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/slab.h>
12 #include <linux/binfmts.h>
13 #include <linux/init.h>
14 #include <linux/file.h>
15 #include <linux/err.h>
16 #include <linux/fs.h>
17
18 static int load_script(struct linux_binprm *bprm,struct pt_regs *regs)
19 {
20 char *cp, *i_name, *i_arg;
21 struct file *file;
22 char interp[BINPRM_BUF_SIZE];
23 int retval;
24
25 if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!') ||
26 (bprm->recursion_depth > BINPRM_MAX_RECURSION))
27 return -ENOEXEC;
28 /*
29 * This section does the #! interpretation.
30 * Sorta complicated, but hopefully it will work. -TYT
31 */
32
33 bprm->recursion_depth++;
34 allow_write_access(bprm->file);
35 fput(bprm->file);
36 bprm->file = NULL;
37
38 bprm->buf[BINPRM_BUF_SIZE - 1] = '\0';
39 if ((cp = strchr(bprm->buf, '\n')) == NULL)
40 cp = bprm->buf+BINPRM_BUF_SIZE-1;
41 *cp = '\0';
42 while (cp > bprm->buf) {
43 cp--;
44 if ((*cp == ' ') || (*cp == '\t'))
45 *cp = '\0';
46 else
47 break;
48 }
49 for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++);
50 if (*cp == '\0')
51 return -ENOEXEC; /* No interpreter name found */
52 i_name = cp;
53 i_arg = NULL;
54 for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++)
55 /* nothing */ ;
56 while ((*cp == ' ') || (*cp == '\t'))
57 *cp++ = '\0';
58 if (*cp)
59 i_arg = cp;
60 strcpy (interp, i_name);
61 /*
62 * OK, we've parsed out the interpreter name and
63 * (optional) argument.
64 * Splice in (1) the interpreter's name for argv[0]
65 * (2) (optional) argument to interpreter
66 * (3) filename of shell script (replace argv[0])
67 *
68 * This is done in reverse order, because of how the
69 * user environment and arguments are stored.
70 */
71 retval = remove_arg_zero(bprm);
72 if (retval)
73 return retval;
74 retval = copy_strings_kernel(1, &bprm->interp, bprm);
75 if (retval < 0) return retval;
76 bprm->argc++;
77 if (i_arg) {
78 retval = copy_strings_kernel(1, &i_arg, bprm);
79 if (retval < 0) return retval;
80 bprm->argc++;
81 }
82 retval = copy_strings_kernel(1, &i_name, bprm);
83 if (retval) return retval;
84 bprm->argc++;
85 bprm->interp = interp;
86
87 /*
88 * OK, now restart the process with the interpreter's dentry.
89 */
90 file = open_exec(interp);
91 if (IS_ERR(file))
92 return PTR_ERR(file);
93
94 bprm->file = file;
95 retval = prepare_binprm(bprm);
96 if (retval < 0)
97 return retval;
98 return search_binary_handler(bprm,regs);
99 }
100
101 static struct linux_binfmt script_format = {
102 .module = THIS_MODULE,
103 .load_binary = load_script,
104 };
105
106 static int __init init_script_binfmt(void)
107 {
108 return register_binfmt(&script_format);
109 }
110
111 static void __exit exit_script_binfmt(void)
112 {
113 unregister_binfmt(&script_format);
114 }
115
116 core_initcall(init_script_binfmt);
117 module_exit(exit_script_binfmt);
118 MODULE_LICENSE("GPL");
119
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