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-rw-r--r--lib/util/getusershell.c132
1 files changed, 132 insertions, 0 deletions
diff --git a/lib/util/getusershell.c b/lib/util/getusershell.c
new file mode 100644
index 0000000..7912816
--- /dev/null
+++ b/lib/util/getusershell.c
@@ -0,0 +1,132 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2019-2020 Todd C. Miller <Todd.Miller@sudo.ws>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * This is an open source non-commercial project. Dear PVS-Studio, please check it.
+ * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "sudo_compat.h"
+#include "sudo_debug.h"
+#include "sudo_gettext.h"
+#include "sudo_util.h"
+
+static char **allowed_shells, **current_shell;
+static char *default_shells[] = {
+ "/bin/sh",
+ "/bin/ksh",
+ "/bin/ksh93",
+ "/bin/bash",
+ "/bin/dash",
+ "/bin/zsh",
+ "/bin/csh",
+ "/bin/tcsh",
+ NULL
+};
+
+static char **
+read_shells(void)
+{
+ size_t maxshells = 16, nshells = 0;
+ size_t linesize = 0;
+ char *line = NULL;
+ FILE *fp;
+ debug_decl(read_shells, SUDO_DEBUG_UTIL);
+
+ if ((fp = fopen("/etc/shells", "r")) == NULL)
+ goto bad;
+
+ free(allowed_shells);
+ allowed_shells = reallocarray(NULL, maxshells, sizeof(char *));
+ if (allowed_shells == NULL)
+ goto bad;
+
+ while (sudo_parseln(&line, &linesize, NULL, fp, PARSELN_CONT_IGN) != -1) {
+ if (nshells + 1 >= maxshells) {
+ char **new_shells;
+
+ new_shells = reallocarray(NULL, maxshells + 16, sizeof(char *));
+ if (new_shells == NULL)
+ goto bad;
+ allowed_shells = new_shells;
+ maxshells += 16;
+ }
+ if ((allowed_shells[nshells] = strdup(line)) == NULL)
+ goto bad;
+ nshells++;
+ }
+ allowed_shells[nshells] = NULL;
+
+ free(line);
+ fclose(fp);
+ debug_return_ptr(allowed_shells);
+bad:
+ free(line);
+ if (fp != NULL)
+ fclose(fp);
+ while (nshells != 0)
+ free(allowed_shells[--nshells]);
+ free(allowed_shells);
+ allowed_shells = NULL;
+ debug_return_ptr(default_shells);
+}
+
+void
+sudo_setusershell(void)
+{
+ debug_decl(setusershell, SUDO_DEBUG_UTIL);
+
+ current_shell = read_shells();
+
+ debug_return;
+}
+
+void
+sudo_endusershell(void)
+{
+ debug_decl(endusershell, SUDO_DEBUG_UTIL);
+
+ if (allowed_shells != NULL) {
+ char **shell;
+
+ for (shell = allowed_shells; *shell != NULL; shell++)
+ free(*shell);
+ free(allowed_shells);
+ allowed_shells = NULL;
+ }
+ current_shell = NULL;
+
+ debug_return;
+}
+
+char *
+sudo_getusershell(void)
+{
+ debug_decl(getusershell, SUDO_DEBUG_UTIL);
+
+ if (current_shell == NULL)
+ current_shell = read_shells();
+
+ debug_return_str(*current_shell++);
+}