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"); 130