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| 2 | |
| 3 | * Test the static transparent flag 'T' of binfmt_misc. A magic-matched
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| 4 | * binary is dispatched to an interpreter with the argument vector left
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| 5 | * untouched, the binary passed through AT_EXECFD and mm->exe_file labeled
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| 6 | * with the binary. The asserting interpreter (binfmt_transparent_interp)
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| 7 | * verifies the constructed identity from inside the process and exits 0.
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| 8 | *
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| 9 | * Needs root for the registration; no bpf toolchain involved.
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| 10 |
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| 11 | #define _GNU_SOURCE
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| 12 | #include <stdio.h>
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| 13 | #include <stdlib.h>
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| 14 |
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| 15 | #include "binfmt_misc_common.h"
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| 16 | #include "kselftest_harness.h"
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| 17 |
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| 18 | #define MAGIC "#TRANSPARENT-SELFTEST#"
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| 19 | #define TARGET_PATH "/tmp/binfmt_transparent_target"
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| 20 | #define INTERP_PATH "/tmp/binfmt_transparent_interp"
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| 21 | #define ENTRY "test_transparent"
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| 22 | #define RULE(flags) ":" ENTRY ":M:0:" MAGIC "::" INTERP_PATH ":" flags
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| 23 |
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| 24 |
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| 25 | static int create_target(void)
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| 26 | {
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| 27 | char buf[128] = MAGIC "\n";
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| 28 | int fd;
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| 29 |
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| 30 | unlink(TARGET_PATH);
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| 31 | fd = open(TARGET_PATH, O_WRONLY | O_CREAT | O_EXCL, 0755);
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| 32 | if (fd < 0)
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| 33 | return -1;
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| 34 | if (write(fd, buf, sizeof(buf)) != (ssize_t)sizeof(buf)) {
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| 35 | close(fd);
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| 36 | return -1;
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| 37 | }
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| 38 | close(fd);
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| 39 | return 0;
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| 40 | }
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| 41 |
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| 42 | FIXTURE(transparent) {
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| 43 | };
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| 44 |
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| 45 | FIXTURE_SETUP(transparent)
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| 46 | {
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| 47 | char src[PATH_MAX];
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| 48 |
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| 49 | if (getuid() != 0)
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| 50 | SKIP(return, "test must be run as root");
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| 51 | if (!binfmt_misc_available())
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| 52 | SKIP(return, "no binfmt_misc");
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| 53 |
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| 54 | ASSERT_EQ(artifact_path(src, sizeof(src), "binfmt_transparent_interp"), 0);
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| 55 | ASSERT_EQ(copy_file(src, INTERP_PATH), 0);
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| 56 | ASSERT_EQ(create_target(), 0);
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| 57 |
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| 58 |
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| 59 | if (!binfmt_flag_supported('T')) {
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| 60 | ASSERT_EQ(errno, EINVAL);
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| 61 | SKIP(return, "kernel without the 'T' flag");
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| 62 | }
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| 63 | }
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| 64 |
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| 65 | FIXTURE_TEARDOWN(transparent)
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| 66 | {
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| 67 | unregister(ENTRY);
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| 68 | unlink(TARGET_PATH);
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| 69 | unlink(INTERP_PATH);
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| 70 | }
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| 71 |
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| 72 |
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| 73 | TEST_F(transparent, plain_entry_registers)
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| 74 | {
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| 75 | ASSERT_EQ(write_reg(RULE("")), 0);
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| 76 | }
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| 77 |
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| 78 |
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| 79 | TEST_F(transparent, rejects_preserve_argv0)
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| 80 | {
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| 81 | ASSERT_NE(write_reg(RULE("TP")), 0);
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| 82 | EXPECT_EQ(errno, EINVAL);
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| 83 | }
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| 84 |
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| 85 |
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| 86 | TEST_F(transparent, dispatch)
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| 87 | {
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| 88 | ASSERT_EQ(write_reg(RULE("T")), 0);
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| 89 |
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| 90 | setenv("BINFMT_TEST_BINARY", TARGET_PATH, 1);
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| 91 | setenv("BINFMT_TEST_ARGV0", PAYLOAD_ARGV0, 1);
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| 92 | EXPECT_EQ(run_payload(TARGET_PATH), 0);
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| 93 | }
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| 94 |
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| 95 | TEST_HARNESS_MAIN
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