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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 | // SPDX-License-Identifier: GPL-2.0 /* * Landlock tests - Ptrace * * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net> * Copyright © 2019-2020 ANSSI */ #define _GNU_SOURCE #include <errno.h> #include <fcntl.h> #include <linux/landlock.h> #include <signal.h> #include <sys/prctl.h> #include <sys/ptrace.h> #include <sys/types.h> #include <sys/wait.h> #include <unistd.h> #include "common.h" static void create_domain(struct __test_metadata *const _metadata) { int ruleset_fd; struct landlock_ruleset_attr ruleset_attr = { .handled_access_fs = LANDLOCK_ACCESS_FS_MAKE_BLOCK, }; ruleset_fd = landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0); EXPECT_LE(0, ruleset_fd) { TH_LOG("Failed to create a ruleset: %s", strerror(errno)); } EXPECT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)); EXPECT_EQ(0, landlock_restrict_self(ruleset_fd, 0)); EXPECT_EQ(0, close(ruleset_fd)); } static int test_ptrace_read(const pid_t pid) { static const char path_template[] = "/proc/%d/environ"; char procenv_path[sizeof(path_template) + 10]; int procenv_path_size, fd; procenv_path_size = snprintf(procenv_path, sizeof(procenv_path), path_template, pid); if (procenv_path_size >= sizeof(procenv_path)) return E2BIG; fd = open(procenv_path, O_RDONLY | O_CLOEXEC); if (fd < 0) return errno; /* * Mixing error codes from close(2) and open(2) should not lead to any * (access type) confusion for this test. */ if (close(fd) != 0) return errno; return 0; } FIXTURE(hierarchy) { }; FIXTURE_VARIANT(hierarchy) { const bool domain_both; const bool domain_parent; const bool domain_child; }; /* * Test multiple tracing combinations between a parent process P1 and a child * process P2. * * Yama's scoped ptrace is presumed disabled. If enabled, this optional * restriction is enforced in addition to any Landlock check, which means that * all P2 requests to trace P1 would be denied. */ /* * No domain * * P1-. P1 -> P2 : allow * \ P2 -> P1 : allow * 'P2 */ FIXTURE_VARIANT_ADD(hierarchy, allow_without_domain) { .domain_both = false, .domain_parent = false, .domain_child = false, }; /* * Child domain * * P1--. P1 -> P2 : allow * \ P2 -> P1 : deny * .'-----. * | P2 | * '------' */ FIXTURE_VARIANT_ADD(hierarchy, allow_with_one_domain) { .domain_both = false, .domain_parent = false, .domain_child = true, }; /* * Parent domain * .------. * | P1 --. P1 -> P2 : deny * '------' \ P2 -> P1 : allow * ' * P2 */ FIXTURE_VARIANT_ADD(hierarchy, deny_with_parent_domain) { .domain_both = false, .domain_parent = true, .domain_child = false, }; /* * Parent + child domain (siblings) * .------. * | P1 ---. P1 -> P2 : deny * '------' \ P2 -> P1 : deny * .---'--. * | P2 | * '------' */ FIXTURE_VARIANT_ADD(hierarchy, deny_with_sibling_domain) { .domain_both = false, .domain_parent = true, .domain_child = true, }; /* * Same domain (inherited) * .-------------. * | P1----. | P1 -> P2 : allow * | \ | P2 -> P1 : allow * | ' | * | P2 | * '-------------' */ FIXTURE_VARIANT_ADD(hierarchy, allow_sibling_domain) { .domain_both = true, .domain_parent = false, .domain_child = false, }; /* * Inherited + child domain * .-----------------. * | P1----. | P1 -> P2 : allow * | \ | P2 -> P1 : deny * | .-'----. | * | | P2 | | * | '------' | * '-----------------' */ FIXTURE_VARIANT_ADD(hierarchy, allow_with_nested_domain) { .domain_both = true, .domain_parent = false, .domain_child = true, }; /* * Inherited + parent domain * .-----------------. * |.------. | P1 -> P2 : deny * || P1 ----. | P2 -> P1 : allow * |'------' \ | * | ' | * | P2 | * '-----------------' */ FIXTURE_VARIANT_ADD(hierarchy, deny_with_nested_and_parent_domain) { .domain_both = true, .domain_parent = true, .domain_child = false, }; /* * Inherited + parent and child domain (siblings) * .-----------------. * | .------. | P1 -> P2 : deny * | | P1 . | P2 -> P1 : deny * | '------'\ | * | \ | * | .--'---. | * | | P2 | | * | '------' | * '-----------------' */ FIXTURE_VARIANT_ADD(hierarchy, deny_with_forked_domain) { .domain_both = true, .domain_parent = true, .domain_child = true, }; FIXTURE_SETUP(hierarchy) { } FIXTURE_TEARDOWN(hierarchy) { } /* Test PTRACE_TRACEME and PTRACE_ATTACH for parent and child. */ TEST_F(hierarchy, trace) { pid_t child, parent; int status, err_proc_read; int pipe_child[2], pipe_parent[2]; char buf_parent; long ret; /* * Removes all effective and permitted capabilities to not interfere * with cap_ptrace_access_check() in case of PTRACE_MODE_FSCREDS. */ drop_caps(_metadata); parent = getpid(); ASSERT_EQ(0, pipe2(pipe_child, O_CLOEXEC)); ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC)); if (variant->domain_both) { create_domain(_metadata); if (!_metadata->passed) /* Aborts before forking. */ return; } child = fork(); ASSERT_LE(0, child); if (child == 0) { char buf_child; ASSERT_EQ(0, close(pipe_parent[1])); ASSERT_EQ(0, close(pipe_child[0])); if (variant->domain_child) create_domain(_metadata); /* Waits for the parent to be in a domain, if any. */ ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1)); /* Tests PTRACE_ATTACH and PTRACE_MODE_READ on the parent. */ err_proc_read = test_ptrace_read(parent); ret = ptrace(PTRACE_ATTACH, parent, NULL, 0); if (variant->domain_child) { EXPECT_EQ(-1, ret); EXPECT_EQ(EPERM, errno); EXPECT_EQ(EACCES, err_proc_read); } else { EXPECT_EQ(0, ret); EXPECT_EQ(0, err_proc_read); } if (ret == 0) { ASSERT_EQ(parent, waitpid(parent, &status, 0)); ASSERT_EQ(1, WIFSTOPPED(status)); ASSERT_EQ(0, ptrace(PTRACE_DETACH, parent, NULL, 0)); } /* Tests child PTRACE_TRACEME. */ ret = ptrace(PTRACE_TRACEME); if (variant->domain_parent) { EXPECT_EQ(-1, ret); EXPECT_EQ(EPERM, errno); } else { EXPECT_EQ(0, ret); } /* * Signals that the PTRACE_ATTACH test is done and the * PTRACE_TRACEME test is ongoing. */ ASSERT_EQ(1, write(pipe_child[1], ".", 1)); if (!variant->domain_parent) { ASSERT_EQ(0, raise(SIGSTOP)); } /* Waits for the parent PTRACE_ATTACH test. */ ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1)); _exit(_metadata->passed ? EXIT_SUCCESS : EXIT_FAILURE); return; } ASSERT_EQ(0, close(pipe_child[1])); ASSERT_EQ(0, close(pipe_parent[0])); if (variant->domain_parent) create_domain(_metadata); /* Signals that the parent is in a domain, if any. */ ASSERT_EQ(1, write(pipe_parent[1], ".", 1)); /* * Waits for the child to test PTRACE_ATTACH on the parent and start * testing PTRACE_TRACEME. */ ASSERT_EQ(1, read(pipe_child[0], &buf_parent, 1)); /* Tests child PTRACE_TRACEME. */ if (!variant->domain_parent) { ASSERT_EQ(child, waitpid(child, &status, 0)); ASSERT_EQ(1, WIFSTOPPED(status)); ASSERT_EQ(0, ptrace(PTRACE_DETACH, child, NULL, 0)); } else { /* The child should not be traced by the parent. */ EXPECT_EQ(-1, ptrace(PTRACE_DETACH, child, NULL, 0)); EXPECT_EQ(ESRCH, errno); } /* Tests PTRACE_ATTACH and PTRACE_MODE_READ on the child. */ err_proc_read = test_ptrace_read(child); ret = ptrace(PTRACE_ATTACH, child, NULL, 0); if (variant->domain_parent) { EXPECT_EQ(-1, ret); EXPECT_EQ(EPERM, errno); EXPECT_EQ(EACCES, err_proc_read); } else { EXPECT_EQ(0, ret); EXPECT_EQ(0, err_proc_read); } if (ret == 0) { ASSERT_EQ(child, waitpid(child, &status, 0)); ASSERT_EQ(1, WIFSTOPPED(status)); ASSERT_EQ(0, ptrace(PTRACE_DETACH, child, NULL, 0)); } /* Signals that the parent PTRACE_ATTACH test is done. */ ASSERT_EQ(1, write(pipe_parent[1], ".", 1)); ASSERT_EQ(child, waitpid(child, &status, 0)); if (WIFSIGNALED(status) || !WIFEXITED(status) || WEXITSTATUS(status) != EXIT_SUCCESS) _metadata->passed = 0; } TEST_HARNESS_MAIN |