diff mbox series

[2/4] io_uring/cmd: Introduce SOCKET_URING_OP_GETSOCKOPT

Message ID 20230724142237.358769-3-leitao@debian.org (mailing list archive)
State New
Headers show
Series io_uring: Initial support for {s,g}etsockopt commands | expand

Commit Message

Breno Leitao July 24, 2023, 2:22 p.m. UTC
Add support for getsockopt command (SOCKET_URING_OP_GETSOCKOPT), where
level is SOL_SOCKET. This is leveraging the sockptr_t infrastructure,
where a sockptr_t is either userspace or kernel space, and handled as
such.

Function io_uring_cmd_getsockopt() is inspired by __sys_getsockopt().

Differently from the getsockopt(2), the optlen field is not a userspace
pointers. In getsockopt(2), userspace provides optlen pointer, which is
overwritten by the kernel.  In this implementation, userspace passes a
u32, and the new value is returned in cqe->res. I.e., optlen is not a
pointer.

Important to say that userspace needs to keep the pointer alive until
the CQE is completed.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
 include/uapi/linux/io_uring.h |  7 ++++++
 io_uring/uring_cmd.c          | 43 +++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

Comments

Stanislav Fomichev July 24, 2023, 5:31 p.m. UTC | #1
On 07/24, Breno Leitao wrote:
> Add support for getsockopt command (SOCKET_URING_OP_GETSOCKOPT), where
> level is SOL_SOCKET. This is leveraging the sockptr_t infrastructure,
> where a sockptr_t is either userspace or kernel space, and handled as
> such.
> 
> Function io_uring_cmd_getsockopt() is inspired by __sys_getsockopt().

We probably need to also have bpf bits in the new
io_uring_cmd_getsockopt?

> Differently from the getsockopt(2), the optlen field is not a userspace
> pointers. In getsockopt(2), userspace provides optlen pointer, which is
> overwritten by the kernel.  In this implementation, userspace passes a
> u32, and the new value is returned in cqe->res. I.e., optlen is not a
> pointer.
> 
> Important to say that userspace needs to keep the pointer alive until
> the CQE is completed.
> 
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
>  include/uapi/linux/io_uring.h |  7 ++++++
>  io_uring/uring_cmd.c          | 43 +++++++++++++++++++++++++++++++++++
>  2 files changed, 50 insertions(+)
> 
> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> index 9fc7195f25df..8152151080db 100644
> --- a/include/uapi/linux/io_uring.h
> +++ b/include/uapi/linux/io_uring.h
> @@ -43,6 +43,10 @@ struct io_uring_sqe {
>  	union {
>  		__u64	addr;	/* pointer to buffer or iovecs */
>  		__u64	splice_off_in;
> +		struct {
> +			__u32	level;
> +			__u32	optname;
> +		};
>  	};
>  	__u32	len;		/* buffer size or number of iovecs */
>  	union {
> @@ -79,6 +83,7 @@ struct io_uring_sqe {
>  	union {
>  		__s32	splice_fd_in;
>  		__u32	file_index;
> +		__u32	optlen;
>  		struct {
>  			__u16	addr_len;
>  			__u16	__pad3[1];
> @@ -89,6 +94,7 @@ struct io_uring_sqe {
>  			__u64	addr3;
>  			__u64	__pad2[1];
>  		};
> +		__u64	optval;
>  		/*
>  		 * If the ring is initialized with IORING_SETUP_SQE128, then
>  		 * this field is used for 80 bytes of arbitrary command data
> @@ -729,6 +735,7 @@ struct io_uring_recvmsg_out {
>  enum {
>  	SOCKET_URING_OP_SIOCINQ		= 0,
>  	SOCKET_URING_OP_SIOCOUTQ,
> +	SOCKET_URING_OP_GETSOCKOPT,
>  };
>  
>  #ifdef __cplusplus
> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
> index 8e7a03c1b20e..16c857cbf3b0 100644
> --- a/io_uring/uring_cmd.c
> +++ b/io_uring/uring_cmd.c
> @@ -166,6 +166,47 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
>  }
>  EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed);
>  
> +static inline int io_uring_cmd_getsockopt(struct socket *sock,
> +					  struct io_uring_cmd *cmd)
> +{
> +	void __user *optval = u64_to_user_ptr(READ_ONCE(cmd->sqe->optval));
> +	int optname = READ_ONCE(cmd->sqe->optname);
> +	int optlen = READ_ONCE(cmd->sqe->optlen);
> +	int level = READ_ONCE(cmd->sqe->level);
> +	void *koptval;
> +	int err;
> +
> +	err = security_socket_getsockopt(sock, level, optname);
> +	if (err)
> +		return err;
> +
> +	koptval = kmalloc(optlen, GFP_KERNEL);
> +	if (!koptval)
> +		return -ENOMEM;
> +
> +	err = copy_from_user(koptval, optval, optlen);
> +	if (err)
> +		goto fail;
> +
> +	err = -EOPNOTSUPP;
> +	if (level == SOL_SOCKET) {
> +		err = sk_getsockopt(sock->sk, level, optname,
> +				    KERNEL_SOCKPTR(koptval),
> +				    KERNEL_SOCKPTR(&optlen));
> +		if (err)
> +			goto fail;
> +	}
> +
> +	err = copy_to_user(optval, koptval, optlen);
> +
> +fail:
> +	kfree(koptval);
> +	if (err)
> +		return err;
> +	else
> +		return optlen;
> +}
> +
>  int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
>  {
>  	struct socket *sock = cmd->file->private_data;
> @@ -187,6 +228,8 @@ int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
>  		if (ret)
>  			return ret;
>  		return arg;
> +	case SOCKET_URING_OP_GETSOCKOPT:
> +		return io_uring_cmd_getsockopt(sock, cmd);
>  	default:
>  		return -EOPNOTSUPP;
>  	}
> -- 
> 2.34.1
>
Willem de Bruijn July 24, 2023, 10:58 p.m. UTC | #2
Breno Leitao wrote:
> Add support for getsockopt command (SOCKET_URING_OP_GETSOCKOPT), where
> level is SOL_SOCKET. This is leveraging the sockptr_t infrastructure,
> where a sockptr_t is either userspace or kernel space, and handled as
> such.
> 
> Function io_uring_cmd_getsockopt() is inspired by __sys_getsockopt().
> 
> Differently from the getsockopt(2), the optlen field is not a userspace
> pointers. In getsockopt(2), userspace provides optlen pointer, which is
> overwritten by the kernel.  In this implementation, userspace passes a
> u32, and the new value is returned in cqe->res. I.e., optlen is not a
> pointer.
> 
> Important to say that userspace needs to keep the pointer alive until
> the CQE is completed.
> 
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
>  include/uapi/linux/io_uring.h |  7 ++++++
>  io_uring/uring_cmd.c          | 43 +++++++++++++++++++++++++++++++++++
>  2 files changed, 50 insertions(+)
> 
> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> index 9fc7195f25df..8152151080db 100644
> --- a/include/uapi/linux/io_uring.h
> +++ b/include/uapi/linux/io_uring.h
> @@ -43,6 +43,10 @@ struct io_uring_sqe {
>  	union {
>  		__u64	addr;	/* pointer to buffer or iovecs */
>  		__u64	splice_off_in;
> +		struct {
> +			__u32	level;
> +			__u32	optname;
> +		};
>  	};
>  	__u32	len;		/* buffer size or number of iovecs */
>  	union {
> @@ -79,6 +83,7 @@ struct io_uring_sqe {
>  	union {
>  		__s32	splice_fd_in;
>  		__u32	file_index;
> +		__u32	optlen;
>  		struct {
>  			__u16	addr_len;
>  			__u16	__pad3[1];
> @@ -89,6 +94,7 @@ struct io_uring_sqe {
>  			__u64	addr3;
>  			__u64	__pad2[1];
>  		};
> +		__u64	optval;
>  		/*
>  		 * If the ring is initialized with IORING_SETUP_SQE128, then
>  		 * this field is used for 80 bytes of arbitrary command data
> @@ -729,6 +735,7 @@ struct io_uring_recvmsg_out {
>  enum {
>  	SOCKET_URING_OP_SIOCINQ		= 0,
>  	SOCKET_URING_OP_SIOCOUTQ,
> +	SOCKET_URING_OP_GETSOCKOPT,
>  };
>  
>  #ifdef __cplusplus
> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
> index 8e7a03c1b20e..16c857cbf3b0 100644
> --- a/io_uring/uring_cmd.c
> +++ b/io_uring/uring_cmd.c
> @@ -166,6 +166,47 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
>  }
>  EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed);
>  
> +static inline int io_uring_cmd_getsockopt(struct socket *sock,
> +					  struct io_uring_cmd *cmd)
> +{
> +	void __user *optval = u64_to_user_ptr(READ_ONCE(cmd->sqe->optval));
> +	int optname = READ_ONCE(cmd->sqe->optname);
> +	int optlen = READ_ONCE(cmd->sqe->optlen);
> +	int level = READ_ONCE(cmd->sqe->level);
> +	void *koptval;
> +	int err;
> +
> +	err = security_socket_getsockopt(sock, level, optname);
> +	if (err)
> +		return err;
> +
> +	koptval = kmalloc(optlen, GFP_KERNEL);
> +	if (!koptval)
> +		return -ENOMEM;

This will try to kmalloc any length that userspace passes?

That is unnecessary ..

> +
> +	err = copy_from_user(koptval, optval, optlen);
> +	if (err)
> +		goto fail;
> +
> +	err = -EOPNOTSUPP;
> +	if (level == SOL_SOCKET) {
> +		err = sk_getsockopt(sock->sk, level, optname,
> +				    KERNEL_SOCKPTR(koptval),
> +				    KERNEL_SOCKPTR(&optlen));

.. sk_getsockopt defines a union of acceptable fields, which
are all fairly small.

I notice that BPF added BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN to
work around the issue of pre-allocating for the worst case.

But that also needs to deal woth other getsockopt levels.


> +		if (err)
> +			goto fail;
> +	}
> +
> +	err = copy_to_user(optval, koptval, optlen);
> +
> +fail:
> +	kfree(koptval);
> +	if (err)
> +		return err;
> +	else
> +		return optlen;
> +}
> +
>  int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
>  {
>  	struct socket *sock = cmd->file->private_data;
> @@ -187,6 +228,8 @@ int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
>  		if (ret)
>  			return ret;
>  		return arg;
> +	case SOCKET_URING_OP_GETSOCKOPT:
> +		return io_uring_cmd_getsockopt(sock, cmd);
>  	default:
>  		return -EOPNOTSUPP;
>  	}
> -- 
> 2.34.1
>
Breno Leitao July 25, 2023, 9:27 a.m. UTC | #3
On Mon, Jul 24, 2023 at 10:31:28AM -0700, Stanislav Fomichev wrote:
> On 07/24, Breno Leitao wrote:
> > Add support for getsockopt command (SOCKET_URING_OP_GETSOCKOPT), where
> > level is SOL_SOCKET. This is leveraging the sockptr_t infrastructure,
> > where a sockptr_t is either userspace or kernel space, and handled as
> > such.
> > 
> > Function io_uring_cmd_getsockopt() is inspired by __sys_getsockopt().
> 
> We probably need to also have bpf bits in the new
> io_uring_cmd_getsockopt?

It might be interesting to have the BPF hook for this function as
well, but I would like to do it in a following patch, so, I can
experiment with it better, if that is OK.
Breno Leitao July 25, 2023, 9:51 a.m. UTC | #4
On Mon, Jul 24, 2023 at 06:58:04PM -0400, Willem de Bruijn wrote:
> Breno Leitao wrote:
> > Add support for getsockopt command (SOCKET_URING_OP_GETSOCKOPT), where
> > level is SOL_SOCKET. This is leveraging the sockptr_t infrastructure,
> > where a sockptr_t is either userspace or kernel space, and handled as
> > such.
> > 
> > Function io_uring_cmd_getsockopt() is inspired by __sys_getsockopt().
> > 
> > Differently from the getsockopt(2), the optlen field is not a userspace
> > pointers. In getsockopt(2), userspace provides optlen pointer, which is
> > overwritten by the kernel.  In this implementation, userspace passes a
> > u32, and the new value is returned in cqe->res. I.e., optlen is not a
> > pointer.
> > 
> > Important to say that userspace needs to keep the pointer alive until
> > the CQE is completed.
> > 
> > Signed-off-by: Breno Leitao <leitao@debian.org>
> > ---
> >  include/uapi/linux/io_uring.h |  7 ++++++
> >  io_uring/uring_cmd.c          | 43 +++++++++++++++++++++++++++++++++++
> >  2 files changed, 50 insertions(+)
> > 
> > diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> > index 9fc7195f25df..8152151080db 100644
> > --- a/include/uapi/linux/io_uring.h
> > +++ b/include/uapi/linux/io_uring.h
> > @@ -43,6 +43,10 @@ struct io_uring_sqe {
> >  	union {
> >  		__u64	addr;	/* pointer to buffer or iovecs */
> >  		__u64	splice_off_in;
> > +		struct {
> > +			__u32	level;
> > +			__u32	optname;
> > +		};
> >  	};
> >  	__u32	len;		/* buffer size or number of iovecs */
> >  	union {
> > @@ -79,6 +83,7 @@ struct io_uring_sqe {
> >  	union {
> >  		__s32	splice_fd_in;
> >  		__u32	file_index;
> > +		__u32	optlen;
> >  		struct {
> >  			__u16	addr_len;
> >  			__u16	__pad3[1];
> > @@ -89,6 +94,7 @@ struct io_uring_sqe {
> >  			__u64	addr3;
> >  			__u64	__pad2[1];
> >  		};
> > +		__u64	optval;
> >  		/*
> >  		 * If the ring is initialized with IORING_SETUP_SQE128, then
> >  		 * this field is used for 80 bytes of arbitrary command data
> > @@ -729,6 +735,7 @@ struct io_uring_recvmsg_out {
> >  enum {
> >  	SOCKET_URING_OP_SIOCINQ		= 0,
> >  	SOCKET_URING_OP_SIOCOUTQ,
> > +	SOCKET_URING_OP_GETSOCKOPT,
> >  };
> >  
> >  #ifdef __cplusplus
> > diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
> > index 8e7a03c1b20e..16c857cbf3b0 100644
> > --- a/io_uring/uring_cmd.c
> > +++ b/io_uring/uring_cmd.c
> > @@ -166,6 +166,47 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
> >  }
> >  EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed);
> >  
> > +static inline int io_uring_cmd_getsockopt(struct socket *sock,
> > +					  struct io_uring_cmd *cmd)
> > +{
> > +	void __user *optval = u64_to_user_ptr(READ_ONCE(cmd->sqe->optval));
> > +	int optname = READ_ONCE(cmd->sqe->optname);
> > +	int optlen = READ_ONCE(cmd->sqe->optlen);
> > +	int level = READ_ONCE(cmd->sqe->level);
> > +	void *koptval;
> > +	int err;
> > +
> > +	err = security_socket_getsockopt(sock, level, optname);
> > +	if (err)
> > +		return err;
> > +
> > +	koptval = kmalloc(optlen, GFP_KERNEL);
> > +	if (!koptval)
> > +		return -ENOMEM;
> 
> This will try to kmalloc any length that userspace passes?

Yes, this value is coming directly from userspace.

> That is unnecessary ..
> > +
> > +	err = copy_from_user(koptval, optval, optlen);
> > +	if (err)
> > +		goto fail;
> > +
> > +	err = -EOPNOTSUPP;
> > +	if (level == SOL_SOCKET) {
> > +		err = sk_getsockopt(sock->sk, level, optname,
> > +				    KERNEL_SOCKPTR(koptval),
> > +				    KERNEL_SOCKPTR(&optlen));
> 
> .. sk_getsockopt defines a union of acceptable fields, which
> are all fairly small.

Right, and they are all I need for SOL_SOCKET level for now.

> I notice that BPF added BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN to
> work around the issue of pre-allocating for the worst case.

I am having a hard time how to understand how
BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN gets the MAX_OPTLEN. Reading this
function, it seems it is conditionally get_user().


	#define BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen)
	({
		int __ret = 0;
		if (cgroup_bpf_enabled(CGROUP_GETSOCKOPT))
			get_user(__ret, optlen);
		__ret;
	})

That said, how is BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN being used to
workaroundthe pre-allocating for the worst case?

> But that also needs to deal woth other getsockopt levels.

Right, and we also have a similar kmalloc() on the setsockopt path
(SOCKET_URING_OP_SETSOCKOPT).

What about if I pass the userspace sockptr (USER_SOCKPTR) to the
{g,s}etsockopt callback directly, instead of kmalloc() in io_uring(), as
I was doing int the RFC[1]? It avoids any extra kmalloc at all.

Something as:

	static inline int io_uring_cmd_getsockopt(struct socket *sock,
						  struct io_uring_cmd *cmd)
	{
		void __user *optval = u64_to_user_ptr(READ_ONCE(cmd->sqe->optval));
		int optlen = READ_ONCE(cmd->sqe->optlen);
		int optname = READ_ONCE(cmd->sqe->optname);
		int level = READ_ONCE(cmd->sqe->level);
		int err;

		err = security_socket_getsockopt(sock, level, optname);
		if (err)
			return err;

		if (level == SOL_SOCKET) {
			err = sk_getsockopt(sock->sk, level, optname,
					    USER_SOCKPTR(optval),
					    KERNEL_SOCKPTR(&optlen));
			if (err < 0)
				return err;
			return optlen;
		}

		return -EOPNOTSUPP;

Thanks for the review!

[1] Link: https://lore.kernel.org/all/20230719102737.2513246-3-leitao@debian.org/
Willem de Bruijn July 25, 2023, 1:56 p.m. UTC | #5
Breno Leitao wrote:
> On Mon, Jul 24, 2023 at 06:58:04PM -0400, Willem de Bruijn wrote:
> > Breno Leitao wrote:
> > > Add support for getsockopt command (SOCKET_URING_OP_GETSOCKOPT), where
> > > level is SOL_SOCKET. This is leveraging the sockptr_t infrastructure,
> > > where a sockptr_t is either userspace or kernel space, and handled as
> > > such.
> > > 
> > > Function io_uring_cmd_getsockopt() is inspired by __sys_getsockopt().
> > > 
> > > Differently from the getsockopt(2), the optlen field is not a userspace
> > > pointers. In getsockopt(2), userspace provides optlen pointer, which is
> > > overwritten by the kernel.  In this implementation, userspace passes a
> > > u32, and the new value is returned in cqe->res. I.e., optlen is not a
> > > pointer.
> > > 
> > > Important to say that userspace needs to keep the pointer alive until
> > > the CQE is completed.
> > > 
> > > Signed-off-by: Breno Leitao <leitao@debian.org>
> > > ---
> > >  include/uapi/linux/io_uring.h |  7 ++++++
> > >  io_uring/uring_cmd.c          | 43 +++++++++++++++++++++++++++++++++++
> > >  2 files changed, 50 insertions(+)
> > > 
> > > diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> > > index 9fc7195f25df..8152151080db 100644
> > > --- a/include/uapi/linux/io_uring.h
> > > +++ b/include/uapi/linux/io_uring.h
> > > @@ -43,6 +43,10 @@ struct io_uring_sqe {
> > >  	union {
> > >  		__u64	addr;	/* pointer to buffer or iovecs */
> > >  		__u64	splice_off_in;
> > > +		struct {
> > > +			__u32	level;
> > > +			__u32	optname;
> > > +		};
> > >  	};
> > >  	__u32	len;		/* buffer size or number of iovecs */
> > >  	union {
> > > @@ -79,6 +83,7 @@ struct io_uring_sqe {
> > >  	union {
> > >  		__s32	splice_fd_in;
> > >  		__u32	file_index;
> > > +		__u32	optlen;
> > >  		struct {
> > >  			__u16	addr_len;
> > >  			__u16	__pad3[1];
> > > @@ -89,6 +94,7 @@ struct io_uring_sqe {
> > >  			__u64	addr3;
> > >  			__u64	__pad2[1];
> > >  		};
> > > +		__u64	optval;
> > >  		/*
> > >  		 * If the ring is initialized with IORING_SETUP_SQE128, then
> > >  		 * this field is used for 80 bytes of arbitrary command data
> > > @@ -729,6 +735,7 @@ struct io_uring_recvmsg_out {
> > >  enum {
> > >  	SOCKET_URING_OP_SIOCINQ		= 0,
> > >  	SOCKET_URING_OP_SIOCOUTQ,
> > > +	SOCKET_URING_OP_GETSOCKOPT,
> > >  };
> > >  
> > >  #ifdef __cplusplus
> > > diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
> > > index 8e7a03c1b20e..16c857cbf3b0 100644
> > > --- a/io_uring/uring_cmd.c
> > > +++ b/io_uring/uring_cmd.c
> > > @@ -166,6 +166,47 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
> > >  }
> > >  EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed);
> > >  
> > > +static inline int io_uring_cmd_getsockopt(struct socket *sock,
> > > +					  struct io_uring_cmd *cmd)
> > > +{
> > > +	void __user *optval = u64_to_user_ptr(READ_ONCE(cmd->sqe->optval));
> > > +	int optname = READ_ONCE(cmd->sqe->optname);
> > > +	int optlen = READ_ONCE(cmd->sqe->optlen);
> > > +	int level = READ_ONCE(cmd->sqe->level);
> > > +	void *koptval;
> > > +	int err;
> > > +
> > > +	err = security_socket_getsockopt(sock, level, optname);
> > > +	if (err)
> > > +		return err;
> > > +
> > > +	koptval = kmalloc(optlen, GFP_KERNEL);
> > > +	if (!koptval)
> > > +		return -ENOMEM;
> > 
> > This will try to kmalloc any length that userspace passes?
> 
> Yes, this value is coming directly from userspace.
> 
> > That is unnecessary ..
> > > +
> > > +	err = copy_from_user(koptval, optval, optlen);
> > > +	if (err)
> > > +		goto fail;
> > > +
> > > +	err = -EOPNOTSUPP;
> > > +	if (level == SOL_SOCKET) {
> > > +		err = sk_getsockopt(sock->sk, level, optname,
> > > +				    KERNEL_SOCKPTR(koptval),
> > > +				    KERNEL_SOCKPTR(&optlen));
> > 
> > .. sk_getsockopt defines a union of acceptable fields, which
> > are all fairly small.
> 
> Right, and they are all I need for SOL_SOCKET level for now.
> 
> > I notice that BPF added BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN to
> > work around the issue of pre-allocating for the worst case.
> 
> I am having a hard time how to understand how
> BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN gets the MAX_OPTLEN. Reading this
> function, it seems it is conditionally get_user().
> 
> 
> 	#define BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen)
> 	({
> 		int __ret = 0;
> 		if (cgroup_bpf_enabled(CGROUP_GETSOCKOPT))
> 			get_user(__ret, optlen);
> 		__ret;
> 	})
> 
> That said, how is BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN being used to
> workaroundthe pre-allocating for the worst case?
> 
> > But that also needs to deal woth other getsockopt levels.
> 
> Right, and we also have a similar kmalloc() on the setsockopt path
> (SOCKET_URING_OP_SETSOCKOPT).
> 
> What about if I pass the userspace sockptr (USER_SOCKPTR) to the
> {g,s}etsockopt callback directly, instead of kmalloc() in io_uring(), as
> I was doing int the RFC[1]? It avoids any extra kmalloc at all.

That looks like a great solution to me.

Avoids the whole problem of kmalloc based on untrusted user input.

> Something as:
> 
> 	static inline int io_uring_cmd_getsockopt(struct socket *sock,
> 						  struct io_uring_cmd *cmd)
> 	{
> 		void __user *optval = u64_to_user_ptr(READ_ONCE(cmd->sqe->optval));
> 		int optlen = READ_ONCE(cmd->sqe->optlen);
> 		int optname = READ_ONCE(cmd->sqe->optname);
> 		int level = READ_ONCE(cmd->sqe->level);
> 		int err;
> 
> 		err = security_socket_getsockopt(sock, level, optname);
> 		if (err)
> 			return err;
> 
> 		if (level == SOL_SOCKET) {
> 			err = sk_getsockopt(sock->sk, level, optname,
> 					    USER_SOCKPTR(optval),
> 					    KERNEL_SOCKPTR(&optlen));
> 			if (err < 0)
> 				return err;
> 			return optlen;
> 		}

Do you have a plan to extend this to other levels?

No need to implement immediately, but it would be good to know
whether it is feasible to extend the current solution when the
need (inevitably) shows up.

> 
> 		return -EOPNOTSUPP;
> 
> Thanks for the review!
> 
> [1] Link: https://lore.kernel.org/all/20230719102737.2513246-3-leitao@debian.org/
Breno Leitao July 25, 2023, 3:23 p.m. UTC | #6
On Tue, Jul 25, 2023 at 09:56:50AM -0400, Willem de Bruijn wrote:
> Breno Leitao wrote:
> > On Mon, Jul 24, 2023 at 06:58:04PM -0400, Willem de Bruijn wrote:
> > > Breno Leitao wrote:
> > > > Add support for getsockopt command (SOCKET_URING_OP_GETSOCKOPT), where
> > > > level is SOL_SOCKET. This is leveraging the sockptr_t infrastructure,
> > > > where a sockptr_t is either userspace or kernel space, and handled as
> > > > such.
> > > > 
> > > > Function io_uring_cmd_getsockopt() is inspired by __sys_getsockopt().
> > > > 
> > > > Differently from the getsockopt(2), the optlen field is not a userspace
> > > > pointers. In getsockopt(2), userspace provides optlen pointer, which is
> > > > overwritten by the kernel.  In this implementation, userspace passes a
> > > > u32, and the new value is returned in cqe->res. I.e., optlen is not a
> > > > pointer.
> > > > 
> > > > Important to say that userspace needs to keep the pointer alive until
> > > > the CQE is completed.
> > > > 
> > > > Signed-off-by: Breno Leitao <leitao@debian.org>
> > > > ---
> > > >  include/uapi/linux/io_uring.h |  7 ++++++
> > > >  io_uring/uring_cmd.c          | 43 +++++++++++++++++++++++++++++++++++
> > > >  2 files changed, 50 insertions(+)
> > > > 
> > > > diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> > > > index 9fc7195f25df..8152151080db 100644
> > > > --- a/include/uapi/linux/io_uring.h
> > > > +++ b/include/uapi/linux/io_uring.h
> > > > @@ -43,6 +43,10 @@ struct io_uring_sqe {
> > > >  	union {
> > > >  		__u64	addr;	/* pointer to buffer or iovecs */
> > > >  		__u64	splice_off_in;
> > > > +		struct {
> > > > +			__u32	level;
> > > > +			__u32	optname;
> > > > +		};
> > > >  	};
> > > >  	__u32	len;		/* buffer size or number of iovecs */
> > > >  	union {
> > > > @@ -79,6 +83,7 @@ struct io_uring_sqe {
> > > >  	union {
> > > >  		__s32	splice_fd_in;
> > > >  		__u32	file_index;
> > > > +		__u32	optlen;
> > > >  		struct {
> > > >  			__u16	addr_len;
> > > >  			__u16	__pad3[1];
> > > > @@ -89,6 +94,7 @@ struct io_uring_sqe {
> > > >  			__u64	addr3;
> > > >  			__u64	__pad2[1];
> > > >  		};
> > > > +		__u64	optval;
> > > >  		/*
> > > >  		 * If the ring is initialized with IORING_SETUP_SQE128, then
> > > >  		 * this field is used for 80 bytes of arbitrary command data
> > > > @@ -729,6 +735,7 @@ struct io_uring_recvmsg_out {
> > > >  enum {
> > > >  	SOCKET_URING_OP_SIOCINQ		= 0,
> > > >  	SOCKET_URING_OP_SIOCOUTQ,
> > > > +	SOCKET_URING_OP_GETSOCKOPT,
> > > >  };
> > > >  
> > > >  #ifdef __cplusplus
> > > > diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
> > > > index 8e7a03c1b20e..16c857cbf3b0 100644
> > > > --- a/io_uring/uring_cmd.c
> > > > +++ b/io_uring/uring_cmd.c
> > > > @@ -166,6 +166,47 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
> > > >  }
> > > >  EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed);
> > > >  
> > > > +static inline int io_uring_cmd_getsockopt(struct socket *sock,
> > > > +					  struct io_uring_cmd *cmd)
> > > > +{
> > > > +	void __user *optval = u64_to_user_ptr(READ_ONCE(cmd->sqe->optval));
> > > > +	int optname = READ_ONCE(cmd->sqe->optname);
> > > > +	int optlen = READ_ONCE(cmd->sqe->optlen);
> > > > +	int level = READ_ONCE(cmd->sqe->level);
> > > > +	void *koptval;
> > > > +	int err;
> > > > +
> > > > +	err = security_socket_getsockopt(sock, level, optname);
> > > > +	if (err)
> > > > +		return err;
> > > > +
> > > > +	koptval = kmalloc(optlen, GFP_KERNEL);
> > > > +	if (!koptval)
> > > > +		return -ENOMEM;
> > > 
> > > This will try to kmalloc any length that userspace passes?
> > 
> > Yes, this value is coming directly from userspace.
> > 
> > > That is unnecessary ..
> > > > +
> > > > +	err = copy_from_user(koptval, optval, optlen);
> > > > +	if (err)
> > > > +		goto fail;
> > > > +
> > > > +	err = -EOPNOTSUPP;
> > > > +	if (level == SOL_SOCKET) {
> > > > +		err = sk_getsockopt(sock->sk, level, optname,
> > > > +				    KERNEL_SOCKPTR(koptval),
> > > > +				    KERNEL_SOCKPTR(&optlen));
> > > 
> > > .. sk_getsockopt defines a union of acceptable fields, which
> > > are all fairly small.
> > 
> > Right, and they are all I need for SOL_SOCKET level for now.
> > 
> > > I notice that BPF added BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN to
> > > work around the issue of pre-allocating for the worst case.
> > 
> > I am having a hard time how to understand how
> > BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN gets the MAX_OPTLEN. Reading this
> > function, it seems it is conditionally get_user().
> > 
> > 
> > 	#define BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen)
> > 	({
> > 		int __ret = 0;
> > 		if (cgroup_bpf_enabled(CGROUP_GETSOCKOPT))
> > 			get_user(__ret, optlen);
> > 		__ret;
> > 	})
> > 
> > That said, how is BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN being used to
> > workaroundthe pre-allocating for the worst case?
> > 
> > > But that also needs to deal woth other getsockopt levels.
> > 
> > Right, and we also have a similar kmalloc() on the setsockopt path
> > (SOCKET_URING_OP_SETSOCKOPT).
> > 
> > What about if I pass the userspace sockptr (USER_SOCKPTR) to the
> > {g,s}etsockopt callback directly, instead of kmalloc() in io_uring(), as
> > I was doing int the RFC[1]? It avoids any extra kmalloc at all.
> 
> That looks like a great solution to me.
> 
> Avoids the whole problem of kmalloc based on untrusted user input.
> 
> > Something as:
> > 
> > 	static inline int io_uring_cmd_getsockopt(struct socket *sock,
> > 						  struct io_uring_cmd *cmd)
> > 	{
> > 		void __user *optval = u64_to_user_ptr(READ_ONCE(cmd->sqe->optval));
> > 		int optlen = READ_ONCE(cmd->sqe->optlen);
> > 		int optname = READ_ONCE(cmd->sqe->optname);
> > 		int level = READ_ONCE(cmd->sqe->level);
> > 		int err;
> > 
> > 		err = security_socket_getsockopt(sock, level, optname);
> > 		if (err)
> > 			return err;
> > 
> > 		if (level == SOL_SOCKET) {
> > 			err = sk_getsockopt(sock->sk, level, optname,
> > 					    USER_SOCKPTR(optval),
> > 					    KERNEL_SOCKPTR(&optlen));
> > 			if (err < 0)
> > 				return err;
> > 			return optlen;
> > 		}
> 
> Do you have a plan to extend this to other levels?
> 
> No need to implement immediately, but it would be good to know
> whether it is feasible to extend the current solution when the
> need (inevitably) shows up.

Yes, I plan to extend getsockopt() to all levels, but it means we need
to convert proto_ops->setsockopt to uset sockptr_t instead of
userpointers. This might require some intrusive changes, but totally
doable.
Stanislav Fomichev July 25, 2023, 5:02 p.m. UTC | #7
On 07/25, Breno Leitao wrote:
> On Mon, Jul 24, 2023 at 10:31:28AM -0700, Stanislav Fomichev wrote:
> > On 07/24, Breno Leitao wrote:
> > > Add support for getsockopt command (SOCKET_URING_OP_GETSOCKOPT), where
> > > level is SOL_SOCKET. This is leveraging the sockptr_t infrastructure,
> > > where a sockptr_t is either userspace or kernel space, and handled as
> > > such.
> > > 
> > > Function io_uring_cmd_getsockopt() is inspired by __sys_getsockopt().
> > 
> > We probably need to also have bpf bits in the new
> > io_uring_cmd_getsockopt?
> 
> It might be interesting to have the BPF hook for this function as
> well, but I would like to do it in a following patch, so, I can
> experiment with it better, if that is OK.

We are not using io_uring, so fine with me. However, having a way to bypass
get/setsockopt bpf might be problematic for some other heavy io_uring
users.

Lemme CC a bunch of Meta folks explicitly. I'm not sure what that state
of bpf support in io_uring.
Martin KaFai Lau July 25, 2023, 5:56 p.m. UTC | #8
On 7/25/23 10:02 AM, Stanislav Fomichev wrote:
> On 07/25, Breno Leitao wrote:
>> On Mon, Jul 24, 2023 at 10:31:28AM -0700, Stanislav Fomichev wrote:
>>> On 07/24, Breno Leitao wrote:
>>>> Add support for getsockopt command (SOCKET_URING_OP_GETSOCKOPT), where
>>>> level is SOL_SOCKET. This is leveraging the sockptr_t infrastructure,
>>>> where a sockptr_t is either userspace or kernel space, and handled as
>>>> such.
>>>>
>>>> Function io_uring_cmd_getsockopt() is inspired by __sys_getsockopt().
>>>
>>> We probably need to also have bpf bits in the new
>>> io_uring_cmd_getsockopt?

I also think this inconsistency behavior should be avoided.

>>
>> It might be interesting to have the BPF hook for this function as
>> well, but I would like to do it in a following patch, so, I can
>> experiment with it better, if that is OK.
> 
> We are not using io_uring, so fine with me. However, having a way to bypass
> get/setsockopt bpf might be problematic for some other heavy io_uring
> users.
> 
> Lemme CC a bunch of Meta folks explicitly. I'm not sure what that state
> of bpf support in io_uring.

We have use cases on the "cgroup/{g,s}etsockopt". It will be a surprise when the 
user moves from the syscall {g,s}etsockopt to SOCKET_URING_OP_*SOCKOPT and 
figured that the bpf handling is skipped.
Breno Leitao July 26, 2023, 9:26 a.m. UTC | #9
On Tue, Jul 25, 2023 at 10:56:23AM -0700, Martin KaFai Lau wrote:
> On 7/25/23 10:02 AM, Stanislav Fomichev wrote:
> > On 07/25, Breno Leitao wrote:
> > > On Mon, Jul 24, 2023 at 10:31:28AM -0700, Stanislav Fomichev wrote:
> > > > On 07/24, Breno Leitao wrote:
> > > > > Add support for getsockopt command (SOCKET_URING_OP_GETSOCKOPT), where
> > > > > level is SOL_SOCKET. This is leveraging the sockptr_t infrastructure,
> > > > > where a sockptr_t is either userspace or kernel space, and handled as
> > > > > such.
> > > > > 
> > > > > Function io_uring_cmd_getsockopt() is inspired by __sys_getsockopt().
> > > > 
> > > > We probably need to also have bpf bits in the new
> > > > io_uring_cmd_getsockopt?
> 
> I also think this inconsistency behavior should be avoided.
> 
> > > 
> > > It might be interesting to have the BPF hook for this function as
> > > well, but I would like to do it in a following patch, so, I can
> > > experiment with it better, if that is OK.
> > 
> > We are not using io_uring, so fine with me. However, having a way to bypass
> > get/setsockopt bpf might be problematic for some other heavy io_uring
> > users.
> > 
> > Lemme CC a bunch of Meta folks explicitly. I'm not sure what that state
> > of bpf support in io_uring.
> 
> We have use cases on the "cgroup/{g,s}etsockopt". It will be a surprise when
> the user moves from the syscall {g,s}etsockopt to SOCKET_URING_OP_*SOCKOPT
> and figured that the bpf handling is skipped.

Ok, I will add the BPF bits in the next revision then. Thanks for
clarifying it.
Breno Leitao July 28, 2023, 5:03 p.m. UTC | #10
Hello Stanislav,

On Tue, Jul 25, 2023 at 10:02:40AM -0700, Stanislav Fomichev wrote:
> On 07/25, Breno Leitao wrote:
> > On Mon, Jul 24, 2023 at 10:31:28AM -0700, Stanislav Fomichev wrote:
> > > On 07/24, Breno Leitao wrote:
> > > > Add support for getsockopt command (SOCKET_URING_OP_GETSOCKOPT), where
> > > > level is SOL_SOCKET. This is leveraging the sockptr_t infrastructure,
> > > > where a sockptr_t is either userspace or kernel space, and handled as
> > > > such.
> > > > 
> > > > Function io_uring_cmd_getsockopt() is inspired by __sys_getsockopt().
> > > 
> > > We probably need to also have bpf bits in the new
> > > io_uring_cmd_getsockopt?
> > 
> > It might be interesting to have the BPF hook for this function as
> > well, but I would like to do it in a following patch, so, I can
> > experiment with it better, if that is OK.

I spent smoe time looking at the problem, and I understand we want to
call something as BPF_CGROUP_RUN_PROG_{G,S}ETSOCKOPT() into
io_uring_cmd_{g,s}etsockopt().

Per the previous conversation with Williem,
io_uring_cmd_{g,s}etsockopt() should use optval as a user pointer (void __user
*optval), and optlen as a kernel integer (it comes as from the io_uring
SQE), such as:

	void __user *optval = u64_to_user_ptr(READ_ONCE(cmd->sqe->optval));
	int optlen = READ_ONCE(cmd->sqe->optlen);

Function BPF_CGROUP_RUN_PROG_GETSOCKOPT() calls
__cgroup_bpf_run_filter_getsockopt() which expects userpointer for
optlen and optval.

At the same time BPF_CGROUP_RUN_PROG_GETSOCKOPT_KERN() expects kernel
pointers for both optlen and optval.

In this current patchset, it has user pointer for optval and kernel value
for optlen. I.e., a third combination.  So, none of the functions would
work properly, and we probably do not want to create another function.

I am wondering if it is a good idea to move
__cgroup_bpf_run_filter_getsockopt() to use sockptr_t, so, it will be
able to adapt to any combination.

Any feedback is appreciate.
Thanks!
Stanislav Fomichev July 28, 2023, 6:07 p.m. UTC | #11
On Fri, Jul 28, 2023 at 10:03 AM Breno Leitao <leitao@debian.org> wrote:
>
> Hello Stanislav,
>
> On Tue, Jul 25, 2023 at 10:02:40AM -0700, Stanislav Fomichev wrote:
> > On 07/25, Breno Leitao wrote:
> > > On Mon, Jul 24, 2023 at 10:31:28AM -0700, Stanislav Fomichev wrote:
> > > > On 07/24, Breno Leitao wrote:
> > > > > Add support for getsockopt command (SOCKET_URING_OP_GETSOCKOPT), where
> > > > > level is SOL_SOCKET. This is leveraging the sockptr_t infrastructure,
> > > > > where a sockptr_t is either userspace or kernel space, and handled as
> > > > > such.
> > > > >
> > > > > Function io_uring_cmd_getsockopt() is inspired by __sys_getsockopt().
> > > >
> > > > We probably need to also have bpf bits in the new
> > > > io_uring_cmd_getsockopt?
> > >
> > > It might be interesting to have the BPF hook for this function as
> > > well, but I would like to do it in a following patch, so, I can
> > > experiment with it better, if that is OK.
>
> I spent smoe time looking at the problem, and I understand we want to
> call something as BPF_CGROUP_RUN_PROG_{G,S}ETSOCKOPT() into
> io_uring_cmd_{g,s}etsockopt().
>
> Per the previous conversation with Williem,
> io_uring_cmd_{g,s}etsockopt() should use optval as a user pointer (void __user
> *optval), and optlen as a kernel integer (it comes as from the io_uring
> SQE), such as:
>
>         void __user *optval = u64_to_user_ptr(READ_ONCE(cmd->sqe->optval));
>         int optlen = READ_ONCE(cmd->sqe->optlen);
>
> Function BPF_CGROUP_RUN_PROG_GETSOCKOPT() calls
> __cgroup_bpf_run_filter_getsockopt() which expects userpointer for
> optlen and optval.
>
> At the same time BPF_CGROUP_RUN_PROG_GETSOCKOPT_KERN() expects kernel
> pointers for both optlen and optval.
>
> In this current patchset, it has user pointer for optval and kernel value
> for optlen. I.e., a third combination.  So, none of the functions would
> work properly, and we probably do not want to create another function.
>
> I am wondering if it is a good idea to move
> __cgroup_bpf_run_filter_getsockopt() to use sockptr_t, so, it will be
> able to adapt to any combination.

Yeah, I think it makes sense. However, note that the intent of that
optlen being a __user pointer is to possibly write some (updated)
value back into the userspace.
Presumably, you'll pass that updated optlen into some io_uring
completion queue? (maybe a stupid question, not super familiar with
io_uring)

> Any feedback is appreciate.
> Thanks!
Breno Leitao July 31, 2023, 10:13 a.m. UTC | #12
On Fri, Jul 28, 2023 at 11:07:10AM -0700, Stanislav Fomichev wrote:
> On Fri, Jul 28, 2023 at 10:03 AM Breno Leitao <leitao@debian.org> wrote:
> >
> > Hello Stanislav,
> >
> > On Tue, Jul 25, 2023 at 10:02:40AM -0700, Stanislav Fomichev wrote:
> > > On 07/25, Breno Leitao wrote:
> > > > On Mon, Jul 24, 2023 at 10:31:28AM -0700, Stanislav Fomichev wrote:
> > > > > On 07/24, Breno Leitao wrote:
> > > > > > Add support for getsockopt command (SOCKET_URING_OP_GETSOCKOPT), where
> > > > > > level is SOL_SOCKET. This is leveraging the sockptr_t infrastructure,
> > > > > > where a sockptr_t is either userspace or kernel space, and handled as
> > > > > > such.
> > > > > >
> > > > > > Function io_uring_cmd_getsockopt() is inspired by __sys_getsockopt().
> > > > >
> > > > > We probably need to also have bpf bits in the new
> > > > > io_uring_cmd_getsockopt?
> > > >
> > > > It might be interesting to have the BPF hook for this function as
> > > > well, but I would like to do it in a following patch, so, I can
> > > > experiment with it better, if that is OK.
> >
> > I spent smoe time looking at the problem, and I understand we want to
> > call something as BPF_CGROUP_RUN_PROG_{G,S}ETSOCKOPT() into
> > io_uring_cmd_{g,s}etsockopt().
> >
> > Per the previous conversation with Williem,
> > io_uring_cmd_{g,s}etsockopt() should use optval as a user pointer (void __user
> > *optval), and optlen as a kernel integer (it comes as from the io_uring
> > SQE), such as:
> >
> >         void __user *optval = u64_to_user_ptr(READ_ONCE(cmd->sqe->optval));
> >         int optlen = READ_ONCE(cmd->sqe->optlen);
> >
> > Function BPF_CGROUP_RUN_PROG_GETSOCKOPT() calls
> > __cgroup_bpf_run_filter_getsockopt() which expects userpointer for
> > optlen and optval.
> >
> > At the same time BPF_CGROUP_RUN_PROG_GETSOCKOPT_KERN() expects kernel
> > pointers for both optlen and optval.
> >
> > In this current patchset, it has user pointer for optval and kernel value
> > for optlen. I.e., a third combination.  So, none of the functions would
> > work properly, and we probably do not want to create another function.
> >
> > I am wondering if it is a good idea to move
> > __cgroup_bpf_run_filter_getsockopt() to use sockptr_t, so, it will be
> > able to adapt to any combination.
> 
> Yeah, I think it makes sense. However, note that the intent of that
> optlen being a __user pointer is to possibly write some (updated)
> value back into the userspace.
> Presumably, you'll pass that updated optlen into some io_uring
> completion queue? (maybe a stupid question, not super familiar with
> io_uring)

On io_uring proposal, the optlen is part of the SQE for setsockopt().
You give a  userpointer (optval) and set the optlen in the SQE->optlen.

For getsockopt(), the optlen is returned as a result of the operation,
in the CQE->res.

If you need more detail about it, I documented this behaviour in the
cover-letter (PS1):

https://lore.kernel.org/all/20230724142237.358769-1-leitao@debian.org/

Thanks for the feedback!
diff mbox series

Patch

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 9fc7195f25df..8152151080db 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -43,6 +43,10 @@  struct io_uring_sqe {
 	union {
 		__u64	addr;	/* pointer to buffer or iovecs */
 		__u64	splice_off_in;
+		struct {
+			__u32	level;
+			__u32	optname;
+		};
 	};
 	__u32	len;		/* buffer size or number of iovecs */
 	union {
@@ -79,6 +83,7 @@  struct io_uring_sqe {
 	union {
 		__s32	splice_fd_in;
 		__u32	file_index;
+		__u32	optlen;
 		struct {
 			__u16	addr_len;
 			__u16	__pad3[1];
@@ -89,6 +94,7 @@  struct io_uring_sqe {
 			__u64	addr3;
 			__u64	__pad2[1];
 		};
+		__u64	optval;
 		/*
 		 * If the ring is initialized with IORING_SETUP_SQE128, then
 		 * this field is used for 80 bytes of arbitrary command data
@@ -729,6 +735,7 @@  struct io_uring_recvmsg_out {
 enum {
 	SOCKET_URING_OP_SIOCINQ		= 0,
 	SOCKET_URING_OP_SIOCOUTQ,
+	SOCKET_URING_OP_GETSOCKOPT,
 };
 
 #ifdef __cplusplus
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index 8e7a03c1b20e..16c857cbf3b0 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -166,6 +166,47 @@  int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
 }
 EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed);
 
+static inline int io_uring_cmd_getsockopt(struct socket *sock,
+					  struct io_uring_cmd *cmd)
+{
+	void __user *optval = u64_to_user_ptr(READ_ONCE(cmd->sqe->optval));
+	int optname = READ_ONCE(cmd->sqe->optname);
+	int optlen = READ_ONCE(cmd->sqe->optlen);
+	int level = READ_ONCE(cmd->sqe->level);
+	void *koptval;
+	int err;
+
+	err = security_socket_getsockopt(sock, level, optname);
+	if (err)
+		return err;
+
+	koptval = kmalloc(optlen, GFP_KERNEL);
+	if (!koptval)
+		return -ENOMEM;
+
+	err = copy_from_user(koptval, optval, optlen);
+	if (err)
+		goto fail;
+
+	err = -EOPNOTSUPP;
+	if (level == SOL_SOCKET) {
+		err = sk_getsockopt(sock->sk, level, optname,
+				    KERNEL_SOCKPTR(koptval),
+				    KERNEL_SOCKPTR(&optlen));
+		if (err)
+			goto fail;
+	}
+
+	err = copy_to_user(optval, koptval, optlen);
+
+fail:
+	kfree(koptval);
+	if (err)
+		return err;
+	else
+		return optlen;
+}
+
 int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
 {
 	struct socket *sock = cmd->file->private_data;
@@ -187,6 +228,8 @@  int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
 		if (ret)
 			return ret;
 		return arg;
+	case SOCKET_URING_OP_GETSOCKOPT:
+		return io_uring_cmd_getsockopt(sock, cmd);
 	default:
 		return -EOPNOTSUPP;
 	}