{compat_,}verify_iovec(): switch to generic copying of iovecs

use {compat_,}rw_copy_check_uvector().  As the result, we are
guaranteed that all iovecs seen in ->msg_iov by ->sendmsg()
and ->recvmsg() will pass access_ok().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 37 insertions, 89 deletions

diff --git a/net/compat.c b/net/compat.c
index 562e920b07f0..7b4b6ad13235 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -31,33 +31,6 @@
 #include <asm/uaccess.h>
 #include <net/compat.h>
 
-static inline int iov_from_user_compat_to_kern(struct iovec *kiov,
-                                          struct compat_iovec __user *uiov32,
-                                          int niov)
-{
-        int tot_len = 0;
-
-        while (niov > 0) {
-                compat_uptr_t buf;
-                compat_size_t len;
-
-                if (get_user(len, &uiov32->iov_len) ||
-                    get_user(buf, &uiov32->iov_base))
-                        return -EFAULT;
-
-                if (len > INT_MAX - tot_len)
-                        len = INT_MAX - tot_len;
-
-                tot_len += len;
-                kiov->iov_base = compat_ptr(buf);
-                kiov->iov_len = (__kernel_size_t) len;
-                uiov32++;
-                kiov++;
-                niov--;
-        }
-        return tot_len;
-}
-
 int get_compat_msghdr(struct msghdr *kmsg, struct compat_msghdr __user *umsg)
 {
         compat_uptr_t tmp1, tmp2, tmp3;
@@ -80,13 +53,15 @@ int get_compat_msghdr(struct msghdr *kmsg, struct compat_msghdr __user *umsg)
 }
 
 /* I've named the args so it is easy to tell whose space the pointers are in. */
-int verify_compat_iovec(struct msghdr *kern_msg, struct iovec *kern_iov,
+int verify_compat_iovec(struct msghdr *kern_msg, struct iovec *iov,
                    struct sockaddr_storage *kern_address, int mode)
 {
-        int tot_len;
+        struct compat_iovec __user *p;
+        struct iovec *res;
+        int err;
 
         if (kern_msg->msg_name && kern_msg->msg_namelen) {
-                if (mode == VERIFY_READ) {
+                if (mode == WRITE) {
                         int err = move_addr_to_kernel(kern_msg->msg_name,
                                                       kern_msg->msg_namelen,
                                                       kern_address);
@@ -99,13 +74,17 @@ int verify_compat_iovec(struct msghdr *kern_msg, struct iovec *kern_iov,
                 kern_msg->msg_namelen = 0;
         }
 
-        tot_len = iov_from_user_compat_to_kern(kern_iov,
-                                          (struct compat_iovec __user *)kern_msg->msg_iov,
-                                          kern_msg->msg_iovlen);
-        if (tot_len >= 0)
-                kern_msg->msg_iov = kern_iov;
+        if (kern_msg->msg_iovlen > UIO_MAXIOV)
+                return -EMSGSIZE;
 
-        return tot_len;
+        p = (struct compat_iovec __user *)kern_msg->msg_iov;
+        err = compat_rw_copy_check_uvector(mode, p, kern_msg->msg_iovlen,
+                                           UIO_FASTIOV, iov, &res);
+        if (err >= 0)
+                kern_msg->msg_iov = res;
+        else if (res != iov)
+                kfree(res);
+        return err;
 }
 
 /* Bleech... */
diff --git a/net/core/iovec.c b/net/core/iovec.c
index e1ec45ab1e63..86beeea61d72 100644
--- a/net/core/iovec.c
+++ b/net/core/iovec.c
@@ -37,13 +37,13 @@
 
 int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr_storage *address, int mode)
 {
-        int size, ct, err;
+        struct iovec *res;
+        int 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,
+                if (mode == WRITE) {
+                        void __user *namep = (void __user __force *)m->msg_name;
+                        int err = move_addr_to_kernel(namep, m->msg_namelen,
                                                   address);
                         if (err < 0)
                                 return err;
@@ -53,24 +53,15 @@ int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr_storage *a
                 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;
-        }
-
+        if (m->msg_iovlen > UIO_MAXIOV)
+                return -EMSGSIZE;
+
+        err = rw_copy_check_uvector(mode, (void __user __force *)m->msg_iov,
+                                    m->msg_iovlen, UIO_FASTIOV, iov, &res);
+        if (err >= 0)
+                m->msg_iov = res;
+        else if (res != iov)
+                kfree(res);
         return err;
 }
 
diff --git a/net/socket.c b/net/socket.c
index 0ae8147e3acc..59020f0b583b 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2032,24 +2032,14 @@ static int ___sys_sendmsg(struct socket *sock, struct user_msghdr __user *msg,
                         return err;
         }
 
-        if (msg_sys->msg_iovlen > UIO_FASTIOV) {
-                err = -EMSGSIZE;
-                if (msg_sys->msg_iovlen > UIO_MAXIOV)
-                        goto out;
-                err = -ENOMEM;
-                iov = kmalloc(msg_sys->msg_iovlen * sizeof(struct iovec),
-                              GFP_KERNEL);
-                if (!iov)
-                        goto out;
-        }
-
         /* This will also move the address data into kernel space */
-        if (MSG_CMSG_COMPAT & flags) {
-                err = verify_compat_iovec(msg_sys, iov, &address, VERIFY_READ);
-        } else
-                err = verify_iovec(msg_sys, iov, &address, VERIFY_READ);
+        if (MSG_CMSG_COMPAT & flags)
+                err = verify_compat_iovec(msg_sys, iovstack, &address, WRITE);
+        else
+                err = verify_iovec(msg_sys, iovstack, &address, WRITE);
         if (err < 0)
                 goto out_freeiov;
+        iov = msg_sys->msg_iov;
         total_len = err;
 
         err = -ENOBUFS;
@@ -2118,7 +2108,6 @@ out_freectl:
 out_freeiov:
         if (iov != iovstack)
                 kfree(iov);
-out:
         return err;
 }
 
@@ -2244,28 +2233,18 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg,
                         return err;
         }
 
-        if (msg_sys->msg_iovlen > UIO_FASTIOV) {
-                err = -EMSGSIZE;
-                if (msg_sys->msg_iovlen > UIO_MAXIOV)
-                        goto out;
-                err = -ENOMEM;
-                iov = kmalloc(msg_sys->msg_iovlen * sizeof(struct iovec),
-                              GFP_KERNEL);
-                if (!iov)
-                        goto out;
-        }
-
         /* Save the user-mode address (verify_iovec will change the
          * kernel msghdr to use the kernel address space)
          */
         uaddr = (__force void __user *)msg_sys->msg_name;
         uaddr_len = COMPAT_NAMELEN(msg);
         if (MSG_CMSG_COMPAT & flags)
-                err = verify_compat_iovec(msg_sys, iov, &addr, VERIFY_WRITE);
+                err = verify_compat_iovec(msg_sys, iovstack, &addr, READ);
         else
-                err = verify_iovec(msg_sys, iov, &addr, VERIFY_WRITE);
+                err = verify_iovec(msg_sys, iovstack, &addr, READ);
         if (err < 0)
                 goto out_freeiov;
+        iov = msg_sys->msg_iov;
         total_len = err;
 
         cmsg_ptr = (unsigned long)msg_sys->msg_control;
@@ -2306,7 +2285,6 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg,
 out_freeiov:
         if (iov != iovstack)
                 kfree(iov);
-out:
         return err;
 }