Subject: [PATCH] hurd: SCM_CREDS support Svante Signell Samuel Thibault * sysdeps/mach/hurd/sendmsg.c (__libc_sendmsg): On SCM_CREDS control messages, record uids, pass a rendez-vous port in the control message, and call __auth_user_authenticate_request to make auth send credentials on that port. Do not wait for a reply. * sysdeps/mach/hurd/recvmsg.c (contains_uid, contains_gid, check_auth): New functions. (__libc_recvmsg): On SCM_CREDS control messages, call check_auth to check the passed credentials thanks to the answer from the auth server. * hurd/Makefile (user-interfaces): Add auth_request and auth_reply. FIXME: this doesn't actually check uid/gid. --- hurd/Makefile | 2 sysdeps/mach/hurd/recvmsg.c | 137 ++++++++++++++++++++++++++++++++++++++++++++ sysdeps/mach/hurd/sendmsg.c | 36 +++++++++++ 3 files changed, 175 insertions(+) --- a/sysdeps/mach/hurd/recvmsg.c +++ b/sysdeps/mach/hurd/recvmsg.c @@ -24,6 +24,123 @@ #include #include +static unsigned +contains_uid (unsigned int n, __uid_t uids[n], __uid_t uid) +{ + unsigned i; + + for (i = 0; i < n; i++) + if (uids[i] == uid) + return 1; + return 0; +} + +static unsigned +contains_gid (unsigned int n, __gid_t gids[n], __gid_t gid) +{ + unsigned i; + + for (i = 0; i < n; i++) + if (gids[i] == gid) + return 1; + return 0; +} + +/* Check the passed credentials. */ +static error_t +check_auth (mach_port_t rendezvous, + __pid_t pid, + __uid_t uid, __uid_t euid, + __gid_t gid, + int ngroups, __gid_t groups[ngroups]) +{ + error_t err; + mach_msg_type_number_t neuids = CMGROUP_MAX, nauids = CMGROUP_MAX; + mach_msg_type_number_t negids = CMGROUP_MAX, nagids = CMGROUP_MAX; + __uid_t euids_buf[neuids], auids_buf[nauids]; + __gid_t egids_buf[negids], agids_buf[nagids]; + __uid_t *euids = euids_buf, *auids = auids_buf; + __gid_t *egids = egids_buf, *agids = agids_buf; + + struct procinfo *pi = NULL; + mach_msg_type_number_t pi_size = 0; + int flags = PI_FETCH_TASKINFO; + char *tw = NULL; + mach_msg_type_number_t tw_size = 0; + unsigned i; + + err = __mach_port_mod_refs (mach_task_self (), rendezvous, + MACH_PORT_RIGHT_SEND, 1); + if (err) + goto out; + + do + err = __USEPORT + (AUTH, __auth_server_authenticate (port, + rendezvous, MACH_MSG_TYPE_COPY_SEND, + MACH_PORT_NULL, 0, + &euids, &neuids, &auids, &nauids, + &egids, &negids, &agids, &nagids)); + while (err == EINTR); + if (err) + goto out; + + /* Check whether this process indeed has these IDs */ + if ( !contains_uid (neuids, euids, uid) + && !contains_uid (nauids, auids, uid) + || !contains_uid (neuids, euids, euid) + && !contains_uid (nauids, auids, euid) + || !contains_gid (negids, egids, gid) + && !contains_gid (nagids, agids, gid) + ) + { + err = EIO; + goto out; + } + + /* Check groups */ + for (i = 0; i < ngroups; i++) + if ( !contains_gid (negids, egids, groups[i]) + && !contains_gid (nagids, agids, groups[i])) + { + err = EIO; + goto out; + } + + /* Check PID */ + /* XXX: Using proc_getprocinfo until + proc_user_authenticate proc_server_authenticate is implemented + */ + /* Get procinfo to check the owner. Maybe he faked the pid, but at least we + check the owner. */ + err = __USEPORT (PROC, __proc_getprocinfo (port, pid, &flags, + (procinfo_t *)&pi, + &pi_size, &tw, &tw_size)); + if (err) + goto out; + + if ( !contains_uid (neuids, euids, pi->owner) + && !contains_uid (nauids, auids, pi->owner)) + err = EIO; + +out: + __mach_port_deallocate (__mach_task_self (), rendezvous); + if (euids != euids_buf) + __vm_deallocate (__mach_task_self(), (vm_address_t) euids, neuids * sizeof(uid_t)); + if (auids != auids_buf) + __vm_deallocate (__mach_task_self(), (vm_address_t) auids, nauids * sizeof(uid_t)); + if (egids != egids_buf) + __vm_deallocate (__mach_task_self(), (vm_address_t) egids, negids * sizeof(uid_t)); + if (agids != agids_buf) + __vm_deallocate (__mach_task_self(), (vm_address_t) agids, nagids * sizeof(uid_t)); + if (tw_size) + __vm_deallocate (__mach_task_self(), (vm_address_t) tw, tw_size); + if (pi_size) + __vm_deallocate (__mach_task_self(), (vm_address_t) pi, pi_size); + + return err; +} + /* Receive a message as described by MESSAGE from socket FD. Returns the number of bytes read or -1 for errors. */ ssize_t @@ -211,6 +328,21 @@ newfds++; } } + else if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_CREDS) + { + /* SCM_CREDS support. */ + /* Check received credentials */ + struct cmsgcred *ucredp = (struct cmsgcred *) CMSG_DATA(cmsg); + + err = check_auth (ports[i], + ucredp->cmcred_pid, + ucredp->cmcred_uid, ucredp->cmcred_euid, + ucredp->cmcred_gid, + ucredp->cmcred_ngroups, ucredp->cmcred_groups); + if (err) + goto cleanup; + i++; + } } for (i = 0; i < nports; i++) @@ -241,6 +373,11 @@ __mach_port_deallocate (__mach_task_self (), ports[ii]); } } + else if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_CREDS) + { + __mach_port_deallocate (__mach_task_self (), ports[ii]); + ii++; + } } } --- a/sysdeps/mach/hurd/sendmsg.c +++ b/sysdeps/mach/hurd/sendmsg.c @@ -19,11 +19,13 @@ #include #include #include +#include #include #include #include #include +#include #include #include "hurd/hurdsocket.h" @@ -113,6 +115,8 @@ if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) nports += (cmsg->cmsg_len - CMSG_ALIGN (sizeof (struct cmsghdr))) / sizeof (int); + else if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_CREDS) + nports++; if (nports) ports = __alloca (nports * sizeof (mach_port_t)); @@ -147,6 +151,38 @@ goto out; } } + else if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_CREDS) + { + /* SCM_CREDS support: send credentials. */ + mach_port_t rendezvous = __mach_reply_port (), reply; + struct cmsgcred *ucredp; + + err = __mach_port_insert_right (mach_task_self (), rendezvous, + rendezvous, MACH_MSG_TYPE_MAKE_SEND); + ports[nports++] = rendezvous; + if (err) + goto out; + + ucredp = (struct cmsgcred *) CMSG_DATA(cmsg); + /* Fill in credentials data */ + ucredp->cmcred_pid = __getpid(); + ucredp->cmcred_uid = __getuid(); + ucredp->cmcred_euid = __geteuid(); + ucredp->cmcred_gid = __getgid(); + ucredp->cmcred_ngroups = + __getgroups (sizeof (ucredp->cmcred_groups) / sizeof (gid_t), + ucredp->cmcred_groups); + + /* And make auth server authenticate us. */ + reply = __mach_reply_port(); + err = __USEPORT + (AUTH, __auth_user_authenticate_request (port, + reply, MACH_MSG_TYPE_MAKE_SEND_ONCE, + rendezvous, MACH_MSG_TYPE_MAKE_SEND)); + __mach_port_deallocate (__mach_task_self (), reply); + if (err) + goto out; + } } if (addr) --- a/hurd/Makefile +++ b/hurd/Makefile @@ -45,6 +45,8 @@ inline-headers = \ interface-library := libhurduser user-interfaces := \ hurd/auth \ + hurd/auth_reply \ + hurd/auth_request \ hurd/crash \ hurd/exec \ hurd/exec_startup \