Jorge Lucangeli Obes | a6b034d | 2012-08-07 15:29:20 -0700 | [diff] [blame] | 1 | /* Copyright (c) 2012 The Chromium OS Authors. All rights reserved. |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 2 | * Use of this source code is governed by a BSD-style license that can be |
| 3 | * found in the LICENSE file. |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 4 | */ |
| 5 | |
Jorge Lucangeli Obes | 960b56b | 2017-11-17 11:49:58 -0500 | [diff] [blame] | 6 | #include <errno.h> |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 7 | #include <stdio.h> |
| 8 | #include <stdlib.h> |
| 9 | #include <string.h> |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 10 | |
| 11 | #include "syscall_filter.h" |
| 12 | |
Jorge Lucangeli Obes | a6b034d | 2012-08-07 15:29:20 -0700 | [diff] [blame] | 13 | #include "util.h" |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 14 | |
Jorge Lucangeli Obes | 3dc257c | 2016-11-01 12:25:04 -0400 | [diff] [blame] | 15 | /* clang-format off */ |
Jorge Lucangeli Obes | a6b034d | 2012-08-07 15:29:20 -0700 | [diff] [blame] | 16 | #define ONE_INSTR 1 |
| 17 | #define TWO_INSTRS 2 |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 18 | |
| 19 | #define compiler_warn(_state, _msg, ...) \ |
| 20 | warn("%s: %s(%zd): " _msg, __func__, (_state)->filename, \ |
| 21 | (_state)->line_number, ## __VA_ARGS__) |
| 22 | |
| 23 | #define compiler_pwarn(_state, _msg, ...) \ |
| 24 | compiler_warn(_state, _msg ": %m", ## __VA_ARGS__) |
Jorge Lucangeli Obes | 3dc257c | 2016-11-01 12:25:04 -0400 | [diff] [blame] | 25 | /* clang-format on */ |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 26 | |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 27 | int seccomp_can_softfail(void) |
Jorge Lucangeli Obes | 7b2e29c | 2016-08-04 12:21:03 -0400 | [diff] [blame] | 28 | { |
Jorge Lucangeli Obes | 565e978 | 2016-08-05 11:03:19 -0400 | [diff] [blame] | 29 | #if defined(USE_SECCOMP_SOFTFAIL) |
Jeff Vander Stoep | 1022fc3 | 2016-08-28 12:24:55 -0700 | [diff] [blame] | 30 | return 1; |
Jorge Lucangeli Obes | 7b2e29c | 2016-08-04 12:21:03 -0400 | [diff] [blame] | 31 | #endif |
| 32 | return 0; |
| 33 | } |
| 34 | |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 35 | int str_to_op(const char *op_str) |
| 36 | { |
| 37 | if (!strcmp(op_str, "==")) { |
| 38 | return EQ; |
| 39 | } else if (!strcmp(op_str, "!=")) { |
| 40 | return NE; |
Luis Hector Chavez | 1c93783 | 2018-07-21 22:45:47 -0700 | [diff] [blame] | 41 | } else if (!strcmp(op_str, "<")) { |
| 42 | return LT; |
| 43 | } else if (!strcmp(op_str, "<=")) { |
| 44 | return LE; |
| 45 | } else if (!strcmp(op_str, ">")) { |
| 46 | return GT; |
| 47 | } else if (!strcmp(op_str, ">=")) { |
| 48 | return GE; |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 49 | } else if (!strcmp(op_str, "&")) { |
| 50 | return SET; |
Jorge Lucangeli Obes | fd6f8e3 | 2016-10-12 11:19:28 -0400 | [diff] [blame] | 51 | } else if (!strcmp(op_str, "in")) { |
| 52 | return IN; |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 53 | } else { |
| 54 | return 0; |
| 55 | } |
| 56 | } |
| 57 | |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 58 | struct sock_filter *new_instr_buf(size_t count) |
| 59 | { |
| 60 | struct sock_filter *buf = calloc(count, sizeof(struct sock_filter)); |
| 61 | if (!buf) |
Jorge Lucangeli Obes | 224e427 | 2012-08-02 14:31:39 -0700 | [diff] [blame] | 62 | die("could not allocate BPF instruction buffer"); |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 63 | |
| 64 | return buf; |
| 65 | } |
| 66 | |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 67 | struct filter_block *new_filter_block(void) |
Jorge Lucangeli Obes | d96baf4 | 2013-03-26 15:11:30 -0700 | [diff] [blame] | 68 | { |
| 69 | struct filter_block *block = calloc(1, sizeof(struct filter_block)); |
| 70 | if (!block) |
| 71 | die("could not allocate BPF filter block"); |
| 72 | |
| 73 | block->instrs = NULL; |
| 74 | block->last = block->next = NULL; |
| 75 | |
| 76 | return block; |
| 77 | } |
| 78 | |
Jorge Lucangeli Obes | 565e978 | 2016-08-05 11:03:19 -0400 | [diff] [blame] | 79 | void append_filter_block(struct filter_block *head, struct sock_filter *instrs, |
| 80 | size_t len) |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 81 | { |
| 82 | struct filter_block *new_last; |
| 83 | |
| 84 | /* |
| 85 | * If |head| has no filter assigned yet, |
| 86 | * we don't create a new node. |
| 87 | */ |
| 88 | if (head->instrs == NULL) { |
| 89 | new_last = head; |
| 90 | } else { |
Jorge Lucangeli Obes | d96baf4 | 2013-03-26 15:11:30 -0700 | [diff] [blame] | 91 | new_last = new_filter_block(); |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 92 | if (head->next != NULL) { |
| 93 | head->last->next = new_last; |
| 94 | head->last = new_last; |
| 95 | } else { |
| 96 | head->last = head->next = new_last; |
| 97 | } |
| 98 | head->total_len += len; |
| 99 | } |
| 100 | |
| 101 | new_last->instrs = instrs; |
| 102 | new_last->total_len = new_last->len = len; |
| 103 | new_last->last = new_last->next = NULL; |
| 104 | } |
| 105 | |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 106 | void extend_filter_block_list(struct filter_block *list, |
Jorge Lucangeli Obes | 565e978 | 2016-08-05 11:03:19 -0400 | [diff] [blame] | 107 | struct filter_block *another) |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 108 | { |
| 109 | if (list->last != NULL) { |
| 110 | list->last->next = another; |
| 111 | list->last = another->last; |
| 112 | } else { |
| 113 | list->next = another; |
| 114 | list->last = another->last; |
| 115 | } |
| 116 | list->total_len += another->total_len; |
| 117 | } |
| 118 | |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 119 | void append_ret_kill(struct filter_block *head) |
| 120 | { |
| 121 | struct sock_filter *filter = new_instr_buf(ONE_INSTR); |
| 122 | set_bpf_ret_kill(filter); |
| 123 | append_filter_block(head, filter, ONE_INSTR); |
| 124 | } |
| 125 | |
Jorge Lucangeli Obes | bda833c | 2012-07-31 16:25:56 -0700 | [diff] [blame] | 126 | void append_ret_trap(struct filter_block *head) |
| 127 | { |
| 128 | struct sock_filter *filter = new_instr_buf(ONE_INSTR); |
| 129 | set_bpf_ret_trap(filter); |
| 130 | append_filter_block(head, filter, ONE_INSTR); |
| 131 | } |
| 132 | |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 133 | void append_ret_errno(struct filter_block *head, int errno_val) |
| 134 | { |
| 135 | struct sock_filter *filter = new_instr_buf(ONE_INSTR); |
| 136 | set_bpf_ret_errno(filter, errno_val); |
| 137 | append_filter_block(head, filter, ONE_INSTR); |
| 138 | } |
| 139 | |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 140 | void append_ret_log(struct filter_block *head) |
| 141 | { |
| 142 | struct sock_filter *filter = new_instr_buf(ONE_INSTR); |
| 143 | set_bpf_ret_log(filter); |
| 144 | append_filter_block(head, filter, ONE_INSTR); |
| 145 | } |
| 146 | |
Jorge Lucangeli Obes | c8b21e1 | 2014-06-13 14:26:16 -0700 | [diff] [blame] | 147 | void append_allow_syscall(struct filter_block *head, int nr) |
| 148 | { |
Jorge Lucangeli Obes | bda833c | 2012-07-31 16:25:56 -0700 | [diff] [blame] | 149 | struct sock_filter *filter = new_instr_buf(ALLOW_SYSCALL_LEN); |
| 150 | size_t len = bpf_allow_syscall(filter, nr); |
| 151 | if (len != ALLOW_SYSCALL_LEN) |
| 152 | die("error building syscall number comparison"); |
| 153 | |
| 154 | append_filter_block(head, filter, len); |
| 155 | } |
| 156 | |
Jorge Lucangeli Obes | 713f6fb | 2016-10-03 13:03:25 -0400 | [diff] [blame] | 157 | void allow_logging_syscalls(struct filter_block *head) |
Jorge Lucangeli Obes | bda833c | 2012-07-31 16:25:56 -0700 | [diff] [blame] | 158 | { |
| 159 | unsigned int i; |
Kees Cook | 03b2af2 | 2014-12-18 17:11:13 -0800 | [diff] [blame] | 160 | for (i = 0; i < log_syscalls_len; i++) { |
| 161 | warn("allowing syscall: %s", log_syscalls[i]); |
Jorge Lucangeli Obes | bda833c | 2012-07-31 16:25:56 -0700 | [diff] [blame] | 162 | append_allow_syscall(head, lookup_syscall(log_syscalls[i])); |
Kees Cook | 03b2af2 | 2014-12-18 17:11:13 -0800 | [diff] [blame] | 163 | } |
Jorge Lucangeli Obes | bda833c | 2012-07-31 16:25:56 -0700 | [diff] [blame] | 164 | } |
| 165 | |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 166 | unsigned int get_label_id(struct bpf_labels *labels, const char *label_str) |
| 167 | { |
| 168 | int label_id = bpf_label_id(labels, label_str); |
| 169 | if (label_id < 0) |
Jorge Lucangeli Obes | 224e427 | 2012-08-02 14:31:39 -0700 | [diff] [blame] | 170 | die("could not allocate BPF label string"); |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 171 | return label_id; |
| 172 | } |
| 173 | |
| 174 | unsigned int group_end_lbl(struct bpf_labels *labels, int nr, int idx) |
| 175 | { |
| 176 | char lbl_str[MAX_BPF_LABEL_LEN]; |
| 177 | snprintf(lbl_str, MAX_BPF_LABEL_LEN, "%d_%d_end", nr, idx); |
| 178 | return get_label_id(labels, lbl_str); |
| 179 | } |
| 180 | |
| 181 | unsigned int success_lbl(struct bpf_labels *labels, int nr) |
| 182 | { |
| 183 | char lbl_str[MAX_BPF_LABEL_LEN]; |
| 184 | snprintf(lbl_str, MAX_BPF_LABEL_LEN, "%d_success", nr); |
| 185 | return get_label_id(labels, lbl_str); |
| 186 | } |
| 187 | |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 188 | int is_implicit_relative_path(const char *filename) |
| 189 | { |
| 190 | return filename[0] != '/' && (filename[0] != '.' || filename[1] != '/'); |
| 191 | } |
| 192 | |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 193 | int compile_atom(struct parser_state *state, struct filter_block *head, |
| 194 | char *atom, struct bpf_labels *labels, int nr, int grp_idx) |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 195 | { |
| 196 | /* Splits the atom. */ |
Luis Hector Chavez | 95582e7 | 2017-09-05 09:13:25 -0700 | [diff] [blame] | 197 | char *atom_ptr = NULL; |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 198 | char *argidx_str = strtok_r(atom, " ", &atom_ptr); |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 199 | if (argidx_str == NULL) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 200 | compiler_warn(state, "empty atom"); |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 201 | return -1; |
| 202 | } |
| 203 | |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 204 | char *operator_str = strtok_r(NULL, " ", &atom_ptr); |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 205 | if (operator_str == NULL) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 206 | compiler_warn(state, "invalid atom '%s'", argidx_str); |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 207 | return -1; |
| 208 | } |
| 209 | |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 210 | char *constant_str = strtok_r(NULL, " ", &atom_ptr); |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 211 | if (constant_str == NULL) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 212 | compiler_warn(state, "invalid atom '%s %s'", argidx_str, |
| 213 | operator_str); |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 214 | return -1; |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 215 | } |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 216 | |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 217 | /* Checks that there are no extra tokens. */ |
| 218 | const char *extra = strtok_r(NULL, " ", &atom_ptr); |
| 219 | if (extra != NULL) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 220 | compiler_warn(state, "extra token '%s'", extra); |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 221 | return -1; |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 222 | } |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 223 | |
| 224 | if (strncmp(argidx_str, "arg", 3)) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 225 | compiler_warn(state, "invalid argument token '%s'", argidx_str); |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 226 | return -1; |
| 227 | } |
| 228 | |
| 229 | char *argidx_ptr; |
| 230 | long int argidx = strtol(argidx_str + 3, &argidx_ptr, 10); |
| 231 | /* |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 232 | * Checks that an actual argument index was parsed, |
| 233 | * and that there was nothing left after the index. |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 234 | */ |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 235 | if (argidx_ptr == argidx_str + 3 || *argidx_ptr != '\0') { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 236 | compiler_warn(state, "invalid argument index '%s'", |
| 237 | argidx_str + 3); |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 238 | return -1; |
| 239 | } |
| 240 | |
| 241 | int op = str_to_op(operator_str); |
| 242 | if (op < MIN_OPERATOR) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 243 | compiler_warn(state, "invalid operator '%s'", operator_str); |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 244 | return -1; |
Jorge Lucangeli Obes | 5389540 | 2016-10-18 12:02:58 -0400 | [diff] [blame] | 245 | } |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 246 | |
Luis Hector Chavez | 40b2574 | 2013-09-22 19:44:06 -0700 | [diff] [blame] | 247 | char *constant_str_ptr; |
| 248 | long int c = parse_constant(constant_str, &constant_str_ptr); |
Jorge Lucangeli Obes | 5389540 | 2016-10-18 12:02:58 -0400 | [diff] [blame] | 249 | if (constant_str_ptr == constant_str) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 250 | compiler_warn(state, "invalid constant '%s'", constant_str); |
Luis Hector Chavez | 40b2574 | 2013-09-22 19:44:06 -0700 | [diff] [blame] | 251 | return -1; |
Jorge Lucangeli Obes | 5389540 | 2016-10-18 12:02:58 -0400 | [diff] [blame] | 252 | } |
Luis Hector Chavez | 40b2574 | 2013-09-22 19:44:06 -0700 | [diff] [blame] | 253 | |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 254 | /* |
| 255 | * Looks up the label for the end of the AND statement |
| 256 | * this atom belongs to. |
| 257 | */ |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 258 | unsigned int id = group_end_lbl(labels, nr, grp_idx); |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 259 | |
| 260 | /* |
| 261 | * Builds a BPF comparison between a syscall argument |
| 262 | * and a constant. |
| 263 | * The comparison lives inside an AND statement. |
| 264 | * If the comparison succeeds, we continue |
| 265 | * to the next comparison. |
| 266 | * If this comparison fails, the whole AND statement |
| 267 | * will fail, so we jump to the end of this AND statement. |
| 268 | */ |
| 269 | struct sock_filter *comp_block; |
| 270 | size_t len = bpf_arg_comp(&comp_block, op, argidx, c, id); |
| 271 | if (len == 0) |
| 272 | return -1; |
| 273 | |
| 274 | append_filter_block(head, comp_block, len); |
| 275 | return 0; |
| 276 | } |
| 277 | |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 278 | int compile_errno(struct parser_state *state, struct filter_block *head, |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 279 | char *ret_errno, enum block_action action) |
Jorge Lucangeli Obes | c8b21e1 | 2014-06-13 14:26:16 -0700 | [diff] [blame] | 280 | { |
Kees Cook | ddb7970 | 2017-04-12 16:36:45 -0700 | [diff] [blame] | 281 | char *errno_ptr = NULL; |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 282 | |
| 283 | /* Splits the 'return' keyword and the actual errno value. */ |
| 284 | char *ret_str = strtok_r(ret_errno, " ", &errno_ptr); |
Luis Hector Chavez | 52f3dd7 | 2017-09-01 19:14:22 -0700 | [diff] [blame] | 285 | if (!ret_str || strncmp(ret_str, "return", strlen("return"))) |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 286 | return -1; |
| 287 | |
| 288 | char *errno_val_str = strtok_r(NULL, " ", &errno_ptr); |
| 289 | |
| 290 | if (errno_val_str) { |
| 291 | char *errno_val_ptr; |
Luis Hector Chavez | 40b2574 | 2013-09-22 19:44:06 -0700 | [diff] [blame] | 292 | int errno_val = parse_constant(errno_val_str, &errno_val_ptr); |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 293 | /* Checks to see if we parsed an actual errno. */ |
Jorge Lucangeli Obes | 5389540 | 2016-10-18 12:02:58 -0400 | [diff] [blame] | 294 | if (errno_val_ptr == errno_val_str || errno_val == -1) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 295 | compiler_warn(state, "invalid errno value '%s'", |
| 296 | errno_val_ptr); |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 297 | return -1; |
Jorge Lucangeli Obes | 5389540 | 2016-10-18 12:02:58 -0400 | [diff] [blame] | 298 | } |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 299 | |
| 300 | append_ret_errno(head, errno_val); |
| 301 | } else { |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 302 | switch (action) { |
| 303 | case ACTION_RET_KILL: |
Jennifer Pullman | c0bfae0 | 2016-05-26 17:00:36 -0700 | [diff] [blame] | 304 | append_ret_kill(head); |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 305 | break; |
| 306 | case ACTION_RET_TRAP: |
Jennifer Pullman | c0bfae0 | 2016-05-26 17:00:36 -0700 | [diff] [blame] | 307 | append_ret_trap(head); |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 308 | break; |
| 309 | case ACTION_RET_LOG: |
| 310 | compiler_warn(state, "invalid action: ACTION_RET_LOG"); |
| 311 | return -1; |
| 312 | } |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 313 | } |
| 314 | return 0; |
| 315 | } |
| 316 | |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 317 | struct filter_block *compile_policy_line(struct parser_state *state, int nr, |
| 318 | const char *policy_line, |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 319 | unsigned int entry_lbl_id, |
| 320 | struct bpf_labels *labels, |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 321 | enum block_action action) |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 322 | { |
| 323 | /* |
| 324 | * |policy_line| should be an expression of the form: |
| 325 | * "arg0 == 3 && arg1 == 5 || arg0 == 0x8" |
| 326 | * |
| 327 | * This is, an expression in DNF (disjunctive normal form); |
| 328 | * a disjunction ('||') of one or more conjunctions ('&&') |
| 329 | * of one or more atoms. |
| 330 | * |
Jorge Lucangeli Obes | d96baf4 | 2013-03-26 15:11:30 -0700 | [diff] [blame] | 331 | * Atoms are of the form "arg{DNUM} {OP} {NUM}" |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 332 | * where: |
| 333 | * - DNUM is a decimal number. |
Jorge Lucangeli Obes | 21c3ab1 | 2016-10-12 18:37:37 -0400 | [diff] [blame] | 334 | * - OP is an operator: ==, !=, & (flags set), or 'in' (inclusion). |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 335 | * - NUM is an octal, decimal, or hexadecimal number. |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 336 | * |
| 337 | * When the syscall arguments make the expression true, |
| 338 | * the syscall is allowed. If not, the process is killed. |
| 339 | * |
Jorge Lucangeli Obes | d96baf4 | 2013-03-26 15:11:30 -0700 | [diff] [blame] | 340 | * To block a syscall without killing the process, |
| 341 | * |policy_line| can be of the form: |
| 342 | * "return <errno>" |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 343 | * |
Jorge Lucangeli Obes | d96baf4 | 2013-03-26 15:11:30 -0700 | [diff] [blame] | 344 | * This "return {NUM}" policy line will block the syscall, |
| 345 | * make it return -1 and set |errno| to NUM. |
| 346 | * |
| 347 | * A regular policy line can also include a "return <errno>" clause, |
| 348 | * separated by a semicolon (';'): |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 349 | * "arg0 == 3 && arg1 == 5 || arg0 == 0x8; return {NUM}" |
| 350 | * |
Jorge Lucangeli Obes | d96baf4 | 2013-03-26 15:11:30 -0700 | [diff] [blame] | 351 | * If the syscall arguments don't make the expression true, |
| 352 | * the syscall will be blocked as above instead of killing the process. |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 353 | */ |
| 354 | |
| 355 | size_t len = 0; |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 356 | int grp_idx = 0; |
| 357 | |
| 358 | /* Checks for empty policy lines. */ |
| 359 | if (strlen(policy_line) == 0) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 360 | compiler_warn(state, "empty policy line"); |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 361 | return NULL; |
| 362 | } |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 363 | |
Jorge Lucangeli Obes | d96baf4 | 2013-03-26 15:11:30 -0700 | [diff] [blame] | 364 | /* We will modify |policy_line|, so let's make a copy. */ |
Mike Frysinger | cf48b44 | 2018-08-07 01:59:51 -0400 | [diff] [blame] | 365 | char *line = strdup(policy_line); |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 366 | if (!line) |
| 367 | return NULL; |
| 368 | |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 369 | /* |
Jorge Lucangeli Obes | d96baf4 | 2013-03-26 15:11:30 -0700 | [diff] [blame] | 370 | * We build the filter section as a collection of smaller |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 371 | * "filter blocks" linked together in a singly-linked list. |
| 372 | */ |
Jorge Lucangeli Obes | d96baf4 | 2013-03-26 15:11:30 -0700 | [diff] [blame] | 373 | struct filter_block *head = new_filter_block(); |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 374 | |
| 375 | /* |
Jorge Lucangeli Obes | d96baf4 | 2013-03-26 15:11:30 -0700 | [diff] [blame] | 376 | * Filter sections begin with a label where the main filter |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 377 | * will jump after checking the syscall number. |
| 378 | */ |
| 379 | struct sock_filter *entry_label = new_instr_buf(ONE_INSTR); |
| 380 | set_bpf_lbl(entry_label, entry_lbl_id); |
| 381 | append_filter_block(head, entry_label, ONE_INSTR); |
| 382 | |
Jorge Lucangeli Obes | d96baf4 | 2013-03-26 15:11:30 -0700 | [diff] [blame] | 383 | /* Checks whether we're unconditionally blocking this syscall. */ |
| 384 | if (strncmp(line, "return", strlen("return")) == 0) { |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 385 | if (compile_errno(state, head, line, action) < 0) { |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 386 | free_block_list(head); |
| 387 | free(line); |
Jorge Lucangeli Obes | d96baf4 | 2013-03-26 15:11:30 -0700 | [diff] [blame] | 388 | return NULL; |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 389 | } |
Jorge Lucangeli Obes | d96baf4 | 2013-03-26 15:11:30 -0700 | [diff] [blame] | 390 | free(line); |
| 391 | return head; |
| 392 | } |
| 393 | |
| 394 | /* Splits the optional "return <errno>" part. */ |
| 395 | char *line_ptr; |
| 396 | char *arg_filter = strtok_r(line, ";", &line_ptr); |
| 397 | char *ret_errno = strtok_r(NULL, ";", &line_ptr); |
| 398 | |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 399 | /* |
| 400 | * Splits the policy line by '||' into conjunctions and each conjunction |
| 401 | * by '&&' into atoms. |
| 402 | */ |
Jorge Lucangeli Obes | 66cfc14 | 2012-11-30 15:42:52 -0800 | [diff] [blame] | 403 | char *arg_filter_str = arg_filter; |
| 404 | char *group; |
| 405 | while ((group = tokenize(&arg_filter_str, "||")) != NULL) { |
| 406 | char *group_str = group; |
| 407 | char *comp; |
| 408 | while ((comp = tokenize(&group_str, "&&")) != NULL) { |
| 409 | /* Compiles each atom into a BPF block. */ |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 410 | if (compile_atom(state, head, comp, labels, nr, |
| 411 | grp_idx) < 0) { |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 412 | free_block_list(head); |
| 413 | free(line); |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 414 | return NULL; |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 415 | } |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 416 | } |
| 417 | /* |
| 418 | * If the AND statement succeeds, we're done, |
| 419 | * so jump to SUCCESS line. |
| 420 | */ |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 421 | unsigned int id = success_lbl(labels, nr); |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 422 | struct sock_filter *group_end_block = new_instr_buf(TWO_INSTRS); |
| 423 | len = set_bpf_jump_lbl(group_end_block, id); |
| 424 | /* |
| 425 | * The end of each AND statement falls after the |
| 426 | * jump to SUCCESS. |
| 427 | */ |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 428 | id = group_end_lbl(labels, nr, grp_idx++); |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 429 | len += set_bpf_lbl(group_end_block + len, id); |
| 430 | append_filter_block(head, group_end_block, len); |
| 431 | } |
| 432 | |
| 433 | /* |
| 434 | * If no AND statements succeed, we end up here, |
| 435 | * because we never jumped to SUCCESS. |
| 436 | * If we have to return an errno, do it, |
| 437 | * otherwise just kill the task. |
| 438 | */ |
| 439 | if (ret_errno) { |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 440 | if (compile_errno(state, head, ret_errno, action) < 0) { |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 441 | free_block_list(head); |
| 442 | free(line); |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 443 | return NULL; |
Jorge Lucangeli Obes | 1a122b8 | 2016-11-01 11:59:33 -0400 | [diff] [blame] | 444 | } |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 445 | } else { |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 446 | switch (action) { |
| 447 | case ACTION_RET_KILL: |
Jennifer Pullman | c0bfae0 | 2016-05-26 17:00:36 -0700 | [diff] [blame] | 448 | append_ret_kill(head); |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 449 | break; |
| 450 | case ACTION_RET_TRAP: |
Jennifer Pullman | c0bfae0 | 2016-05-26 17:00:36 -0700 | [diff] [blame] | 451 | append_ret_trap(head); |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 452 | break; |
| 453 | case ACTION_RET_LOG: |
| 454 | append_ret_log(head); |
| 455 | break; |
| 456 | } |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 457 | } |
| 458 | |
| 459 | /* |
| 460 | * Every time the filter succeeds we jump to a predefined SUCCESS |
| 461 | * label. Add that label and BPF RET_ALLOW code now. |
| 462 | */ |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 463 | unsigned int id = success_lbl(labels, nr); |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 464 | struct sock_filter *success_block = new_instr_buf(TWO_INSTRS); |
| 465 | len = set_bpf_lbl(success_block, id); |
| 466 | len += set_bpf_ret_allow(success_block + len); |
| 467 | append_filter_block(head, success_block, len); |
| 468 | |
| 469 | free(line); |
| 470 | return head; |
| 471 | } |
| 472 | |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 473 | int parse_include_statement(struct parser_state *state, char *policy_line, |
| 474 | unsigned int include_level, |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 475 | const char **ret_filename) |
| 476 | { |
| 477 | if (strncmp("@include", policy_line, strlen("@include")) != 0) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 478 | compiler_warn(state, "invalid statement '%s'", policy_line); |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 479 | return -1; |
| 480 | } |
| 481 | |
| 482 | if (policy_line[strlen("@include")] != ' ') { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 483 | compiler_warn(state, "invalid include statement '%s'", |
| 484 | policy_line); |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 485 | return -1; |
| 486 | } |
| 487 | |
| 488 | /* |
| 489 | * Disallow nested includes: only the initial policy file can have |
| 490 | * @include statements. |
| 491 | * Nested includes are not currently necessary and make the policy |
| 492 | * harder to understand. |
| 493 | */ |
| 494 | if (include_level > 0) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 495 | compiler_warn(state, "@include statement nested too deep"); |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 496 | return -1; |
| 497 | } |
| 498 | |
| 499 | char *statement = policy_line; |
| 500 | /* Discard "@include" token. */ |
| 501 | (void)strsep(&statement, " "); |
| 502 | |
| 503 | /* |
| 504 | * compile_filter() below receives a FILE*, so it's not trivial to open |
| 505 | * included files relative to the initial policy filename. |
| 506 | * To avoid mistakes, force the included file path to be absolute |
| 507 | * (start with '/'), or to explicitly load the file relative to CWD by |
| 508 | * using './'. |
| 509 | */ |
| 510 | const char *filename = statement; |
| 511 | if (is_implicit_relative_path(filename)) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 512 | compiler_warn( |
| 513 | state, |
| 514 | "implicit relative path '%s' not supported, use './%s'", |
| 515 | filename, filename); |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 516 | return -1; |
| 517 | } |
| 518 | |
| 519 | *ret_filename = filename; |
| 520 | return 0; |
| 521 | } |
| 522 | |
Mike Frysinger | 29c7234 | 2019-03-15 01:39:31 -0400 | [diff] [blame] | 523 | /* |
| 524 | * This is like getline() but supports line wrapping with \. |
| 525 | */ |
| 526 | static ssize_t getmultiline(char **lineptr, size_t *n, FILE *stream) |
| 527 | { |
| 528 | ssize_t ret = getline(lineptr, n, stream); |
| 529 | if (ret < 0) |
| 530 | return ret; |
| 531 | |
| 532 | char *line = *lineptr; |
| 533 | /* Eat the newline to make processing below easier. */ |
| 534 | if (ret > 0 && line[ret - 1] == '\n') |
| 535 | line[--ret] = '\0'; |
| 536 | |
| 537 | /* If the line doesn't end in a backslash, we're done. */ |
| 538 | if (ret <= 0 || line[ret - 1] != '\\') |
| 539 | return ret; |
| 540 | |
| 541 | /* This line ends in a backslash. Get the nextline. */ |
| 542 | line[--ret] = '\0'; |
| 543 | size_t next_n = 0; |
| 544 | char *next_line = NULL; |
| 545 | ssize_t next_ret = getmultiline(&next_line, &next_n, stream); |
| 546 | if (next_ret == -1) { |
| 547 | free(next_line); |
| 548 | /* We couldn't fully read the line, so return an error. */ |
| 549 | return -1; |
| 550 | } |
| 551 | |
| 552 | /* Merge the lines. */ |
| 553 | *n = ret + next_ret + 2; |
| 554 | line = realloc(line, *n); |
| 555 | line[ret] = ' '; |
| 556 | memcpy(&line[ret + 1], next_line, next_ret + 1); |
| 557 | free(next_line); |
| 558 | *lineptr = line; |
Mike Frysinger | e4c6965 | 2019-06-26 04:33:17 -0400 | [diff] [blame] | 559 | return *n - 1; |
Mike Frysinger | 29c7234 | 2019-03-15 01:39:31 -0400 | [diff] [blame] | 560 | } |
| 561 | |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 562 | int compile_file(const char *filename, FILE *policy_file, |
| 563 | struct filter_block *head, struct filter_block **arg_blocks, |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 564 | struct bpf_labels *labels, |
| 565 | const struct filter_options *filteropts, |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 566 | unsigned int include_level) |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 567 | { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 568 | /* clang-format off */ |
| 569 | struct parser_state state = { |
| 570 | .filename = filename, |
| 571 | .line_number = 0, |
| 572 | }; |
| 573 | /* clang-format on */ |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 574 | /* |
| 575 | * Loop through all the lines in the policy file. |
| 576 | * Build a jump table for the syscall number. |
| 577 | * If the policy line has an arg filter, build the arg filter |
| 578 | * as well. |
| 579 | * Chain the filter sections together and dump them into |
| 580 | * the final buffer at the end. |
| 581 | */ |
| 582 | char *line = NULL; |
| 583 | size_t len = 0; |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 584 | int ret = 0; |
| 585 | |
Mike Frysinger | 29c7234 | 2019-03-15 01:39:31 -0400 | [diff] [blame] | 586 | while (getmultiline(&line, &len, policy_file) != -1) { |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 587 | char *policy_line = line; |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 588 | policy_line = strip(policy_line); |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 589 | |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 590 | state.line_number++; |
| 591 | |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 592 | /* Allow comments and empty lines. */ |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 593 | if (*policy_line == '#' || *policy_line == '\0') { |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 594 | /* Reuse |line| in the next getline() call. */ |
| 595 | continue; |
| 596 | } |
| 597 | |
Matt Delco | b1b2eba | 2020-01-10 12:03:27 -0800 | [diff] [blame] | 598 | /* Allow @include and @frequency statements. */ |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 599 | if (*policy_line == '@') { |
| 600 | const char *filename = NULL; |
Matt Delco | b1b2eba | 2020-01-10 12:03:27 -0800 | [diff] [blame] | 601 | |
| 602 | /* Ignore @frequency statements. */ |
| 603 | if (strncmp("@frequency", policy_line, |
| 604 | strlen("@frequency")) == 0) { |
| 605 | compiler_warn(&state, |
| 606 | "ignored @frequency statement"); |
| 607 | continue; |
| 608 | } |
| 609 | |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 610 | if (parse_include_statement(&state, policy_line, |
| 611 | include_level, |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 612 | &filename) != 0) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 613 | compiler_warn( |
| 614 | &state, |
| 615 | "failed to parse include statement"); |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 616 | ret = -1; |
| 617 | goto free_line; |
| 618 | } |
| 619 | |
| 620 | FILE *included_file = fopen(filename, "re"); |
| 621 | if (included_file == NULL) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 622 | compiler_pwarn(&state, "fopen('%s') failed", |
| 623 | filename); |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 624 | ret = -1; |
| 625 | goto free_line; |
| 626 | } |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 627 | if (compile_file(filename, included_file, head, |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 628 | arg_blocks, labels, filteropts, |
Zach Reizner | e926051 | 2019-02-27 18:06:34 -0800 | [diff] [blame] | 629 | include_level + 1) == -1) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 630 | compiler_warn(&state, "'@include %s' failed", |
| 631 | filename); |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 632 | fclose(included_file); |
| 633 | ret = -1; |
| 634 | goto free_line; |
| 635 | } |
| 636 | fclose(included_file); |
| 637 | continue; |
| 638 | } |
| 639 | |
| 640 | /* |
| 641 | * If it's not a comment, or an empty line, or an @include |
| 642 | * statement, treat |policy_line| as a regular policy line. |
| 643 | */ |
| 644 | char *syscall_name = strsep(&policy_line, ":"); |
lhchavez | d0b4070 | 2017-09-01 04:17:41 +0000 | [diff] [blame] | 645 | if (policy_line == NULL) { |
| 646 | warn("compile_file: malformed policy line, missing " |
| 647 | "':'"); |
| 648 | ret = -1; |
| 649 | goto free_line; |
| 650 | } |
| 651 | |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 652 | policy_line = strip(policy_line); |
| 653 | if (*policy_line == '\0') { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 654 | compiler_warn(&state, "empty policy line"); |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 655 | ret = -1; |
| 656 | goto free_line; |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 657 | } |
| 658 | |
Jorge Lucangeli Obes | c499257 | 2017-04-28 10:49:01 -0400 | [diff] [blame] | 659 | syscall_name = strip(syscall_name); |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 660 | int nr = lookup_syscall(syscall_name); |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 661 | if (nr < 0) { |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 662 | compiler_warn(&state, "nonexistent syscall '%s'", |
| 663 | syscall_name); |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 664 | if (filteropts->allow_logging) { |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 665 | /* |
| 666 | * If we're logging failures, assume we're in a |
| 667 | * debugging case and continue. |
| 668 | * This is not super risky because an invalid |
| 669 | * syscall name is likely caused by a typo or by |
| 670 | * leftover lines from a different architecture. |
| 671 | * In either case, not including a policy line |
| 672 | * is equivalent to killing the process if the |
| 673 | * syscall is made, so there's no added attack |
| 674 | * surface. |
| 675 | */ |
| 676 | /* Reuse |line| in the next getline() call. */ |
| 677 | continue; |
| 678 | } |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 679 | ret = -1; |
| 680 | goto free_line; |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 681 | } |
| 682 | |
| 683 | /* |
| 684 | * For each syscall, add either a simple ALLOW, |
| 685 | * or an arg filter block. |
| 686 | */ |
| 687 | if (strcmp(policy_line, "1") == 0) { |
| 688 | /* Add simple ALLOW. */ |
| 689 | append_allow_syscall(head, nr); |
| 690 | } else { |
| 691 | /* |
| 692 | * Create and jump to the label that will hold |
| 693 | * the arg filter block. |
| 694 | */ |
| 695 | unsigned int id = bpf_label_id(labels, syscall_name); |
| 696 | struct sock_filter *nr_comp = |
| 697 | new_instr_buf(ALLOW_SYSCALL_LEN); |
| 698 | bpf_allow_syscall_args(nr_comp, nr, id); |
| 699 | append_filter_block(head, nr_comp, ALLOW_SYSCALL_LEN); |
| 700 | |
| 701 | /* Build the arg filter block. */ |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 702 | struct filter_block *block = |
| 703 | compile_policy_line(&state, nr, policy_line, id, |
| 704 | labels, filteropts->action); |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 705 | |
| 706 | if (!block) { |
| 707 | if (*arg_blocks) { |
| 708 | free_block_list(*arg_blocks); |
lhchavez | d38280c | 2017-09-01 14:00:05 +0000 | [diff] [blame] | 709 | *arg_blocks = NULL; |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 710 | } |
Jorge Lucangeli Obes | 32201f8 | 2019-06-12 14:45:06 -0400 | [diff] [blame] | 711 | warn("could not allocate filter block"); |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 712 | ret = -1; |
| 713 | goto free_line; |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 714 | } |
| 715 | |
| 716 | if (*arg_blocks) { |
| 717 | extend_filter_block_list(*arg_blocks, block); |
| 718 | } else { |
| 719 | *arg_blocks = block; |
| 720 | } |
| 721 | } |
| 722 | /* Reuse |line| in the next getline() call. */ |
| 723 | } |
Jorge Lucangeli Obes | 960b56b | 2017-11-17 11:49:58 -0500 | [diff] [blame] | 724 | /* getline(3) returned -1. This can mean EOF or the below errors. */ |
| 725 | if (errno == EINVAL || errno == ENOMEM) { |
| 726 | if (*arg_blocks) { |
| 727 | free_block_list(*arg_blocks); |
| 728 | *arg_blocks = NULL; |
| 729 | } |
Jorge Lucangeli Obes | 32201f8 | 2019-06-12 14:45:06 -0400 | [diff] [blame] | 730 | warn("getmultiline() failed"); |
Jorge Lucangeli Obes | 960b56b | 2017-11-17 11:49:58 -0500 | [diff] [blame] | 731 | ret = -1; |
| 732 | } |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 733 | |
| 734 | free_line: |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 735 | free(line); |
Jorge Lucangeli Obes | bce4ccb | 2017-03-20 13:38:43 -0400 | [diff] [blame] | 736 | return ret; |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 737 | } |
| 738 | |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 739 | int compile_filter(const char *filename, FILE *initial_file, |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 740 | struct sock_fprog *prog, |
| 741 | const struct filter_options *filteropts) |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 742 | { |
Luis Hector Chavez | 1a87c8a | 2017-09-02 13:18:31 -0700 | [diff] [blame] | 743 | int ret = 0; |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 744 | struct bpf_labels labels; |
| 745 | labels.count = 0; |
| 746 | |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 747 | if (!initial_file) { |
| 748 | warn("compile_filter: |initial_file| is NULL"); |
Jorge Lucangeli Obes | 6135db9 | 2012-07-27 13:37:30 -0700 | [diff] [blame] | 749 | return -1; |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 750 | } |
Jorge Lucangeli Obes | 6135db9 | 2012-07-27 13:37:30 -0700 | [diff] [blame] | 751 | |
Jorge Lucangeli Obes | d96baf4 | 2013-03-26 15:11:30 -0700 | [diff] [blame] | 752 | struct filter_block *head = new_filter_block(); |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 753 | struct filter_block *arg_blocks = NULL; |
| 754 | |
| 755 | /* Start filter by validating arch. */ |
| 756 | struct sock_filter *valid_arch = new_instr_buf(ARCH_VALIDATION_LEN); |
| 757 | size_t len = bpf_validate_arch(valid_arch); |
| 758 | append_filter_block(head, valid_arch, len); |
| 759 | |
Jorge Lucangeli Obes | bda833c | 2012-07-31 16:25:56 -0700 | [diff] [blame] | 760 | /* Load syscall number. */ |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 761 | struct sock_filter *load_nr = new_instr_buf(ONE_INSTR); |
| 762 | len = bpf_load_syscall_nr(load_nr); |
| 763 | append_filter_block(head, load_nr, len); |
| 764 | |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 765 | /* |
| 766 | * On kernels without SECCOMP_RET_LOG, Minijail can attempt to write the |
| 767 | * first failing syscall to syslog(3). In order for syslog(3) to work, |
| 768 | * some syscalls need to be unconditionally allowed. |
| 769 | */ |
| 770 | if (filteropts->allow_syscalls_for_logging) |
Jorge Lucangeli Obes | 713f6fb | 2016-10-03 13:03:25 -0400 | [diff] [blame] | 771 | allow_logging_syscalls(head); |
Jorge Lucangeli Obes | bda833c | 2012-07-31 16:25:56 -0700 | [diff] [blame] | 772 | |
Luis Hector Chavez | 7624e71 | 2017-08-28 19:30:59 -0700 | [diff] [blame] | 773 | if (compile_file(filename, initial_file, head, &arg_blocks, &labels, |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 774 | filteropts, 0 /* include_level */) != 0) { |
Jorge Lucangeli Obes | 45932a5 | 2017-03-15 17:02:58 -0400 | [diff] [blame] | 775 | warn("compile_filter: compile_file() failed"); |
Luis Hector Chavez | 1a87c8a | 2017-09-02 13:18:31 -0700 | [diff] [blame] | 776 | ret = -1; |
| 777 | goto free_filter; |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 778 | } |
| 779 | |
Jorge Lucangeli Obes | bda833c | 2012-07-31 16:25:56 -0700 | [diff] [blame] | 780 | /* |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 781 | * If none of the syscalls match, either fall through to LOG, TRAP, or |
| 782 | * KILL. |
Jorge Lucangeli Obes | bda833c | 2012-07-31 16:25:56 -0700 | [diff] [blame] | 783 | */ |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 784 | switch (filteropts->action) { |
| 785 | case ACTION_RET_KILL: |
Jorge Lucangeli Obes | bda833c | 2012-07-31 16:25:56 -0700 | [diff] [blame] | 786 | append_ret_kill(head); |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 787 | break; |
| 788 | case ACTION_RET_TRAP: |
Jorge Lucangeli Obes | bda833c | 2012-07-31 16:25:56 -0700 | [diff] [blame] | 789 | append_ret_trap(head); |
Jorge Lucangeli Obes | e1a8689 | 2019-06-10 16:17:03 -0400 | [diff] [blame] | 790 | break; |
| 791 | case ACTION_RET_LOG: |
| 792 | if (filteropts->allow_logging) { |
| 793 | append_ret_log(head); |
| 794 | } else { |
| 795 | warn("compile_filter: cannot use RET_LOG without " |
| 796 | "allowing logging"); |
| 797 | ret = -1; |
| 798 | goto free_filter; |
| 799 | } |
| 800 | break; |
| 801 | default: |
| 802 | warn("compile_filter: invalid log action %d", |
| 803 | filteropts->action); |
| 804 | ret = -1; |
| 805 | goto free_filter; |
| 806 | } |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 807 | |
| 808 | /* Allocate the final buffer, now that we know its size. */ |
Jorge Lucangeli Obes | 565e978 | 2016-08-05 11:03:19 -0400 | [diff] [blame] | 809 | size_t final_filter_len = |
| 810 | head->total_len + (arg_blocks ? arg_blocks->total_len : 0); |
Luis Hector Chavez | 1a87c8a | 2017-09-02 13:18:31 -0700 | [diff] [blame] | 811 | if (final_filter_len > BPF_MAXINSNS) { |
| 812 | ret = -1; |
| 813 | goto free_filter; |
| 814 | } |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 815 | |
| 816 | struct sock_filter *final_filter = |
Jorge Lucangeli Obes | 565e978 | 2016-08-05 11:03:19 -0400 | [diff] [blame] | 817 | calloc(final_filter_len, sizeof(struct sock_filter)); |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 818 | |
Luis Hector Chavez | 1a87c8a | 2017-09-02 13:18:31 -0700 | [diff] [blame] | 819 | if (flatten_block_list(head, final_filter, 0, final_filter_len) < 0) { |
| 820 | free(final_filter); |
| 821 | ret = -1; |
| 822 | goto free_filter; |
| 823 | } |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 824 | |
Jorge Lucangeli Obes | 565e978 | 2016-08-05 11:03:19 -0400 | [diff] [blame] | 825 | if (flatten_block_list(arg_blocks, final_filter, head->total_len, |
Luis Hector Chavez | 1a87c8a | 2017-09-02 13:18:31 -0700 | [diff] [blame] | 826 | final_filter_len) < 0) { |
| 827 | free(final_filter); |
| 828 | ret = -1; |
| 829 | goto free_filter; |
| 830 | } |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 831 | |
Luis Hector Chavez | 1a87c8a | 2017-09-02 13:18:31 -0700 | [diff] [blame] | 832 | if (bpf_resolve_jumps(&labels, final_filter, final_filter_len) < 0) { |
| 833 | free(final_filter); |
| 834 | ret = -1; |
| 835 | goto free_filter; |
| 836 | } |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 837 | |
| 838 | prog->filter = final_filter; |
| 839 | prog->len = final_filter_len; |
Luis Hector Chavez | 1a87c8a | 2017-09-02 13:18:31 -0700 | [diff] [blame] | 840 | |
| 841 | free_filter: |
| 842 | free_block_list(head); |
| 843 | free_block_list(arg_blocks); |
| 844 | free_label_strings(&labels); |
| 845 | return ret; |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 846 | } |
| 847 | |
| 848 | int flatten_block_list(struct filter_block *head, struct sock_filter *filter, |
Jorge Lucangeli Obes | 565e978 | 2016-08-05 11:03:19 -0400 | [diff] [blame] | 849 | size_t index, size_t cap) |
Jorge Lucangeli Obes | d446726 | 2012-03-23 16:19:59 -0700 | [diff] [blame] | 850 | { |
| 851 | size_t _index = index; |
| 852 | |
| 853 | struct filter_block *curr; |
| 854 | size_t i; |
| 855 | |
| 856 | for (curr = head; curr; curr = curr->next) { |
| 857 | for (i = 0; i < curr->len; i++) { |
| 858 | if (_index >= cap) |
| 859 | return -1; |
| 860 | filter[_index++] = curr->instrs[i]; |
| 861 | } |
| 862 | } |
| 863 | return 0; |
| 864 | } |
| 865 | |
Jorge Lucangeli Obes | fc8ab53 | 2012-03-20 10:14:31 -0700 | [diff] [blame] | 866 | void free_block_list(struct filter_block *head) |
| 867 | { |
| 868 | struct filter_block *current, *prev; |
| 869 | |
| 870 | current = head; |
| 871 | while (current) { |
| 872 | free(current->instrs); |
| 873 | prev = current; |
| 874 | current = current->next; |
| 875 | free(prev); |
| 876 | } |
| 877 | } |