1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Landlock test helpers 4 * 5 * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net> 6 * Copyright © 2019-2020 ANSSI 7 * Copyright © 2021 Microsoft Corporation 8 */ 9 10 #include <errno.h> 11 #include <linux/landlock.h> 12 #include <linux/securebits.h> 13 #include <sys/capability.h> 14 #include <sys/socket.h> 15 #include <sys/syscall.h> 16 #include <sys/types.h> 17 #include <sys/wait.h> 18 #include <unistd.h> 19 20 #include "../kselftest_harness.h" 21 22 #ifndef __maybe_unused 23 #define __maybe_unused __attribute__((__unused__)) 24 #endif 25 26 /* TEST_F_FORK() should not be used for new tests. */ 27 #define TEST_F_FORK(fixture_name, test_name) TEST_F(fixture_name, test_name) 28 29 #ifndef landlock_create_ruleset 30 static inline int 31 landlock_create_ruleset(const struct landlock_ruleset_attr *const attr, 32 const size_t size, const __u32 flags) 33 { 34 return syscall(__NR_landlock_create_ruleset, attr, size, flags); 35 } 36 #endif 37 38 #ifndef landlock_add_rule 39 static inline int landlock_add_rule(const int ruleset_fd, 40 const enum landlock_rule_type rule_type, 41 const void *const rule_attr, 42 const __u32 flags) 43 { 44 return syscall(__NR_landlock_add_rule, ruleset_fd, rule_type, rule_attr, 45 flags); 46 } 47 #endif 48 49 #ifndef landlock_restrict_self 50 static inline int landlock_restrict_self(const int ruleset_fd, 51 const __u32 flags) 52 { 53 return syscall(__NR_landlock_restrict_self, ruleset_fd, flags); 54 } 55 #endif 56 57 static void _init_caps(struct __test_metadata *const _metadata, bool drop_all) 58 { 59 cap_t cap_p; 60 /* Only these three capabilities are useful for the tests. */ 61 const cap_value_t caps[] = { 62 /* clang-format off */ 63 CAP_DAC_OVERRIDE, 64 CAP_MKNOD, 65 CAP_NET_ADMIN, 66 CAP_NET_BIND_SERVICE, 67 CAP_SYS_ADMIN, 68 CAP_SYS_CHROOT, 69 /* clang-format on */ 70 }; 71 const unsigned int noroot = SECBIT_NOROOT | SECBIT_NOROOT_LOCKED; 72 73 if ((cap_get_secbits() & noroot) != noroot) 74 EXPECT_EQ(0, cap_set_secbits(noroot)); 75 76 cap_p = cap_get_proc(); 77 EXPECT_NE(NULL, cap_p); 78 EXPECT_NE(-1, cap_clear(cap_p)); 79 if (!drop_all) { 80 EXPECT_NE(-1, cap_set_flag(cap_p, CAP_PERMITTED, 81 ARRAY_SIZE(caps), caps, CAP_SET)); 82 } 83 84 /* Automatically resets ambient capabilities. */ 85 EXPECT_NE(-1, cap_set_proc(cap_p)) 86 { 87 TH_LOG("Failed to set capabilities: %s", strerror(errno)); 88 } 89 EXPECT_NE(-1, cap_free(cap_p)); 90 91 /* Quickly checks that ambient capabilities are cleared. */ 92 EXPECT_NE(-1, cap_get_ambient(caps[0])); 93 } 94 95 /* We cannot put such helpers in a library because of kselftest_harness.h . */ 96 static void __maybe_unused disable_caps(struct __test_metadata *const _metadata) 97 { 98 _init_caps(_metadata, false); 99 } 100 101 static void __maybe_unused drop_caps(struct __test_metadata *const _metadata) 102 { 103 _init_caps(_metadata, true); 104 } 105 106 static void _change_cap(struct __test_metadata *const _metadata, 107 const cap_flag_t flag, const cap_value_t cap, 108 const cap_flag_value_t value) 109 { 110 cap_t cap_p; 111 112 cap_p = cap_get_proc(); 113 EXPECT_NE(NULL, cap_p); 114 EXPECT_NE(-1, cap_set_flag(cap_p, flag, 1, &cap, value)); 115 EXPECT_NE(-1, cap_set_proc(cap_p)) 116 { 117 TH_LOG("Failed to set capability %d: %s", cap, strerror(errno)); 118 } 119 EXPECT_NE(-1, cap_free(cap_p)); 120 } 121 122 static void __maybe_unused set_cap(struct __test_metadata *const _metadata, 123 const cap_value_t cap) 124 { 125 _change_cap(_metadata, CAP_EFFECTIVE, cap, CAP_SET); 126 } 127 128 static void __maybe_unused clear_cap(struct __test_metadata *const _metadata, 129 const cap_value_t cap) 130 { 131 _change_cap(_metadata, CAP_EFFECTIVE, cap, CAP_CLEAR); 132 } 133 134 static void __maybe_unused 135 set_ambient_cap(struct __test_metadata *const _metadata, const cap_value_t cap) 136 { 137 _change_cap(_metadata, CAP_INHERITABLE, cap, CAP_SET); 138 139 EXPECT_NE(-1, cap_set_ambient(cap, CAP_SET)) 140 { 141 TH_LOG("Failed to set ambient capability %d: %s", cap, 142 strerror(errno)); 143 } 144 } 145 146 static void __maybe_unused clear_ambient_cap( 147 struct __test_metadata *const _metadata, const cap_value_t cap) 148 { 149 EXPECT_EQ(1, cap_get_ambient(cap)); 150 _change_cap(_metadata, CAP_INHERITABLE, cap, CAP_CLEAR); 151 EXPECT_EQ(0, cap_get_ambient(cap)); 152 } 153 154 /* Receives an FD from a UNIX socket. Returns the received FD, or -errno. */ 155 static int __maybe_unused recv_fd(int usock) 156 { 157 int fd_rx; 158 union { 159 /* Aligned ancillary data buffer. */ 160 char buf[CMSG_SPACE(sizeof(fd_rx))]; 161 struct cmsghdr _align; 162 } cmsg_rx = {}; 163 char data = '\0'; 164 struct iovec io = { 165 .iov_base = &data, 166 .iov_len = sizeof(data), 167 }; 168 struct msghdr msg = { 169 .msg_iov = &io, 170 .msg_iovlen = 1, 171 .msg_control = &cmsg_rx.buf, 172 .msg_controllen = sizeof(cmsg_rx.buf), 173 }; 174 struct cmsghdr *cmsg; 175 int res; 176 177 res = recvmsg(usock, &msg, MSG_CMSG_CLOEXEC); 178 if (res < 0) 179 return -errno; 180 181 cmsg = CMSG_FIRSTHDR(&msg); 182 if (cmsg->cmsg_len != CMSG_LEN(sizeof(fd_rx))) 183 return -EIO; 184 185 memcpy(&fd_rx, CMSG_DATA(cmsg), sizeof(fd_rx)); 186 return fd_rx; 187 } 188 189 /* Sends an FD on a UNIX socket. Returns 0 on success or -errno. */ 190 static int __maybe_unused send_fd(int usock, int fd_tx) 191 { 192 union { 193 /* Aligned ancillary data buffer. */ 194 char buf[CMSG_SPACE(sizeof(fd_tx))]; 195 struct cmsghdr _align; 196 } cmsg_tx = {}; 197 char data_tx = '.'; 198 struct iovec io = { 199 .iov_base = &data_tx, 200 .iov_len = sizeof(data_tx), 201 }; 202 struct msghdr msg = { 203 .msg_iov = &io, 204 .msg_iovlen = 1, 205 .msg_control = &cmsg_tx.buf, 206 .msg_controllen = sizeof(cmsg_tx.buf), 207 }; 208 struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); 209 210 cmsg->cmsg_len = CMSG_LEN(sizeof(fd_tx)); 211 cmsg->cmsg_level = SOL_SOCKET; 212 cmsg->cmsg_type = SCM_RIGHTS; 213 memcpy(CMSG_DATA(cmsg), &fd_tx, sizeof(fd_tx)); 214 215 if (sendmsg(usock, &msg, 0) < 0) 216 return -errno; 217 return 0; 218 } 219 220 static void __maybe_unused 221 enforce_ruleset(struct __test_metadata *const _metadata, const int ruleset_fd) 222 { 223 ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)); 224 ASSERT_EQ(0, landlock_restrict_self(ruleset_fd, 0)) 225 { 226 TH_LOG("Failed to enforce ruleset: %s", strerror(errno)); 227 } 228 } 229