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