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/file.h> 9 #include <linux/security.h> 10 #include <linux/pid.h> 11 #include <linux/nsproxy.h> 12 #include <linux/sched/signal.h> 13 #include <net/compat.h> 14 15 /* Well, we should have at least one descriptor open 16 * to accept passed FDs 8) 17 */ 18 #define SCM_MAX_FD 253 19 20 struct scm_creds { 21 u32 pid; 22 kuid_t uid; 23 kgid_t gid; 24 }; 25 26 struct scm_fp_list { 27 short count; 28 short count_unix; 29 short max; 30 struct user_struct *user; 31 struct file *fp[SCM_MAX_FD]; 32 }; 33 34 struct scm_cookie { 35 struct pid *pid; /* Skb credentials */ 36 struct scm_fp_list *fp; /* Passed files */ 37 struct scm_creds creds; /* Skb credentials */ 38 #ifdef CONFIG_SECURITY_NETWORK 39 u32 secid; /* Passed security ID */ 40 #endif 41 }; 42 43 void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm); 44 void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm); 45 int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm); 46 void __scm_destroy(struct scm_cookie *scm); 47 struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl); 48 49 #ifdef CONFIG_SECURITY_NETWORK 50 static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm) 51 { 52 security_socket_getpeersec_dgram(sock, NULL, &scm->secid); 53 } 54 #else 55 static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm) 56 { } 57 #endif /* CONFIG_SECURITY_NETWORK */ 58 59 static __inline__ void scm_set_cred(struct scm_cookie *scm, 60 struct pid *pid, kuid_t uid, kgid_t gid) 61 { 62 scm->pid = get_pid(pid); 63 scm->creds.pid = pid_vnr(pid); 64 scm->creds.uid = uid; 65 scm->creds.gid = gid; 66 } 67 68 static __inline__ void scm_destroy_cred(struct scm_cookie *scm) 69 { 70 put_pid(scm->pid); 71 scm->pid = NULL; 72 } 73 74 static __inline__ void scm_destroy(struct scm_cookie *scm) 75 { 76 scm_destroy_cred(scm); 77 if (scm->fp) 78 __scm_destroy(scm); 79 } 80 81 static __inline__ int scm_send(struct socket *sock, struct msghdr *msg, 82 struct scm_cookie *scm, bool forcecreds) 83 { 84 memset(scm, 0, sizeof(*scm)); 85 scm->creds.uid = INVALID_UID; 86 scm->creds.gid = INVALID_GID; 87 if (forcecreds) 88 scm_set_cred(scm, task_tgid(current), current_uid(), current_gid()); 89 unix_get_peersec_dgram(sock, scm); 90 if (msg->msg_controllen <= 0) 91 return 0; 92 return __scm_send(sock, msg, scm); 93 } 94 95 #ifdef CONFIG_SECURITY_NETWORK 96 static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm) 97 { 98 char *secdata; 99 u32 seclen; 100 int err; 101 102 if (test_bit(SOCK_PASSSEC, &sock->flags)) { 103 err = security_secid_to_secctx(scm->secid, &secdata, &seclen); 104 105 if (!err) { 106 put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, seclen, secdata); 107 security_release_secctx(secdata, seclen); 108 } 109 } 110 } 111 112 static inline bool scm_has_secdata(struct socket *sock) 113 { 114 return test_bit(SOCK_PASSSEC, &sock->flags); 115 } 116 #else 117 static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm) 118 { } 119 120 static inline bool scm_has_secdata(struct socket *sock) 121 { 122 return false; 123 } 124 #endif /* CONFIG_SECURITY_NETWORK */ 125 126 static __inline__ void scm_pidfd_recv(struct msghdr *msg, struct scm_cookie *scm) 127 { 128 struct file *pidfd_file = NULL; 129 int len, pidfd; 130 131 /* put_cmsg() doesn't return an error if CMSG is truncated, 132 * that's why we need to opencode these checks here. 133 */ 134 if (msg->msg_flags & MSG_CMSG_COMPAT) 135 len = sizeof(struct compat_cmsghdr) + sizeof(int); 136 else 137 len = sizeof(struct cmsghdr) + sizeof(int); 138 139 if (msg->msg_controllen < len) { 140 msg->msg_flags |= MSG_CTRUNC; 141 return; 142 } 143 144 if (!scm->pid) 145 return; 146 147 pidfd = pidfd_prepare(scm->pid, 0, &pidfd_file); 148 149 if (put_cmsg(msg, SOL_SOCKET, SCM_PIDFD, sizeof(int), &pidfd)) { 150 if (pidfd_file) { 151 put_unused_fd(pidfd); 152 fput(pidfd_file); 153 } 154 155 return; 156 } 157 158 if (pidfd_file) 159 fd_install(pidfd, pidfd_file); 160 } 161 162 static inline bool __scm_recv_common(struct socket *sock, struct msghdr *msg, 163 struct scm_cookie *scm, int flags) 164 { 165 if (!msg->msg_control) { 166 if (test_bit(SOCK_PASSCRED, &sock->flags) || 167 test_bit(SOCK_PASSPIDFD, &sock->flags) || 168 scm->fp || scm_has_secdata(sock)) 169 msg->msg_flags |= MSG_CTRUNC; 170 scm_destroy(scm); 171 return false; 172 } 173 174 if (test_bit(SOCK_PASSCRED, &sock->flags)) { 175 struct user_namespace *current_ns = current_user_ns(); 176 struct ucred ucreds = { 177 .pid = scm->creds.pid, 178 .uid = from_kuid_munged(current_ns, scm->creds.uid), 179 .gid = from_kgid_munged(current_ns, scm->creds.gid), 180 }; 181 put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds); 182 } 183 184 scm_passec(sock, msg, scm); 185 186 if (scm->fp) 187 scm_detach_fds(msg, scm); 188 189 return true; 190 } 191 192 static inline void scm_recv(struct socket *sock, struct msghdr *msg, 193 struct scm_cookie *scm, int flags) 194 { 195 if (!__scm_recv_common(sock, msg, scm, flags)) 196 return; 197 198 scm_destroy_cred(scm); 199 } 200 201 static inline void scm_recv_unix(struct socket *sock, struct msghdr *msg, 202 struct scm_cookie *scm, int flags) 203 { 204 if (!__scm_recv_common(sock, msg, scm, flags)) 205 return; 206 207 if (test_bit(SOCK_PASSPIDFD, &sock->flags)) 208 scm_pidfd_recv(msg, scm); 209 210 scm_destroy_cred(scm); 211 } 212 213 static inline int scm_recv_one_fd(struct file *f, int __user *ufd, 214 unsigned int flags) 215 { 216 if (!ufd) 217 return -EFAULT; 218 return receive_fd(f, ufd, flags); 219 } 220 221 #endif /* __LINUX_NET_SCM_H */ 222 223