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
load_script(struct linux_binprm * bprm)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
init_script_binfmt(void)117 static int __init init_script_binfmt(void)
118 {
119 register_binfmt(&script_format);
120 return 0;
121 }
122
exit_script_binfmt(void)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
