include/net/scm.h

   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
  15 struct scm_creds {
  16         u32     pid;
  17         kuid_t  uid;
  18         kgid_t  gid;
  19 };
  20
  21 struct scm_fp_list {
  22         short                   count;
  23         short                   max;
  24         struct user_struct      *user;
  25         struct file             *fp[SCM_MAX_FD];
  26 };
  27
  28 struct 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
  37 void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm);
  38 void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm);
  39 int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm);
  40 void __scm_destroy(struct scm_cookie *scm);
  41 struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl);
  42
  43 #ifdef CONFIG_SECURITY_NETWORK
  44 static __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
  49 static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
  50 { }
  51 #endif /* CONFIG_SECURITY_NETWORK */
  52
  53 static __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
  62 static __inline__ void scm_destroy_cred(struct scm_cookie *scm)
  63 {
  64         put_pid(scm->pid);
  65         scm->pid  = NULL;
  66 }
  67
  68 static __inline__ void scm_destroy(struct scm_cookie *scm)
  69 {
  70         scm_destroy_cred(scm);
  71         if (scm->fp)
  72                 __scm_destroy(scm);
  73 }
  74
  75 static __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
  90 static 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
 106 static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
 107 { }
 108 #endif /* CONFIG_SECURITY_NETWORK */
 109
 110 static __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