Root/fs/binfmt_script.c

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

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