1#ifndef __LINUX_NET_SCM_H
2#define __LINUX_NET_SCM_H
3
4#include <linux/limits.h>
5#include <linux/net.h>
6#include <linux/security.h>
7#include <linux/pid.h>
8#include <linux/nsproxy.h>
9
10/* Well, we should have at least one descriptor open
11 * to accept passed FDs 8)
12 */
13#define SCM_MAX_FD	253
14
15struct scm_creds {
16	u32	pid;
17	kuid_t	uid;
18	kgid_t	gid;
19};
20
21struct scm_fp_list {
22	short			count;
23	short			max;
24	struct user_struct	*user;
25	struct file		*fp[SCM_MAX_FD];
26};
27
28struct scm_cookie {
29	struct pid		*pid;		/* Skb credentials */
30	struct scm_fp_list	*fp;		/* Passed files		*/
31	struct scm_creds	creds;		/* Skb credentials	*/
32#ifdef CONFIG_SECURITY_NETWORK
33	u32			secid;		/* Passed security ID 	*/
34#endif
35};
36
37void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm);
38void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm);
39int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm);
40void __scm_destroy(struct scm_cookie *scm);
41struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl);
42
43#ifdef CONFIG_SECURITY_NETWORK
44static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
45{
46	security_socket_getpeersec_dgram(sock, NULL, &scm->secid);
47}
48#else
49static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
50{ }
51#endif /* CONFIG_SECURITY_NETWORK */
52
53static __inline__ void scm_set_cred(struct scm_cookie *scm,
54				    struct pid *pid, kuid_t uid, kgid_t gid)
55{
56	scm->pid  = get_pid(pid);
57	scm->creds.pid = pid_vnr(pid);
58	scm->creds.uid = uid;
59	scm->creds.gid = gid;
60}
61
62static __inline__ void scm_destroy_cred(struct scm_cookie *scm)
63{
64	put_pid(scm->pid);
65	scm->pid  = NULL;
66}
67
68static __inline__ void scm_destroy(struct scm_cookie *scm)
69{
70	scm_destroy_cred(scm);
71	if (scm->fp)
72		__scm_destroy(scm);
73}
74
75static __inline__ int scm_send(struct socket *sock, struct msghdr *msg,
76			       struct scm_cookie *scm, bool forcecreds)
77{
78	memset(scm, 0, sizeof(*scm));
79	scm->creds.uid = INVALID_UID;
80	scm->creds.gid = INVALID_GID;
81	if (forcecreds)
82		scm_set_cred(scm, task_tgid(current), current_uid(), current_gid());
83	unix_get_peersec_dgram(sock, scm);
84	if (msg->msg_controllen <= 0)
85		return 0;
86	return __scm_send(sock, msg, scm);
87}
88
89#ifdef CONFIG_SECURITY_NETWORK
90static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
91{
92	char *secdata;
93	u32 seclen;
94	int err;
95
96	if (test_bit(SOCK_PASSSEC, &sock->flags)) {
97		err = security_secid_to_secctx(scm->secid, &secdata, &seclen);
98
99		if (!err) {
100			put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, seclen, secdata);
101			security_release_secctx(secdata, seclen);
102		}
103	}
104}
105#else
106static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
107{ }
108#endif /* CONFIG_SECURITY_NETWORK */
109
110static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg,
111				struct scm_cookie *scm, int flags)
112{
113	if (!msg->msg_control) {
114		if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp)
115			msg->msg_flags |= MSG_CTRUNC;
116		scm_destroy(scm);
117		return;
118	}
119
120	if (test_bit(SOCK_PASSCRED, &sock->flags)) {
121		struct user_namespace *current_ns = current_user_ns();
122		struct ucred ucreds = {
123			.pid = scm->creds.pid,
124			.uid = from_kuid_munged(current_ns, scm->creds.uid),
125			.gid = from_kgid_munged(current_ns, scm->creds.gid),
126		};
127		put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds);
128	}
129
130	scm_destroy_cred(scm);
131
132	scm_passec(sock, msg, scm);
133
134	if (!scm->fp)
135		return;
136
137	scm_detach_fds(msg, scm);
138}
139
140
141#endif /* __LINUX_NET_SCM_H */
142
143