| Kyle Swenson | 8d8f654 | 2021-03-15 11:02:55 -0600 | [diff] [blame^] | 1 | /* |
| 2 | * linux/fs/binfmt_script.c |
| 3 | * |
| 4 | * Copyright (C) 1996 Martin von Löwis |
| 5 | * original #!-checking implemented by tytso. |
| 6 | */ |
| 7 | |
| 8 | #include <linux/module.h> |
| 9 | #include <linux/string.h> |
| 10 | #include <linux/stat.h> |
| 11 | #include <linux/binfmts.h> |
| 12 | #include <linux/init.h> |
| 13 | #include <linux/file.h> |
| 14 | #include <linux/err.h> |
| 15 | #include <linux/fs.h> |
| 16 | |
| 17 | static int load_script(struct linux_binprm *bprm) |
| 18 | { |
| 19 | const char *i_arg, *i_name; |
| 20 | char *cp; |
| 21 | struct file *file; |
| 22 | char interp[BINPRM_BUF_SIZE]; |
| 23 | int retval; |
| 24 | |
| 25 | if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!')) |
| 26 | return -ENOEXEC; |
| 27 | |
| 28 | /* |
| 29 | * If the script filename will be inaccessible after exec, typically |
| 30 | * because it is a "/dev/fd/<fd>/.." path against an O_CLOEXEC fd, give |
| 31 | * up now (on the assumption that the interpreter will want to load |
| 32 | * this file). |
| 33 | */ |
| 34 | if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE) |
| 35 | return -ENOENT; |
| 36 | |
| 37 | /* |
| 38 | * This section does the #! interpretation. |
| 39 | * Sorta complicated, but hopefully it will work. -TYT |
| 40 | */ |
| 41 | |
| 42 | allow_write_access(bprm->file); |
| 43 | fput(bprm->file); |
| 44 | bprm->file = NULL; |
| 45 | |
| 46 | bprm->buf[BINPRM_BUF_SIZE - 1] = '\0'; |
| 47 | if ((cp = strchr(bprm->buf, '\n')) == NULL) |
| 48 | cp = bprm->buf+BINPRM_BUF_SIZE-1; |
| 49 | *cp = '\0'; |
| 50 | while (cp > bprm->buf) { |
| 51 | cp--; |
| 52 | if ((*cp == ' ') || (*cp == '\t')) |
| 53 | *cp = '\0'; |
| 54 | else |
| 55 | break; |
| 56 | } |
| 57 | for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++); |
| 58 | if (*cp == '\0') |
| 59 | return -ENOEXEC; /* No interpreter name found */ |
| 60 | i_name = cp; |
| 61 | i_arg = NULL; |
| 62 | for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++) |
| 63 | /* nothing */ ; |
| 64 | while ((*cp == ' ') || (*cp == '\t')) |
| 65 | *cp++ = '\0'; |
| 66 | if (*cp) |
| 67 | i_arg = cp; |
| 68 | strcpy (interp, i_name); |
| 69 | /* |
| 70 | * OK, we've parsed out the interpreter name and |
| 71 | * (optional) argument. |
| 72 | * Splice in (1) the interpreter's name for argv[0] |
| 73 | * (2) (optional) argument to interpreter |
| 74 | * (3) filename of shell script (replace argv[0]) |
| 75 | * |
| 76 | * This is done in reverse order, because of how the |
| 77 | * user environment and arguments are stored. |
| 78 | */ |
| 79 | retval = remove_arg_zero(bprm); |
| 80 | if (retval) |
| 81 | return retval; |
| 82 | retval = copy_strings_kernel(1, &bprm->interp, bprm); |
| 83 | if (retval < 0) return retval; |
| 84 | bprm->argc++; |
| 85 | if (i_arg) { |
| 86 | retval = copy_strings_kernel(1, &i_arg, bprm); |
| 87 | if (retval < 0) return retval; |
| 88 | bprm->argc++; |
| 89 | } |
| 90 | retval = copy_strings_kernel(1, &i_name, bprm); |
| 91 | if (retval) return retval; |
| 92 | bprm->argc++; |
| 93 | retval = bprm_change_interp(interp, bprm); |
| 94 | if (retval < 0) |
| 95 | return retval; |
| 96 | |
| 97 | /* |
| 98 | * OK, now restart the process with the interpreter's dentry. |
| 99 | */ |
| 100 | file = open_exec(interp); |
| 101 | if (IS_ERR(file)) |
| 102 | return PTR_ERR(file); |
| 103 | |
| 104 | bprm->file = file; |
| 105 | retval = prepare_binprm(bprm); |
| 106 | if (retval < 0) |
| 107 | return retval; |
| 108 | return search_binary_handler(bprm); |
| 109 | } |
| 110 | |
| 111 | static struct linux_binfmt script_format = { |
| 112 | .module = THIS_MODULE, |
| 113 | .load_binary = load_script, |
| 114 | }; |
| 115 | |
| 116 | static int __init init_script_binfmt(void) |
| 117 | { |
| 118 | register_binfmt(&script_format); |
| 119 | return 0; |
| 120 | } |
| 121 | |
| 122 | static void __exit exit_script_binfmt(void) |
| 123 | { |
| 124 | unregister_binfmt(&script_format); |
| 125 | } |
| 126 | |
| 127 | core_initcall(init_script_binfmt); |
| 128 | module_exit(exit_script_binfmt); |
| 129 | MODULE_LICENSE("GPL"); |