kernel: do preparation work for copyless read/write

kernel-src/arch/x86-64/e9.c

@@ -1,6 +1,7 @@
 #include <arch/io.h>
 #include <kernel/devfs.h>
 #include <logging.h>
+#include <kernel/usercopy.h>
 
 void arch_e9_putc(char c) {
 #ifdef X86_64_ENABLE_E9
@@ -16,11 +17,18 @@ void arch_e9_puts(char *c) {
 #endif
 }
 
+#ifdef X86_64_ENABLE_E9
 static int devwrite(int minor, void *bufferp, size_t count, uintmax_t offset, int flags, size_t *wcount) {
 	uint8_t *buffer = bufferp;
 
-	for (uintmax_t i = 0; i < count; ++i)
-		outb(0xe9, buffer[i]);
+	for (uintmax_t i = 0; i < count; ++i) {
+		char c;
+		int error = USERCOPY_POSSIBLY_FROM_USER(&c, &buffer[i], 1);
+		if (error)
+			return error;
+
+		outb(0xe9, c);
+	}
 
 	*wcount = count;
 	return 0;
@@ -29,6 +37,7 @@ static int devwrite(int minor, void *bufferp, size_t count, uintmax_t offset, in
 static devops_t devops = {
 	.write = devwrite
 };
+#endif
 
 void arch_e9_initdev() {
 #ifdef X86_64_ENABLE_E9

kernel-src/fs/ext2.c

@@ -1317,6 +1317,8 @@ static int ext2_readlink(vnode_t *vnode, char **link, cred_t *cred) {
 	return err;
 }
 
+// this *should*, by the rules of the vnode ops, accept a user buffer. however, this will never be the case. all I/O will
+// go through the page cache
 static int ext2_read(vnode_t *vnode, void *buffer, size_t size, uintmax_t offset, int flags, size_t *readc, cred_t *cred) {
 	if (vnode->type == V_TYPE_DIR)
 		return EISDIR;
@@ -1356,6 +1358,8 @@ static int ext2_read(vnode_t *vnode, void *buffer, size_t size, uintmax_t offset
 	return err;
 }
 
+// this *should*, by the rules of the vnode ops, accept a user buffer. however, this will never be the case. all I/O will
+// go through the page cache
 int ext2_write(vnode_t *vnode, void *buffer, size_t size, uintmax_t offset, int flags, size_t *writec, cred_t *cred) {
 	if (vnode->type == V_TYPE_DIR)
 		return EISDIR;

kernel-src/fs/pipefs.c

@@ -130,6 +130,7 @@ static int internalpoll(vnode_t *node, polldata_t *data, int events) {
 	return revents;
 }
 
+// buffer can possibly be a user address
 int pipefs_read(vnode_t *node, void *buffer, size_t size, uintmax_t offset, int flags, size_t *readc, cred_t *cred) {
 	pipenode_t *pipenode = (pipenode_t *)node;
 	INTERNAL_LOCK(node);
@@ -171,6 +172,8 @@ int pipefs_read(vnode_t *node, void *buffer, size_t size, uintmax_t offset, int
 	}
 
 	*readc = ringbuffer_read(&pipenode->data, buffer, size);
+	if (*readc == RINGBUFFER_USER_COPY_FAILED)
+		error = EFAULT;
 
 	// signal that there is space to write for any threads blocked on this pipe
 	if (RINGBUFFER_DATACOUNT(&pipenode->data) < BUFFER_SIZE - PIPE_ATOMIC_SIZE)
@@ -190,6 +193,8 @@ static int writetopipe(pipenode_t *pipenode, void *buffer, size_t size, size_t *
 	}
 
 	*writec = ringbuffer_write(&pipenode->data, buffer, size);
+	if (*writec == RINGBUFFER_USER_COPY_FAILED)
+		return EFAULT;
 
 	__assert(*writec);
 	poll_event(&pipenode->pollheader, POLLIN);

kernel-src/io/acpi/dev.c

@@ -7,15 +7,11 @@
 
 static ringbuffer_t ringbuffer;
 static pollheader_t pollheader;
-static spinlock_t lock;
+static mutex_t mutex;
 
 void acpi_signaldevice(char c) {
-	long ipl = spinlock_acquireraiseipl(&lock, IPL_DPC);
-
 	if (ringbuffer_write(&ringbuffer, &c, 1))
 		poll_event(&pollheader, POLLIN);
-
-	spinlock_releaseloweripl(&lock, ipl);
 }
 
 static int internalpoll(polldata_t *data, int events) {
@@ -43,13 +39,11 @@ static int read(int minor, void *buffer, size_t size, uintmax_t offset, int flag
 	if (error)
 		return error;
 
+	MUTEX_ACQUIRE(&mutex, false);
+
 	for (;;) {
-		long ipl = spinlock_acquireraiseipl(&lock, IPL_DPC);
-
 		int revents = internalpoll(&desc.data[0], POLLIN);
 
-		spinlock_releaseloweripl(&lock, ipl);
-
 		if (revents)
 			break;
 
@@ -66,13 +60,14 @@ static int read(int minor, void *buffer, size_t size, uintmax_t offset, int flag
 		poll_leave(&desc);
 	}
 
-	long ipl = spinlock_acquireraiseipl(&lock, IPL_DPC);
-
+	// this abuses a behavior of how the ringbuffer works to not need a lock for reading
+	// (as it would need interrupts to be off)
 	*readc = ringbuffer_read(&ringbuffer, buffer, size);
-
-	spinlock_releaseloweripl(&lock, ipl);
+	if (*readc == RINGBUFFER_USER_COPY_FAILED)
+		error = EFAULT;
 
 	leave:
+	MUTEX_RELEASE(&mutex);
 	poll_leave(&desc);
 	poll_destroydesc(&desc);
 	return error;
@@ -98,11 +93,9 @@ static int write(int minor, void *buffer, size_t size, uintmax_t offset, int fla
 }
 
 static int poll(int minor, polldata_t *data, int events) {
-	long ipl = spinlock_acquireraiseipl(&lock, IPL_DPC);
-
+	MUTEX_ACQUIRE(&mutex, false);
 	int revents = internalpoll(data, events);
-
-	spinlock_releaseloweripl(&lock, ipl);
+	MUTEX_RELEASE(&mutex);
 	return revents;
 }
 

kernel-src/io/fb.c

@@ -99,7 +99,10 @@ static int read(int minor, void *buffer, size_t size, uintmax_t offset, int flag
 	if(size + offset > end)
 		size = end - offset;
 
-	memcpy(buffer, (void *)((uintptr_t)fbs[minor]->address + offset), size);
+	int error = USERCOPY_POSSIBLY_TO_USER(buffer, (void *)((uintptr_t)fbs[minor]->address + offset), size);
+	if (error)
+		return error;
+
 	*readc = size;
 
 	return 0;
@@ -118,7 +121,10 @@ static int write(int minor, void *buffer, size_t size, uintmax_t offset, int fla
 	if(size + offset > end)
 		size = end - offset;
 
-	memcpy((void *)((uintptr_t)fbs[minor]->address + offset), buffer, size);
+	int error = USERCOPY_POSSIBLY_FROM_USER((void *)((uintptr_t)fbs[minor]->address + offset), buffer, size);
+	if (error)
+		return error;
+
 	*writec = size;
 
 	return 0;

kernel-src/io/keyboard.c

@@ -5,6 +5,7 @@
 #include <kernel/devfs.h>
 #include <hashtable.h>
 #include <kernel/poll.h>
+#include <kernel/usercopy.h>
 
 #define BUFFER_PACKET_CAPACITY 100
 #define BUFFER_SIZE (BUFFER_PACKET_CAPACITY * sizeof(kbpacket_t))
@@ -165,25 +166,34 @@ static int read(int minor, void *buffer, size_t size, uintmax_t offset, int flag
 
 	for (int i = 0; i < count; ++i) {
 		kbpacket_t *buff = (kbpacket_t *)((uintptr_t)buffer + i * sizeof(kbpacket_t));
-		bool ok = keyboard_get(kb, buff);
+		kbpacket_t packet;
+
+		bool ok = keyboard_get(kb, &packet);
 		if (ok == false) {
 			if (i == 0 && (flags & V_FFLAGS_NONBLOCKING) == 0) {
-				int err = keyboard_wait(kb, buff);
-				*readc += err ? 0 : sizeof(kbpacket_t);
-				return err;
+				int error = keyboard_wait(kb, &packet);
+				if (error)
+					return error;
+
+				error = USERCOPY_POSSIBLY_TO_USER(buff, &packet, sizeof(kbpacket_t));
+
+				*readc += error ? 0 : sizeof(kbpacket_t);
+				return error;
 			}
 
 			break;
 		}
 
+		int error = USERCOPY_POSSIBLY_TO_USER(buff, &packet, sizeof(kbpacket_t));
+		if (error)
+			return error;
+
 		*readc += sizeof(kbpacket_t);
 	}
 
 	return 0;
 }
 
-
-
 static int poll(int minor, polldata_t *data, int events) {
 	int revents = 0;
 	keyboard_t *kb = getkb(minor);

kernel-src/io/mouse.c

@@ -122,6 +122,11 @@ static int read(int minor, void *buffer, size_t size, uintmax_t offset, int flag
 	}
 
 	*readc = ringbuffer_read(&mouse->packetbuffer, buffer, sizeof(mousepacket_t) * packetcount);
+	if (*readc == RINGBUFFER_USER_COPY_FAILED) {
+		error = EFAULT;
+		goto leave;
+	}
+
 	__assert(*readc);
 
 	leave:

kernel-src/io/net/localsocket.c

@@ -365,6 +365,11 @@ static int localsock_send(socket_t *socket, sockdesc_t *sockdesc) {
 	}
 
 	sockdesc->donecount = ringbuffer_write(&peer->ringbuffer, sockdesc->buffer, sockdesc->count);
+	if (sockdesc->donecount == RINGBUFFER_USER_COPY_FAILED) {
+		error = EFAULT;
+		goto leave;
+	}
+
 	__assert(sockdesc->donecount > 0);
 
 	error = sendctrl(socket, sockdesc->ctrl, sockdesc->ctrllen, sockdesc->donecount);
@@ -465,8 +470,17 @@ static int localsock_recv(socket_t *socket, sockdesc_t *sockdesc) {
 
 	if (flags & SOCKET_RECV_FLAGS_PEEK) {
 		sockdesc->donecount = ringbuffer_peek(&localsocket->ringbuffer, sockdesc->buffer, 0, recvcount);
+		if (sockdesc->donecount == RINGBUFFER_USER_COPY_FAILED) {
+			error = EFAULT;
+			goto leave;
+		}
 	} else {
 		sockdesc->donecount = ringbuffer_read(&localsocket->ringbuffer, sockdesc->buffer, recvcount);
+		if (sockdesc->donecount == RINGBUFFER_USER_COPY_FAILED) {
+			error = EPIPE;
+			goto leave;
+		}
+
 		localsocket_t *peer = pair->client == localsocket ? pair->server : pair->client;
 		// signal that there is space to write for any threads blocked on this socket
 		if (peer && sockdesc->donecount)

kernel-src/io/net/tcp.c

@@ -1305,8 +1305,13 @@ static int tcp_send(socket_t *socket, sockdesc_t *sockdesc) {
 	size_t writesize = min(TCB_RINGBUFFER_SIZE - RINGBUFFER_DATACOUNT(&tcb->transmitbuffer), sockdesc->count);
 	__assert(writesize);
 
-	__assert(ringbuffer_write(&tcb->transmitbuffer, sockdesc->buffer, writesize) == writesize);
-	sockdesc->donecount = writesize;
+	sockdesc->donecount = ringbuffer_write(&tcb->transmitbuffer, sockdesc->buffer, writesize);
+	if (sockdesc->donecount == RINGBUFFER_USER_COPY_FAILED) {
+		error = EFAULT;
+		goto leave;
+	}
+
+	__assert(sockdesc->donecount == writesize);
 
 	if (tcb->sndnext == tcb->sndunack)
 		error = tcp_transmitnextsegment(tcb);
@@ -1381,14 +1386,24 @@ static int tcp_recv(socket_t *socket, sockdesc_t *sockdesc) {
 
 	size_t copycount = min(RINGBUFFER_DATACOUNT(&tcb->receivebuffer), sockdesc->count);
 	if (flags & SOCKET_RECV_FLAGS_PEEK) {
-		__assert(ringbuffer_peek(&tcb->receivebuffer, sockdesc->buffer, 0, copycount) == copycount);
+		sockdesc->donecount = ringbuffer_peek(&tcb->receivebuffer, sockdesc->buffer, 0, copycount);
+		if (sockdesc->donecount == RINGBUFFER_USER_COPY_FAILED) {
+			error = EFAULT;
+			goto cleanup;
+		}
 	} else {
-		__assert(ringbuffer_read(&tcb->receivebuffer, sockdesc->buffer, copycount) == copycount);
+		sockdesc->donecount = ringbuffer_read(&tcb->receivebuffer, sockdesc->buffer, copycount);
+		if (sockdesc->donecount == RINGBUFFER_USER_COPY_FAILED) {
+			error = EFAULT;
+			goto cleanup;
+		}
+
 		tcb->rcvwindow += copycount;
 		// notify about the window increase
 		tcp_ack(tcb);
 	}
-	sockdesc->donecount = copycount;
+
+	__assert(sockdesc->donecount == copycount);
 
 	cleanup:
 	MUTEX_RELEASE(&tcb->mutex);

kernel-src/io/net/udp.c

@@ -262,6 +262,7 @@ static int udp_recv(socket_t *socket, sockdesc_t *sockdesc) {
 	bool intstate = interrupt_set(false);
 	spinlock_acquire(&udpsocket->ringbufferlock);
 
+	// TODO rewrite this to handle a possible sleep in the ringbuffer
 	size_t copycount;
 	dataheader_t header;
 	if (flags & SOCKET_RECV_FLAGS_PEEK) {

kernel-src/io/pty.c

@@ -132,10 +132,10 @@ static int read(int minor, void *buffer, size_t size, uintmax_t offset, int flag
 	if (pty == NULL)
 		return ENODEV;
 
-
+	int e = 0;
 	for (;;) {
 		polldesc_t desc = {0};
-		int e = poll_initdesc(&desc, 1);
+		e = poll_initdesc(&desc, 1);
 		if (e)
 			return e;
 
@@ -146,6 +146,8 @@ static int read(int minor, void *buffer, size_t size, uintmax_t offset, int flag
 
 		if (revents) {
 			*readc = ringbuffer_read(&pty->ringbuffer, buffer, size);
+			if (*readc == RINGBUFFER_USER_COPY_FAILED)
+				e = EFAULT;
 
 			spinlock_release(&pty->lock);
 			interrupt_set(intstatus);
@@ -173,7 +175,7 @@ static int read(int minor, void *buffer, size_t size, uintmax_t offset, int flag
 			return e;
 	}
 
-	return 0;
+	return e;
 }
 
 static int poll(int minor, polldata_t *data, int events) {
@@ -215,8 +217,15 @@ static int write(int minor, void *buffer, size_t size, uintmax_t offset, int fla
 
 	char *str = buffer;
 
-	for (int i = 0; i < size; ++i)
-		tty_process(pty->tty, str[i]);
+	for (int i = 0; i < size; ++i) {
+		// bruh
+		char c;
+		int error = USERCOPY_POSSIBLY_FROM_USER(&c, &str[i], sizeof(char));
+		if (error)
+			return error;
+
+		tty_process(pty->tty, c);
+	}
 
 	*writec = size;
 	return 0;

kernel-src/io/tty.c

@@ -195,8 +195,13 @@ static int read(int minor, void *buffer, size_t size, uintmax_t offset, int flag
 	if (min == 0 && time == 0) {
 		MUTEX_ACQUIRE(&tty->readmutex, false);
 		*readc = ringbuffer_read(&tty->readbuffer, buffer, size);
+
+		int error = 0;
+		if (*readc == RINGBUFFER_USER_COPY_FAILED)
+			error = EFAULT;
+
 		MUTEX_RELEASE(&tty->readmutex);
-		return 0;
+		return error;
 	}
 
 	// time is in 1/10 of a second
@@ -207,8 +212,6 @@ static int read(int minor, void *buffer, size_t size, uintmax_t offset, int flag
 	size_t readcount = 0;
 	size_t spaceleft = size;
 
-	// TODO hangup stuff
-
 	for (;;) {
 		// for VMIN > 0 and VTIME > 0, the timeout is inter byte only.
 		size_t effectivetimeout = (min > 0 && time > 0 && spins == 0) ? 0 : timeoutus;
@@ -225,13 +228,19 @@ static int read(int minor, void *buffer, size_t size, uintmax_t offset, int flag
 			MUTEX_ACQUIRE(&tty->readmutex, false);
 
 			size_t actuallyread = ringbuffer_read(&tty->readbuffer, (void *)((uintptr_t)buffer + readcount), spaceleft);
-			readcount += actuallyread;
-			spaceleft -= actuallyread;
+
 			MUTEX_RELEASE(&tty->readmutex);
 
-			// XXX is this valid?
-			if (spaceleft > 0 && readcount < min)
-				continue;
+			if (actuallyread == RINGBUFFER_USER_COPY_FAILED) {
+				error = EFAULT;
+			} else {
+				readcount += actuallyread;
+				spaceleft -= actuallyread;
+
+				// XXX is this valid?
+				if (spaceleft > 0 && readcount < min && (revents & POLLHUP) == 0)
+					continue;
+			}
 
 			poll_leave(&desc);
 			poll_destroydesc(&desc);
@@ -276,11 +285,18 @@ static int write(int minor, void *_buffer, size_t size, uintmax_t offset, int fl
 
 	*writec = size;
 	for (int i = 0; i < size; ++i) {
-		if (buffer[i] == '\n' && (tty->termios.c_oflag & ONLCR)) {
+		// bruh
+		char c;
+		int error = USERCOPY_POSSIBLY_FROM_USER(&c, &buffer[i], sizeof(char));
+		if (error)
+			return error;
+
+		if (c == '\n' && (tty->termios.c_oflag & ONLCR)) {
 			char cr = '\r';
 			tty->writetodevice(tty->deviceinternal, &cr, 1);
 		}
-		tty->writetodevice(tty->deviceinternal, &buffer[i], 1);
+
+		tty->writetodevice(tty->deviceinternal, &c, 1);
 	}
 
 	return 0;