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| 2 | |
| 3 | * Simple tool to set SECBIT_EXEC_RESTRICT_FILE, SECBIT_EXEC_DENY_INTERACTIVE,
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| 4 | * before executing a command.
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| 5 | *
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| 6 | * Copyright © 2024 Microsoft Corporation
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| 7 |
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| 8 |
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| 9 | #define _GNU_SOURCE
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| 10 | #define __SANE_USERSPACE_TYPES__
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| 11 | #include <errno.h>
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| 12 | #include <linux/prctl.h>
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| 13 | #include <linux/securebits.h>
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| 14 | #include <stdbool.h>
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| 15 | #include <stdio.h>
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| 16 | #include <stdlib.h>
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| 17 | #include <string.h>
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| 18 | #include <sys/prctl.h>
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| 19 | #include <unistd.h>
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| 20 |
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| 21 | static void print_usage(const char *argv0)
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| 22 | {
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| 23 | fprintf(stderr, "usage: %s -f|-i -- <cmd> [args]...\n\n", argv0);
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| 24 | fprintf(stderr, "Execute a command with\n");
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| 25 | fprintf(stderr, "- SECBIT_EXEC_RESTRICT_FILE set: -f\n");
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| 26 | fprintf(stderr, "- SECBIT_EXEC_DENY_INTERACTIVE set: -i\n");
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| 27 | }
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| 28 |
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| 29 | int main(const int argc, char *const argv[], char *const *const envp)
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| 30 | {
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| 31 | const char *cmd_path;
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| 32 | char *const *cmd_argv;
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| 33 | int opt, secbits_cur, secbits_new;
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| 34 | bool has_policy = false;
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| 35 |
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| 36 | secbits_cur = prctl(PR_GET_SECUREBITS);
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| 37 | if (secbits_cur == -1) {
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| 38 | |
| 39 | * This should never happen, except with a buggy seccomp
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| 40 | * filter.
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| 41 |
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| 42 | perror("ERROR: Failed to get securebits");
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| 43 | return 1;
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| 44 | }
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| 45 |
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| 46 | secbits_new = secbits_cur;
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| 47 | while ((opt = getopt(argc, argv, "fi")) != -1) {
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| 48 | switch (opt) {
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| 49 | case 'f':
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| 50 | secbits_new |= SECBIT_EXEC_RESTRICT_FILE |
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| 51 | SECBIT_EXEC_RESTRICT_FILE_LOCKED;
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| 52 | has_policy = true;
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| 53 | break;
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| 54 | case 'i':
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| 55 | secbits_new |= SECBIT_EXEC_DENY_INTERACTIVE |
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| 56 | SECBIT_EXEC_DENY_INTERACTIVE_LOCKED;
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| 57 | has_policy = true;
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| 58 | break;
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| 59 | default:
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| 60 | print_usage(argv[0]);
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| 61 | return 1;
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| 62 | }
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| 63 | }
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| 64 |
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| 65 | if (!argv[optind] || !has_policy) {
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| 66 | print_usage(argv[0]);
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| 67 | return 1;
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| 68 | }
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| 69 |
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| 70 | if (secbits_cur != secbits_new &&
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| 71 | prctl(PR_SET_SECUREBITS, secbits_new)) {
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| 72 | perror("Failed to set secure bit(s).");
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| 73 | fprintf(stderr,
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| 74 | "Hint: The running kernel may not support this feature.\n");
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| 75 | return 1;
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| 76 | }
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| 77 |
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| 78 | cmd_path = argv[optind];
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| 79 | cmd_argv = argv + optind;
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| 80 | fprintf(stderr, "Executing command...\n");
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| 81 | execvpe(cmd_path, cmd_argv, envp);
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| 82 | fprintf(stderr, "Failed to execute \"%s\": %s\n", cmd_path,
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| 83 | strerror(errno));
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| 84 | return 1;
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| 85 | }
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