utils-std

commit: 674085dfb15cb489526870849c3d1e1d5bb8c004
parent b4f92de9131cdd1a60f288fc373d4b1517b27161
Author: Haelwenn (lanodan) Monnier <contact@hacktivis.me>
Date:   Sat, 23 Mar 2024 04:58:22 +0100

cmd/chroot: Add length-check on $SHELL

Diffstat:
M
cmd/chroot.c
24
++++++++++++++++++------

1 file changed, 18 insertions(+), 6 deletions(-)
diff --git a/cmd/chroot.c b/cmd/chroot.c
@@ -3,12 +3,15 @@
 // SPDX-License-Identifier: MPL-2.0
 
 #define _DEFAULT_SOURCE // chroot isn't POSIX
-#include <assert.h>     // assert
-#include <errno.h>      // errno
-#include <stdbool.h>    // false
-#include <stdio.h>      // fprintf, perror
-#include <stdlib.h>     // getenv
-#include <unistd.h>     // chroot, execl, execv
+
+#include <assert.h>  // assert
+#include <errno.h>   // errno
+#include <limits.h>  // PATH_MAX
+#include <stdbool.h> // false
+#include <stdio.h>   // fprintf, perror
+#include <stdlib.h>  // getenv
+#include <string.h>  // strlen
+#include <unistd.h>  // chroot, execl, execv
 
 int
 main(int argc, char *argv[])
@@ -20,6 +23,7 @@ main(int argc, char *argv[])
 		return 125;
 	}
 
+	/* flawfinder: ignore. chdir(/) done, can't close more fds, shouldn't drop root */
 	if(chroot(argv[1]) < 0)
 	{
 		perror("chroot");
@@ -36,8 +40,16 @@ main(int argc, char *argv[])
 	errno   = 0;
 	if(argc == 2)
 	{
+		/* flawfinder: ignore. NULL and length are checked */
 		char *shell = getenv("SHELL");
 		if(shell == NULL) shell = "/bin/sh";
+		if(strnlen(shell, PATH_MAX) >= PATH_MAX)
+		{
+			fprintf(stderr,
+			        "chroot: Warning: $SHELL is longer than {PATH_MAX}(= %d), using '/bin/sh'\n",
+			        PATH_MAX);
+			shell = "/bin/sh";
+		}
 
 		/* flawfinder: ignore. No restrictions on commands is intended */
 		ret = execlp(shell, shell, "-i", NULL);