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/file.h>
9 #include <linux/security.h>
10 #include <linux/pid.h>
11 #include <linux/nsproxy.h>
12 #include <linux/sched/signal.h>
13 #include <net/compat.h>
14
15 /* Well, we should have at least one descriptor open
16 * to accept passed FDs 8)
17 */
18 #define SCM_MAX_FD 253
19
20 struct scm_creds {
21 u32 pid;
22 kuid_t uid;
23 kgid_t gid;
24 };
25
26 #ifdef CONFIG_UNIX
27 struct unix_edge;
28 #endif
29
30 struct scm_fp_list {
31 short count;
32 short count_unix;
33 short max;
34 #ifdef CONFIG_UNIX
35 bool inflight;
36 bool dead;
37 struct list_head vertices;
38 struct unix_edge *edges;
39 #endif
40 struct user_struct *user;
41 struct file *fp[SCM_MAX_FD];
42 };
43
44 struct scm_cookie {
45 struct pid *pid; /* Skb credentials */
46 struct scm_fp_list *fp; /* Passed files */
47 struct scm_creds creds; /* Skb credentials */
48 #ifdef CONFIG_SECURITY_NETWORK
49 u32 secid; /* Passed security ID */
50 #endif
51 };
52
53 void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm);
54 void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm);
55 int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm);
56 void __scm_destroy(struct scm_cookie *scm);
57 struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl);
58
59 #ifdef CONFIG_SECURITY_NETWORK
unix_get_peersec_dgram(struct socket * sock,struct scm_cookie * scm)60 static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
61 {
62 security_socket_getpeersec_dgram(sock, NULL, &scm->secid);
63 }
64 #else
unix_get_peersec_dgram(struct socket * sock,struct scm_cookie * scm)65 static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
66 { }
67 #endif /* CONFIG_SECURITY_NETWORK */
68
scm_set_cred(struct scm_cookie * scm,struct pid * pid,kuid_t uid,kgid_t gid)69 static __inline__ void scm_set_cred(struct scm_cookie *scm,
70 struct pid *pid, kuid_t uid, kgid_t gid)
71 {
72 scm->pid = get_pid(pid);
73 scm->creds.pid = pid_vnr(pid);
74 scm->creds.uid = uid;
75 scm->creds.gid = gid;
76 }
77
scm_destroy_cred(struct scm_cookie * scm)78 static __inline__ void scm_destroy_cred(struct scm_cookie *scm)
79 {
80 put_pid(scm->pid);
81 scm->pid = NULL;
82 }
83
scm_destroy(struct scm_cookie * scm)84 static __inline__ void scm_destroy(struct scm_cookie *scm)
85 {
86 scm_destroy_cred(scm);
87 if (scm->fp)
88 __scm_destroy(scm);
89 }
90
scm_send(struct socket * sock,struct msghdr * msg,struct scm_cookie * scm,bool forcecreds)91 static __inline__ int scm_send(struct socket *sock, struct msghdr *msg,
92 struct scm_cookie *scm, bool forcecreds)
93 {
94 memset(scm, 0, sizeof(*scm));
95 scm->creds.uid = INVALID_UID;
96 scm->creds.gid = INVALID_GID;
97 if (forcecreds)
98 scm_set_cred(scm, task_tgid(current), current_uid(), current_gid());
99 unix_get_peersec_dgram(sock, scm);
100 if (msg->msg_controllen <= 0)
101 return 0;
102 return __scm_send(sock, msg, scm);
103 }
104
105 #ifdef CONFIG_SECURITY_NETWORK
scm_passec(struct socket * sock,struct msghdr * msg,struct scm_cookie * scm)106 static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
107 {
108 char *secdata;
109 u32 seclen;
110 int err;
111
112 if (test_bit(SOCK_PASSSEC, &sock->flags)) {
113 err = security_secid_to_secctx(scm->secid, &secdata, &seclen);
114
115 if (!err) {
116 put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, seclen, secdata);
117 security_release_secctx(secdata, seclen);
118 }
119 }
120 }
121
scm_has_secdata(struct socket * sock)122 static inline bool scm_has_secdata(struct socket *sock)
123 {
124 return test_bit(SOCK_PASSSEC, &sock->flags);
125 }
126 #else
scm_passec(struct socket * sock,struct msghdr * msg,struct scm_cookie * scm)127 static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
128 { }
129
scm_has_secdata(struct socket * sock)130 static inline bool scm_has_secdata(struct socket *sock)
131 {
132 return false;
133 }
134 #endif /* CONFIG_SECURITY_NETWORK */
135
scm_pidfd_recv(struct msghdr * msg,struct scm_cookie * scm)136 static __inline__ void scm_pidfd_recv(struct msghdr *msg, struct scm_cookie *scm)
137 {
138 struct file *pidfd_file = NULL;
139 int len, pidfd;
140
141 /* put_cmsg() doesn't return an error if CMSG is truncated,
142 * that's why we need to opencode these checks here.
143 */
144 if (msg->msg_flags & MSG_CMSG_COMPAT)
145 len = sizeof(struct compat_cmsghdr) + sizeof(int);
146 else
147 len = sizeof(struct cmsghdr) + sizeof(int);
148
149 if (msg->msg_controllen < len) {
150 msg->msg_flags |= MSG_CTRUNC;
151 return;
152 }
153
154 if (!scm->pid)
155 return;
156
157 pidfd = pidfd_prepare(scm->pid, 0, &pidfd_file);
158
159 if (put_cmsg(msg, SOL_SOCKET, SCM_PIDFD, sizeof(int), &pidfd)) {
160 if (pidfd_file) {
161 put_unused_fd(pidfd);
162 fput(pidfd_file);
163 }
164
165 return;
166 }
167
168 if (pidfd_file)
169 fd_install(pidfd, pidfd_file);
170 }
171
__scm_recv_common(struct socket * sock,struct msghdr * msg,struct scm_cookie * scm,int flags)172 static inline bool __scm_recv_common(struct socket *sock, struct msghdr *msg,
173 struct scm_cookie *scm, int flags)
174 {
175 if (!msg->msg_control) {
176 if (test_bit(SOCK_PASSCRED, &sock->flags) ||
177 test_bit(SOCK_PASSPIDFD, &sock->flags) ||
178 scm->fp || scm_has_secdata(sock))
179 msg->msg_flags |= MSG_CTRUNC;
180 scm_destroy(scm);
181 return false;
182 }
183
184 if (test_bit(SOCK_PASSCRED, &sock->flags)) {
185 struct user_namespace *current_ns = current_user_ns();
186 struct ucred ucreds = {
187 .pid = scm->creds.pid,
188 .uid = from_kuid_munged(current_ns, scm->creds.uid),
189 .gid = from_kgid_munged(current_ns, scm->creds.gid),
190 };
191 put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds);
192 }
193
194 scm_passec(sock, msg, scm);
195
196 if (scm->fp)
197 scm_detach_fds(msg, scm);
198
199 return true;
200 }
201
scm_recv(struct socket * sock,struct msghdr * msg,struct scm_cookie * scm,int flags)202 static inline void scm_recv(struct socket *sock, struct msghdr *msg,
203 struct scm_cookie *scm, int flags)
204 {
205 if (!__scm_recv_common(sock, msg, scm, flags))
206 return;
207
208 scm_destroy_cred(scm);
209 }
210
scm_recv_unix(struct socket * sock,struct msghdr * msg,struct scm_cookie * scm,int flags)211 static inline void scm_recv_unix(struct socket *sock, struct msghdr *msg,
212 struct scm_cookie *scm, int flags)
213 {
214 if (!__scm_recv_common(sock, msg, scm, flags))
215 return;
216
217 if (test_bit(SOCK_PASSPIDFD, &sock->flags))
218 scm_pidfd_recv(msg, scm);
219
220 scm_destroy_cred(scm);
221 }
222
scm_recv_one_fd(struct file * f,int __user * ufd,unsigned int flags)223 static inline int scm_recv_one_fd(struct file *f, int __user *ufd,
224 unsigned int flags)
225 {
226 if (!ufd)
227 return -EFAULT;
228 return receive_fd(f, ufd, flags);
229 }
230
231 #endif /* __LINUX_NET_SCM_H */
232
233