diff options
Diffstat (limited to 'include/net/scm.h')
| -rw-r--r-- | include/net/scm.h | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/include/net/scm.h b/include/net/scm.h new file mode 100644 index 0000000000..e8c76b4be2 --- /dev/null +++ b/include/net/scm.h @@ -0,0 +1,212 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __LINUX_NET_SCM_H +#define __LINUX_NET_SCM_H + +#include <linux/limits.h> +#include <linux/net.h> +#include <linux/cred.h> +#include <linux/security.h> +#include <linux/pid.h> +#include <linux/nsproxy.h> +#include <linux/sched/signal.h> +#include <net/compat.h> + +/* Well, we should have at least one descriptor open + * to accept passed FDs 8) + */ +#define SCM_MAX_FD 253 + +struct scm_creds { + u32 pid; + kuid_t uid; + kgid_t gid; +}; + +struct scm_fp_list { + short count; + short max; + struct user_struct *user; + struct file *fp[SCM_MAX_FD]; +}; + +struct scm_cookie { + struct pid *pid; /* Skb credentials */ + struct scm_fp_list *fp; /* Passed files */ + struct scm_creds creds; /* Skb credentials */ +#ifdef CONFIG_SECURITY_NETWORK + u32 secid; /* Passed security ID */ +#endif +}; + +void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm); +void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm); +int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm); +void __scm_destroy(struct scm_cookie *scm); +struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl); + +#ifdef CONFIG_SECURITY_NETWORK +static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm) +{ + security_socket_getpeersec_dgram(sock, NULL, &scm->secid); +} +#else +static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm) +{ } +#endif /* CONFIG_SECURITY_NETWORK */ + +static __inline__ void scm_set_cred(struct scm_cookie *scm, + struct pid *pid, kuid_t uid, kgid_t gid) +{ + scm->pid = get_pid(pid); + scm->creds.pid = pid_vnr(pid); + scm->creds.uid = uid; + scm->creds.gid = gid; +} + +static __inline__ void scm_destroy_cred(struct scm_cookie *scm) +{ + put_pid(scm->pid); + scm->pid = NULL; +} + +static __inline__ void scm_destroy(struct scm_cookie *scm) +{ + scm_destroy_cred(scm); + if (scm->fp) + __scm_destroy(scm); +} + +static __inline__ int scm_send(struct socket *sock, struct msghdr *msg, + struct scm_cookie *scm, bool forcecreds) +{ + memset(scm, 0, sizeof(*scm)); + scm->creds.uid = INVALID_UID; + scm->creds.gid = INVALID_GID; + if (forcecreds) + scm_set_cred(scm, task_tgid(current), current_uid(), current_gid()); + unix_get_peersec_dgram(sock, scm); + if (msg->msg_controllen <= 0) + return 0; + return __scm_send(sock, msg, scm); +} + +#ifdef CONFIG_SECURITY_NETWORK +static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm) +{ + char *secdata; + u32 seclen; + int err; + + if (test_bit(SOCK_PASSSEC, &sock->flags)) { + err = security_secid_to_secctx(scm->secid, &secdata, &seclen); + + if (!err) { + put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, seclen, secdata); + security_release_secctx(secdata, seclen); + } + } +} + +static inline bool scm_has_secdata(struct socket *sock) +{ + return test_bit(SOCK_PASSSEC, &sock->flags); +} +#else +static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm) +{ } + +static inline bool scm_has_secdata(struct socket *sock) +{ + return false; +} +#endif /* CONFIG_SECURITY_NETWORK */ + +static __inline__ void scm_pidfd_recv(struct msghdr *msg, struct scm_cookie *scm) +{ + struct file *pidfd_file = NULL; + int len, 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_flags & MSG_CMSG_COMPAT) + len = sizeof(struct compat_cmsghdr) + sizeof(int); + else + len = sizeof(struct cmsghdr) + sizeof(int); + + if (msg->msg_controllen < len) { + msg->msg_flags |= MSG_CTRUNC; + return; + } + + if (!scm->pid) + return; + + 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 bool __scm_recv_common(struct socket *sock, struct msghdr *msg, + struct scm_cookie *scm, int flags) +{ + if (!msg->msg_control) { + 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 false; + } + + if (test_bit(SOCK_PASSCRED, &sock->flags)) { + struct user_namespace *current_ns = current_user_ns(); + struct ucred ucreds = { + .pid = scm->creds.pid, + .uid = from_kuid_munged(current_ns, scm->creds.uid), + .gid = from_kgid_munged(current_ns, scm->creds.gid), + }; + put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds); + } + + scm_passec(sock, msg, scm); + + if (scm->fp) + scm_detach_fds(msg, scm); + + return true; +} + +static inline void scm_recv(struct socket *sock, struct msghdr *msg, + struct scm_cookie *scm, int flags) +{ + if (!__scm_recv_common(sock, msg, scm, flags)) + return; + + scm_destroy_cred(scm); +} + +static inline void scm_recv_unix(struct socket *sock, struct msghdr *msg, + struct scm_cookie *scm, int flags) +{ + if (!__scm_recv_common(sock, msg, scm, flags)) + return; + + if (test_bit(SOCK_PASSPIDFD, &sock->flags)) + scm_pidfd_recv(msg, scm); + + scm_destroy_cred(scm); +} + +#endif /* __LINUX_NET_SCM_H */ + |