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/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
18static 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
101static struct linux_binfmt script_format = {
102    .module = THIS_MODULE,
103    .load_binary = load_script,
104};
105
106static int __init init_script_binfmt(void)
107{
108    return register_binfmt(&script_format);
109}
110
111static void __exit exit_script_binfmt(void)
112{
113    unregister_binfmt(&script_format);
114}
115
116core_initcall(init_script_binfmt);
117module_exit(exit_script_binfmt);
118MODULE_LICENSE("GPL");
119

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