1 files changed, 83 insertions, 0 deletions

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 9d96e283520c..75232ad0a5e7 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -317,6 +317,32 @@ int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
 }
 EXPORT_SYMBOL(iov_iter_fault_in_readable);
 
+/*
+ * Fault in one or more iovecs of the given iov_iter, to a maximum length of
+ * bytes.  For each iovec, fault in each page that constitutes the iovec.
+ *
+ * Return 0 on success, or non-zero if the memory could not be accessed (i.e.
+ * because it is an invalid address).
+ */
+int iov_iter_fault_in_multipages_readable(struct iov_iter *i, size_t bytes)
+{
+        size_t skip = i->iov_offset;
+        const struct iovec *iov;
+        int err;
+        struct iovec v;
+
+        if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
+                iterate_iovec(i, bytes, v, iov, skip, ({
+                        err = fault_in_multipages_readable(v.iov_base,
+                                        v.iov_len);
+                        if (unlikely(err))
+                        return err;
+                0;}))
+        }
+        return 0;
+}
+EXPORT_SYMBOL(iov_iter_fault_in_multipages_readable);
+
 void iov_iter_init(struct iov_iter *i, int direction,
                         const struct iovec *iov, unsigned long nr_segs,
                         size_t count)
@@ -766,3 +792,60 @@ const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
                                    flags);
 }
 EXPORT_SYMBOL(dup_iter);
+
+int import_iovec(int type, const struct iovec __user * uvector,
+                 unsigned nr_segs, unsigned fast_segs,
+                 struct iovec **iov, struct iov_iter *i)
+{
+        ssize_t n;
+        struct iovec *p;
+        n = rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
+                                  *iov, &p);
+        if (n < 0) {
+                if (p != *iov)
+                        kfree(p);
+                *iov = NULL;
+                return n;
+        }
+        iov_iter_init(i, type, p, nr_segs, n);
+        *iov = p == *iov ? NULL : p;
+        return 0;
+}
+EXPORT_SYMBOL(import_iovec);
+
+#ifdef CONFIG_COMPAT
+#include <linux/compat.h>
+
+int compat_import_iovec(int type, const struct compat_iovec __user * uvector,
+                 unsigned nr_segs, unsigned fast_segs,
+                 struct iovec **iov, struct iov_iter *i)
+{
+        ssize_t n;
+        struct iovec *p;
+        n = compat_rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
+                                  *iov, &p);
+        if (n < 0) {
+                if (p != *iov)
+                        kfree(p);
+                *iov = NULL;
+                return n;
+        }
+        iov_iter_init(i, type, p, nr_segs, n);
+        *iov = p == *iov ? NULL : p;
+        return 0;
+}
+#endif
+
+int import_single_range(int rw, void __user *buf, size_t len,
+                 struct iovec *iov, struct iov_iter *i)
+{
+        if (len > MAX_RW_COUNT)
+                len = MAX_RW_COUNT;
+        if (unlikely(!access_ok(!rw, buf, len)))
+                return -EFAULT;
+
+        iov->iov_base = buf;
+        iov->iov_len = len;
+        iov_iter_init(i, rw, iov, 1, len);
+        return 0;
+}