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author | Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> | 2023-06-08 22:26:25 +0200 |
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committer | David S. Miller <davem@davemloft.net> | 2023-06-12 10:45:49 +0100 |
commit | 5e2ff6704a275be009be8979af17c52361b79b89 (patch) | |
tree | d99f0a156317459d398fe1cec5106155155c7b9d /include/net/scm.h | |
parent | 55d7c91406b4b486ea8c50e2fb31f1e1a0ef5143 (diff) | |
download | linux-stable-5e2ff6704a275be009be8979af17c52361b79b89.tar.gz linux-stable-5e2ff6704a275be009be8979af17c52361b79b89.tar.bz2 linux-stable-5e2ff6704a275be009be8979af17c52361b79b89.zip |
scm: add SO_PASSPIDFD and SCM_PIDFD
Implement SCM_PIDFD, a new type of CMSG type analogical to SCM_CREDENTIALS,
but it contains pidfd instead of plain pid, which allows programmers not
to care about PID reuse problem.
We mask SO_PASSPIDFD feature if CONFIG_UNIX is not builtin because
it depends on a pidfd_prepare() API which is not exported to the kernel
modules.
Idea comes from UAPI kernel group:
https://uapi-group.org/kernel-features/
Big thanks to Christian Brauner and Lennart Poettering for productive
discussions about this.
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: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Tested-by: Luca Boccassi <bluca@debian.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Christian Brauner <brauner@kernel.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>
Diffstat (limited to 'include/net/scm.h')
-rw-r--r-- | include/net/scm.h | 39 |
1 files changed, 37 insertions, 2 deletions
diff --git a/include/net/scm.h b/include/net/scm.h index 585adc1346bd..c67f765a165b 100644 --- a/include/net/scm.h +++ b/include/net/scm.h @@ -120,12 +120,44 @@ static inline bool scm_has_secdata(struct socket *sock) } #endif /* CONFIG_SECURITY_NETWORK */ +static __inline__ void scm_pidfd_recv(struct msghdr *msg, struct scm_cookie *scm) +{ + struct file *pidfd_file = NULL; + int pidfd; + + /* + * put_cmsg() doesn't return an error if CMSG is truncated, + * that's why we need to opencode these checks here. + */ + if ((msg->msg_controllen <= sizeof(struct cmsghdr)) || + (msg->msg_controllen - sizeof(struct cmsghdr)) < sizeof(int)) { + msg->msg_flags |= MSG_CTRUNC; + return; + } + + WARN_ON_ONCE(!scm->pid); + pidfd = pidfd_prepare(scm->pid, 0, &pidfd_file); + + if (put_cmsg(msg, SOL_SOCKET, SCM_PIDFD, sizeof(int), &pidfd)) { + if (pidfd_file) { + put_unused_fd(pidfd); + fput(pidfd_file); + } + + return; + } + + if (pidfd_file) + fd_install(pidfd, pidfd_file); +} + static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm, int flags) { if (!msg->msg_control) { - if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp || - scm_has_secdata(sock)) + if (test_bit(SOCK_PASSCRED, &sock->flags) || + test_bit(SOCK_PASSPIDFD, &sock->flags) || + scm->fp || scm_has_secdata(sock)) msg->msg_flags |= MSG_CTRUNC; scm_destroy(scm); return; @@ -141,6 +173,9 @@ static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg, put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds); } + if (test_bit(SOCK_PASSPIDFD, &sock->flags)) + scm_pidfd_recv(msg, scm); + scm_destroy_cred(scm); scm_passec(sock, msg, scm); |