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
unix_get_peersec_dgram(struct socket * sock,struct scm_cookie * scm)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
unix_get_peersec_dgram(struct socket * sock,struct scm_cookie * scm)52 static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
53 { }
54 #endif /* CONFIG_SECURITY_NETWORK */
55
scm_set_cred(struct scm_cookie * scm,struct pid * pid,kuid_t uid,kgid_t gid)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
scm_destroy_cred(struct scm_cookie * scm)65 static __inline__ void scm_destroy_cred(struct scm_cookie *scm)
66 {
67 put_pid(scm->pid);
68 scm->pid = NULL;
69 }
70
scm_destroy(struct scm_cookie * scm)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
scm_send(struct socket * sock,struct msghdr * msg,struct scm_cookie * scm,bool forcecreds)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
scm_passec(struct socket * sock,struct msghdr * msg,struct scm_cookie * scm)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 #else
scm_passec(struct socket * sock,struct msghdr * msg,struct scm_cookie * scm)109 static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
110 { }
111 #endif /* CONFIG_SECURITY_NETWORK */
112
scm_recv(struct socket * sock,struct msghdr * msg,struct scm_cookie * scm,int flags)113 static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg,
114 struct scm_cookie *scm, int flags)
115 {
116 if (!msg->msg_control) {
117 if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp)
118 msg->msg_flags |= MSG_CTRUNC;
119 scm_destroy(scm);
120 return;
121 }
122
123 if (test_bit(SOCK_PASSCRED, &sock->flags)) {
124 struct user_namespace *current_ns = current_user_ns();
125 struct ucred ucreds = {
126 .pid = scm->creds.pid,
127 .uid = from_kuid_munged(current_ns, scm->creds.uid),
128 .gid = from_kgid_munged(current_ns, scm->creds.gid),
129 };
130 put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds);
131 }
132
133 scm_destroy_cred(scm);
134
135 scm_passec(sock, msg, scm);
136
137 if (!scm->fp)
138 return;
139
140 scm_detach_fds(msg, scm);
141 }
142
143
144 #endif /* __LINUX_NET_SCM_H */
145
146