signal: do auth check

kernel-src/include/kernel/jobctl.h

@@ -13,7 +13,7 @@ pid_t jobctl_getpgid(proc_t *proc);
 pid_t jobctl_getsid(proc_t *proc);
 int jobctl_setctty(proc_t *proc, void *ctty, bool steal);
 void *jobctl_getctty(proc_t *proc);
-int jobctl_signal(proc_t *proc, int signal);
+int jobctl_signal(proc_t *proc, int signal, proc_t *sender);
 proc_t *jobctl_getforeground(proc_t *proc);
 int jobctl_setforeground(proc_t *session, proc_t *pgrp);
 

kernel-src/io/tty.c

@@ -74,7 +74,7 @@ void tty_process(tty_t *tty, char c) {
 		if (signal >= 0) {
 			proc_t *pgrp = getforeground(tty);
 			if (pgrp) {
-				jobctl_signal(pgrp, signal);
+				jobctl_signal(pgrp, signal, NULL);
 				PROC_RELEASE(pgrp);
 			}
 			return;
@@ -311,7 +311,7 @@ int tty_ioctl(tty_t *tty, unsigned long req, void *arg, int *result, cred_t *cre
 
 			proc_t *foreground = getforeground(tty);
 			if (foreground) {
-				jobctl_signal(foreground, SIGWINCH);
+				jobctl_signal(foreground, SIGWINCH, NULL);
 				PROC_RELEASE(foreground);
 			}
 			break;
@@ -524,7 +524,7 @@ void tty_unregister(tty_t *tty) {
 
 	proc_t *foreground = getforeground(tty);
 	if (foreground) {
-		jobctl_signal(foreground, SIGHUP);
+		jobctl_signal(foreground, SIGHUP, NULL);
 		PROC_RELEASE(foreground);
 	}
 }

kernel-src/sys/defaultauth.c

@@ -249,7 +249,6 @@ static int credlistener(cred_t *cred, int actions, void *arg0, void *arg1, void
 
 static int process(cred_t *cred, int actions, void *arg0, void *arg1, void *arg2) {
 	proc_t *proc = arg0;
-	int *signal = arg1;
 
 	int weight = 0;
 	if (actions & AUTH_ACTIONS_PROCESS_SIGNAL) {
@@ -260,10 +259,6 @@ static int process(cred_t *cred, int actions, void *arg0, void *arg1, void *arg2
 				cred->euid == proc->cred.uid ||
 				cred->euid == proc->cred.suid)
 			weight += 1;
-		else if (*signal == SIGCONT) {
-			// TODO SIGCONT is supposed to work on the same process group; we are being a bit more permissive here for now
-			weight += 1;
-		}
 
 		DONE_CHECK(actions);
 	}

kernel-src/sys/jobctl.c

@@ -1,6 +1,7 @@
 #include <kernel/jobctl.h>
 #include <kernel/interrupt.h>
 #include <kernel/tty.h>
+#include <kernel/auth.h>
 #include <errno.h>
 #include <logging.h>
 
@@ -278,8 +279,8 @@ void jobctl_detach(proc_t *proc) {
 		PROC_RELEASE(unholdsession);
 	} else {
 		jobctl_setctty(proc, NULL, 0);
-		jobctl_signal(foreground, SIGHUP);
-		jobctl_signal(foreground, SIGCONT);
+		jobctl_signal(foreground, SIGHUP, NULL);
+		jobctl_signal(foreground, SIGCONT, NULL);
 		PROC_RELEASE(foreground);
 	}
 }
@@ -378,11 +379,13 @@ void jobctl_procremove(proc_t *proc) {
 
 // proc can be null if the signal is being sent to the calling processes own process group
 // since that is only passed from a userland thread, we can assume _cpu()->thread->proc is not null
-int jobctl_signal(proc_t *proc, int signal) {
+int jobctl_signal(proc_t *proc, int signal, proc_t *sender) {
 	int error = 0;
 	bool intstatus = interrupt_set(false);
 	proc_t *leader;
 	proc_t *tmpproc = _cpu()->thread->proc;
+	pid_t senderpgid = sender ? jobctl_getpgid(sender) : 0;
+
 	if (proc == NULL) {
 		spinlock_acquire(&tmpproc->jobctllock);
 		leader = tmpproc->pgrp.leader ? tmpproc->pgrp.leader : tmpproc;
@@ -400,11 +403,21 @@ int jobctl_signal(proc_t *proc, int signal) {
 
 	spinlock_acquire(&leader->pgrp.lock);
 
+	size_t donecount = 0;
 	proc_t *iterator = leader;
 	while (iterator) {
-		signal_signalproc(iterator, signal);
+		// only send the signal if:
+		// there isn't a specific sender (for example, ^C from the tty)
+		// the signal is SIGCONT and they are from the same process group
+		// the auth check passes
+		if (senderpgid == 0 || (signal == SIGCONT && leader->pid == senderpgid) || auth_process_check(&sender->cred, AUTH_ACTIONS_PROCESS_SIGNAL, iterator) == 0) {
+			signal_signalproc(iterator, signal);
+			++donecount;
+		}
+
 		iterator = iterator->pgrp.nextmember;
 	}
+	error = donecount == 0 ? EPERM : 0;
 
 	spinlock_release(&leader->pgrp.lock);
 

kernel-src/sys/syscalls/kill.c

@@ -2,6 +2,7 @@
 #include <arch/cpu.h>
 #include <logging.h>
 #include <kernel/jobctl.h>
+#include <kernel/auth.h>
 
 syscallret_t syscall_kill(context_t *context, int pid, int signal) {
 	syscallret_t ret = {
@@ -30,16 +31,27 @@ syscallret_t syscall_kill(context_t *context, int pid, int signal) {
 		return ret;
 	}
 
-	if (pid >= 1)
-		signal_signalproc(target, signal);
-	else
-		ret.errno = jobctl_signal(target, signal);
+	// null signal is meant to find out about the existance of a process
+	if (signal == 0)
+		goto leave;
 
+	if (pid >= 1) {
+		if (signal != SIGCONT && jobctl_getpgid(target) != jobctl_getpgid(_cpu()->thread->proc)) {
+			ret.errno = auth_process_check(&_cpu()->thread->proc->cred, AUTH_ACTIONS_PROCESS_SIGNAL, target);
+			if (ret.errno)
+				goto leave;
+		}
+
+		signal_signalproc(target, signal);
+	} else {
+		ret.errno = jobctl_signal(target, signal, _cpu()->thread->proc);
+	}
+
+	leave:
 	if (target) {
 		PROC_RELEASE(target);
 	}
 
-	ret.errno = 0;
-	ret.ret = 0;
+	ret.ret = ret.errno ? -1 : 0;
 	return ret;
 }