Fixed MTP to work with TWRP

net/core/iovec.c

@@ -0,0 +1,184 @@
+/*
+ *	iovec manipulation routines.
+ *
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ *
+ *	Fixes:
+ *		Andrew Lunn	:	Errors in iovec copying.
+ *		Pedro Roque	:	Added memcpy_fromiovecend and
+ *					csum_..._fromiovecend.
+ *		Andi Kleen	:	fixed error handling for 2.1
+ *		Alexey Kuznetsov:	2.1 optimisations
+ *		Andi Kleen	:	Fix csum*fromiovecend for IPv6.
+ */
+
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/net.h>
+#include <linux/in6.h>
+#include <asm/uaccess.h>
+#include <asm/byteorder.h>
+#include <net/checksum.h>
+#include <net/sock.h>
+
+/*
+ *	Verify iovec. The caller must ensure that the iovec is big enough
+ *	to hold the message iovec.
+ *
+ *	Save time not doing access_ok. copy_*_user will make this work
+ *	in any case.
+ */
+
+int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr_storage *address, int mode)
+{
+	int size, ct, err;
+
+	if (m->msg_name && m->msg_namelen) {
+		if (mode == VERIFY_READ) {
+			void __user *namep;
+			namep = (void __user __force *) m->msg_name;
+			err = move_addr_to_kernel(namep, m->msg_namelen,
+						  address);
+			if (err < 0)
+				return err;
+		}
+		m->msg_name = address;
+	} else {
+		m->msg_name = NULL;
+		m->msg_namelen = 0;
+	}
+
+	size = m->msg_iovlen * sizeof(struct iovec);
+	if (copy_from_user(iov, (void __user __force *) m->msg_iov, size))
+		return -EFAULT;
+
+	m->msg_iov = iov;
+	err = 0;
+
+	for (ct = 0; ct < m->msg_iovlen; ct++) {
+		size_t len = iov[ct].iov_len;
+
+		if (len > INT_MAX - err) {
+			len = INT_MAX - err;
+			iov[ct].iov_len = len;
+		}
+		err += len;
+	}
+
+	return err;
+}
+
+/*
+ *	And now for the all-in-one: copy and checksum from a user iovec
+ *	directly to a datagram
+ *	Calls to csum_partial but the last must be in 32 bit chunks
+ *
+ *	ip_build_xmit must ensure that when fragmenting only the last
+ *	call to this function will be unaligned also.
+ */
+int csum_partial_copy_fromiovecend(unsigned char *kdata, struct iovec *iov,
+				 int offset, unsigned int len, __wsum *csump)
+{
+	__wsum csum = *csump;
+	int partial_cnt = 0, err = 0;
+
+	/* Skip over the finished iovecs */
+	while (offset >= iov->iov_len) {
+		offset -= iov->iov_len;
+		iov++;
+	}
+
+	while (len > 0) {
+		u8 __user *base = iov->iov_base + offset;
+		int copy = min_t(unsigned int, len, iov->iov_len - offset);
+
+		offset = 0;
+
+		/* There is a remnant from previous iov. */
+		if (partial_cnt) {
+			int par_len = 4 - partial_cnt;
+
+			/* iov component is too short ... */
+			if (par_len > copy) {
+				if (copy_from_user(kdata, base, copy))
+					goto out_fault;
+				kdata += copy;
+				base += copy;
+				partial_cnt += copy;
+				len -= copy;
+				iov++;
+				if (len)
+					continue;
+				*csump = csum_partial(kdata - partial_cnt,
+							 partial_cnt, csum);
+				goto out;
+			}
+			if (copy_from_user(kdata, base, par_len))
+				goto out_fault;
+			csum = csum_partial(kdata - partial_cnt, 4, csum);
+			kdata += par_len;
+			base  += par_len;
+			copy  -= par_len;
+			len   -= par_len;
+			partial_cnt = 0;
+		}
+
+		if (len > copy) {
+			partial_cnt = copy % 4;
+			if (partial_cnt) {
+				copy -= partial_cnt;
+				if (copy_from_user(kdata + copy, base + copy,
+						partial_cnt))
+					goto out_fault;
+			}
+		}
+
+		if (copy) {
+			csum = csum_and_copy_from_user(base, kdata, copy,
+							csum, &err);
+			if (err)
+				goto out;
+		}
+		len   -= copy + partial_cnt;
+		kdata += copy + partial_cnt;
+		iov++;
+	}
+	*csump = csum;
+out:
+	return err;
+
+out_fault:
+	err = -EFAULT;
+	goto out;
+}
+EXPORT_SYMBOL(csum_partial_copy_fromiovecend);
+
+unsigned long iov_pages(const struct iovec *iov, int offset,
+			unsigned long nr_segs)
+{
+	unsigned long seg, base;
+	int pages = 0, len, size;
+
+	while (nr_segs && (offset >= iov->iov_len)) {
+		offset -= iov->iov_len;
+		++iov;
+		--nr_segs;
+	}
+
+	for (seg = 0; seg < nr_segs; seg++) {
+		base = (unsigned long)iov[seg].iov_base + offset;
+		len = iov[seg].iov_len - offset;
+		size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT;
+		pages += size;
+		offset = 0;
+	}
+
+	return pages;
+}
+EXPORT_SYMBOL(iov_pages);