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