--- /dev/null
+Makefile
+build
+Makefile.in
+configure
+aclocal.m4
--- /dev/null
+COPYING
+missing
+mkinstalldirs
+install-sh
--- /dev/null
+;;; -*-emacs-lisp-*-
+
+(setq skel-alist
+ (append
+ '((full-title . "chkpath")
+ (program . "chkpath")
+ (author . "Mark Wooding"))
+ skel-alist))
--- /dev/null
+## -*-makefile-*-
+##
+## $Id: Makefile.am,v 1.1 1999/04/06 20:12:07 mdw Exp $
+##
+## Makefile for chkpath
+##
+## (c) 1999 Mark Wooding
+##
+
+##----- Licensing notice ----------------------------------------------------
+##
+## This file is part of chkpath.
+##
+## chkpath is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 2 of the License, or
+## (at your option) any later version.
+##
+## chkpath is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with chkpath; if not, write to the Free Software Foundation,
+## Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+##----- Revision history ----------------------------------------------------
+##
+## $Log: Makefile.am,v $
+## Revision 1.1 1999/04/06 20:12:07 mdw
+## Initial revision
+##
+
+AUTOMAKE_OPTIONS = foreign
+
+SUBDIRS = mLib
+
+bin_PROGRAMS = chkpath tmpdir
+man_MANS = chkpath.1 tmpdir.1
+INCLUDES = -I$(srcdir)/mLib
+LDADD = mLib/libmLib.a
+
+chkpath_SOURCES = chkpath.c path.c
+tmpdir_SOURCES = tmpdir.c path.c
+
+##----- That's all, folks ---------------------------------------------------
--- /dev/null
+# Kludgy makefile
+
+# --- Fiddle with these if you like ---
+
+srcdir = @srcdir@
+prefix = /usr/local
+exec_prefix = $(prefix)
+bindir = $(exec_prefix)/bin
+mandir = $(prefix)/man
+
+VPATH = @srcdir@
+
+CC = gcc
+LD = gcc
+PACKAGE = chkpath
+VERSION = 1.0.0
+CFLAGS = -O2 -g -DVERSION="\"$(VERSION)\"" -pedantic -Wall
+LIBS = -lmLib
+INSTALL = install
+INSTALL_BINARY = $(INSTALL) -c -s
+INSTALL_MAN = $(INSTALL) -c -m 644
+
+# --- Don't fiddle any more ---
+
+PROGRAMS = chkpath tmpdir
+MANPAGES = chkpath.1 tmpdir.1
+SOURCES = chkpath.c path.c tmpdir.c
+DIST = Makefile Makefile.main $(SOURCES) $(MANPAGES)
+
+all: Makefile $(PROGRAMS)
+
+Makefile: $(srcdir)/Makefile.main
+ sed -e 's/@''srcdir@/$(srcdir)/' \
+ $(srcdir)/Makefile.main >Makefile
+
+CHKPATH_OBJ = chkpath.o path.o
+chkpath: $(CHKPATH_OBJ)
+ $(LD) $(CHKPATH_OBJ) $(LIBS) -o chkpath
+
+TMPDIR_OBJ = tmpdir.o path.o
+tmpdir: $(TMPDIR_OBJ)
+ $(LD) $(TMPDIR_OBJ) $(LIBS) -o tmpdir
+
+install: $(PROGRAMS)
+ @for i in $(PROGRAMS); do \
+ echo " $(INSTALL_BINARY) $$i $(bindir)/$$i"; \
+ $(INSTALL_BINARY) $$i $(bindir)/$$i; \
+ done
+ @for i in $(MANPAGES); do \
+ mansec=`echo $$i | sed -e 's/^.*\.//'`; \
+ echo " $(INSTALL_MAN) $(srcdir)/$$i $(mandir)/man$$mansec/$$i"; \
+ $(INSTALL_MAN) $(srcdir)/$$i $(mandir)/man$$mansec/$$i; \
+ done
+
+uninstall:
+ for i in $(PROGRAMS); do rm -f $(bindir)/$$i; done
+ for i in $(MANPAGES); do \
+ mansec=`echo $$i | sed -e 's/^.*\.//'`; \
+ rm -f $(mandir)/man$$mansec/$$i; \
+ done
+
+arch:
+ mkdir $(ARCH) || true
+ cd $(ARCH); make -f ../Makefile.main Makefile srcdir=.. MAKEFLAGS=
+
+clean:
+ rm -f *.o *~ chkpath tmpdir
+
+distdir = $(PACKAGE)-$(VERSION)
+distdir:
+ mkdir $(distdir)
+ for i in $(DIST); do \
+ if [ -f $$i ]; then \
+ ln $$i $(distdir)/$$i; \
+ else \
+ ln $(srcdir)/$$i $(distdir)/$$i; \
+ fi; \
+ done
+
+dist: distdir
+ GZIP=-9 tar chozf $(PACKAGE)-$(VERSION).tar.gz $(distdir)
+ rm -rf $(distdir)
--- /dev/null
+/* -*-c-*-
+ *
+ * $Id: checkpath.c,v 1.1 1999/04/06 20:12:07 mdw Exp $
+ *
+ * Check a path for safety
+ *
+ * (c) 1999 Mark Wooding
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of chkpath.
+ *
+ * chkpath is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * chkpath is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with chkpath; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+/*----- Revision history --------------------------------------------------*
+ *
+ * $Log: checkpath.c,v $
+ * Revision 1.1 1999/04/06 20:12:07 mdw
+ * Initial revision
+ *
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <pwd.h>
+#include <grp.h>
+
+#include <mLib/alloc.h>
+#include <mLib/dstr.h>
+
+#include "path.h"
+
+/*----- Data structures ---------------------------------------------------*/
+
+/* --- An item in the directory list --- *
+ *
+ * Each directory becomes an element on a list which is manipulated in a
+ * stack-like way.
+ */
+
+struct elt {
+ struct elt *e_link; /* Pointer to the next one along */
+ size_t e_offset; /* Offset of name in path string */
+ unsigned e_flags; /* Various useful flags */
+ char e_name[1]; /* Name of the directory */
+};
+
+enum {
+ f_sticky = 1 /* Directory has sticky bit set */
+};
+
+enum {
+ f_last = 1 /* This is the final item to check */
+};
+
+/*----- Static variables --------------------------------------------------*/
+
+static struct elt rootnode = { 0, 0, 0 }; /* Root of the list */
+static struct elt *sp; /* Stack pointer for list */
+static dstr d; /* Current path string */
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @splitpath@ --- *
+ *
+ * Arguments: @const char *path@ = path string to break apart
+ * @struct elt *tail@ = tail block to attach to end of list
+ *
+ * Returns: Pointer to the new list head.
+ *
+ * Use: Breaks a path string into directories and adds each one
+ * as a node on the list, in the right order. These can then
+ * be pushed onto the directory stack as required.
+ */
+
+static struct elt *splitpath(const char *path, struct elt *tail)
+{
+ struct elt *head, **ee = &head, *e;
+
+ while (*path) {
+ size_t n;
+
+ /* --- Either a leading `/', or a doubled one --- *
+ *
+ * Either way, ignore it.
+ */
+
+ if (*path == '/') {
+ path++;
+ continue;
+ }
+
+ /* --- Skip to the next directory separator --- *
+ *
+ * Build a list element for it, and link it on.
+ */
+
+ n = strcspn(path, "/");
+ e = xmalloc(sizeof(struct elt) + n + 1);
+ memcpy(e->e_name, path, n);
+ e->e_name[n] = 0;
+ e->e_flags = 0;
+ *ee = e;
+ ee = &e->e_link;
+ path += n;
+ }
+
+ /* --- Done --- */
+
+ *ee = tail;
+ return (head);
+}
+
+/* --- @pop@ --- *
+ *
+ * Arguments: ---
+ *
+ * Returns: ---
+ *
+ * Use: Removes the top item from the directory stack.
+ */
+
+static void pop(void)
+{
+ if (sp->e_link) {
+ struct elt *e = sp->e_link;
+ d.len = sp->e_offset;
+ DPUTZ(&d);
+ sp = e;
+ }
+}
+
+/* --- @popall@ --- *
+ *
+ * Arguments: ---
+ *
+ * Returns: ---
+ *
+ * Use: Removes all the items from the directory stack.
+ */
+
+static void popall(void)
+{
+ while (sp->e_link)
+ pop();
+}
+
+/* --- @push@ --- *
+ *
+ * Arguments: @struct elt *e@ = pointer to directory element
+ *
+ * Returns: ---
+ *
+ * Use: Pushes a new subdirectory onto the stack.
+ */
+
+static void push(struct elt *e)
+{
+ e->e_link = sp;
+ e->e_offset = d.len;
+ DPUTC(&d, '/');
+ DPUTS(&d, e->e_name);
+ sp = e;
+}
+
+/* --- @report@ --- *
+ *
+ * Arguments: @struct chkpath *cp@ = pointer to context
+ * @int what@ = what sort of report is this?
+ * @int verbose@ = how verbose is this?
+ * @const char *p@ = what path does it refer to?
+ * @const char *msg@ = the message to give to the user
+ *
+ * Returns: ---
+ *
+ * Use: Formats and presents messages to the client.
+ */
+
+static void report(struct chkpath *cp, int what, int verbose,
+ const char *p, const char *msg, ...)
+{
+ /* --- Decide whether to bin this message --- */
+
+ if (!cp->cp_report || verbose > cp->cp_verbose || !(cp->cp_what & what))
+ return;
+
+ /* --- Format the message nicely --- */
+
+ if (cp->cp_what & CP_REPORT) {
+ dstr d;
+ va_list ap;
+ const char *q = msg;
+ size_t n;
+ int e = errno;
+
+ dstr_create(&d);
+ va_start(ap, msg);
+ if (verbose > 1)
+ dstr_puts(&d, "[ ");
+ if (p)
+ dstr_putf(&d, "Path: %s: ", p);
+ while (*q) {
+ if (*q == '%') {
+ q++;
+ switch (*q) {
+ case 'e':
+ dstr_puts(&d, strerror(e));
+ break;
+ case 'u': {
+ uid_t u = (uid_t)va_arg(ap, int);
+ struct passwd *pw = getpwuid(u);
+ if (pw)
+ dstr_putf(&d, "`%s'", pw->pw_name);
+ else
+ dstr_putf(&d, "%i", (int)u);
+ } break;
+ case 'g': {
+ gid_t g = (gid_t)va_arg(ap, int);
+ struct group *gr = getgrgid(g);
+ if (gr)
+ dstr_putf(&d, "`%s'", gr->gr_name);
+ else
+ dstr_putf(&d, "%i", (int)g);
+ } break;
+ case 's': {
+ const char *s = va_arg(ap, const char *);
+ dstr_puts(&d, s);
+ } break;
+ case '%':
+ dstr_putc(&d, '%');
+ break;
+ default:
+ dstr_putc(&d, '%');
+ dstr_putc(&d, *q);
+ break;
+ }
+ q++;
+ } else {
+ n = strcspn(q, "%");
+ DPUTM(&d, q, n);
+ q += n;
+ }
+ }
+ if (verbose > 1)
+ dstr_puts(&d, " ]");
+ DPUTZ(&d);
+ cp->cp_report(what, verbose, p, d.buf, cp->cp_arg);
+ dstr_destroy(&d);
+ va_end(ap);
+ } else
+ cp->cp_report(what, verbose, p, 0, cp->cp_arg);
+}
+
+/* --- @sanity@ --- *
+ *
+ * Arguments: @const char *p@ = name of directory to check
+ * @struct stat *st@ = pointer to @stat@(2) block for it
+ * @struct chkpath *cp@ = pointer to caller parameters
+ * @unsigned f@ = various flags
+ *
+ * Returns: Zero if everything's OK, else bitmask of problems.
+ *
+ * Use: Performs the main load of sanity-checking on a directory.
+ */
+
+static int sanity(const char *p, struct stat *st,
+ struct chkpath *cp, unsigned f)
+{
+ int bad = 0;
+ int sticky = (cp->cp_what & CP_STICKYOK) || !(f & f_last) ? 01000 : 0;
+
+ /* --- Check for world-writability --- */
+
+ if ((cp->cp_what & CP_WRWORLD) &&
+ (st->st_mode & (0002 | sticky)) == 0002) {
+ bad |= CP_WRWORLD;
+ report(cp, CP_WRWORLD, 1, p, "** world writable **");
+ }
+
+ /* --- Check for group-writability --- */
+
+ if ((cp->cp_what & (CP_WRGRP | CP_WROTHGRP)) &&
+ (st->st_mode & (0020 | sticky)) == 0020) {
+ if (cp->cp_what & CP_WRGRP) {
+ bad |= CP_WRGRP;
+ report(cp, CP_WRGRP, 1, p, "writable by group %g", st->st_gid);
+ } else {
+ int i;
+ for (i = 0; i < cp->cp_gids; i++) {
+ if (st->st_gid == cp->cp_gid[i])
+ goto good_gid;
+ }
+ bad |= CP_WROTHGRP;
+ report(cp, CP_WROTHGRP, 1, p, "writable by group %g", st->st_gid);
+ good_gid:;
+ }
+ }
+
+ /* --- Check for user-writability --- */
+
+ if ((cp->cp_what & CP_WROTHUSR) &&
+ st->st_uid != cp->cp_uid &&
+ st->st_uid != 0) {
+ bad |= CP_WROTHUSR;
+ report(cp, CP_WROTHUSR, 1, p, "owner is user %u", st->st_uid);
+ }
+
+ /* --- Done sanity check --- */
+
+ return (bad);
+}
+
+/* --- @path_check@ --- *
+ *
+ * Arguments: @const char *p@ = directory name which needs checking
+ * @struct chkpath *cp@ = caller parameters for the check
+ *
+ * Returns: Zero if all is well, otherwise bitmask of problems.
+ *
+ * Use: Scrutinises a directory path to see what evil things other
+ * users could do to it.
+ */
+
+int path_check(const char *p, struct chkpath *cp)
+{
+ char cwd[PATH_MAX];
+ struct elt *e, *ee;
+ struct stat st;
+ int bad = 0;
+
+ /* --- Initialise stack pointer and path string --- */
+
+ sp = &rootnode;
+ dstr_destroy(&d);
+
+ /* --- Try to find the current directory --- */
+
+ if (!getcwd(cwd, sizeof(cwd))) {
+ report(cp, CP_ERROR, 0, 0, "can't find current directory: %e");
+ return (CP_ERROR);
+ }
+
+ /* --- Check that the root directory is OK --- */
+
+ if (stat("/", &st)) {
+ report(cp, CP_ERROR, 0, 0, "can't stat root directory: %e");
+ return (CP_ERROR);
+ }
+
+ report(cp, CP_REPORT, 3, p, "begin scan");
+ bad |= sanity("/", &st, cp, 0);
+
+ /* --- Get the initial list of things to process --- */
+
+ ee = splitpath(p, 0);
+ if (*p != '/')
+ ee = splitpath(cwd, ee);
+
+ /* --- While there are list items which still need doing --- */
+
+ while (ee) {
+ e = ee->e_link;
+
+ /* --- Strip off simple `.' elements --- */
+
+ if (strcmp(ee->e_name, ".") == 0) {
+ free(ee);
+ ee = e;
+ continue;
+ }
+
+ /* --- Backtrack on `..' elements --- */
+
+ else if (strcmp(ee->e_name, "..") == 0) {
+ pop();
+ free(ee);
+ ee = e;
+ continue;
+ }
+
+ /* --- Everything else gets pushed on the end --- */
+
+ push(ee);
+ ee = e;
+
+ /* --- Find out what sort of a thing this is --- */
+
+ if (lstat(d.buf, &st)) {
+ report(cp, CP_ERROR, 0, d.buf, "can't stat: %e");
+ bad |= CP_ERROR;
+ break;
+ }
+
+ /* --- Handle symbolic links specially --- */
+
+ if (S_ISLNK(st.st_mode)) {
+ char buf[PATH_MAX];
+ int i;
+
+ /* --- Resolve the link --- */
+
+ if ((i = readlink(d.buf, buf, sizeof(buf))) < 0) {
+ report(cp, CP_ERROR, 0, d.buf, "can't readlink: %e");
+ bad |= CP_ERROR;
+ break;
+ }
+ buf[i] = 0;
+ report(cp, CP_SYMLINK, 2, d.buf, "symlink -> `%s'", buf);
+
+ /* --- Handle sticky parents --- *
+ *
+ * If I make a symlink in a sticky directory, I can later modify it.
+ * However, nobody else can (except the owner of the directory, and
+ * we'll already have noticed that if we care).
+ */
+
+ if ((cp->cp_what & CP_WROTHUSR) &&
+ (sp->e_link->e_flags & f_sticky) &&
+ st.st_uid != cp->cp_uid && st.st_uid != 0) {
+ bad |= CP_WROTHUSR;
+ report(cp, CP_WROTHUSR, 1, d.buf,
+ "symlink modifiable by user %u", st.st_uid);
+ }
+
+ /* --- Sort out what to do from here --- */
+
+ if (buf[0] == '/')
+ popall();
+ else
+ pop();
+ ee = splitpath(buf, ee);
+ continue;
+ }
+
+ /* --- Run the sanity check on this path element --- */
+
+ bad |= sanity(d.buf, &st, cp, ee ? 0 : f_last);
+
+ if (S_ISDIR(st.st_mode)) {
+ if (st.st_mode & 01000)
+ sp->e_flags |= f_sticky;
+ report(cp, CP_REPORT, 4, d.buf, "directory");
+ continue;
+ }
+
+ /* --- Something else I don't understand --- */
+
+ break;
+ }
+
+ /* --- Check for leftover junk --- */
+
+ if (ee) {
+ if (!(bad & CP_ERROR))
+ report(cp, CP_ERROR, 0, 0, "junk left over after reaching leaf");
+ while (ee) {
+ e = ee->e_link;
+ free(ee);
+ ee = e;
+ }
+ }
+
+ popall();
+ return (bad);
+}
+
+/* --- @path_setids@ --- *
+ *
+ * Arguments: @struct chkpath *cp@ = pointer to block to fill in
+ *
+ * Returns: Zero if OK, else @-1@.
+ *
+ * Use: Fills in the user ids and things in the structure.
+ */
+
+void path_setids(struct chkpath *cp)
+{
+ int n, i;
+ gid_t g = getgid();
+
+ cp->cp_uid = getuid();
+ n = getgroups(sizeof(cp->cp_gid) / sizeof(cp->cp_gid[0]), cp->cp_gid);
+
+ for (i = 0; i < n; i++) {
+ if (cp->cp_gid[i] == g)
+ goto gid_ok;
+ }
+ cp->cp_gid[n++] = g;
+gid_ok:
+ cp->cp_gids = n;
+}
+
+/*----- That's all, folks -------------------------------------------------*/
--- /dev/null
+/* -*-c-*-
+ *
+ * $Id: checkpath.h,v 1.1 1999/04/06 20:12:07 mdw Exp $
+ *
+ * Check a path for safety
+ *
+ * (c) 1999 Mark Wooding
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of chkpath.
+ *
+ * chkpath is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * chkpath is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with chkpath; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+/*----- Revision history --------------------------------------------------*
+ *
+ * $Log: checkpath.h,v $
+ * Revision 1.1 1999/04/06 20:12:07 mdw
+ * Initial revision
+ *
+ */
+
+#ifndef PATH_H
+#define PATH_H
+
+#ifdef __cplusplus
+ extern "C" {
+#endif
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <limits.h>
+#include <sys/types.h>
+
+/*----- Data structures ---------------------------------------------------*/
+
+/* --- Search request --- *
+ *
+ * This contains parameters from the caller to control what problems are
+ * looked for, and what to do when they're found.
+ */
+
+struct chkpath {
+ uid_t cp_uid; /* Uid that's considered OK */
+ gid_t cp_gid[NGROUPS_MAX + 1]; /* Array of groups that are OK */
+ int cp_gids; /* Number of groups in the array */
+ int cp_verbose; /* Verbosity level to spit up */
+ int cp_what; /* What things to check for */
+ void (*cp_report)(int /*what*/, int /*verb*/,
+ const char */*dir*/, const char */*msg*/,
+ void */*p*/);
+ void *cp_arg; /* Argument for cp_report */
+};
+
+/* --- Flags for `@what@' fields in the above --- */
+
+#define CP_ERROR 1 /* Error report */
+#define CP_WRWORLD 2 /* Check write by world */
+#define CP_WRGRP 4 /* Check write by any group */
+#define CP_WROTHGRP 8 /* Check write by other group */
+#define CP_WROTHUSR 16 /* Check write by other user */
+#define CP_SYMLINK 32 /* Report symbolic links */
+#define CP_REPORT 64 /* Make user-readable reports */
+#define CP_STICKYOK 128 /* Don't care if sticky is set */
+
+/*----- Functions provided ------------------------------------------------*/
+
+/* --- @path_check@ --- *
+ *
+ * Arguments: @const char *p@ = directory name which needs checking
+ * @struct chkpath *cp@ = caller parameters for the check
+ *
+ * Returns: Zero if all is well, otherwise bitmask of problems.
+ *
+ * Use: Scrutinises a directory path to see what evil things other
+ * users could do to it.
+ */
+
+extern int path_check(const char */*p*/, struct chkpath */*cp*/);
+
+/* --- @path_setids@ --- *
+ *
+ * Arguments: @struct chkpath *cp@ = pointer to block to fill in
+ *
+ * Returns: ---
+ *
+ * Use: Fills in the user ids and things in the structure.
+ */
+
+extern void path_setids(struct chkpath */*cp*/);
+
+/*----- That's all, folks -------------------------------------------------*/
+
+#ifdef __cplusplus
+ }
+#endif
+
+#endif
--- /dev/null
+.TH chkpath 1 "6 April 1999" "Local tools"
+.SH NAME
+chkpath \- check a path string for security
+.SH SYNOPSIS
+.B chkpath
+.RB [ \-vqstp ]
+.RI [ path ...]
+.SH USAGE
+The
+.B chkpath
+command checks one or more path strings (i.e., lists of directories
+separated by colons) for security. If no path strings are given, the
+value of the
+.B PATH
+environment variable is examined.
+.PP
+Each directory in turn is broken into its consitituent parts and every
+step which must be made through the filesystem to reach that directory
+from the root is scrutinized for vulnerabilities. The checks made
+against each directory and symbolic link along the way are as follows:
+.IP 1.
+No step should be a directory which is world-writable unless its sticky
+bit is set, and it's not the final step.
+.IP 2.
+No step should be a directory which is group-writable unless its sticky
+bit is set, and it's not the final step. (However, see the
+.B \-t
+option below.)
+.IP 3.
+No step should be a directory owned by another user (other than root).
+.IP 4.
+No step should be a symbolic link inside a sticky directory and owned by
+another user.
+.PP
+The author is not aware of any weaknesses in this ruleset. The
+objective is that nobody other than the user and the superuser should be
+able to add or change the set of files available within the directories
+of the path(s).
+.SS OPTIONS
+The following command line options are available:
+.TP
+.B "\-h, \-\-help"
+Displays a relatively verbose message describing how to use
+.BR chkpath .
+.TP
+.B "\-V, \-\-version"
+Displays
+.BR chkpath 's
+version number.
+.TP
+.B "\-u, \-\-usage"
+Displays a very terse usage summary.
+.TP
+.B "\-v, \-\-verbose"
+Makes
+.B chkpath
+more verbose about what it's doing. This option has a cumulative
+effect, so put more in for more verbosity. Note that verbose doesn't
+mean the same as interesting. The default is to report problems with
+directories and system errors.
+.TP
+.B "\-q, \-\-quiet"
+Makes
+.B chkpath
+less verbose about what it's doing. This option, like
+.BR \-v ,
+has a cumulative effect. Each
+.B \-q
+cancels out a
+.B \-v
+option.
+.TP
+.B "\-s, \-\-sticky"
+Modifies the ruleset slightly so that any step through the filesystem is
+OK, even if world- or group-writable (but not owned by someone else), as
+long as the directory's sticky bit is set. The default is that sticky
+directories are considered safe only if they're not the final step.
+Turning this option on isn't recommended: if you use a sticky directory
+in your path then other people can add malicious commands whose names
+are common typos of standard ones.
+.TP
+.B "\-t, \-\-trust\-group"
+Modifies the ruleset slightly so that
+.B chkpath
+doesn't warn about directories group-owned by groups you're a member
+of. In other words, it trusts your fellow group-members
+.IR "in their capacity as group-owners only" .
+.B chkpath
+will still warn about directories owned by people in your groups.
+.TP
+.B "\-p, \-\-print"
+Writes on standard output a colon-separated list of the directories
+which
+.B chkpath
+considered `safe'. This can be used to filter out unsafe directories in
+an automatic way:
+.RS 10
+.nf
+.ft B
+.sp 1
+PATH=`chkpath -qqp`
+.ft R
+.fi
+.RE
+.SH BUGS
+None known.
+.SH SEE ALSO
+.BR tmpdir (1).
+.SH AUTHOR
+Mark Wooding (mdw@nsict.org).
--- /dev/null
+/* -*-c-*-
+ *
+ * $Id: chkpath.c,v 1.1 1999/04/06 20:12:07 mdw Exp $
+ *
+ * Check a user's file search path
+ *
+ * (c) 1999 Mark Wooding
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of chkpath.
+ *
+ * chkpath is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * chkpath is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with chkpath; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+/*----- Revision history --------------------------------------------------*
+ *
+ * $Log: chkpath.c,v $
+ * Revision 1.1 1999/04/06 20:12:07 mdw
+ * Initial revision
+ *
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <mLib/alloc.h>
+#include <mLib/mdwopt.h>
+#include <mLib/quis.h>
+#include <mLib/report.h>
+
+#include "path.h"
+
+/*----- Main code ---------------------------------------------------------*/
+
+static void report(int what, int verbose,
+ const char *p, const char *msg,
+ void *arg)
+{
+ moan("%s", msg);
+}
+
+/* --- @usage@ --- */
+
+static void usage(FILE *fp)
+{
+ fprintf(fp, "Usage: %s [-vqstp] [PATH...]\n", QUIS);
+}
+
+/* --- @version@ --- */
+
+static void version(FILE *fp)
+{
+ fprintf(fp, "%s version %s\n", QUIS, VERSION);
+}
+
+/* --- @help@ --- */
+
+static void help(FILE *fp)
+{
+ version(fp);
+ putc('\n', fp);
+ usage(fp);
+ fputs("\n\
+Checks a path string (by default the PATH variable) for security. It\n\
+ensures that only `root' or the calling user can write to all the parent\n\
+directories of the path elements, so nobody can maliciously replace the\n\
+binaries unexpectedly.\n\
+\n\
+Options provided are:\n\
+\n\
+-h, --help Display this help message.\n\
+-V, --version Display the program's version number.\n\
+-u, --usage Show a terse usage summary.\n\
+\n\
+-v, --verbose Be verbose about the search progress (cumulative).\n\
+-q, --quiet Be quiet about the search progress (cumulative).\n\
+-s, --sticky Consider sticky directories secure against\n\
+ modification by world and group (not recommended).\n\
+-t, --trust-group Consider other members of your group trustworthy.\n\
+-p, --print Write the secure path elements to standard output.\n\
+",
+ fp);
+}
+
+int main(int argc, char *argv[])
+{
+ int bad = 0;
+ int i;
+ char *p, *q, *path;
+ struct chkpath cp;
+ int f = 0;
+
+ enum {
+ f_print = 1,
+ f_colon = 2
+ };
+
+ /* --- Initialize the world --- */
+
+ ego(argv[0]);
+
+ /* --- Set up path scanning defaults --- */
+
+ cp.cp_verbose = 1;
+ cp.cp_what = (CP_WRWORLD | CP_WRGRP | CP_WROTHUSR |
+ CP_ERROR | CP_REPORT | CP_SYMLINK);
+ cp.cp_report = report;
+ cp.cp_arg = 0;
+ path_setids(&cp);
+
+ /* --- Parse the options --- */
+
+ for (;;) {
+ static struct option opts[] = {
+ { "help", 0, 0, 'h' },
+ { "version", 0, 0, 'V' },
+ { "usage", 0, 0, 'u' },
+ { "verbose", 0, 0, 'v' },
+ { "quiet", 0, 0, 'q' },
+ { "sticky", 0, 0, 's' },
+ { "trust-group", 0, 0, 't' },
+ { "print", 0, 0, 'p' },
+ { 0, 0, 0, 0 }
+ };
+ int i = mdwopt(argc, argv, "hVu vqstp", opts, 0, 0, 0);
+
+ if (i < 0)
+ break;
+ switch (i) {
+ case 'h':
+ help(stdout);
+ exit(0);
+ case 'V':
+ version(stdout);
+ exit(0);
+ case 'u':
+ usage(stdout);
+ exit(0);
+ case 'v':
+ cp.cp_verbose++;
+ break;
+ case 'q':
+ if (cp.cp_verbose)
+ cp.cp_verbose--;
+ break;
+ case 's':
+ cp.cp_what |= CP_STICKYOK;
+ break;
+ case 't':
+ cp.cp_what = (cp.cp_what & ~CP_WRGRP) | CP_WROTHGRP;
+ break;
+ case 'p':
+ f |= f_print;
+ break;
+ default:
+ bad = 1;
+ break;
+ }
+ }
+
+ if (bad) {
+ usage(stderr);
+ exit(1);
+ }
+
+ /* --- Sort out what needs doing --- */
+
+ if (optind == argc) {
+ path = getenv("PATH");
+ argv = &path;
+ argc = 1;
+ optind = 0;
+ }
+
+ for (i = optind; i < argc; i++) {
+ p = xstrdup(argv[i]);
+ q = strtok(p, ":");
+ while (q) {
+ int b = path_check(q, &cp);
+ if (!b && (f & f_print)) {
+ if (f & f_colon)
+ putchar(':');
+ fputs(q, stdout);
+ f |= f_colon;
+ }
+ bad |= b;
+ q = strtok(0, ":");
+ }
+ free(p);
+ }
+
+ if (f & f_colon)
+ putchar('\n');
+
+ return (bad);
+}
+
+/*----- That's all, folks -------------------------------------------------*/
--- /dev/null
+dnl -*-fundamental-*-
+dnl
+dnl $Id: configure.in,v 1.1 1999/04/06 20:12:08 mdw Exp $
+dnl
+dnl Configurator for chkpath
+dnl
+dnl (c) 1999 Mark Wooding
+dnl
+
+dnl ----- Licensing notice --------------------------------------------------
+dnl
+dnl This file is part of chkpath.
+dnl
+dnl chkpath is free software; you can redistribute it and/or modify
+dnl it under the terms of the GNU General Public License as published by
+dnl the Free Software Foundation; either version 2 of the License, or
+dnl (at your option) any later version.
+dnl
+dnl chkpath is distributed in the hope that it will be useful,
+dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
+dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+dnl GNU General Public License for more details.
+dnl
+dnl You should have received a copy of the GNU General Public License
+dnl along with chkpath; if not, write to the Free Software Foundation,
+dnl Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+dnl ----- Revision history --------------------------------------------------
+dnl
+dnl $Log: configure.in,v $
+dnl Revision 1.1 1999/04/06 20:12:08 mdw
+dnl Initial revision
+dnl
+
+AC_INIT(chkpath.c)
+AM_INIT_AUTOMAKE(chkpath, 1.0.0)
+AC_PROG_CC
+mdw_GCC_FLAGS
+AC_CONFIG_SUBDIRS(mLib)
+AC_OUTPUT(Makefile)
+
+dnl ----- That's all, folks -------------------------------------------------
--- /dev/null
+/* -*-c-*-
+ *
+ * $Id: path.c,v 1.1 1999/04/06 20:12:07 mdw Exp $
+ *
+ * Check a path for safety
+ *
+ * (c) 1999 Mark Wooding
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of chkpath.
+ *
+ * chkpath is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * chkpath is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with chkpath; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+/*----- Revision history --------------------------------------------------*
+ *
+ * $Log: path.c,v $
+ * Revision 1.1 1999/04/06 20:12:07 mdw
+ * Initial revision
+ *
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <pwd.h>
+#include <grp.h>
+
+#include <mLib/alloc.h>
+#include <mLib/dstr.h>
+
+#include "path.h"
+
+/*----- Data structures ---------------------------------------------------*/
+
+/* --- An item in the directory list --- *
+ *
+ * Each directory becomes an element on a list which is manipulated in a
+ * stack-like way.
+ */
+
+struct elt {
+ struct elt *e_link; /* Pointer to the next one along */
+ size_t e_offset; /* Offset of name in path string */
+ unsigned e_flags; /* Various useful flags */
+ char e_name[1]; /* Name of the directory */
+};
+
+enum {
+ f_sticky = 1 /* Directory has sticky bit set */
+};
+
+enum {
+ f_last = 1 /* This is the final item to check */
+};
+
+/*----- Static variables --------------------------------------------------*/
+
+static struct elt rootnode = { 0, 0, 0 }; /* Root of the list */
+static struct elt *sp; /* Stack pointer for list */
+static dstr d; /* Current path string */
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @splitpath@ --- *
+ *
+ * Arguments: @const char *path@ = path string to break apart
+ * @struct elt *tail@ = tail block to attach to end of list
+ *
+ * Returns: Pointer to the new list head.
+ *
+ * Use: Breaks a path string into directories and adds each one
+ * as a node on the list, in the right order. These can then
+ * be pushed onto the directory stack as required.
+ */
+
+static struct elt *splitpath(const char *path, struct elt *tail)
+{
+ struct elt *head, **ee = &head, *e;
+
+ while (*path) {
+ size_t n;
+
+ /* --- Either a leading `/', or a doubled one --- *
+ *
+ * Either way, ignore it.
+ */
+
+ if (*path == '/') {
+ path++;
+ continue;
+ }
+
+ /* --- Skip to the next directory separator --- *
+ *
+ * Build a list element for it, and link it on.
+ */
+
+ n = strcspn(path, "/");
+ e = xmalloc(sizeof(struct elt) + n + 1);
+ memcpy(e->e_name, path, n);
+ e->e_name[n] = 0;
+ e->e_flags = 0;
+ *ee = e;
+ ee = &e->e_link;
+ path += n;
+ }
+
+ /* --- Done --- */
+
+ *ee = tail;
+ return (head);
+}
+
+/* --- @pop@ --- *
+ *
+ * Arguments: ---
+ *
+ * Returns: ---
+ *
+ * Use: Removes the top item from the directory stack.
+ */
+
+static void pop(void)
+{
+ if (sp->e_link) {
+ struct elt *e = sp->e_link;
+ d.len = sp->e_offset;
+ DPUTZ(&d);
+ sp = e;
+ }
+}
+
+/* --- @popall@ --- *
+ *
+ * Arguments: ---
+ *
+ * Returns: ---
+ *
+ * Use: Removes all the items from the directory stack.
+ */
+
+static void popall(void)
+{
+ while (sp->e_link)
+ pop();
+}
+
+/* --- @push@ --- *
+ *
+ * Arguments: @struct elt *e@ = pointer to directory element
+ *
+ * Returns: ---
+ *
+ * Use: Pushes a new subdirectory onto the stack.
+ */
+
+static void push(struct elt *e)
+{
+ e->e_link = sp;
+ e->e_offset = d.len;
+ DPUTC(&d, '/');
+ DPUTS(&d, e->e_name);
+ sp = e;
+}
+
+/* --- @report@ --- *
+ *
+ * Arguments: @struct chkpath *cp@ = pointer to context
+ * @int what@ = what sort of report is this?
+ * @int verbose@ = how verbose is this?
+ * @const char *p@ = what path does it refer to?
+ * @const char *msg@ = the message to give to the user
+ *
+ * Returns: ---
+ *
+ * Use: Formats and presents messages to the client.
+ */
+
+static void report(struct chkpath *cp, int what, int verbose,
+ const char *p, const char *msg, ...)
+{
+ /* --- Decide whether to bin this message --- */
+
+ if (!cp->cp_report || verbose > cp->cp_verbose || !(cp->cp_what & what))
+ return;
+
+ /* --- Format the message nicely --- */
+
+ if (cp->cp_what & CP_REPORT) {
+ dstr d;
+ va_list ap;
+ const char *q = msg;
+ size_t n;
+ int e = errno;
+
+ dstr_create(&d);
+ va_start(ap, msg);
+ if (verbose > 1)
+ dstr_puts(&d, "[ ");
+ if (p)
+ dstr_putf(&d, "Path: %s: ", p);
+ while (*q) {
+ if (*q == '%') {
+ q++;
+ switch (*q) {
+ case 'e':
+ dstr_puts(&d, strerror(e));
+ break;
+ case 'u': {
+ uid_t u = (uid_t)va_arg(ap, int);
+ struct passwd *pw = getpwuid(u);
+ if (pw)
+ dstr_putf(&d, "`%s'", pw->pw_name);
+ else
+ dstr_putf(&d, "%i", (int)u);
+ } break;
+ case 'g': {
+ gid_t g = (gid_t)va_arg(ap, int);
+ struct group *gr = getgrgid(g);
+ if (gr)
+ dstr_putf(&d, "`%s'", gr->gr_name);
+ else
+ dstr_putf(&d, "%i", (int)g);
+ } break;
+ case 's': {
+ const char *s = va_arg(ap, const char *);
+ dstr_puts(&d, s);
+ } break;
+ case '%':
+ dstr_putc(&d, '%');
+ break;
+ default:
+ dstr_putc(&d, '%');
+ dstr_putc(&d, *q);
+ break;
+ }
+ q++;
+ } else {
+ n = strcspn(q, "%");
+ DPUTM(&d, q, n);
+ q += n;
+ }
+ }
+ if (verbose > 1)
+ dstr_puts(&d, " ]");
+ DPUTZ(&d);
+ cp->cp_report(what, verbose, p, d.buf, cp->cp_arg);
+ dstr_destroy(&d);
+ va_end(ap);
+ } else
+ cp->cp_report(what, verbose, p, 0, cp->cp_arg);
+}
+
+/* --- @sanity@ --- *
+ *
+ * Arguments: @const char *p@ = name of directory to check
+ * @struct stat *st@ = pointer to @stat@(2) block for it
+ * @struct chkpath *cp@ = pointer to caller parameters
+ * @unsigned f@ = various flags
+ *
+ * Returns: Zero if everything's OK, else bitmask of problems.
+ *
+ * Use: Performs the main load of sanity-checking on a directory.
+ */
+
+static int sanity(const char *p, struct stat *st,
+ struct chkpath *cp, unsigned f)
+{
+ int bad = 0;
+ int sticky = (cp->cp_what & CP_STICKYOK) || !(f & f_last) ? 01000 : 0;
+
+ /* --- Check for world-writability --- */
+
+ if ((cp->cp_what & CP_WRWORLD) &&
+ (st->st_mode & (0002 | sticky)) == 0002) {
+ bad |= CP_WRWORLD;
+ report(cp, CP_WRWORLD, 1, p, "** world writable **");
+ }
+
+ /* --- Check for group-writability --- */
+
+ if ((cp->cp_what & (CP_WRGRP | CP_WROTHGRP)) &&
+ (st->st_mode & (0020 | sticky)) == 0020) {
+ if (cp->cp_what & CP_WRGRP) {
+ bad |= CP_WRGRP;
+ report(cp, CP_WRGRP, 1, p, "writable by group %g", st->st_gid);
+ } else {
+ int i;
+ for (i = 0; i < cp->cp_gids; i++) {
+ if (st->st_gid == cp->cp_gid[i])
+ goto good_gid;
+ }
+ bad |= CP_WROTHGRP;
+ report(cp, CP_WROTHGRP, 1, p, "writable by group %g", st->st_gid);
+ good_gid:;
+ }
+ }
+
+ /* --- Check for user-writability --- */
+
+ if ((cp->cp_what & CP_WROTHUSR) &&
+ st->st_uid != cp->cp_uid &&
+ st->st_uid != 0) {
+ bad |= CP_WROTHUSR;
+ report(cp, CP_WROTHUSR, 1, p, "owner is user %u", st->st_uid);
+ }
+
+ /* --- Done sanity check --- */
+
+ return (bad);
+}
+
+/* --- @path_check@ --- *
+ *
+ * Arguments: @const char *p@ = directory name which needs checking
+ * @struct chkpath *cp@ = caller parameters for the check
+ *
+ * Returns: Zero if all is well, otherwise bitmask of problems.
+ *
+ * Use: Scrutinises a directory path to see what evil things other
+ * users could do to it.
+ */
+
+int path_check(const char *p, struct chkpath *cp)
+{
+ char cwd[PATH_MAX];
+ struct elt *e, *ee;
+ struct stat st;
+ int bad = 0;
+
+ /* --- Initialise stack pointer and path string --- */
+
+ sp = &rootnode;
+ dstr_destroy(&d);
+
+ /* --- Try to find the current directory --- */
+
+ if (!getcwd(cwd, sizeof(cwd))) {
+ report(cp, CP_ERROR, 0, 0, "can't find current directory: %e");
+ return (CP_ERROR);
+ }
+
+ /* --- Check that the root directory is OK --- */
+
+ if (stat("/", &st)) {
+ report(cp, CP_ERROR, 0, 0, "can't stat root directory: %e");
+ return (CP_ERROR);
+ }
+
+ report(cp, CP_REPORT, 3, p, "begin scan");
+ bad |= sanity("/", &st, cp, 0);
+
+ /* --- Get the initial list of things to process --- */
+
+ ee = splitpath(p, 0);
+ if (*p != '/')
+ ee = splitpath(cwd, ee);
+
+ /* --- While there are list items which still need doing --- */
+
+ while (ee) {
+ e = ee->e_link;
+
+ /* --- Strip off simple `.' elements --- */
+
+ if (strcmp(ee->e_name, ".") == 0) {
+ free(ee);
+ ee = e;
+ continue;
+ }
+
+ /* --- Backtrack on `..' elements --- */
+
+ else if (strcmp(ee->e_name, "..") == 0) {
+ pop();
+ free(ee);
+ ee = e;
+ continue;
+ }
+
+ /* --- Everything else gets pushed on the end --- */
+
+ push(ee);
+ ee = e;
+
+ /* --- Find out what sort of a thing this is --- */
+
+ if (lstat(d.buf, &st)) {
+ report(cp, CP_ERROR, 0, d.buf, "can't stat: %e");
+ bad |= CP_ERROR;
+ break;
+ }
+
+ /* --- Handle symbolic links specially --- */
+
+ if (S_ISLNK(st.st_mode)) {
+ char buf[PATH_MAX];
+ int i;
+
+ /* --- Resolve the link --- */
+
+ if ((i = readlink(d.buf, buf, sizeof(buf))) < 0) {
+ report(cp, CP_ERROR, 0, d.buf, "can't readlink: %e");
+ bad |= CP_ERROR;
+ break;
+ }
+ buf[i] = 0;
+ report(cp, CP_SYMLINK, 2, d.buf, "symlink -> `%s'", buf);
+
+ /* --- Handle sticky parents --- *
+ *
+ * If I make a symlink in a sticky directory, I can later modify it.
+ * However, nobody else can (except the owner of the directory, and
+ * we'll already have noticed that if we care).
+ */
+
+ if ((cp->cp_what & CP_WROTHUSR) &&
+ (sp->e_link->e_flags & f_sticky) &&
+ st.st_uid != cp->cp_uid && st.st_uid != 0) {
+ bad |= CP_WROTHUSR;
+ report(cp, CP_WROTHUSR, 1, d.buf,
+ "symlink modifiable by user %u", st.st_uid);
+ }
+
+ /* --- Sort out what to do from here --- */
+
+ if (buf[0] == '/')
+ popall();
+ else
+ pop();
+ ee = splitpath(buf, ee);
+ continue;
+ }
+
+ /* --- Run the sanity check on this path element --- */
+
+ bad |= sanity(d.buf, &st, cp, ee ? 0 : f_last);
+
+ if (S_ISDIR(st.st_mode)) {
+ if (st.st_mode & 01000)
+ sp->e_flags |= f_sticky;
+ report(cp, CP_REPORT, 4, d.buf, "directory");
+ continue;
+ }
+
+ /* --- Something else I don't understand --- */
+
+ break;
+ }
+
+ /* --- Check for leftover junk --- */
+
+ if (ee) {
+ if (!(bad & CP_ERROR))
+ report(cp, CP_ERROR, 0, 0, "junk left over after reaching leaf");
+ while (ee) {
+ e = ee->e_link;
+ free(ee);
+ ee = e;
+ }
+ }
+
+ popall();
+ return (bad);
+}
+
+/* --- @path_setids@ --- *
+ *
+ * Arguments: @struct chkpath *cp@ = pointer to block to fill in
+ *
+ * Returns: Zero if OK, else @-1@.
+ *
+ * Use: Fills in the user ids and things in the structure.
+ */
+
+void path_setids(struct chkpath *cp)
+{
+ int n, i;
+ gid_t g = getgid();
+
+ cp->cp_uid = getuid();
+ n = getgroups(sizeof(cp->cp_gid) / sizeof(cp->cp_gid[0]), cp->cp_gid);
+
+ for (i = 0; i < n; i++) {
+ if (cp->cp_gid[i] == g)
+ goto gid_ok;
+ }
+ cp->cp_gid[n++] = g;
+gid_ok:
+ cp->cp_gids = n;
+}
+
+/*----- That's all, folks -------------------------------------------------*/
--- /dev/null
+/* -*-c-*-
+ *
+ * $Id: path.h,v 1.1 1999/04/06 20:12:07 mdw Exp $
+ *
+ * Check a path for safety
+ *
+ * (c) 1999 Mark Wooding
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of chkpath.
+ *
+ * chkpath is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * chkpath is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with chkpath; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+/*----- Revision history --------------------------------------------------*
+ *
+ * $Log: path.h,v $
+ * Revision 1.1 1999/04/06 20:12:07 mdw
+ * Initial revision
+ *
+ */
+
+#ifndef PATH_H
+#define PATH_H
+
+#ifdef __cplusplus
+ extern "C" {
+#endif
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <limits.h>
+#include <sys/types.h>
+
+/*----- Data structures ---------------------------------------------------*/
+
+/* --- Search request --- *
+ *
+ * This contains parameters from the caller to control what problems are
+ * looked for, and what to do when they're found.
+ */
+
+struct chkpath {
+ uid_t cp_uid; /* Uid that's considered OK */
+ gid_t cp_gid[NGROUPS_MAX + 1]; /* Array of groups that are OK */
+ int cp_gids; /* Number of groups in the array */
+ int cp_verbose; /* Verbosity level to spit up */
+ int cp_what; /* What things to check for */
+ void (*cp_report)(int /*what*/, int /*verb*/,
+ const char */*dir*/, const char */*msg*/,
+ void */*p*/);
+ void *cp_arg; /* Argument for cp_report */
+};
+
+/* --- Flags for `@what@' fields in the above --- */
+
+#define CP_ERROR 1 /* Error report */
+#define CP_WRWORLD 2 /* Check write by world */
+#define CP_WRGRP 4 /* Check write by any group */
+#define CP_WROTHGRP 8 /* Check write by other group */
+#define CP_WROTHUSR 16 /* Check write by other user */
+#define CP_SYMLINK 32 /* Report symbolic links */
+#define CP_REPORT 64 /* Make user-readable reports */
+#define CP_STICKYOK 128 /* Don't care if sticky is set */
+
+/*----- Functions provided ------------------------------------------------*/
+
+/* --- @path_check@ --- *
+ *
+ * Arguments: @const char *p@ = directory name which needs checking
+ * @struct chkpath *cp@ = caller parameters for the check
+ *
+ * Returns: Zero if all is well, otherwise bitmask of problems.
+ *
+ * Use: Scrutinises a directory path to see what evil things other
+ * users could do to it.
+ */
+
+extern int path_check(const char */*p*/, struct chkpath */*cp*/);
+
+/* --- @path_setids@ --- *
+ *
+ * Arguments: @struct chkpath *cp@ = pointer to block to fill in
+ *
+ * Returns: ---
+ *
+ * Use: Fills in the user ids and things in the structure.
+ */
+
+extern void path_setids(struct chkpath */*cp*/);
+
+/*----- That's all, folks -------------------------------------------------*/
+
+#ifdef __cplusplus
+ }
+#endif
+
+#endif
--- /dev/null
+.TH tmpdir 1 "6 April 1999" "Local tools"
+.SH NAME
+tmpdir \- choose, or check a choice of, temporary directory
+.SH SYNOPSIS
+.B tmpdir
+.RB [ \-bc ]
+.RB [ \-v
+.IR dir ]
+.SH USAGE
+The
+.B tmpdir
+program creates a secure place for temporary files to be stored, and
+outputs an assignment to the
+.B TMPDIR
+variable suitable for execution by a shell.
+.PP
+Many programs aren't sufficiently careful about how they handle
+temporary files. For example, if a program which creates files in
+.B /tmp
+without making careful checks beforehand, a malicious user who can
+predict the name that the program will use can create a symbolic link
+with that name: when run, the program will then overwrite some file
+using your current privileges. Similarly, many programs create
+temporary files using generous default permissions, which may well be a
+mistake.
+.PP
+The
+.B tmpdir
+program finds a secure place for temporary files, creating one if
+necessary. The criteria it uses to choose a place are as follows:
+.IP 1.
+The temporary directory must be owned by the user, and have mode 700
+(i.e., readable, writable and searchable only by the owner).
+.IP 2.
+The path through the filesystem to the temporary directory must be
+secure against modifications by other malicious users. See the
+.BR chkpath (1)
+manual page for a description of how this is done: the two programs work
+in the same way.
+.PP
+First,
+.B tmpdir
+checks to see whether the current value of the
+.B TMPDIR
+environment variable is a secure place for temporary files. If so, it
+is accepted immediately. Otherwise, it tries to find or create a
+directory in
+.B /tmp
+(on the assumption that this is a fast disk suitable for temporary
+files), with the name
+.BI /tmp/ user \- suffix
+for some
+.IR suffix .
+If that fails, it tries to create a directory in your home directory,
+with the name
+.BI ~/tmp\- suffix\fR.
+If
+.I that
+fails too, then
+.B tmpdir
+gives up: if your home directory's not secure (or full) than a secure
+temporary directory is the least of your worries.
+.SS OPTIONS
+The following options are supported:
+.TP
+.B "\-b, \-\-bourne"
+Output an assignment using Bourne shell syntax. The default is to
+examine the user's shell and decide which syntax to use based on that.
+.TP
+.B "\-c, \-\-cshell"
+Output an assignment using C shell syntax.
+.TP
+.BI "\-v, --verify=" dir
+Don't try to find a temporary directory; just see whether
+.I dir
+is secure, and exit successfully if it is (and unsuccessfully if it
+isn't).
+.SH BUGS
+None known.
+.SH SEE ALSO
+.BR chkpath (1),
+.BR tmpnam (3),
+.BR tmpfile (3).
+.SH AUTHOR
+Mark Wooding (mdw@nsict.org).
--- /dev/null
+/* -*-c-*-
+ *
+ * $Id: tmpdir.c,v 1.1 1999/04/06 20:12:07 mdw Exp $
+ *
+ * Choose and check temporary directories
+ *
+ * (c) 1999 Mark Wooding
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of chkpath.
+ *
+ * chkpath is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * chkpath is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with chkpath; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+/*----- Revision history --------------------------------------------------*
+ *
+ * $Log: tmpdir.c,v $
+ * Revision 1.1 1999/04/06 20:12:07 mdw
+ * Initial revision
+ *
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <pwd.h>
+
+#include <mLib/alloc.h>
+#include <mLib/dstr.h>
+#include <mLib/mdwopt.h>
+#include <mLib/quis.h>
+#include <mLib/report.h>
+
+#include "path.h"
+
+/*----- Static variables --------------------------------------------------*/
+
+static uid_t me;
+static struct chkpath cp;
+static struct passwd *pw;
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @ok@ --- *
+ *
+ * Arguments: @const char *p@ = pathname to check
+ * @int *f@ = try-to-create flag
+ *
+ * Returns: Nonzero if the directory is OK
+ *
+ * Use: Ensures that a directory is OK. If @f@ is a real pointer,
+ * and @*f@ is set, then try to create the directory.
+ */
+
+static int ok(const char *p, int *f)
+{
+ struct stat st;
+
+ /* --- Read the directory status --- */
+
+ if (lstat(p, &st)) {
+
+ /* --- Maybe create it if it doesn't exist --- */
+
+ if (errno != ENOENT || !f || !*f)
+ return (0);
+ if (mkdir(p, 0700)) {
+ *f = 0;
+ return (0);
+ }
+
+ /* --- Now read the new status --- *
+ *
+ * This fixes a race condition between the previous @lstat@ call and
+ * the @mkdir@.
+ */
+
+ if (lstat(p, &st))
+ return (0);
+ }
+
+ /* --- Make sure the directory is good --- *
+ *
+ * It must be a genuine directory (not a link); it must be readable
+ * and writable only by its owner, and that owner must be me.
+ */
+
+ if (S_ISDIR(st.st_mode) && (st.st_mode & 0777) == 0700 && st.st_uid == me)
+ return (1);
+ return (0);
+}
+
+/* --- @trytmp@ --- *
+ *
+ * Arguments: @const char *parent@ = parent directory name
+ * @const char *base@ = subdirectory base name
+ *
+ * Returns: Pointer to directory name, or null. (String needs freeing.)
+ *
+ * Use: Tries to find or create an appropriate temporary directory.
+ */
+
+static char *trytmp(const char *parent, const char *base)
+{
+ static char c[] = { "0123456789"
+ "abcdefghijklmnopqrstuvwxyz"
+ "ABCDEFGHIJKLMNOPQRSTUVWXYZ" };
+ char *p, *q;
+ char *qq;
+ dstr d;
+ int createflag = 1;
+
+ /* --- Make sure the parent directory is sane --- *
+ *
+ * Must make sure that all the lead-up to the temporary directory is safe.
+ * Otherwise other people can play with symlinks or rename directories
+ * after I've done all this careful work to make the endpoint directory
+ * safe.
+ */
+
+ if (path_check(parent, &cp))
+ return (0);
+
+ /* --- See whether the trivial version will work --- */
+
+ dstr_create(&d);
+ dstr_putf(&d, "%s/%s", parent, base);
+ if (ok(d.buf, &createflag))
+ goto good;
+
+ /* --- Now try with various suffixes --- */
+
+ DENSURE(&d, 4);
+ qq = d.buf + d.len;
+ *qq++ = '-';
+
+ for (p = c; *p; p++) {
+ qq[0] = *p;
+ qq[1] = 0;
+ if (ok(d.buf, &createflag))
+ goto good;
+ for (q = c; *q; q++) {
+ qq[1] = *q;
+ qq[2] = 0;
+ if (ok(d.buf, &createflag))
+ goto good;
+ }
+ }
+
+ /* --- No joy --- */
+
+ dstr_destroy(&d);
+ return (0);
+
+good:
+ p = xstrdup(d.buf);
+ dstr_destroy(&d);
+ return (p);
+}
+
+/* --- @fullcheck@ --- *
+ *
+ * Arguments: @const char *p@ = pointer to path to check
+ *
+ * Returns: Zero if it's a bad directory.
+ *
+ * Use: Runs a thorough check on a directory.
+ */
+
+static int fullcheck(const char *p)
+{
+ return (path_check(p, &cp) == 0 && ok(p, 0));
+}
+
+/* --- @goodtmp@ --- *
+ *
+ * Arguments: ---
+ *
+ * Returns: Pointer to a known-good secure temporary directory, or
+ * null.
+ *
+ * Use: Finds a good place to store temporary files.
+ */
+
+static char *goodtmp(void)
+{
+ char *p, *q;
+
+ /* --- First of all, try the user's current choice --- */
+
+ if ((p = getenv("TMPDIR")) != 0 && fullcheck(p))
+ return (p);
+
+ /* --- Try making a directory in `/tmp' --- */
+
+ if (!(q = getenv("USER")) && !(q = getenv("LOGNAME")))
+ q = pw->pw_name;
+ if ((q = trytmp("/tmp", q)) != 0)
+ return (q);
+
+ /* --- That failed: try a directory in the user's home --- */
+
+ if (!(q = getenv("HOME")))
+ q = pw->pw_dir;
+ if ((q = trytmp(q, "tmp")) != 0)
+ return (q);
+
+ /* --- Still no joy: give up --- *
+ *
+ * To be fair, if the user can't find a safe place in his own home
+ * directory then he's pretty stuffed.
+ */
+
+ return (0);
+}
+
+/* --- @usage@ --- */
+
+static void usage(FILE *fp)
+{
+ fprintf(fp, "Usage: %s [-bc] [-v PATH]\n", QUIS);
+}
+
+/* --- @version@ --- */
+
+static void version(FILE *fp)
+{
+ fprintf(fp, "%s version %s\n", QUIS, VERSION);
+}
+
+/* --- @help@ --- */
+
+static void help(FILE *fp)
+{
+ version(fp);
+ putc('\n', fp);
+ usage(fp);
+ fputs("\n\
+Sets a suitable and secure temporary directory, or checks that a given\n\
+directory is suitable for use with temporary files. A directory is\n\
+considered good for a particular user if it's readable and writable only\n\
+by that user, and if all its parents are modifiable only by the user or\n\
+root.\n\
+\n\
+Options supported:\n\
+\n\
+-h, --help Display this help text.\n\
+-V, --version Display the program's version number.\n\
+-u, --usage Display a terse usage summary.\n\
+\n\
+-b, --bourne Output a `TMPDIR' setting for Bourne shell users.\n\
+-c, --cshell Output a `TMPDIR' setting for C shell users.\n\
+-v, --verify PATH Check whether PATH is good, setting exit status.\n\
+\n\
+The default action is to examine the caller's shell and output a suitable\n\
+setting for that shell type.\n\
+",
+ fp);
+}
+
+/* --- @main@ --- *
+ *
+ * Arguments: @int argc@ = number of command line arguments
+ * @char *argv[]@ = the actual argument strings
+ *
+ * Returns: Zero if all went well, else nonzero.
+ *
+ * Use: Performs helpful operations on temporary directories.
+ */
+
+int main(int argc, char *argv[])
+{
+ int shell = 0;
+ int duff = 0;
+
+ enum {
+ sh_unknown,
+ sh_bourne,
+ sh_csh
+ };
+
+ /* --- Initialize variables --- */
+
+ ego(argv[0]);
+ me = getuid();
+ cp.cp_what = CP_WRWORLD | CP_WRGRP | CP_WROTHUSR | CP_STICKYOK;
+ cp.cp_verbose = 0;
+ cp.cp_report = 0;
+ path_setids(&cp);
+ pw = getpwuid(me);
+ if (!pw)
+ die(1, "you don't exist");
+
+ /* --- Parse arguments --- */
+
+ for (;;) {
+ static struct option opts[] = {
+ { "help", 0, 0, 'h' },
+ { "version", 0, 0, 'V' },
+ { "usage", 0, 0, 'u' },
+ { "bourne", 0, 0, 'b' },
+ { "cshell", 0, 0, 'c' },
+ { "verify", gFlag_argReq, 0, 'v' },
+ { 0, 0, 0, 0 }
+ };
+ int i = mdwopt(argc, argv, "hVu bcv:", opts, 0, 0, 0);
+
+ if (i < 0)
+ break;
+ switch (i) {
+ case 'h':
+ help(stdout);
+ exit(0);
+ case 'V':
+ version(stdout);
+ exit(0);
+ case 'u':
+ usage(stdout);
+ exit(0);
+ case 'b':
+ shell = sh_bourne;
+ break;
+ case 'c':
+ shell = sh_csh;
+ break;
+ case 'v':
+ return (!fullcheck(optarg));
+ break;
+ default:
+ duff = 1;
+ break;
+ }
+ }
+
+ if (duff || optind != argc) {
+ usage(stderr);
+ exit(1);
+ }
+
+ /* --- Choose a shell --- */
+
+ if (!shell) {
+ char *p;
+ if (!(p = getenv("SHELL")))
+ p = pw->pw_shell;
+ if (strstr(p, "csh"))
+ shell = sh_csh;
+ else
+ shell = sh_bourne;
+ }
+
+ /* --- Start the checking --- */
+
+ {
+ char *p = goodtmp();
+ if (!p)
+ die(1, "no good tmp directory");
+ switch (shell) {
+ case sh_bourne:
+ printf("TMPDIR=\"%s\"; export TMPDIR\n", p);
+ break;
+ case sh_csh:
+ printf("setenv TMPDIR \"%s\"\n", p);
+ break;
+ }
+ }
+
+ return (0);
+}
+
+/*----- That's all, folks -------------------------------------------------*/
~mdw / checkpath / commitdiff