[git commit] setlogcons: make it NOEXEC, better --help text

Denys Vlasenko vda.linux at googlemail.com
Sun Aug 6 16:17:58 UTC 2017


commit: https://git.busybox.net/busybox/commit/?id=341ce0a31eb2bdc352ef61df1954983c5235c818
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master

Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 NOFORK_NOEXEC.lst          |  2 +-
 console-tools/setlogcons.c | 20 ++++++++++++++++----
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/NOFORK_NOEXEC.lst b/NOFORK_NOEXEC.lst
index 30690af..8145e25 100644
--- a/NOFORK_NOEXEC.lst
+++ b/NOFORK_NOEXEC.lst
@@ -308,7 +308,7 @@ setarch - noexec. spawner
 setconsole
 setfont
 setkeycodes
-setlogcons
+setlogcons - noexec
 setpriv - spawner, changes state, let's play safe and not be noexec
 setserial - noexec
 setsid - spawner, uses fork_or_rexec() [not audited to work in noexec], let's play safe and not be noexec
diff --git a/console-tools/setlogcons.c b/console-tools/setlogcons.c
index 1b5814e..6778a4d 100644
--- a/console-tools/setlogcons.c
+++ b/console-tools/setlogcons.c
@@ -15,14 +15,26 @@
 //config:	help
 //config:	This program redirects the output console of kernel messages.
 
-//applet:IF_SETLOGCONS(APPLET(setlogcons, BB_DIR_USR_SBIN, BB_SUID_DROP))
+//applet:IF_SETLOGCONS(APPLET_NOEXEC(setlogcons, setlogcons, BB_DIR_USR_SBIN, BB_SUID_DROP, setlogcons))
 
 //kbuild:lib-$(CONFIG_SETLOGCONS) += setlogcons.o
 
 //usage:#define setlogcons_trivial_usage
 //usage:       "[N]"
 //usage:#define setlogcons_full_usage "\n\n"
-//usage:       "Redirect the kernel output to console N. Default:0 (current console)"
+//usage:       "Pin kernel output to VT console N. Default:0 (do not pin)"
+
+// Comment from kernel source:
+/* ...
+ * By default, the kernel messages are always printed on the current virtual
+ * console. However, the user may modify that default with the
+ * TIOCL_SETKMSGREDIRECT ioctl call.
+ *
+ * This function sets the kernel message console to be @new. It returns the old
+ * virtual console number. The virtual terminal number 0 (both as parameter and
+ * return value) means no redirection (i.e. always printed on the currently
+ * active console).
+ */
 
 #include "libbb.h"
 
@@ -33,8 +45,8 @@ int setlogcons_main(int argc UNUSED_PARAM, char **argv)
 		char fn;
 		char subarg;
 	} arg = {
-		11, /* redirect kernel messages */
-		0   /* to specified console (current as default) */
+		11, /* redirect kernel messages (TIOCL_SETKMSGREDIRECT) */
+		0
 	};
 
 	if (argv[1])


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