mirror of
https://github.com/torvalds/linux.git
synced 2024-11-24 21:21:41 +00:00
8099b047ec
load_script() simply truncates bprm->buf and this is very wrong if the length of shebang string exceeds BINPRM_BUF_SIZE-2. This can silently truncate i_arg or (worse) we can execute the wrong binary if buf[2:126] happens to be the valid executable path. Change load_script() to return ENOEXEC if it can't find '\n' or zero in bprm->buf. Note that '\0' can come from either prepare_binprm()->memset() or from kernel_read(), we do not care. Link: http://lkml.kernel.org/r/20181112160931.GA28463@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Ben Woodard <woodard@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
135 lines
3.0 KiB
C
135 lines
3.0 KiB
C
/*
|
|
* linux/fs/binfmt_script.c
|
|
*
|
|
* Copyright (C) 1996 Martin von Löwis
|
|
* original #!-checking implemented by tytso.
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/string.h>
|
|
#include <linux/stat.h>
|
|
#include <linux/binfmts.h>
|
|
#include <linux/init.h>
|
|
#include <linux/file.h>
|
|
#include <linux/err.h>
|
|
#include <linux/fs.h>
|
|
|
|
static int load_script(struct linux_binprm *bprm)
|
|
{
|
|
const char *i_arg, *i_name;
|
|
char *cp;
|
|
struct file *file;
|
|
int retval;
|
|
|
|
if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!'))
|
|
return -ENOEXEC;
|
|
|
|
/*
|
|
* If the script filename will be inaccessible after exec, typically
|
|
* because it is a "/dev/fd/<fd>/.." path against an O_CLOEXEC fd, give
|
|
* up now (on the assumption that the interpreter will want to load
|
|
* this file).
|
|
*/
|
|
if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
|
|
return -ENOENT;
|
|
|
|
/*
|
|
* This section does the #! interpretation.
|
|
* Sorta complicated, but hopefully it will work. -TYT
|
|
*/
|
|
|
|
allow_write_access(bprm->file);
|
|
fput(bprm->file);
|
|
bprm->file = NULL;
|
|
|
|
for (cp = bprm->buf+2;; cp++) {
|
|
if (cp >= bprm->buf + BINPRM_BUF_SIZE)
|
|
return -ENOEXEC;
|
|
if (!*cp || (*cp == '\n'))
|
|
break;
|
|
}
|
|
*cp = '\0';
|
|
|
|
while (cp > bprm->buf) {
|
|
cp--;
|
|
if ((*cp == ' ') || (*cp == '\t'))
|
|
*cp = '\0';
|
|
else
|
|
break;
|
|
}
|
|
for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++);
|
|
if (*cp == '\0')
|
|
return -ENOEXEC; /* No interpreter name found */
|
|
i_name = cp;
|
|
i_arg = NULL;
|
|
for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++)
|
|
/* nothing */ ;
|
|
while ((*cp == ' ') || (*cp == '\t'))
|
|
*cp++ = '\0';
|
|
if (*cp)
|
|
i_arg = cp;
|
|
/*
|
|
* OK, we've parsed out the interpreter name and
|
|
* (optional) argument.
|
|
* Splice in (1) the interpreter's name for argv[0]
|
|
* (2) (optional) argument to interpreter
|
|
* (3) filename of shell script (replace argv[0])
|
|
*
|
|
* This is done in reverse order, because of how the
|
|
* user environment and arguments are stored.
|
|
*/
|
|
retval = remove_arg_zero(bprm);
|
|
if (retval)
|
|
return retval;
|
|
retval = copy_strings_kernel(1, &bprm->interp, bprm);
|
|
if (retval < 0)
|
|
return retval;
|
|
bprm->argc++;
|
|
if (i_arg) {
|
|
retval = copy_strings_kernel(1, &i_arg, bprm);
|
|
if (retval < 0)
|
|
return retval;
|
|
bprm->argc++;
|
|
}
|
|
retval = copy_strings_kernel(1, &i_name, bprm);
|
|
if (retval)
|
|
return retval;
|
|
bprm->argc++;
|
|
retval = bprm_change_interp(i_name, bprm);
|
|
if (retval < 0)
|
|
return retval;
|
|
|
|
/*
|
|
* OK, now restart the process with the interpreter's dentry.
|
|
*/
|
|
file = open_exec(i_name);
|
|
if (IS_ERR(file))
|
|
return PTR_ERR(file);
|
|
|
|
bprm->file = file;
|
|
retval = prepare_binprm(bprm);
|
|
if (retval < 0)
|
|
return retval;
|
|
return search_binary_handler(bprm);
|
|
}
|
|
|
|
static struct linux_binfmt script_format = {
|
|
.module = THIS_MODULE,
|
|
.load_binary = load_script,
|
|
};
|
|
|
|
static int __init init_script_binfmt(void)
|
|
{
|
|
register_binfmt(&script_format);
|
|
return 0;
|
|
}
|
|
|
|
static void __exit exit_script_binfmt(void)
|
|
{
|
|
unregister_binfmt(&script_format);
|
|
}
|
|
|
|
core_initcall(init_script_binfmt);
|
|
module_exit(exit_script_binfmt);
|
|
MODULE_LICENSE("GPL");
|