[PATCH net-next v7 2/4] net: core: add getsockopt SO_PEERPIDFD
From: Alexander Mikhalitsyn
Date: Thu Jun 08 2023 - 16:27:19 EST
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@xxxxxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
Cc: Leon Romanovsky <leon@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Cc: Lennart Poettering <mzxreary@xxxxxxxxxxx>
Cc: Luca Boccassi <bluca@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Stanislav Fomichev <sdf@xxxxxxxxxx>
Cc: bpf@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: netdev@xxxxxxxxxxxxxxx
Cc: linux-arch@xxxxxxxxxxxxxxx
Reviewed-by: Christian Brauner <brauner@xxxxxxxxxx>
Acked-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
Tested-by: Luca Boccassi <bluca@xxxxxxxxxx>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx>
---
v5:
- started using (struct proto)->bpf_bypass_getsockopt hook
v4:
- return -ESRCH if sk->sk_peer_pid is NULL from getsockopt() syscall
- return errors from pidfd_prepare() as it is from getsockopt() syscall
v3:
- fixed possible fd leak (thanks to Christian Brauner)
v2:
According to review comments from Kuniyuki Iwashima and Christian Brauner:
- use pidfd_create(..) retval as a result
- whitespace change
---
arch/alpha/include/uapi/asm/socket.h | 1 +
arch/mips/include/uapi/asm/socket.h | 1 +
arch/parisc/include/uapi/asm/socket.h | 1 +
arch/sparc/include/uapi/asm/socket.h | 1 +
include/uapi/asm-generic/socket.h | 1 +
net/core/sock.c | 33 +++++++++++++++++++++++++
net/unix/af_unix.c | 16 ++++++++++++
tools/include/uapi/asm-generic/socket.h | 1 +
8 files changed, 55 insertions(+)
diff --git a/arch/alpha/include/uapi/asm/socket.h b/arch/alpha/include/uapi/asm/socket.h
index ff310613ae64..e94f621903fe 100644
--- 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 762dcb80e4ec..60ebaed28a4c 100644
--- 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 df16a3e16d64..be264c2b1a11 100644
--- 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 6e2847804fea..682da3714686 100644
--- 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 b76169fdb80b..8ce8a39a1e5f 100644
--- 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 ed4eb4ba738b..ea66b1afadd0 100644
--- 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 c46c2f5d860c..73c61a010b01 100644
--- 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 fbbc4bf53ee3..54d9c8bf7c55 100644
--- 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__)
--
2.34.1