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| author |   Christoph Hellwig <hch@lst.de> | 2020-05-11 13:59:13 +0200 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2020-05-11 16:59:16 -0700 |
| commit | 1f466e1f15cf1dac7c86798d694649fc42cd868a (patch) | |
| tree | 1f8ca24224e9aa0dbaf924bec224deb08d1ab505 /net/compat.c | |
| parent | net/scm: cleanup scm_detach_fds (diff) | |
| download | linux-dev-1f466e1f15cf1dac7c86798d694649fc42cd868a.tar.xz linux-dev-1f466e1f15cf1dac7c86798d694649fc42cd868a.zip | |
net: cleanly handle kernel vs user buffers for ->msg_control
The msg_control field in struct msghdr can either contain a user
pointer when used with the recvmsg system call, or a kernel pointer
when used with sendmsg. To complicate things further kernel_recvmsg
can stuff a kernel pointer in and then use set_fs to make the uaccess
helpers accept it.
Replace it with a union of a kernel pointer msg_control field, and
a user pointer msg_control_user one, and allow kernel_recvmsg operate
on a proper kernel pointer using a bitfield to override the normal
choice of a user pointer for recvmsg.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/compat.c')
| -rw-r--r-- | net/compat.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/net/compat.c b/net/compat.c index 4bed96e84d9a..69fc6d1e4e6e 100644 --- a/net/compat.c +++ b/net/compat.c @@ -56,7 +56,8 @@ int __get_compat_msghdr(struct msghdr *kmsg, if (kmsg->msg_namelen > sizeof(struct sockaddr_storage)) kmsg->msg_namelen = sizeof(struct sockaddr_storage); - kmsg->msg_control = compat_ptr(msg.msg_control); + kmsg->msg_control_is_user = true; + kmsg->msg_control_user = compat_ptr(msg.msg_control); kmsg->msg_controllen = msg.msg_controllen; if (save_addr) @@ -121,7 +122,7 @@ int get_compat_msghdr(struct msghdr *kmsg, ((ucmlen) >= sizeof(struct compat_cmsghdr) && \ (ucmlen) <= (unsigned long) \ ((mhdr)->msg_controllen - \ - ((char *)(ucmsg) - (char *)(mhdr)->msg_control))) + ((char __user *)(ucmsg) - (char __user *)(mhdr)->msg_control_user))) static inline struct compat_cmsghdr __user *cmsg_compat_nxthdr(struct msghdr *msg, struct compat_cmsghdr __user *cmsg, int cmsg_len) |