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From: Christoph Hellwig <hch@lst.de>
To: "David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	Eric Dumazet <edumazet@google.com>
Cc: linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
	linux-sctp@vger.kernel.org, linux-hams@vger.kernel.org,
	linux-bluetooth@vger.kernel.org,
	bridge@lists.linux-foundation.org, linux-can@vger.kernel.org,
	dccp@vger.kernel.org, linux-decnet-user@lists.sourceforge.net,
	linux-wpan@vger.kernel.org, linux-s390@vger.kernel.org,
	mptcp@lists.01.org, lvs-devel@vger.kernel.org,
	rds-devel@oss.oracle.com, linux-afs@lists.infradead.org,
	tipc-discussion@lists.sourceforge.net, linux-x25@vger.kernel.org
Subject: [PATCH 03/24] net: add a new sockptr_t type
Date: Mon, 20 Jul 2020 14:47:16 +0200
Message-ID: <20200720124737.118617-4-hch@lst.de> (raw)
In-Reply-To: <20200720124737.118617-1-hch@lst.de>

Add a uptr_t type that can hold a pointer to either a user or kernel
memory region, and simply helpers to copy to and from it.  For
architectures like x86 that have non-overlapping user and kernel
address space it just is a union and uses a TASK_SIZE check to
select the proper copy routine.  For architectures with overlapping
address spaces a flag to indicate the address space is used instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/sockptr.h | 121 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 121 insertions(+)
 create mode 100644 include/linux/sockptr.h

diff --git a/include/linux/sockptr.h b/include/linux/sockptr.h
new file mode 100644
index 00000000000000..e41dfa52555dec
--- /dev/null
+++ b/include/linux/sockptr.h
@@ -0,0 +1,121 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2020 Christoph Hellwig.
+ *
+ * Support for "universal" pointers that can point to either kernel or userspace
+ * memory.
+ */
+#ifndef _LINUX_SOCKPTR_H
+#define _LINUX_SOCKPTR_H
+
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+
+#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
+typedef union {
+	void		*kernel;
+	void __user	*user;
+} sockptr_t;
+
+static inline bool sockptr_is_kernel(sockptr_t sockptr)
+{
+	return (unsigned long)sockptr.kernel >= TASK_SIZE;
+}
+
+static inline sockptr_t KERNEL_SOCKPTR(void *p)
+{
+	return (sockptr_t) { .kernel = p };
+}
+#else /* CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE */
+typedef struct {
+	union {
+		void		*kernel;
+		void __user	*user;
+	};
+	bool		is_kernel : 1;
+} sockptr_t;
+
+static inline bool sockptr_is_kernel(sockptr_t sockptr)
+{
+	return sockptr.is_kernel;
+}
+
+static inline sockptr_t KERNEL_SOCKPTR(void *p)
+{
+	return (sockptr_t) { .kernel = p, .is_kernel = true };
+}
+#endif /* CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE */
+
+static inline sockptr_t USER_SOCKPTR(void __user *p)
+{
+	return (sockptr_t) { .user = p };
+}
+
+static inline bool sockptr_is_null(sockptr_t sockptr)
+{
+	return !sockptr.user && !sockptr.kernel;
+}
+
+static inline int copy_from_sockptr(void *dst, sockptr_t src, size_t size)
+{
+	if (!sockptr_is_kernel(src))
+		return copy_from_user(dst, src.user, size);
+	memcpy(dst, src.kernel, size);
+	return 0;
+}
+
+static inline int copy_to_sockptr(sockptr_t dst, const void *src, size_t size)
+{
+	if (!sockptr_is_kernel(dst))
+		return copy_to_user(dst.user, src, size);
+	memcpy(dst.kernel, src, size);
+	return 0;
+}
+
+static inline void *memdup_sockptr(sockptr_t src, size_t len)
+{
+	void *p = kmalloc_track_caller(len, GFP_USER | __GFP_NOWARN);
+
+	if (!p)
+		return ERR_PTR(-ENOMEM);
+	if (copy_from_sockptr(p, src, len)) {
+		kfree(p);
+		return ERR_PTR(-EFAULT);
+	}
+	return p;
+}
+
+static inline void *memdup_sockptr_nul(sockptr_t src, size_t len)
+{
+	char *p = kmalloc_track_caller(len + 1, GFP_KERNEL);
+
+	if (!p)
+		return ERR_PTR(-ENOMEM);
+	if (copy_from_sockptr(p, src, len)) {
+		kfree(p);
+		return ERR_PTR(-EFAULT);
+	}
+	p[len] = '\0';
+	return p;
+}
+
+static inline void sockptr_advance(sockptr_t sockptr, size_t len)
+{
+	if (sockptr_is_kernel(sockptr))
+		sockptr.kernel += len;
+	else
+		sockptr.user += len;
+}
+
+static inline long strncpy_from_sockptr(char *dst, sockptr_t src, size_t count)
+{
+	if (sockptr_is_kernel(src)) {
+		size_t len = min(strnlen(src.kernel, count - 1) + 1, count);
+
+		memcpy(dst, src.kernel, len);
+		return len;
+	}
+	return strncpy_from_user(dst, src.user, count);
+}
+
+#endif /* _LINUX_SOCKPTR_H */
-- 
2.27.0


  parent reply index

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-20 12:47 get rid of the address_space override in setsockopt Christoph Hellwig
2020-07-20 12:47 ` [PATCH 01/24] bpfilter: reject kernel addresses Christoph Hellwig
2020-07-20 12:47 ` [PATCH 02/24] bpfilter: fix up a sparse annotation Christoph Hellwig
2020-07-21  2:40   ` Luc Van Oostenryck
2020-07-21  5:23     ` Christoph Hellwig
2020-07-21  5:28       ` Al Viro
2020-07-20 12:47 ` Christoph Hellwig [this message]
2020-07-20 16:37   ` [PATCH 03/24] net: add a new sockptr_t type Eric Biggers
2020-07-20 17:43     ` Christoph Hellwig
2020-07-20 17:55       ` Eric Biggers
2020-07-22  7:56         ` Christoph Hellwig
2020-07-21  9:55     ` David Laight
2020-07-21 10:14   ` David Laight
2020-07-20 12:47 ` [PATCH 04/24] net: switch copy_bpf_fprog_from_user to sockptr_t Christoph Hellwig
2020-07-20 12:47 ` [PATCH 05/24] net: switch sock_setbindtodevice " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 06/24] net: switch sock_set_timeout " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 07/24] " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 08/24] net/xfrm: switch xfrm_user_policy " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 09/24] netfilter: remove the unused user argument to do_update_counters Christoph Hellwig
2020-07-20 12:47 ` [PATCH 10/24] netfilter: switch xt_copy_counters to sockptr_t Christoph Hellwig
2020-07-20 12:47 ` [PATCH 11/24] netfilter: switch nf_setsockopt " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 12/24] bpfilter: switch bpfilter_ip_set_sockopt " Christoph Hellwig
2020-07-21  8:36   ` David Laight
2020-07-22  8:00     ` 'Christoph Hellwig'
2020-07-22  8:01       ` 'Christoph Hellwig'
2020-07-20 12:47 ` [PATCH 13/24] net/ipv4: switch ip_mroute_setsockopt " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 14/24] net/ipv4: merge ip_options_get and ip_options_get_from_user Christoph Hellwig
2020-07-20 12:47 ` [PATCH 15/24] net/ipv4: switch do_ip_setsockopt to sockptr_t Christoph Hellwig
2020-07-20 12:47 ` [PATCH 16/24] net/ipv6: switch ip6_mroute_setsockopt " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 17/24] net/ipv6: split up ipv6_flowlabel_opt Christoph Hellwig
2020-07-20 12:47 ` [PATCH 18/24] net/ipv6: switch ipv6_flowlabel_opt to sockptr_t Christoph Hellwig
2020-07-20 12:47 ` [PATCH 19/24] net/ipv6: factor out a ipv6_set_opt_hdr helper Christoph Hellwig
2020-07-20 12:47 ` [PATCH 20/24] net/ipv6: switch do_ipv6_setsockopt to sockptr_t Christoph Hellwig
2020-07-20 12:47 ` [PATCH 21/24] net/udp: switch udp_lib_setsockopt " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 22/24] net/tcp: switch ->md5_parse " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 23/24] net/tcp: switch do_tcp_setsockopt " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 24/24] net: pass a sockptr_t into ->setsockopt Christoph Hellwig
2020-07-20 14:19   ` Stefan Schmidt
2020-07-20 23:20     ` David Miller
2020-07-22  8:26   ` [MPTCP] " Matthieu Baerts
2020-07-20 16:38 ` get rid of the address_space override in setsockopt Eric Biggers
2020-07-20 17:43   ` Christoph Hellwig
2020-07-20 20:47 ` Alexei Starovoitov
2020-07-22  7:56   ` Christoph Hellwig
2020-07-22 17:09     ` Alexei Starovoitov
2020-07-21  9:38 ` David Laight
2020-07-22  8:06   ` 'Christoph Hellwig'
2020-07-22  8:21     ` David Laight
2020-07-21 10:26 ` David Laight
2020-07-22  8:07   ` 'Christoph Hellwig'

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