From c39ef2130491b2382f2c81774c825527d4bdf4e2 Mon Sep 17 00:00:00 2001 From: Kevin Brodsky Date: Thu, 13 Apr 2023 12:47:03 +0100 Subject: [PATCH] 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 Cc: Eric Dumazet Cc: "David S. Miller" Cc: Jakub Kicinski Signed-off-by: Kevin Brodsky Reviewed-by: Christoph Hellwig Signed-off-by: David S. Miller --- net/compat.c | 12 ++++++------ net/core/scm.c | 9 ++++++--- net/ipv4/tcp.c | 4 ++-- 3 files changed, 14 insertions(+), 11 deletions(-) diff --git a/net/compat.c b/net/compat.c index 161b7bea1f62..000a2e054d4c 100644 --- 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 acb7d776fa6e..3cd7dd377e53 100644 --- 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 fd68d49490f2..20db115c38c4 100644 --- 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;