net: core: add getsockopt SO_PEERPIDFD

Add SO_PEERPIDFD which allows to get pidfd of peer socket holder pidfd.
This thing is direct analog of SO_PEERCRED which allows to get plain PID.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: David Ahern <dsahern@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Kuniyuki Iwashima <kuniyu@amazon.com>
Cc: Lennart Poettering <mzxreary@0pointer.de>
Cc: Luca Boccassi <bluca@debian.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: bpf@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Reviewed-by: Christian Brauner <brauner@kernel.org>
Acked-by: Stanislav Fomichev <sdf@google.com>
Tested-by: Luca Boccassi <bluca@debian.org>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/alpha/include/uapi/asm/socket.h b/arch/alpha/include/uapi/asm/socket.h
index ff31061..e94f621 100644 (file)
--- a/arch/alpha/include/uapi/asm/socket.h
+++ b/arch/alpha/include/uapi/asm/socket.h
@@ -138,6 +138,7 @@
 #define SO_RCVMARK             75
 
 #define SO_PASSPIDFD           76
+#define SO_PEERPIDFD           77
 
 #if !defined(__KERNEL__)
 

diff --git a/arch/mips/include/uapi/asm/socket.h b/arch/mips/include/uapi/asm/socket.h
index 762dcb8..60ebaed 100644 (file)
--- a/arch/mips/include/uapi/asm/socket.h
+++ b/arch/mips/include/uapi/asm/socket.h
@@ -149,6 +149,7 @@
 #define SO_RCVMARK             75
 
 #define SO_PASSPIDFD           76
+#define SO_PEERPIDFD           77
 
 #if !defined(__KERNEL__)
 

diff --git a/arch/parisc/include/uapi/asm/socket.h b/arch/parisc/include/uapi/asm/socket.h
index df16a3e..be264c2 100644 (file)
--- a/arch/parisc/include/uapi/asm/socket.h
+++ b/arch/parisc/include/uapi/asm/socket.h
@@ -130,6 +130,7 @@
 #define SO_RCVMARK             0x4049
 
 #define SO_PASSPIDFD           0x404A
+#define SO_PEERPIDFD           0x404B
 
 #if !defined(__KERNEL__)
 

diff --git a/arch/sparc/include/uapi/asm/socket.h b/arch/sparc/include/uapi/asm/socket.h
index 6e28478..682da37 100644 (file)
--- a/arch/sparc/include/uapi/asm/socket.h
+++ b/arch/sparc/include/uapi/asm/socket.h
@@ -131,6 +131,7 @@
 #define SO_RCVMARK               0x0054
 
 #define SO_PASSPIDFD             0x0055
+#define SO_PEERPIDFD             0x0056
 
 #if !defined(__KERNEL__)
 

diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
index b76169f..8ce8a39 100644 (file)
--- a/include/uapi/asm-generic/socket.h
+++ b/include/uapi/asm-generic/socket.h
@@ -133,6 +133,7 @@
 #define SO_RCVMARK             75
 
 #define SO_PASSPIDFD           76
+#define SO_PEERPIDFD           77
 
 #if !defined(__KERNEL__)
 

diff --git a/net/core/sock.c b/net/core/sock.c
index ed4eb4b..ea66b1a 100644 (file)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1758,6 +1758,39 @@ int sk_getsockopt(struct sock *sk, int level, int optname,
                goto lenout;
        }
 
+       case SO_PEERPIDFD:
+       {
+               struct pid *peer_pid;
+               struct file *pidfd_file = NULL;
+               int pidfd;
+
+               if (len > sizeof(pidfd))
+                       len = sizeof(pidfd);
+
+               spin_lock(&sk->sk_peer_lock);
+               peer_pid = get_pid(sk->sk_peer_pid);
+               spin_unlock(&sk->sk_peer_lock);
+
+               if (!peer_pid)
+                       return -ESRCH;
+
+               pidfd = pidfd_prepare(peer_pid, 0, &pidfd_file);
+               put_pid(peer_pid);
+               if (pidfd < 0)
+                       return pidfd;
+
+               if (copy_to_sockptr(optval, &pidfd, len) ||
+                   copy_to_sockptr(optlen, &len, sizeof(int))) {
+                       put_unused_fd(pidfd);
+                       fput(pidfd_file);
+
+                       return -EFAULT;
+               }
+
+               fd_install(pidfd, pidfd_file);
+               return 0;
+       }
+
        case SO_PEERGROUPS:
        {
                const struct cred *cred;

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index c46c2f5..73c61a0 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -921,11 +921,26 @@ static void unix_unhash(struct sock *sk)
         */
 }
 
+static bool unix_bpf_bypass_getsockopt(int level, int optname)
+{
+       if (level == SOL_SOCKET) {
+               switch (optname) {
+               case SO_PEERPIDFD:
+                       return true;
+               default:
+                       return false;
+               }
+       }
+
+       return false;
+}
+
 struct proto unix_dgram_proto = {
        .name                   = "UNIX",
        .owner                  = THIS_MODULE,
        .obj_size               = sizeof(struct unix_sock),
        .close                  = unix_close,
+       .bpf_bypass_getsockopt  = unix_bpf_bypass_getsockopt,
 #ifdef CONFIG_BPF_SYSCALL
        .psock_update_sk_prot   = unix_dgram_bpf_update_proto,
 #endif
@@ -937,6 +952,7 @@ struct proto unix_stream_proto = {
        .obj_size               = sizeof(struct unix_sock),
        .close                  = unix_close,
        .unhash                 = unix_unhash,
+       .bpf_bypass_getsockopt  = unix_bpf_bypass_getsockopt,
 #ifdef CONFIG_BPF_SYSCALL
        .psock_update_sk_prot   = unix_stream_bpf_update_proto,
 #endif

diff --git a/tools/include/uapi/asm-generic/socket.h b/tools/include/uapi/asm-generic/socket.h
index fbbc4bf..54d9c8b 100644 (file)
--- a/tools/include/uapi/asm-generic/socket.h
+++ b/tools/include/uapi/asm-generic/socket.h
@@ -122,6 +122,7 @@
 #define SO_RCVMARK             75
 
 #define SO_PASSPIDFD           76
+#define SO_PEERPIDFD           77
 
 #if !defined(__KERNEL__)