compat_ioctl: unify copy-in of ppp filters

Now that isdn4linux is gone, the is only one implementation of PPPIOCSPASS
and PPPIOCSACTIVE in ppp_generic.c, so this is where the compat_ioctl
support should be implemented.

The two commands are implemented in very similar ways, so introduce
new helpers to allow sharing between the two and between native and
compat mode.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[arnd: rebased, and added changelog text]
Cc: netdev@vger.kernel.org
Cc: linux-ppp@vger.kernel.org
Cc: Paul Mackerras <paulus@samba.org>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/net/ppp/ppp_generic.c

@@ -554,29 +554,58 @@ static __poll_t ppp_poll(struct file *file, poll_table *wait)
 }
 
 #ifdef CONFIG_PPP_FILTER
-static int get_filter(void __user *arg, struct sock_filter **p)
+static struct bpf_prog *get_filter(struct sock_fprog *uprog)
+{
+	struct sock_fprog_kern fprog;
+	struct bpf_prog *res = NULL;
+	int err;
+
+	if (!uprog->len)
+		return NULL;
+
+	/* uprog->len is unsigned short, so no overflow here */
+	fprog.len = uprog->len * sizeof(struct sock_filter);
+	fprog.filter = memdup_user(uprog->filter, fprog.len);
+	if (IS_ERR(fprog.filter))
+		return ERR_CAST(fprog.filter);
+
+	err = bpf_prog_create(&res, &fprog);
+	kfree(fprog.filter);
+
+	return err ? ERR_PTR(err) : res;
+}
+
+static struct bpf_prog *ppp_get_filter(struct sock_fprog __user *p)
 {
 	struct sock_fprog uprog;
-	struct sock_filter *code = NULL;
-	int len;
 
-	if (copy_from_user(&uprog, arg, sizeof(uprog)))
-		return -EFAULT;
+	if (copy_from_user(&uprog, p, sizeof(struct sock_fprog)))
+		return ERR_PTR(-EFAULT);
+	return get_filter(&uprog);
+}
 
-	if (!uprog.len) {
-		*p = NULL;
-		return 0;
-	}
+#ifdef CONFIG_COMPAT
+struct sock_fprog32 {
+	unsigned short len;
+	compat_caddr_t filter;
+};
+
+#define PPPIOCSPASS32		_IOW('t', 71, struct sock_fprog32)
+#define PPPIOCSACTIVE32		_IOW('t', 70, struct sock_fprog32)
 
-	len = uprog.len * sizeof(struct sock_filter);
-	code = memdup_user(uprog.filter, len);
-	if (IS_ERR(code))
-		return PTR_ERR(code);
+static struct bpf_prog *compat_ppp_get_filter(struct sock_fprog32 __user *p)
+{
+	struct sock_fprog32 uprog32;
+	struct sock_fprog uprog;
 
-	*p = code;
-	return uprog.len;
+	if (copy_from_user(&uprog32, p, sizeof(struct sock_fprog32)))
+		return ERR_PTR(-EFAULT);
+	uprog.len = uprog32.len;
+	uprog.filter = compat_ptr(uprog32.filter);
+	return get_filter(&uprog);
 }
-#endif /* CONFIG_PPP_FILTER */
+#endif
+#endif
 
 static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
@@ -753,55 +782,25 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 
 #ifdef CONFIG_PPP_FILTER
 	case PPPIOCSPASS:
+	case PPPIOCSACTIVE:
 	{
-		struct sock_filter *code;
-
-		err = get_filter(argp, &code);
-		if (err >= 0) {
-			struct bpf_prog *pass_filter = NULL;
-			struct sock_fprog_kern fprog = {
-				.len = err,
-				.filter = code,
-			};
+		struct bpf_prog *filter = ppp_get_filter(argp);
+		struct bpf_prog **which;
 
-			err = 0;
-			if (fprog.filter)
-				err = bpf_prog_create(&pass_filter, &fprog);
-			if (!err) {
-				ppp_lock(ppp);
-				if (ppp->pass_filter)
-					bpf_prog_destroy(ppp->pass_filter);
-				ppp->pass_filter = pass_filter;
-				ppp_unlock(ppp);
-			}
-			kfree(code);
-		}
+		if (IS_ERR(filter)) {
+			err = PTR_ERR(filter);
 			break;
 		}
-	case PPPIOCSACTIVE:
-	{
-		struct sock_filter *code;
-
-		err = get_filter(argp, &code);
-		if (err >= 0) {
-			struct bpf_prog *active_filter = NULL;
-			struct sock_fprog_kern fprog = {
-				.len = err,
-				.filter = code,
-			};
-
-			err = 0;
-			if (fprog.filter)
-				err = bpf_prog_create(&active_filter, &fprog);
-			if (!err) {
+		if (cmd == PPPIOCSPASS)
+			which = &ppp->pass_filter;
+		else
+			which = &ppp->active_filter;
 		ppp_lock(ppp);
-				if (ppp->active_filter)
-					bpf_prog_destroy(ppp->active_filter);
-				ppp->active_filter = active_filter;
+		if (*which)
+			bpf_prog_destroy(*which);
+		*which = filter;
 		ppp_unlock(ppp);
-			}
-			kfree(code);
-		}
+		err = 0;
 		break;
 	}
 #endif /* CONFIG_PPP_FILTER */
@@ -827,6 +826,51 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	return err;
 }
 
+#ifdef CONFIG_COMPAT
+static long ppp_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct ppp_file *pf;
+	int err = -ENOIOCTLCMD;
+	void __user *argp = (void __user *)arg;
+
+	mutex_lock(&ppp_mutex);
+
+	pf = file->private_data;
+	if (pf && pf->kind == INTERFACE) {
+		struct ppp *ppp = PF_TO_PPP(pf);
+		switch (cmd) {
+#ifdef CONFIG_PPP_FILTER
+		case PPPIOCSPASS32:
+		case PPPIOCSACTIVE32:
+		{
+			struct bpf_prog *filter = compat_ppp_get_filter(argp);
+			struct bpf_prog **which;
+
+			if (IS_ERR(filter)) {
+				err = PTR_ERR(filter);
+				break;
+			}
+			if (cmd == PPPIOCSPASS32)
+				which = &ppp->pass_filter;
+			else
+				which = &ppp->active_filter;
+			ppp_lock(ppp);
+			if (*which)
+				bpf_prog_destroy(*which);
+			*which = filter;
+			ppp_unlock(ppp);
+			err = 0;
+			break;
+		}
+#endif /* CONFIG_PPP_FILTER */
+		}
+	}
+	mutex_unlock(&ppp_mutex);
+
+	return err;
+}
+#endif
+
 static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
 			struct file *file, unsigned int cmd, unsigned long arg)
 {
@@ -895,6 +939,9 @@ static const struct file_operations ppp_device_fops = {
 	.write		= ppp_write,
 	.poll		= ppp_poll,
 	.unlocked_ioctl	= ppp_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= ppp_compat_ioctl,
+#endif
 	.open		= ppp_open,
 	.release	= ppp_release,
 	.llseek		= noop_llseek,

fs/compat_ioctl.c

@@ -99,40 +99,6 @@ static int sg_grt_trans(struct file *file,
 }
 #endif /* CONFIG_BLOCK */
 
-struct sock_fprog32 {
-	unsigned short	len;
-	compat_caddr_t	filter;
-};
-
-#define PPPIOCSPASS32	_IOW('t', 71, struct sock_fprog32)
-#define PPPIOCSACTIVE32	_IOW('t', 70, struct sock_fprog32)
-
-static int ppp_sock_fprog_ioctl_trans(struct file *file,
-		unsigned int cmd, struct sock_fprog32 __user *u_fprog32)
-{
-	struct sock_fprog __user *u_fprog64 = compat_alloc_user_space(sizeof(struct sock_fprog));
-	void __user *fptr64;
-	u32 fptr32;
-	u16 flen;
-
-	if (get_user(flen, &u_fprog32->len) ||
-	    get_user(fptr32, &u_fprog32->filter))
-		return -EFAULT;
-
-	fptr64 = compat_ptr(fptr32);
-
-	if (put_user(flen, &u_fprog64->len) ||
-	    put_user(fptr64, &u_fprog64->filter))
-		return -EFAULT;
-
-	if (cmd == PPPIOCSPASS32)
-		cmd = PPPIOCSPASS;
-	else
-		cmd = PPPIOCSACTIVE;
-
-	return do_ioctl(file, cmd, (unsigned long) u_fprog64);
-}
-
 struct ppp_option_data32 {
 	compat_caddr_t	ptr;
 	u32			length;
@@ -285,9 +251,6 @@ static long do_ioctl_trans(unsigned int cmd,
 		return ppp_gidle(file, cmd, argp);
 	case PPPIOCSCOMPRESS32:
 		return ppp_scompress(file, cmd, argp);
-	case PPPIOCSPASS32:
-	case PPPIOCSACTIVE32:
-		return ppp_sock_fprog_ioctl_trans(file, cmd, argp);
 #ifdef CONFIG_BLOCK
 	case SG_GET_REQUEST_TABLE:
 		return sg_grt_trans(file, cmd, argp);