net: Ensure ->msg_control_user is used for user buffers

Since commit 1f466e1f15cf ("net: cleanly handle kernel vs user
buffers for ->msg_control"), pointers to user buffers should be
stored in struct msghdr::msg_control_user, instead of the
msg_control field.  Most users of msg_control have already been
converted (where user buffers are involved), but not all of them.

This patch attempts to address the remaining cases. An exception is
made for null checks, as it should be safe to use msg_control
unconditionally for that purpose.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Eric Dumazet <edumazet@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/compat.c b/net/compat.c
index 161b7be..000a2e0 100644 (file)
--- a/net/compat.c
+++ b/net/compat.c
@@ -113,7 +113,7 @@ int get_compat_msghdr(struct msghdr *kmsg,
 
 #define CMSG_COMPAT_FIRSTHDR(msg)                      \
        (((msg)->msg_controllen) >= sizeof(struct compat_cmsghdr) ?     \
-        (struct compat_cmsghdr __user *)((msg)->msg_control) :         \
+        (struct compat_cmsghdr __user *)((msg)->msg_control_user) :    \
         (struct compat_cmsghdr __user *)NULL)
 
 #define CMSG_COMPAT_OK(ucmlen, ucmsg, mhdr) \
@@ -126,7 +126,7 @@ static inline struct compat_cmsghdr __user *cmsg_compat_nxthdr(struct msghdr *ms
                struct compat_cmsghdr __user *cmsg, int cmsg_len)
 {
        char __user *ptr = (char __user *)cmsg + CMSG_COMPAT_ALIGN(cmsg_len);
-       if ((unsigned long)(ptr + 1 - (char __user *)msg->msg_control) >
+       if ((unsigned long)(ptr + 1 - (char __user *)msg->msg_control_user) >
                        msg->msg_controllen)
                return NULL;
        return (struct compat_cmsghdr __user *)ptr;
@@ -225,7 +225,7 @@ Efault:
 
 int put_cmsg_compat(struct msghdr *kmsg, int level, int type, int len, void *data)
 {
-       struct compat_cmsghdr __user *cm = (struct compat_cmsghdr __user *) kmsg->msg_control;
+       struct compat_cmsghdr __user *cm = (struct compat_cmsghdr __user *) kmsg->msg_control_user;
        struct compat_cmsghdr cmhdr;
        struct old_timeval32 ctv;
        struct old_timespec32 cts[3];
@@ -274,7 +274,7 @@ int put_cmsg_compat(struct msghdr *kmsg, int level, int type, int len, void *dat
        cmlen = CMSG_COMPAT_SPACE(len);
        if (kmsg->msg_controllen < cmlen)
                cmlen = kmsg->msg_controllen;
-       kmsg->msg_control += cmlen;
+       kmsg->msg_control_user += cmlen;
        kmsg->msg_controllen -= cmlen;
        return 0;
 }
@@ -289,7 +289,7 @@ static int scm_max_fds_compat(struct msghdr *msg)
 void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm)
 {
        struct compat_cmsghdr __user *cm =
-               (struct compat_cmsghdr __user *)msg->msg_control;
+               (struct compat_cmsghdr __user *)msg->msg_control_user;
        unsigned int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0;
        int fdmax = min_t(int, scm_max_fds_compat(msg), scm->fp->count);
        int __user *cmsg_data = CMSG_COMPAT_DATA(cm);
@@ -313,7 +313,7 @@ void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm)
                        cmlen = CMSG_COMPAT_SPACE(i * sizeof(int));
                        if (msg->msg_controllen < cmlen)
                                cmlen = msg->msg_controllen;
-                       msg->msg_control += cmlen;
+                       msg->msg_control_user += cmlen;
                        msg->msg_controllen -= cmlen;
                }
        }

diff --git a/net/core/scm.c b/net/core/scm.c
index acb7d77..3cd7dd3 100644 (file)
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -250,7 +250,10 @@ int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
        }
 
        cmlen = min(CMSG_SPACE(len), msg->msg_controllen);
-       msg->msg_control += cmlen;
+       if (msg->msg_control_is_user)
+               msg->msg_control_user += cmlen;
+       else
+               msg->msg_control += cmlen;
        msg->msg_controllen -= cmlen;
        return 0;
 
@@ -299,7 +302,7 @@ static int scm_max_fds(struct msghdr *msg)
 void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
 {
        struct cmsghdr __user *cm =
-               (__force struct cmsghdr __user *)msg->msg_control;
+               (__force struct cmsghdr __user *)msg->msg_control_user;
        unsigned int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0;
        int fdmax = min_t(int, scm_max_fds(msg), scm->fp->count);
        int __user *cmsg_data = CMSG_USER_DATA(cm);
@@ -332,7 +335,7 @@ void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
                        cmlen = CMSG_SPACE(i * sizeof(int));
                        if (msg->msg_controllen < cmlen)
                                cmlen = msg->msg_controllen;
-                       msg->msg_control += cmlen;
+                       msg->msg_control_user += cmlen;
                        msg->msg_controllen -= cmlen;
                }
        }

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index fd68d49..20db115 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2165,7 +2165,7 @@ static void tcp_zc_finalize_rx_tstamp(struct sock *sk,
        struct msghdr cmsg_dummy;
 
        msg_control_addr = (unsigned long)zc->msg_control;
-       cmsg_dummy.msg_control = (void *)msg_control_addr;
+       cmsg_dummy.msg_control_user = (void __user *)msg_control_addr;
        cmsg_dummy.msg_controllen =
                (__kernel_size_t)zc->msg_controllen;
        cmsg_dummy.msg_flags = in_compat_syscall()
@@ -2176,7 +2176,7 @@ static void tcp_zc_finalize_rx_tstamp(struct sock *sk,
            zc->msg_controllen == cmsg_dummy.msg_controllen) {
                tcp_recv_timestamp(&cmsg_dummy, sk, tss);
                zc->msg_control = (__u64)
-                       ((uintptr_t)cmsg_dummy.msg_control);
+                       ((uintptr_t)cmsg_dummy.msg_control_user);
                zc->msg_controllen =
                        (__u64)cmsg_dummy.msg_controllen;
                zc->msg_flags = (__u32)cmsg_dummy.msg_flags;