24367027d6
This makes it harder to make mistakes while editing the code. Since the sizeof's can be autocalculated, let the machine do that. It also reduces the cognitive load while reading the code. Cc: Christian Göttsche <cgzones@googlemail.com> Cc: Serge Hallyn <serge@hallyn.com> Cc: Iker Pedrosa <ipedrosa@redhat.com> Signed-off-by: Alejandro Colomar <alx@kernel.org>
110 lines
2.3 KiB
C
110 lines
2.3 KiB
C
/*
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* SPDX-FileCopyrightText: 1991 , Julianne Frances Haugh
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* SPDX-FileCopyrightText: 1991 , Chip Rosenthal
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* SPDX-FileCopyrightText: 1996 - 1998, Marek Michałkiewicz
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* SPDX-FileCopyrightText: 2003 - 2005, Tomasz Kłoczko
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* SPDX-FileCopyrightText: 2007 - 2010, Nicolas François
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <config.h>
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#include "defines.h"
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#include <stdio.h>
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#include "getdef.h"
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#include "prototypes.h"
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#include "strlcpy.h"
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#ident "$Id$"
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/*
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* This is now rather generic function which decides if "tty" is listed
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* under "cfgin" in config (directly or indirectly). Fallback to default if
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* something is bad.
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*/
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static bool is_listed (const char *cfgin, const char *tty, bool def)
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{
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FILE *fp;
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char buf[1024], *s;
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const char *cons;
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/*
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* If the CONSOLE configuration definition isn't given,
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* fallback to default.
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*/
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cons = getdef_str (cfgin);
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if (NULL == cons) {
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return def;
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}
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/*
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* If this isn't a filename, then it is a ":" delimited list of
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* console devices upon which root logins are allowed.
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*/
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if (*cons != '/') {
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char *pbuf;
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STRLCPY(buf, cons);
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pbuf = &buf[0];
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while ((s = strtok (pbuf, ":")) != NULL) {
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if (strcmp (s, tty) == 0) {
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return true;
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}
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pbuf = NULL;
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}
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return false;
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}
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/*
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* If we can't open the console list, then call everything a
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* console - otherwise root will never be allowed to login.
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*/
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fp = fopen (cons, "r");
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if (NULL == fp) {
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return def;
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}
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/*
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* See if this tty is listed in the console file.
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*/
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while (fgets (buf, sizeof (buf), fp) != NULL) {
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/* Remove optional trailing '\n'. */
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buf[strcspn (buf, "\n")] = '\0';
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if (strcmp (buf, tty) == 0) {
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(void) fclose (fp);
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return true;
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}
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}
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/*
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* This tty isn't a console.
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*/
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(void) fclose (fp);
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return false;
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}
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/*
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* console - return 1 if the "tty" is a console device, else 0.
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*
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* Note - we need to take extreme care here to avoid locking out root logins
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* if something goes awry. That's why we do things like call everything a
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* console if the consoles file can't be opened. Because of this, we must
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* warn the user to protect against the remove of the consoles file since
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* that would allow an unauthorized root login.
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*/
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bool console (const char *tty)
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{
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if (strncmp (tty, "/dev/", 5) == 0) {
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tty += 5;
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}
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return is_listed ("CONSOLE", tty, true);
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}
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