linux.git/net/core/scm.c, branch v6.2

memcg: enable accounting for scm_fp_list objects

2021-07-20T13:00:38+00:00

unix sockets allows to send file descriptors via SCM_RIGHTS type messages.
Each such send call forces kernel to allocate up to 2Kb memory for
struct scm_fp_list.

It makes sense to account for them to restrict the host's memory
consumption from inside the memcg-limited container.

Signed-off-by: Vasily Averin 
Signed-off-by: David S. Miller

scm: fix a typo in put_cmsg()

2021-04-16T18:41:07+00:00

We need to store cmlen instead of len in cm->cmsg_len.

Fixes: 38ebcf5096a8 ("scm: optimize put_cmsg()")
Signed-off-by: Eric Dumazet 
Reported-by: Jakub Kicinski 
Signed-off-by: David S. Miller

scm: optimize put_cmsg()

2021-04-16T00:03:33+00:00

Calling two copy_to_user() for very small regions has very high overhead.

Switch to inlined unsafe_put_user() to save one stac/clac sequence,
and avoid copy_to_user().

Signed-off-by: Eric Dumazet 
Cc: Soheil Hassas Yeganeh 
Acked-by: Soheil Hassas Yeganeh 
Signed-off-by: David S. Miller

fs: Add receive_fd() wrapper for __receive_fd()

2020-07-13T18:03:44+00:00

For both pidfd and seccomp, the __user pointer is not used. Update
__receive_fd() to make writing to ufd optional via a NULL check. However,
for the receive_fd_user() wrapper, ufd is NULL checked so an -EFAULT
can be returned to avoid changing the SCM_RIGHTS interface behavior. Add
new wrapper receive_fd() for pidfd and seccomp that does not use the ufd
argument. For the new helper, the allocated fd needs to be returned on
success. Update the existing callers to handle it.

Cc: Alexander Viro 
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Sargun Dhillon 
Acked-by: Christian Brauner 
Signed-off-by: Kees Cook

fs: Move __scm_install_fd() to __receive_fd()

2020-07-13T18:03:44+00:00

In preparation for users of the "install a received file" logic outside
of net/ (pidfd and seccomp), relocate and rename __scm_install_fd() from
net/core/scm.c to __receive_fd() in fs/file.c, and provide a wrapper
named receive_fd_user(), as future patches will change the interface
to __receive_fd().

Additionally add a comment to fd_install() as a counterpoint to how
__receive_fd() interacts with fput().

Cc: Alexander Viro 
Cc: "David S. Miller" 
Cc: Jakub Kicinski 
Cc: Dmitry Kadashev 
Cc: Jens Axboe 
Cc: Arnd Bergmann 
Cc: Sargun Dhillon 
Cc: Ido Schimmel 
Cc: Ioana Ciornei 
Cc: linux-fsdevel@vger.kernel.org
Cc: netdev@vger.kernel.org
Reviewed-by: Sargun Dhillon 
Acked-by: Christian Brauner 
Signed-off-by: Kees Cook

net/scm: Regularize compat handling of scm_detach_fds()

2020-07-13T18:03:44+00:00

Duplicate the cleanups from commit 2618d530dd8b ("net/scm: cleanup
scm_detach_fds") into the compat code.

Replace open-coded __receive_sock() with a call to the helper.

Move the check added in commit 1f466e1f15cf ("net: cleanly handle kernel
vs user buffers for ->msg_control") to before the compat call, even
though it should be impossible for an in-kernel call to also be compat.

Correct the int "flags" argument to unsigned int to match fd_install()
and similar APIs.

Regularize any remaining differences, including a whitespace issue,
a checkpatch warning, and add the check from commit 6900317f5eff ("net,
scm: fix PaX detected msg_controllen overflow in scm_detach_fds") which
fixed an overflow unique to 64-bit. To avoid confusion when comparing
the compat handler to the native handler, just include the same check
in the compat handler.

Cc: Christoph Hellwig 
Cc: Sargun Dhillon 
Cc: Jakub Kicinski 
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Acked-by: Christian Brauner 
Signed-off-by: Kees Cook

net: ignore sock_from_file errors in __scm_install_fd

2020-05-13T19:30:54+00:00

The code had historically been ignoring these errors, and my recent
refactoring changed that, which broke ssh in some setups.

Fixes: 2618d530dd8b ("net/scm: cleanup scm_detach_fds")
Reported-by: Ido Schimmel 
Signed-off-by: Christoph Hellwig 
Tested-by: Ido Schimmel 
Tested-by: Ioana Ciornei 
Signed-off-by: David S. Miller

net: cleanly handle kernel vs user buffers for ->msg_control

2020-05-11T23:59:16+00:00

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 
Signed-off-by: David S. Miller

net/scm: cleanup scm_detach_fds

2020-05-11T23:59:16+00:00

Factor out two helpes to keep the code tidy.

Signed-off-by: Christoph Hellwig 
Signed-off-by: David S. Miller

net: add a CMSG_USER_DATA macro

2020-05-11T23:59:16+00:00

Add a variant of CMSG_DATA that operates on user pointer to avoid
sparse warnings about casting to/from user pointers.  Also fix up
CMSG_DATA to rely on the gcc extension that allows void pointer
arithmetics to cut down on the amount of casts.

Signed-off-by: Christoph Hellwig 
Signed-off-by: David S. Miller