Linux Kernel  3.7.1
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binfmt_script.c
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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,struct pt_regs *regs)
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] != '!') ||
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  register_binfmt(&script_format);
109  return 0;
110 }
111 
112 static void __exit exit_script_binfmt(void)
113 {
114  unregister_binfmt(&script_format);
115 }
116 
117 core_initcall(init_script_binfmt);
118 module_exit(exit_script_binfmt);
119 MODULE_LICENSE("GPL");