Line data Source code
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 3120 : static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
53 3120 : { }
54 : #endif /* CONFIG_SECURITY_NETWORK */
55 :
56 1276 : static __inline__ void scm_set_cred(struct scm_cookie *scm,
57 : struct pid *pid, kuid_t uid, kgid_t gid)
58 : {
59 1276 : scm->pid = get_pid(pid);
60 1276 : scm->creds.pid = pid_vnr(pid);
61 1276 : scm->creds.uid = uid;
62 1276 : scm->creds.gid = gid;
63 1276 : }
64 :
65 10135 : static __inline__ void scm_destroy_cred(struct scm_cookie *scm)
66 : {
67 10135 : put_pid(scm->pid);
68 10135 : scm->pid = NULL;
69 : }
70 :
71 6211 : static __inline__ void scm_destroy(struct scm_cookie *scm)
72 : {
73 6211 : scm_destroy_cred(scm);
74 6211 : if (scm->fp)
75 54 : __scm_destroy(scm);
76 6211 : }
77 :
78 3120 : static __inline__ int scm_send(struct socket *sock, struct msghdr *msg,
79 : struct scm_cookie *scm, bool forcecreds)
80 : {
81 3120 : memset(scm, 0, sizeof(*scm));
82 3120 : scm->creds.uid = INVALID_UID;
83 3120 : scm->creds.gid = INVALID_GID;
84 3120 : if (forcecreds)
85 405 : scm_set_cred(scm, task_tgid(current), current_uid(), current_gid());
86 3120 : unix_get_peersec_dgram(sock, scm);
87 3120 : if (msg->msg_controllen <= 0)
88 : return 0;
89 323 : 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 : #else
109 3924 : static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
110 3924 : { }
111 : #endif /* CONFIG_SECURITY_NETWORK */
112 :
113 4305 : static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg,
114 : struct scm_cookie *scm, int flags)
115 : {
116 4305 : if (!msg->msg_control) {
117 380 : if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp)
118 89 : msg->msg_flags |= MSG_CTRUNC;
119 380 : scm_destroy(scm);
120 380 : return;
121 : }
122 :
123 3925 : if (test_bit(SOCK_PASSCRED, &sock->flags)) {
124 1163 : struct user_namespace *current_ns = current_user_ns();
125 3489 : struct ucred ucreds = {
126 1163 : .pid = scm->creds.pid,
127 1163 : .uid = from_kuid_munged(current_ns, scm->creds.uid),
128 1163 : .gid = from_kgid_munged(current_ns, scm->creds.gid),
129 : };
130 1163 : put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds);
131 : }
132 :
133 3924 : scm_destroy_cred(scm);
134 :
135 3924 : scm_passec(sock, msg, scm);
136 :
137 3924 : if (!scm->fp)
138 : return;
139 :
140 54 : scm_detach_fds(msg, scm);
141 : }
142 :
143 :
144 : #endif /* __LINUX_NET_SCM_H */
145 :
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