summaryrefslogtreecommitdiffstats
path: root/lib/env.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/env.c')
-rw-r--r--lib/env.c236
1 files changed, 236 insertions, 0 deletions
diff --git a/lib/env.c b/lib/env.c
new file mode 100644
index 0000000..9b5fd32
--- /dev/null
+++ b/lib/env.c
@@ -0,0 +1,236 @@
+/*
+ * SPDX-FileCopyrightText: 1989 - 1992, Julianne Frances Haugh
+ * SPDX-FileCopyrightText: 1996 - 1999, Marek Michałkiewicz
+ * SPDX-FileCopyrightText: 2003 - 2005, Tomasz Kłoczko
+ * SPDX-FileCopyrightText: 2008 - 2009, Nicolas François
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <config.h>
+
+#ident "$Id$"
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "alloc.h"
+#include "prototypes.h"
+#include "defines.h"
+#include "shadowlog.h"
+#include "string/sprintf.h"
+
+
+/*
+ * NEWENVP_STEP must be a power of two. This is the number
+ * of (char *) pointers to allocate at a time, to avoid using
+ * realloc() too often.
+ */
+#define NEWENVP_STEP 16
+size_t newenvc = 0;
+/*@null@*/char **newenvp = NULL;
+
+static const char *const forbid[] = {
+ "_RLD_=",
+ "BASH_ENV=", /* GNU creeping featurism strikes again... */
+ "ENV=",
+ "HOME=",
+ "IFS=",
+ "KRB_CONF=",
+ "LD_", /* anything with the LD_ prefix */
+ "LIBPATH=",
+ "MAIL=",
+ "NLSPATH=",
+ "PATH=",
+ "SHELL=",
+ "SHLIB_PATH=",
+ NULL
+};
+
+/* these are allowed, but with no slashes inside
+ (to work around security problems in GNU gettext) */
+static const char *const noslash[] = {
+ "LANG=",
+ "LANGUAGE=",
+ "LC_", /* anything with the LC_ prefix */
+ NULL
+};
+
+/*
+ * initenv() must be called once before using addenv().
+ */
+void initenv (void)
+{
+ newenvp = XMALLOC(NEWENVP_STEP, char *);
+ *newenvp = NULL;
+}
+
+
+void addenv (const char *string, /*@null@*/const char *value)
+{
+ char *cp, *newstring;
+ size_t i, n;
+
+ if (NULL != value) {
+ xasprintf(&newstring, "%s=%s", string, value);
+ } else {
+ newstring = xstrdup (string);
+ }
+
+ /*
+ * Search for a '=' character within the string and if none is found
+ * just ignore the whole string.
+ */
+
+ cp = strchr (newstring, '=');
+ if (NULL == cp) {
+ free(newstring);
+ return;
+ }
+
+ n = (size_t) (cp - newstring);
+
+ /*
+ * If this environment variable is already set, change its value.
+ */
+ for (i = 0; i < newenvc; i++) {
+ if ( (strncmp (newstring, newenvp[i], n) == 0)
+ && (('=' == newenvp[i][n]) || ('\0' == newenvp[i][n]))) {
+ break;
+ }
+ }
+
+ if (i < newenvc) {
+ free(newenvp[i]);
+ newenvp[i] = newstring;
+ return;
+ }
+
+ /*
+ * Otherwise, save the new environment variable
+ */
+ newenvp[newenvc++] = newstring;
+
+ /*
+ * And extend the environment if needed.
+ */
+
+ /*
+ * Check whether newenvc is a multiple of NEWENVP_STEP.
+ * If so we have to resize the vector.
+ * the expression (newenvc & (NEWENVP_STEP - 1)) == 0
+ * is equal to (newenvc % NEWENVP_STEP) == 0
+ * as long as NEWENVP_STEP is a power of 2.
+ */
+
+ if ((newenvc & (NEWENVP_STEP - 1)) == 0) {
+ bool update_environ;
+
+ update_environ = (environ == newenvp);
+
+ newenvp = XREALLOC(newenvp, newenvc + NEWENVP_STEP, char *);
+
+ /*
+ * If this is our current environment, update
+ * environ so that it doesn't point to some
+ * free memory area (realloc() could move it).
+ */
+ if (update_environ)
+ environ = newenvp;
+ }
+
+ /*
+ * The last entry of newenvp must be NULL
+ */
+
+ newenvp[newenvc] = NULL;
+}
+
+
+/*
+ * set_env - copy command line arguments into the environment
+ */
+void set_env (int argc, char *const *argv)
+{
+ int noname = 1;
+ char variable[1024];
+ char *cp;
+
+ for (; argc > 0; argc--, argv++) {
+ if (strlen (*argv) >= sizeof variable) {
+ continue; /* ignore long entries */
+ }
+
+ cp = strchr (*argv, '=');
+ if (NULL == cp) {
+ assert(SNPRINTF(variable, "L%d", noname) != -1);
+ noname++;
+ addenv (variable, *argv);
+ } else {
+ const char *const *p;
+
+ for (p = forbid; NULL != *p; p++) {
+ if (strncmp (*argv, *p, strlen (*p)) == 0) {
+ break;
+ }
+ }
+
+ if (NULL != *p) {
+ stpcpy(mempcpy(variable, *argv, (size_t)(cp - *argv)), "");
+ printf (_("You may not change $%s\n"),
+ variable);
+ continue;
+ }
+
+ addenv (*argv, NULL);
+ }
+ }
+}
+
+/*
+ * sanitize_env - remove some nasty environment variables
+ * If you fall into a total paranoia, you should call this
+ * function for any root-setuid program or anything the user
+ * might change the environment with. 99% useless as almost
+ * all modern Unixes will handle setuid executables properly,
+ * but... I feel better with that silly precaution. -j.
+ */
+
+void sanitize_env (void)
+{
+ char **envp = environ;
+ const char *const *bad;
+ char **cur;
+ char **move;
+
+ for (cur = envp; NULL != *cur; cur++) {
+ for (bad = forbid; NULL != *bad; bad++) {
+ if (strncmp (*cur, *bad, strlen (*bad)) == 0) {
+ for (move = cur; NULL != *move; move++) {
+ *move = *(move + 1);
+ }
+ cur--;
+ break;
+ }
+ }
+ }
+
+ for (cur = envp; NULL != *cur; cur++) {
+ for (bad = noslash; NULL != *bad; bad++) {
+ if (strncmp (*cur, *bad, strlen (*bad)) != 0) {
+ continue;
+ }
+ if (strchr (*cur, '/') == NULL) {
+ continue; /* OK */
+ }
+ for (move = cur; NULL != *move; move++) {
+ *move = *(move + 1);
+ }
+ cur--;
+ break;
+ }
+ }
+}
+