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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160// SPDX-License-Identifier: GPL-2.0-only/* * 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 inline bool spacetab(char c) { return c == ' ' || c == '\t'; }static inline const char *next_non_spacetab(const char *first, const char *last){ for (; first <= last; first++) if (!spacetab(*first)) return first; return NULL;}static inline const char *next_terminator(const char *first, const char *last){ for (; first <= last; first++) if (spacetab(*first) || !*first) return first; return NULL;}
static int load_script(struct linux_binprm *bprm){ const char *i_name, *i_sep, *i_arg, *i_end, *buf_end; struct file *file; int retval;
/* Not ours to exec if we don't start with "#!". */ if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!')) return -ENOEXEC;
/* * This section handles parsing the #! line into separate * interpreter path and argument strings. We must be careful * because bprm->buf is not yet guaranteed to be NUL-terminated * (though the buffer will have trailing NUL padding when the * file size was smaller than the buffer size). * * We do not want to exec a truncated interpreter path, so either * we find a newline (which indicates nothing is truncated), or * we find a space/tab/NUL after the interpreter path (which * itself may be preceded by spaces/tabs). Truncating the * arguments is fine: the interpreter can re-read the script to * parse them on its own. */ buf_end = bprm->buf + sizeof(bprm->buf) - 1; i_end = strnchr(bprm->buf, sizeof(bprm->buf), '\n'); if (!i_end) { i_end = next_non_spacetab(bprm->buf + 2, buf_end); if (!i_end) return -ENOEXEC; /* Entire buf is spaces/tabs */ /* * If there is no later space/tab/NUL we must assume the * interpreter path is truncated. */ if (!next_terminator(i_end, buf_end)) return -ENOEXEC; i_end = buf_end; } /* Trim any trailing spaces/tabs from i_end */ while (spacetab(i_end[-1])) i_end--;
/* Skip over leading spaces/tabs */ i_name = next_non_spacetab(bprm->buf+2, i_end); if (!i_name || (i_name == i_end)) return -ENOEXEC; /* No interpreter name found */
/* Is there an optional argument? */ i_arg = NULL; i_sep = next_terminator(i_name, i_end); if (i_sep && (*i_sep != '\0')) i_arg = next_non_spacetab(i_sep, i_end);
/* * 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;
/* * 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_string_kernel(bprm->interp, bprm); if (retval < 0) return retval; bprm->argc++; *((char *)i_end) = '\0'; if (i_arg) { *((char *)i_sep) = '\0'; retval = copy_string_kernel(i_arg, bprm); if (retval < 0) return retval; bprm->argc++; } retval = copy_string_kernel(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->interpreter = file; return 0;}
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_DESCRIPTION("Kernel support for scripts starting with #!");MODULE_LICENSE("GPL");