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 13 /* Well, we should have at least one descriptor open 14 * to accept passed FDs 8) 15 */ 16 #define SCM_MAX_FD 253 17 18 struct scm_creds { 19 u32 pid; 20 kuid_t uid; 21 kgid_t gid; 22 }; 23 24 struct scm_fp_list { 25 short count; 26 short max; 27 struct user_struct *user; 28 struct file *fp[SCM_MAX_FD]; 29 }; 30 31 struct scm_cookie { 32 struct pid *pid; /* Skb credentials */ 33 struct scm_fp_list *fp; /* Passed files */ 34 struct scm_creds creds; /* Skb credentials */ 35 #ifdef CONFIG_SECURITY_NETWORK 36 u32 secid; /* Passed security ID */ 37 #endif 38 }; 39 40 void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm); 41 void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm); 42 int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm); 43 void __scm_destroy(struct scm_cookie *scm); 44 struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl); 45 46 #ifdef CONFIG_SECURITY_NETWORK 47 static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm) 48 { 49 security_socket_getpeersec_dgram(sock, NULL, &scm->secid); 50 } 51 #else 52 static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm) 53 { } 54 #endif /* CONFIG_SECURITY_NETWORK */ 55 56 static __inline__ void scm_set_cred(struct scm_cookie *scm, 57 struct pid *pid, kuid_t uid, kgid_t gid) 58 { 59 scm->pid = get_pid(pid); 60 scm->creds.pid = pid_vnr(pid); 61 scm->creds.uid = uid; 62 scm->creds.gid = gid; 63 } 64 65 static __inline__ void scm_destroy_cred(struct scm_cookie *scm) 66 { 67 put_pid(scm->pid); 68 scm->pid = NULL; 69 } 70 71 static __inline__ void scm_destroy(struct scm_cookie *scm) 72 { 73 scm_destroy_cred(scm); 74 if (scm->fp) 75 __scm_destroy(scm); 76 } 77 78 static __inline__ int scm_send(struct socket *sock, struct msghdr *msg, 79 struct scm_cookie *scm, bool forcecreds) 80 { 81 memset(scm, 0, sizeof(*scm)); 82 scm->creds.uid = INVALID_UID; 83 scm->creds.gid = INVALID_GID; 84 if (forcecreds) 85 scm_set_cred(scm, task_tgid(current), current_uid(), current_gid()); 86 unix_get_peersec_dgram(sock, scm); 87 if (msg->msg_controllen <= 0) 88 return 0; 89 return __scm_send(sock, msg, scm); 90 } 91 92 #ifdef CONFIG_SECURITY_NETWORK 93 static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm) 94 { 95 char *secdata; 96 u32 seclen; 97 int err; 98 99 if (test_bit(SOCK_PASSSEC, &sock->flags)) { 100 err = security_secid_to_secctx(scm->secid, &secdata, &seclen); 101 102 if (!err) { 103 put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, seclen, secdata); 104 security_release_secctx(secdata, seclen); 105 } 106 } 107 } 108 109 static inline bool scm_has_secdata(struct socket *sock) 110 { 111 return test_bit(SOCK_PASSSEC, &sock->flags); 112 } 113 #else 114 static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm) 115 { } 116 117 static inline bool scm_has_secdata(struct socket *sock) 118 { 119 return false; 120 } 121 #endif /* CONFIG_SECURITY_NETWORK */ 122 123 static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg, 124 struct scm_cookie *scm, int flags) 125 { 126 if (!msg->msg_control) { 127 if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp || 128 scm_has_secdata(sock)) 129 msg->msg_flags |= MSG_CTRUNC; 130 scm_destroy(scm); 131 return; 132 } 133 134 if (test_bit(SOCK_PASSCRED, &sock->flags)) { 135 struct user_namespace *current_ns = current_user_ns(); 136 struct ucred ucreds = { 137 .pid = scm->creds.pid, 138 .uid = from_kuid_munged(current_ns, scm->creds.uid), 139 .gid = from_kgid_munged(current_ns, scm->creds.gid), 140 }; 141 put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds); 142 } 143 144 scm_destroy_cred(scm); 145 146 scm_passec(sock, msg, scm); 147 148 if (!scm->fp) 149 return; 150 151 scm_detach_fds(msg, scm); 152 } 153 154 155 #endif /* __LINUX_NET_SCM_H */ 156 157