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