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