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Date:	Mon, 30 Jan 2012 14:51:14 +1030
From:	Christopher Yeoh <cyeoh@....ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Cc:	Oleg Nesterov <oleg@...hat.com>
Subject: [PATCH] Cleanup of rw_copy_check_uvector and
 compat_rw_copy_check_uvector

Hi Andrew,

This is the cleanup of rw_copy_check_uvector and
compat_rw_copy_check_uvector discussed with Oleg a couple of weeks a
go. Its a much better way of handling that the functions sometimes
need to omit checking the memory that the iovecs point to compared to
what I originally did for CMA.

Regards,

Chris
-- 
cyeoh@...ibm.com
Signed-off-by: Chris Yeoh <yeohc@....ibm.com>
 fs/aio.c               |    4 ++--
 fs/compat.c            |    6 +++---
 fs/read_write.c        |    7 +++----
 include/linux/compat.h |    3 +--
 include/linux/fs.h     |   10 ++++++++--
 mm/process_vm_access.c |   16 ++++++++--------
 security/keys/compat.c |    2 +-
 security/keys/keyctl.c |    2 +-
 8 files changed, 27 insertions(+), 23 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index 969beb0..149f60bc 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1467,13 +1467,13 @@ static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb, bool compat)
 		ret = compat_rw_copy_check_uvector(type,
 				(struct compat_iovec __user *)kiocb->ki_buf,
 				kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
-				&kiocb->ki_iovec, 1);
+				&kiocb->ki_iovec);
 	else
 #endif
 		ret = rw_copy_check_uvector(type,
 				(struct iovec __user *)kiocb->ki_buf,
 				kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
-				&kiocb->ki_iovec, 1);
+				&kiocb->ki_iovec);
 	if (ret < 0)
 		goto out;
 
diff --git a/fs/compat.c b/fs/compat.c
index fa9d721..ff1437d 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -539,7 +539,7 @@ out:
 ssize_t compat_rw_copy_check_uvector(int type,
 		const struct compat_iovec __user *uvector, unsigned long nr_segs,
 		unsigned long fast_segs, struct iovec *fast_pointer,
-		struct iovec **ret_pointer, int check_access)
+		struct iovec **ret_pointer)
 {
 	compat_ssize_t tot_len;
 	struct iovec *iov = *ret_pointer = fast_pointer;
@@ -586,7 +586,7 @@ ssize_t compat_rw_copy_check_uvector(int type,
 		}
 		if (len < 0)	/* size_t not fitting in compat_ssize_t .. */
 			goto out;
-		if (check_access &&
+		if (type >=0 &&
 		    !access_ok(vrfy_dir(type), compat_ptr(buf), len)) {
 			ret = -EFAULT;
 			goto out;
@@ -1101,7 +1101,7 @@ static ssize_t compat_do_readv_writev(int type, struct file *file,
 		goto out;
 
 	tot_len = compat_rw_copy_check_uvector(type, uvector, nr_segs,
-					       UIO_FASTIOV, iovstack, &iov, 1);
+					       UIO_FASTIOV, iovstack, &iov);
 	if (tot_len == 0) {
 		ret = 0;
 		goto out;
diff --git a/fs/read_write.c b/fs/read_write.c
index 5ad4248..1d8ae78 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -633,8 +633,7 @@ ssize_t do_loop_readv_writev(struct file *filp, struct iovec *iov,
 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
 			      unsigned long nr_segs, unsigned long fast_segs,
 			      struct iovec *fast_pointer,
-			      struct iovec **ret_pointer,
-			      int check_access)
+			      struct iovec **ret_pointer)
 {
 	unsigned long seg;
 	ssize_t ret;
@@ -690,7 +689,7 @@ ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
 			ret = -EINVAL;
 			goto out;
 		}
-		if (check_access
+		if (type >= 0
 		    && unlikely(!access_ok(vrfy_dir(type), buf, len))) {
 			ret = -EFAULT;
 			goto out;
@@ -723,7 +722,7 @@ static ssize_t do_readv_writev(int type, struct file *file,
 	}
 
 	ret = rw_copy_check_uvector(type, uvector, nr_segs,
-				    ARRAY_SIZE(iovstack), iovstack, &iov, 1);
+				    ARRAY_SIZE(iovstack), iovstack, &iov);
 	if (ret <= 0)
 		goto out;
 
diff --git a/include/linux/compat.h b/include/linux/compat.h
index 41c9f65..9961ec3 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -547,8 +547,7 @@ extern ssize_t compat_rw_copy_check_uvector(int type,
 		const struct compat_iovec __user *uvector,
 		unsigned long nr_segs,
 		unsigned long fast_segs, struct iovec *fast_pointer,
-		struct iovec **ret_pointer,
-		int check_access);
+		struct iovec **ret_pointer);
 
 extern void __user *compat_alloc_user_space(unsigned long len);
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 0244082..461d689 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -169,6 +169,13 @@ struct inodes_stat_t {
 #define WRITE_FUA		(WRITE | REQ_SYNC | REQ_NOIDLE | REQ_FUA)
 #define WRITE_FLUSH_FUA		(WRITE | REQ_SYNC | REQ_NOIDLE | REQ_FLUSH | REQ_FUA)
 
+
+/* Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
+   that indicates that they should check the contents of the iovec are
+   valid, but not check the memory that the iovec elements
+   points too */
+#define CHECK_IOVEC_ONLY -1
+
 #define SEL_IN		1
 #define SEL_OUT		2
 #define SEL_EX		4
@@ -1660,8 +1667,7 @@ struct seq_file;
 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
 			      unsigned long nr_segs, unsigned long fast_segs,
 			      struct iovec *fast_pointer,
-			      struct iovec **ret_pointer,
-			      int check_access);
+			      struct iovec **ret_pointer);
 
 extern ssize_t vfs_read(struct file *, char __user *, size_t, loff_t *);
 extern ssize_t vfs_write(struct file *, const char __user *, size_t, loff_t *);
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index 82b6824..3a5d779 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -368,15 +368,15 @@ static ssize_t process_vm_rw(pid_t pid,
 	/* Check iovecs */
 	if (vm_write)
 		rc = rw_copy_check_uvector(WRITE, lvec, liovcnt, UIO_FASTIOV,
-					   iovstack_l, &iov_l, 1);
+					   iovstack_l, &iov_l);
 	else
 		rc = rw_copy_check_uvector(READ, lvec, liovcnt, UIO_FASTIOV,
-					   iovstack_l, &iov_l, 1);
+					   iovstack_l, &iov_l);
 	if (rc <= 0)
 		goto free_iovecs;
 
-	rc = rw_copy_check_uvector(READ, rvec, riovcnt, UIO_FASTIOV,
-				   iovstack_r, &iov_r, 0);
+	rc = rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV,
+				   iovstack_r, &iov_r);
 	if (rc <= 0)
 		goto free_iovecs;
 
@@ -435,16 +435,16 @@ compat_process_vm_rw(compat_pid_t pid,
 	if (vm_write)
 		rc = compat_rw_copy_check_uvector(WRITE, lvec, liovcnt,
 						  UIO_FASTIOV, iovstack_l,
-						  &iov_l, 1);
+						  &iov_l);
 	else
 		rc = compat_rw_copy_check_uvector(READ, lvec, liovcnt,
 						  UIO_FASTIOV, iovstack_l,
-						  &iov_l, 1);
+						  &iov_l);
 	if (rc <= 0)
 		goto free_iovecs;
-	rc = compat_rw_copy_check_uvector(READ, rvec, riovcnt,
+	rc = compat_rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt,
 					  UIO_FASTIOV, iovstack_r,
-					  &iov_r, 0);
+					  &iov_r);
 	if (rc <= 0)
 		goto free_iovecs;
 
diff --git a/security/keys/compat.c b/security/keys/compat.c
index 4c48e13..338b510 100644
--- a/security/keys/compat.c
+++ b/security/keys/compat.c
@@ -38,7 +38,7 @@ long compat_keyctl_instantiate_key_iov(
 
 	ret = compat_rw_copy_check_uvector(WRITE, _payload_iov, ioc,
 					   ARRAY_SIZE(iovstack),
-					   iovstack, &iov, 1);
+					   iovstack, &iov);
 	if (ret < 0)
 		return ret;
 	if (ret == 0)
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 0b3f5d7..eca5191 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -1065,7 +1065,7 @@ long keyctl_instantiate_key_iov(key_serial_t id,
 		goto no_payload;
 
 	ret = rw_copy_check_uvector(WRITE, _payload_iov, ioc,
-				    ARRAY_SIZE(iovstack), iovstack, &iov, 1);
+				    ARRAY_SIZE(iovstack), iovstack, &iov);
 	if (ret < 0)
 		return ret;
 	if (ret == 0)

--
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