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/* 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 */
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