The non-compat codepaths for sys_...msg() verify that MSG_CMSG_COMPAT is not set. By moving this check to the __sys_...msg() functions (and making it dependent on a static flag passed to this function), we can call the __sys...msg() functions instead of the syscall functions in all cases. __sys_recvmmsg() does not need this trickery, as the check is handled within the do_sys_recvmmsg() function internal to net/socket.c.
This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.ga17...@light.dominikbrodowski.net Cc: David S. Miller <da...@davemloft.net> Cc: netdev@vger.kernel.org Signed-off-by: Dominik Brodowski <li...@dominikbrodowski.net> --- include/linux/socket.h | 13 +++++++++---- net/compat.c | 8 +++++--- net/socket.c | 38 +++++++++++++++++++++++--------------- 3 files changed, 37 insertions(+), 22 deletions(-) diff --git a/include/linux/socket.h b/include/linux/socket.h index cad120e4ed4b..e2b6bd4fe977 100644 --- a/include/linux/socket.h +++ b/include/linux/socket.h @@ -346,13 +346,18 @@ extern int put_cmsg(struct msghdr*, int level, int type, int len, void *data); struct timespec; -/* The __sys_...msg variants allow MSG_CMSG_COMPAT */ -extern long __sys_recvmsg(int fd, struct user_msghdr __user *msg, unsigned flags); -extern long __sys_sendmsg(int fd, struct user_msghdr __user *msg, unsigned flags); +/* The __sys_...msg variants allow MSG_CMSG_COMPAT iff + * forbid_cmsg_compat==false + */ +extern long __sys_recvmsg(int fd, struct user_msghdr __user *msg, + unsigned int flags, bool forbid_cmsg_compat); +extern long __sys_sendmsg(int fd, struct user_msghdr __user *msg, + unsigned int flags, bool forbid_cmsg_compat); extern int __sys_recvmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen, unsigned int flags, struct timespec *timeout); extern int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, - unsigned int vlen, unsigned int flags); + unsigned int vlen, unsigned int flags, + bool forbid_cmsg_compat); /* helpers which do the actual work for syscalls */ extern int __sys_recvfrom(int fd, void __user *ubuf, size_t size, diff --git a/net/compat.c b/net/compat.c index f1ec23e9dfce..5caa48987bb2 100644 --- a/net/compat.c +++ b/net/compat.c @@ -736,19 +736,21 @@ static unsigned char nas[21] = { COMPAT_SYSCALL_DEFINE3(sendmsg, int, fd, struct compat_msghdr __user *, msg, unsigned int, flags) { - return __sys_sendmsg(fd, (struct user_msghdr __user *)msg, flags | MSG_CMSG_COMPAT); + return __sys_sendmsg(fd, (struct user_msghdr __user *)msg, + flags | MSG_CMSG_COMPAT, false); } COMPAT_SYSCALL_DEFINE4(sendmmsg, int, fd, struct compat_mmsghdr __user *, mmsg, unsigned int, vlen, unsigned int, flags) { return __sys_sendmmsg(fd, (struct mmsghdr __user *)mmsg, vlen, - flags | MSG_CMSG_COMPAT); + flags | MSG_CMSG_COMPAT, false); } COMPAT_SYSCALL_DEFINE3(recvmsg, int, fd, struct compat_msghdr __user *, msg, unsigned int, flags) { - return __sys_recvmsg(fd, (struct user_msghdr __user *)msg, flags | MSG_CMSG_COMPAT); + return __sys_recvmsg(fd, (struct user_msghdr __user *)msg, + flags | MSG_CMSG_COMPAT, false); } COMPAT_SYSCALL_DEFINE4(recv, int, fd, void __user *, buf, compat_size_t, len, unsigned int, flags) diff --git a/net/socket.c b/net/socket.c index 54d19b0edab1..a70793a7ce78 100644 --- a/net/socket.c +++ b/net/socket.c @@ -2137,12 +2137,16 @@ static int ___sys_sendmsg(struct socket *sock, struct user_msghdr __user *msg, * BSD sendmsg interface */ -long __sys_sendmsg(int fd, struct user_msghdr __user *msg, unsigned flags) +long __sys_sendmsg(int fd, struct user_msghdr __user *msg, unsigned int flags, + bool forbid_cmsg_compat) { int fput_needed, err; struct msghdr msg_sys; struct socket *sock; + if (forbid_cmsg_compat && (flags & MSG_CMSG_COMPAT)) + return -EINVAL; + sock = sockfd_lookup_light(fd, &err, &fput_needed); if (!sock) goto out; @@ -2156,9 +2160,7 @@ long __sys_sendmsg(int fd, struct user_msghdr __user *msg, unsigned flags) SYSCALL_DEFINE3(sendmsg, int, fd, struct user_msghdr __user *, msg, unsigned int, flags) { - if (flags & MSG_CMSG_COMPAT) - return -EINVAL; - return __sys_sendmsg(fd, msg, flags); + return __sys_sendmsg(fd, msg, flags, true); } /* @@ -2166,7 +2168,7 @@ SYSCALL_DEFINE3(sendmsg, int, fd, struct user_msghdr __user *, msg, unsigned int */ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen, - unsigned int flags) + unsigned int flags, bool forbid_cmsg_compat) { int fput_needed, err, datagrams; struct socket *sock; @@ -2176,6 +2178,9 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen, struct used_address used_address; unsigned int oflags = flags; + if (forbid_cmsg_compat && (flags & MSG_CMSG_COMPAT)) + return -EINVAL; + if (vlen > UIO_MAXIOV) vlen = UIO_MAXIOV; @@ -2232,9 +2237,7 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen, SYSCALL_DEFINE4(sendmmsg, int, fd, struct mmsghdr __user *, mmsg, unsigned int, vlen, unsigned int, flags) { - if (flags & MSG_CMSG_COMPAT) - return -EINVAL; - return __sys_sendmmsg(fd, mmsg, vlen, flags); + return __sys_sendmmsg(fd, mmsg, vlen, flags, true); } static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg, @@ -2307,12 +2310,16 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg, * BSD recvmsg interface */ -long __sys_recvmsg(int fd, struct user_msghdr __user *msg, unsigned flags) +long __sys_recvmsg(int fd, struct user_msghdr __user *msg, unsigned int flags, + bool forbid_cmsg_compat) { int fput_needed, err; struct msghdr msg_sys; struct socket *sock; + if (forbid_cmsg_compat && (flags & MSG_CMSG_COMPAT)) + return -EINVAL; + sock = sockfd_lookup_light(fd, &err, &fput_needed); if (!sock) goto out; @@ -2327,9 +2334,7 @@ long __sys_recvmsg(int fd, struct user_msghdr __user *msg, unsigned flags) SYSCALL_DEFINE3(recvmsg, int, fd, struct user_msghdr __user *, msg, unsigned int, flags) { - if (flags & MSG_CMSG_COMPAT) - return -EINVAL; - return __sys_recvmsg(fd, msg, flags); + return __sys_recvmsg(fd, msg, flags, true); } /* @@ -2580,13 +2585,16 @@ SYSCALL_DEFINE2(socketcall, int, call, unsigned long __user *, args) (int __user *)a[4]); break; case SYS_SENDMSG: - err = sys_sendmsg(a0, (struct user_msghdr __user *)a1, a[2]); + err = __sys_sendmsg(a0, (struct user_msghdr __user *)a1, + a[2], true); break; case SYS_SENDMMSG: - err = sys_sendmmsg(a0, (struct mmsghdr __user *)a1, a[2], a[3]); + err = __sys_sendmmsg(a0, (struct mmsghdr __user *)a1, a[2], + a[3], true); break; case SYS_RECVMSG: - err = sys_recvmsg(a0, (struct user_msghdr __user *)a1, a[2]); + err = __sys_recvmsg(a0, (struct user_msghdr __user *)a1, + a[2], true); break; case SYS_RECVMMSG: err = do_sys_recvmmsg(a0, (struct mmsghdr __user *)a1, a[2], -- 2.16.3
