1/* SPDX-License-Identifier: GPL-2.0 */ 2#ifndef __LINUX_NET_SCM_H 3#define __LINUX_NET_SCM_H 4 5#include <linux/limits.h> 6#include <linux/net.h> 7#include <linux/cred.h> 8#include <linux/security.h> 9#include <linux/pid.h> 10#include <linux/nsproxy.h> 11#include <linux/sched/signal.h> 12#include <net/compat.h> 13 14/* Well, we should have at least one descriptor open 15 * to accept passed FDs 8) 16 */ 17#define SCM_MAX_FD 253 18 19struct scm_creds { 20 u32 pid; 21 kuid_t uid; 22 kgid_t gid; 23}; 24 25struct scm_fp_list { 26 short count; 27 short max; 28 struct user_struct *user; 29 struct file *fp[SCM_MAX_FD]; 30}; 31 32struct scm_cookie { 33 struct pid *pid; /* Skb credentials */ 34 struct scm_fp_list *fp; /* Passed files */ 35 struct scm_creds creds; /* Skb credentials */ 36#ifdef CONFIG_SECURITY_NETWORK 37 u32 secid; /* Passed security ID */ 38#endif 39}; 40 41void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm); 42void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm); 43int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm); 44void __scm_destroy(struct scm_cookie *scm); 45struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl); 46 47#ifdef CONFIG_SECURITY_NETWORK 48static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm) 49{ 50 security_socket_getpeersec_dgram(sock, NULL, &scm->secid); 51} 52#else 53static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm) 54{ } 55#endif /* CONFIG_SECURITY_NETWORK */ 56 57static __inline__ void scm_set_cred(struct scm_cookie *scm, 58 struct pid *pid, kuid_t uid, kgid_t gid) 59{ 60 scm->pid = get_pid(pid); 61 scm->creds.pid = pid_vnr(pid); 62 scm->creds.uid = uid; 63 scm->creds.gid = gid; 64} 65 66static __inline__ void scm_destroy_cred(struct scm_cookie *scm) 67{ 68 put_pid(scm->pid); 69 scm->pid = NULL; 70} 71 72static __inline__ void scm_destroy(struct scm_cookie *scm) 73{ 74 scm_destroy_cred(scm); 75 if (scm->fp) 76 __scm_destroy(scm); 77} 78 79static __inline__ int scm_send(struct socket *sock, struct msghdr *msg, 80 struct scm_cookie *scm, bool forcecreds) 81{ 82 memset(scm, 0, sizeof(*scm)); 83 scm->creds.uid = INVALID_UID; 84 scm->creds.gid = INVALID_GID; 85 if (forcecreds) 86 scm_set_cred(scm, task_tgid(current), current_uid(), current_gid()); 87 unix_get_peersec_dgram(sock, scm); 88 if (msg->msg_controllen <= 0) 89 return 0; 90 return __scm_send(sock, msg, scm); 91} 92 93#ifdef CONFIG_SECURITY_NETWORK 94static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm) 95{ 96 char *secdata; 97 u32 seclen; 98 int err; 99 100 if (test_bit(SOCK_PASSSEC, &sock->flags)) { 101 err = security_secid_to_secctx(scm->secid, &secdata, &seclen); 102 103 if (!err) { 104 put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, seclen, secdata); 105 security_release_secctx(secdata, seclen); 106 } 107 } 108} 109 110static inline bool scm_has_secdata(struct socket *sock) 111{ 112 return test_bit(SOCK_PASSSEC, &sock->flags); 113} 114#else 115static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm) 116{ } 117 118static inline bool scm_has_secdata(struct socket *sock) 119{ 120 return false; 121} 122#endif /* CONFIG_SECURITY_NETWORK */ 123 124static __inline__ void scm_pidfd_recv(struct msghdr *msg, struct scm_cookie *scm) 125{ 126 struct file *pidfd_file = NULL; 127 int len, pidfd; 128 129 /* put_cmsg() doesn't return an error if CMSG is truncated, 130 * that's why we need to opencode these checks here. 131 */ 132 if (msg->msg_flags & MSG_CMSG_COMPAT) 133 len = sizeof(struct compat_cmsghdr) + sizeof(int); 134 else 135 len = sizeof(struct cmsghdr) + sizeof(int); 136 137 if (msg->msg_controllen < len) { 138 msg->msg_flags |= MSG_CTRUNC; 139 return; 140 } 141 142 if (!scm->pid) 143 return; 144 145 pidfd = pidfd_prepare(scm->pid, 0, &pidfd_file); 146 147 if (put_cmsg(msg, SOL_SOCKET, SCM_PIDFD, sizeof(int), &pidfd)) { 148 if (pidfd_file) { 149 put_unused_fd(pidfd); 150 fput(pidfd_file); 151 } 152 153 return; 154 } 155 156 if (pidfd_file) 157 fd_install(pidfd, pidfd_file); 158} 159 160static inline bool __scm_recv_common(struct socket *sock, struct msghdr *msg, 161 struct scm_cookie *scm, int flags) 162{ 163 if (!msg->msg_control) { 164 if (test_bit(SOCK_PASSCRED, &sock->flags) || 165 test_bit(SOCK_PASSPIDFD, &sock->flags) || 166 scm->fp || scm_has_secdata(sock)) 167 msg->msg_flags |= MSG_CTRUNC; 168 scm_destroy(scm); 169 return false; 170 } 171 172 if (test_bit(SOCK_PASSCRED, &sock->flags)) { 173 struct user_namespace *current_ns = current_user_ns(); 174 struct ucred ucreds = { 175 .pid = scm->creds.pid, 176 .uid = from_kuid_munged(current_ns, scm->creds.uid), 177 .gid = from_kgid_munged(current_ns, scm->creds.gid), 178 }; 179 put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds); 180 } 181 182 scm_passec(sock, msg, scm); 183 184 if (scm->fp) 185 scm_detach_fds(msg, scm); 186 187 return true; 188} 189 190static inline void scm_recv(struct socket *sock, struct msghdr *msg, 191 struct scm_cookie *scm, int flags) 192{ 193 if (!__scm_recv_common(sock, msg, scm, flags)) 194 return; 195 196 scm_destroy_cred(scm); 197} 198 199static inline void scm_recv_unix(struct socket *sock, struct msghdr *msg, 200 struct scm_cookie *scm, int flags) 201{ 202 if (!__scm_recv_common(sock, msg, scm, flags)) 203 return; 204 205 if (test_bit(SOCK_PASSPIDFD, &sock->flags)) 206 scm_pidfd_recv(msg, scm); 207 208 scm_destroy_cred(scm); 209} 210 211#endif /* __LINUX_NET_SCM_H */ 212 213