decode_filter(const struct bpf_filter *filter) 151 { 152 if (filter->jt || filter->jf) 153 decode_bpf_jump(filter); 154 else 155 decode_bpf_stmt(filter); 156 } 157 158 #endif /* HAVE_LINUX_FILTER_H */ 159 160 #ifndef BPF_MAXINSNS 161 # define BPF_MAXINSNS 4096 162 #endif 163 164 static void 165 decode_fprog(struct tcb *tcp, unsigned short len, unsigned long addr) 166 { 167 if (!len || abbrev(tcp)) { 168 tprintf("{len = %u, filter = ", len); 169 printaddr(addr); 170 tprints("}"); 171 } else { 172 unsigned int i = 0; 173 174 tprints("["); 175 while (i < len && i < BPF_MAXINSNS) { 176 struct bpf_filter filter; 177 178 if (umove(tcp, addr, &filter) < 0) 179 break; 180 if (i) 181 tprints(", "); 182 decode_filter(&filter); 183 184 addr += sizeof(filter); 185 ++i; 186 } 187 if (i < len) 188 tprints("..."); 189 tprints("]"); 190 } 191 } 192 193 #include "seccomp_fprog.h" 194 195 void 196 print_seccomp_filter(struct tcb *tcp, unsigned long addr) 197 { 198 struct seccomp_fprog fprog; 199 200 if (fetch_seccomp_fprog(tcp, addr, &fprog)) 201 decode_fprog(tcp, fprog.len, fprog.filter); 202 } 203 204 static void 205 decode_seccomp_set_mode_strict(unsigned int flags, unsigned long addr) 206 { 207 tprintf("%u, ", flags); 208 printaddr(addr); 209 } 210 211 SYS_FUNC(seccomp) 212 { 213 unsigned int op = tcp->u_arg[0]; 214 215 printxval(seccomp_ops, op, "SECCOMP_SET_MODE_???"); 216 tprints(", "); 217 218 if (op == SECCOMP_SET_MODE_FILTER) { 219 printflags(seccomp_filter_flags, tcp->u_arg[1], 220 "SECCOMP_FILTER_FLAG_???"); 221 tprints(", "); 222 print_seccomp_filter(tcp, tcp->u_arg[2]); 223 } else { 224 decode_seccomp_set_mode_strict(tcp->u_arg[1], 225 tcp->u_arg[2]); 226 } 227 228 return RVAL_DECODED; 229 } 230
