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158 lines
4.2 KiB
158 lines
4.2 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* linux/fs/binfmt_script.c |
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* |
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* Copyright (C) 1996 Martin von Löwis |
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* original #!-checking implemented by tytso. |
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*/ |
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#include <linux/module.h> |
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#include <linux/string.h> |
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#include <linux/stat.h> |
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#include <linux/binfmts.h> |
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#include <linux/init.h> |
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#include <linux/file.h> |
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#include <linux/err.h> |
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#include <linux/fs.h> |
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static inline bool spacetab(char c) { return c == ' ' || c == '\t'; } |
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static inline const char *next_non_spacetab(const char *first, const char *last) |
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{ |
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for (; first <= last; first++) |
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if (!spacetab(*first)) |
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return first; |
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return NULL; |
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} |
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static inline const char *next_terminator(const char *first, const char *last) |
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{ |
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for (; first <= last; first++) |
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if (spacetab(*first) || !*first) |
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return first; |
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return NULL; |
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} |
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static int load_script(struct linux_binprm *bprm) |
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{ |
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const char *i_name, *i_sep, *i_arg, *i_end, *buf_end; |
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struct file *file; |
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int retval; |
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/* Not ours to exec if we don't start with "#!". */ |
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if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!')) |
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return -ENOEXEC; |
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/* |
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* This section handles parsing the #! line into separate |
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* interpreter path and argument strings. We must be careful |
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* because bprm->buf is not yet guaranteed to be NUL-terminated |
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* (though the buffer will have trailing NUL padding when the |
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* file size was smaller than the buffer size). |
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* |
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* We do not want to exec a truncated interpreter path, so either |
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* we find a newline (which indicates nothing is truncated), or |
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* we find a space/tab/NUL after the interpreter path (which |
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* itself may be preceded by spaces/tabs). Truncating the |
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* arguments is fine: the interpreter can re-read the script to |
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* parse them on its own. |
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*/ |
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buf_end = bprm->buf + sizeof(bprm->buf) - 1; |
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i_end = strnchr(bprm->buf, sizeof(bprm->buf), '\n'); |
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if (!i_end) { |
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i_end = next_non_spacetab(bprm->buf + 2, buf_end); |
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if (!i_end) |
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return -ENOEXEC; /* Entire buf is spaces/tabs */ |
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/* |
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* If there is no later space/tab/NUL we must assume the |
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* interpreter path is truncated. |
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*/ |
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if (!next_terminator(i_end, buf_end)) |
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return -ENOEXEC; |
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i_end = buf_end; |
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} |
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/* Trim any trailing spaces/tabs from i_end */ |
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while (spacetab(i_end[-1])) |
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i_end--; |
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/* Skip over leading spaces/tabs */ |
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i_name = next_non_spacetab(bprm->buf+2, i_end); |
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if (!i_name || (i_name == i_end)) |
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return -ENOEXEC; /* No interpreter name found */ |
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/* Is there an optional argument? */ |
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i_arg = NULL; |
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i_sep = next_terminator(i_name, i_end); |
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if (i_sep && (*i_sep != '\0')) |
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i_arg = next_non_spacetab(i_sep, i_end); |
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/* |
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* If the script filename will be inaccessible after exec, typically |
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* because it is a "/dev/fd/<fd>/.." path against an O_CLOEXEC fd, give |
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* up now (on the assumption that the interpreter will want to load |
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* this file). |
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*/ |
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if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE) |
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return -ENOENT; |
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/* |
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* OK, we've parsed out the interpreter name and |
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* (optional) argument. |
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* Splice in (1) the interpreter's name for argv[0] |
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* (2) (optional) argument to interpreter |
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* (3) filename of shell script (replace argv[0]) |
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* |
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* This is done in reverse order, because of how the |
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* user environment and arguments are stored. |
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*/ |
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retval = remove_arg_zero(bprm); |
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if (retval) |
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return retval; |
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retval = copy_string_kernel(bprm->interp, bprm); |
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if (retval < 0) |
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return retval; |
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bprm->argc++; |
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*((char *)i_end) = '\0'; |
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if (i_arg) { |
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*((char *)i_sep) = '\0'; |
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retval = copy_string_kernel(i_arg, bprm); |
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if (retval < 0) |
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return retval; |
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bprm->argc++; |
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} |
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retval = copy_string_kernel(i_name, bprm); |
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if (retval) |
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return retval; |
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bprm->argc++; |
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retval = bprm_change_interp(i_name, bprm); |
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if (retval < 0) |
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return retval; |
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/* |
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* OK, now restart the process with the interpreter's dentry. |
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*/ |
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file = open_exec(i_name); |
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if (IS_ERR(file)) |
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return PTR_ERR(file); |
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bprm->interpreter = file; |
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return 0; |
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} |
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static struct linux_binfmt script_format = { |
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.module = THIS_MODULE, |
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.load_binary = load_script, |
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}; |
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static int __init init_script_binfmt(void) |
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{ |
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register_binfmt(&script_format); |
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return 0; |
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} |
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static void __exit exit_script_binfmt(void) |
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{ |
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unregister_binfmt(&script_format); |
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} |
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core_initcall(init_script_binfmt); |
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module_exit(exit_script_binfmt); |
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MODULE_LICENSE("GPL");
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