wall: access FILE under real user's credentials
While at it, move applet/config/kbuild bits into wall.c.
(This way, it's more visible that applet is suid'ed).
function old new delta
wall_main 87 138 +51
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/miscutils/wall.c b/miscutils/wall.c
index 762f53b..c74f4f2 100644
--- a/miscutils/wall.c
+++ b/miscutils/wall.c
@@ -6,6 +6,18 @@
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
+//config:config WALL
+//config: bool "wall"
+//config: default y
+//config: depends on FEATURE_UTMP
+//config: help
+//config: Write a message to all users that are logged in.
+
+/* Needs to be run by root or be suid root - needs to write to /dev/TTY: */
+//applet:IF_WALL(APPLET(wall, BB_DIR_USR_BIN, BB_SUID_REQUIRE))
+
+//kbuild:lib-$(CONFIG_WALL) += wall.o
+
//usage:#define wall_trivial_usage
//usage: "[FILE]"
//usage:#define wall_full_usage "\n\n"
@@ -22,8 +34,19 @@
{
struct utmp *ut;
char *msg;
- int fd = argv[1] ? xopen(argv[1], O_RDONLY) : STDIN_FILENO;
+ int fd;
+ fd = STDIN_FILENO;
+ if (argv[1]) {
+ /* The applet is setuid.
+ * Access to the file must be under user's uid/gid.
+ */
+ setfsuid(getuid());
+ setfsgid(getgid());
+ fd = xopen(argv[1], O_RDONLY);
+ setfsuid(geteuid());
+ setfsgid(getegid());
+ }
msg = xmalloc_read(fd, NULL);
if (ENABLE_FEATURE_CLEAN_UP && argv[1])
close(fd);