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 int retval; 23 24 if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!')) 25 return -ENOEXEC; 26 27 /* 28 * If the script filename will be inaccessible after exec, typically 29 * because it is a "/dev/fd/<fd>/.." path against an O_CLOEXEC fd, give 30 * up now (on the assumption that the interpreter will want to load 31 * this file). 32 */ 33 if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE) 34 return -ENOENT; 35 36 /* 37 * This section does the #! interpretation. 38 * Sorta complicated, but hopefully it will work. -TYT 39 */ 40 41 allow_write_access(bprm->file); 42 fput(bprm->file); 43 bprm->file = NULL; 44 45 bprm->buf[BINPRM_BUF_SIZE - 1] = '\0'; 46 if ((cp = strchr(bprm->buf, '\n')) == NULL) 47 cp = bprm->buf+BINPRM_BUF_SIZE-1; 48 *cp = '\0'; 49 while (cp > bprm->buf) { 50 cp--; 51 if ((*cp == ' ') || (*cp == '\t')) 52 *cp = '\0'; 53 else 54 break; 55 } 56 for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++); 57 if (*cp == '\0') 58 return -ENOEXEC; /* No interpreter name found */ 59 i_name = cp; 60 i_arg = NULL; 61 for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++) 62 /* nothing */ ; 63 while ((*cp == ' ') || (*cp == '\t')) 64 *cp++ = '\0'; 65 if (*cp) 66 i_arg = cp; 67 /* 68 * OK, we've parsed out the interpreter name and 69 * (optional) argument. 70 * Splice in (1) the interpreter's name for argv[0] 71 * (2) (optional) argument to interpreter 72 * (3) filename of shell script (replace argv[0]) 73 * 74 * This is done in reverse order, because of how the 75 * user environment and arguments are stored. 76 */ 77 retval = remove_arg_zero(bprm); 78 if (retval) 79 return retval; 80 retval = copy_strings_kernel(1, &bprm->interp, bprm); 81 if (retval < 0) 82 return retval; 83 bprm->argc++; 84 if (i_arg) { 85 retval = copy_strings_kernel(1, &i_arg, bprm); 86 if (retval < 0) 87 return retval; 88 bprm->argc++; 89 } 90 retval = copy_strings_kernel(1, &i_name, bprm); 91 if (retval) 92 return retval; 93 bprm->argc++; 94 retval = bprm_change_interp(i_name, bprm); 95 if (retval < 0) 96 return retval; 97 98 /* 99 * OK, now restart the process with the interpreter's dentry. 100 */ 101 file = open_exec(i_name); 102 if (IS_ERR(file)) 103 return PTR_ERR(file); 104 105 bprm->file = file; 106 retval = prepare_binprm(bprm); 107 if (retval < 0) 108 return retval; 109 return search_binary_handler(bprm); 110 } 111 112 static struct linux_binfmt script_format = { 113 .module = THIS_MODULE, 114 .load_binary = load_script, 115 }; 116 117 static int __init init_script_binfmt(void) 118 { 119 register_binfmt(&script_format); 120 return 0; 121 } 122 123 static void __exit exit_script_binfmt(void) 124 { 125 unregister_binfmt(&script_format); 126 } 127 128 core_initcall(init_script_binfmt); 129 module_exit(exit_script_binfmt); 130 MODULE_LICENSE("GPL"); 131