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 161b7bea1f6204ff9120a0c2347f6105c8975772..000a2e054d4c48010ab878d33384760544202a40 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 acb7d776fa6ec29cdd9ae7d3a9970384c887ac75..3cd7dd377e53fbdf793260fd4e40207a45ba33f0 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 fd68d49490f2849a41397be5bf78dbf07cadd7ff..20db115c38c492c010733d5a0a3efbb7dbbea13e 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;