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Subject[PATCH 1/2] compat: factor out compat_rw_copy_check_uvector from compat_do_readv_writev
Date
This patch factors out code that will be used by both compat_do_readv_writev
and the compat aio submission code paths.

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
---
fs/compat.c | 130 ++++++++++++++++++++++++++++-------------------
include/linux/compat.h | 4 ++
2 files changed, 81 insertions(+), 53 deletions(-)

diff --git a/fs/compat.c b/fs/compat.c
index 4b6ed03..ae0066d 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -568,6 +568,79 @@ out:
return ret;
}

+/* A write operation does a read from user space and vice versa */
+#define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
+
+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)
+{
+ compat_ssize_t tot_len;
+ struct iovec *iov = *ret_pointer = fast_pointer;
+ ssize_t ret = 0;
+ int seg;
+
+ /*
+ * SuS says "The readv() function *may* fail if the iovcnt argument
+ * was less than or equal to 0, or greater than {IOV_MAX}. Linux has
+ * traditionally returned zero for zero segments, so...
+ */
+ if (nr_segs == 0)
+ goto out;
+
+ ret = -EINVAL;
+ if (nr_segs > UIO_MAXIOV || nr_segs < 0)
+ goto out;
+ if (nr_segs > fast_segs) {
+ ret = -ENOMEM;
+ iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
+ if (iov == NULL) {
+ *ret_pointer = fast_pointer;
+ goto out;
+ }
+ }
+ *ret_pointer = iov;
+
+ /*
+ * Single unix specification:
+ * We should -EINVAL if an element length is not >= 0 and fitting an
+ * ssize_t. The total length is fitting an ssize_t
+ *
+ * Be careful here because iov_len is a size_t not an ssize_t
+ */
+ tot_len = 0;
+ ret = -EINVAL;
+ for (seg = 0; seg < nr_segs; seg++) {
+ compat_ssize_t tmp = tot_len;
+ compat_uptr_t buf;
+ compat_ssize_t len;
+
+ if (__get_user(len, &uvector->iov_len) ||
+ __get_user(buf, &uvector->iov_base)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ if (len < 0) /* size_t not fitting in compat_ssize_t .. */
+ goto out;
+ tot_len += len;
+ if (tot_len < tmp) /* maths overflow on the compat_ssize_t */
+ goto out;
+ if (!access_ok(vrfy_dir(type), buf, len)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ iov->iov_base = compat_ptr(buf);
+ iov->iov_len = (compat_size_t) len;
+ uvector++;
+ iov++;
+ }
+ ret = tot_len;
+
+out:
+ return ret;
+}
+
static inline long
copy_iocb(long nr, u32 __user *ptr32, struct iocb __user * __user *ptr64)
{
@@ -1077,70 +1150,21 @@ static ssize_t compat_do_readv_writev(int type, struct file *file,
{
compat_ssize_t tot_len;
struct iovec iovstack[UIO_FASTIOV];
- struct iovec *iov=iovstack, *vector;
+ struct iovec *iov;
ssize_t ret;
- int seg;
io_fn_t fn;
iov_fn_t fnv;

- /*
- * SuS says "The readv() function *may* fail if the iovcnt argument
- * was less than or equal to 0, or greater than {IOV_MAX}. Linux has
- * traditionally returned zero for zero segments, so...
- */
- ret = 0;
- if (nr_segs == 0)
- goto out;
-
- /*
- * First get the "struct iovec" from user memory and
- * verify all the pointers
- */
ret = -EINVAL;
- if ((nr_segs > UIO_MAXIOV) || (nr_segs <= 0))
- goto out;
if (!file->f_op)
goto out;
- if (nr_segs > UIO_FASTIOV) {
- ret = -ENOMEM;
- iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
- if (!iov)
- goto out;
- }
+
ret = -EFAULT;
if (!access_ok(VERIFY_READ, uvector, nr_segs*sizeof(*uvector)))
goto out;

- /*
- * Single unix specification:
- * We should -EINVAL if an element length is not >= 0 and fitting an
- * ssize_t. The total length is fitting an ssize_t
- *
- * Be careful here because iov_len is a size_t not an ssize_t
- */
- tot_len = 0;
- vector = iov;
- ret = -EINVAL;
- for (seg = 0 ; seg < nr_segs; seg++) {
- compat_ssize_t tmp = tot_len;
- compat_ssize_t len;
- compat_uptr_t buf;
-
- if (__get_user(len, &uvector->iov_len) ||
- __get_user(buf, &uvector->iov_base)) {
- ret = -EFAULT;
- goto out;
- }
- if (len < 0) /* size_t not fitting an compat_ssize_t .. */
- goto out;
- tot_len += len;
- if (tot_len < tmp) /* maths overflow on the compat_ssize_t */
- goto out;
- vector->iov_base = compat_ptr(buf);
- vector->iov_len = (compat_size_t) len;
- uvector++;
- vector++;
- }
+ tot_len = compat_rw_copy_check_uvector(type, uvector, nr_segs,
+ UIO_FASTIOV, iovstack, &iov);
if (tot_len == 0) {
ret = 0;
goto out;
diff --git a/include/linux/compat.h b/include/linux/compat.h
index 717c691..168f7da 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -356,5 +356,9 @@ asmlinkage long compat_sys_newfstatat(unsigned int dfd, char __user * filename,
asmlinkage long compat_sys_openat(unsigned int dfd, const char __user *filename,
int flags, int mode);

+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);
#endif /* CONFIG_COMPAT */
#endif /* _LINUX_COMPAT_H */
--
1.6.2.5


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