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 #endif /* HAVE_LINUX_FILTER_H */ 112 113 static void 114 decode_bpf_stmt(const struct bpf_filter *filter) 115 { 116 #ifdef HAVE_LINUX_FILTER_H 117 tprints("BPF_STMT("); 118 decode_bpf_code(filter->code); 119 tprints(", "); 120 if (BPF_CLASS(filter->code) == BPF_RET) { 121 unsigned int action = SECCOMP_RET_ACTION & filter->k; 122 unsigned int data = filter->k & ~action; 123 124 printxval(seccomp_ret_action, action, "SECCOMP_RET_???"); 125 if (data) 126 tprintf("|%#x)", data); 127 else 128 tprints(")"); 129 } else { 130 tprintf("%#x)", filter->k); 131 } 132 #else 133 tprintf("BPF_STMT(%#x, %#x)", filter->code, filter->k); 134 #endif /* HAVE_LINUX_FILTER_H */ 135 } 136 137 static void 138 decode_bpf_jump(const struct bpf_filter *filter) 139 { 140 #ifdef HAVE_LINUX_FILTER_H 141 tprints("BPF_JUMP("); 142 decode_bpf_code(filter->code); 143 tprintf(", %#x, %#x, %#x)", 144 filter->k, filter->jt, filter->jf); 145 #else 146 tprintf("BPF_JUMP(%#x, %#x, %#x, %#x)", 147 filter->code, filter->k, filter->jt, filter->jf); 148 #endif /* HAVE_LINUX_FILTER_H */ 149 } 150 151 #ifndef BPF_MAXINSNS 152 # define BPF_MAXINSNS 4096 153 #endif 154 155 static bool 156 print_bpf_filter(struct tcb *tcp, void *elem_buf, size_t elem_size, void *data) 157 { 158 const struct bpf_filter *filter = elem_buf; 159 unsigned int *pn = data; 160 161 if ((*pn)++ >= BPF_MAXINSNS) { 162 tprints("..."); 163 return false; 164 } 165 166 if (filter->jt || filter->jf) 167 decode_bpf_jump(filter); 168 else 169 decode_bpf_stmt(filter); 170 171 return true; 172 } 173 174 void 175 print_seccomp_fprog(struct tcb *const tcp, const kernel_ulong_t addr, 176 const unsigned short len) 177 { 178 if (abbrev(tcp)) { 179 printaddr(addr); 180 } else { 181 unsigned int insns = 0; 182 struct bpf_filter filter; 183 184 print_array(tcp, addr, len, &filter, sizeof(filter), 185 umoven_or_printaddr, print_bpf_filter, &insns); 186 } 187 } 188 189 #include "seccomp_fprog.h" 190 191 void 192 print_seccomp_filter(struct tcb *const tcp, const kernel_ulong_t addr) 193 { 194 struct seccomp_fprog fprog; 195 196 if (fetch_seccomp_fprog(tcp, addr, &fprog)) { 197 tprintf("{len=%hu, filter=", fprog.len); 198 print_seccomp_fprog(tcp, fprog.filter, fprog.len); 199 tprints("}"); 200 } 201 } 202 203 static void 204 decode_seccomp_set_mode_strict(const unsigned int flags, 205 const kernel_ulong_t 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
