X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Fcore%2Fselinux-access.c;h=bc195f3c56e746746bd03d3a5cb2edc0baeb9f34;hp=30eab68336b76f41c7e2b9005ecb10d26099a093;hb=b6e8f1f03dc8b7579f8c6b00372f136d74c45232;hpb=e2417e4143bb892e4599b01de7b031763421bb64 diff --git a/src/core/selinux-access.c b/src/core/selinux-access.c index 30eab6833..bc195f3c5 100644 --- a/src/core/selinux-access.c +++ b/src/core/selinux-access.c @@ -1,4 +1,3 @@ - /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ /*** @@ -20,33 +19,30 @@ along with systemd; If not, see . ***/ -#include "util.h" -#include "job.h" -#include "manager.h" #include "selinux-access.h" #ifdef HAVE_SELINUX -#include "dbus.h" -#include "log.h" -#include "dbus-unit.h" -#include "bus-errors.h" -#include "dbus-common.h" #include #include #include +#include #include #include #ifdef HAVE_AUDIT #include #endif -#include +#include -/* FD to send audit messages to */ -static int audit_fd = -1; -static int selinux_enabled = -1; -static int first_time = 1; -static int selinux_enforcing = 0; +#include "util.h" +#include "log.h" +#include "bus-errors.h" +#include "dbus-common.h" +#include "audit.h" +#include "selinux-util.h" +#include "audit-fd.h" + +static bool initialized = false; struct auditstruct { const char *path; @@ -56,108 +52,17 @@ struct auditstruct { gid_t gid; }; -/* - Define a mapping between the systemd method calls and the SELinux access to check. - We define two tables, one for access checks on unit files, and one for - access checks for the system in general. - - If we do not find a match in either table, then the "undefined" system - check will be called. -*/ - -static const char * const unit_methods[][2] = {{ "DisableUnitFiles", "disable" }, - { "EnableUnitFiles", "enable" }, - { "GetUnit", "status" }, - { "GetUnitFileState", "status" }, - { "Kill", "stop" }, - { "KillUnit", "stop" }, - { "LinkUnitFiles", "enable" }, - { "MaskUnitFiles", "disable" }, - { "PresetUnitFiles", "enable" }, - { "ReenableUnitFiles", "enable" }, - { "Reexecute", "start" }, - { "ReloadOrRestart", "start" }, - { "ReloadOrRestartUnit", "start" }, - { "ReloadOrTryRestart", "start" }, - { "ReloadOrTryRestartUnit", "start" }, - { "ReloadUnit", "reload" }, - { "ResetFailedUnit", "stop" }, - { "Restart", "start" }, - { "RestartUnit", "start" }, - { "Start", "start" }, - { "StartUnit", "start" }, - { "StartUnitReplace", "start" }, - { "Stop", "stop" }, - { "StopUnit", "stop" }, - { "TryRestart", "start" }, - { "TryRestartUnit", "start" }, - { "UnmaskUnitFiles", "enable" }, - { NULL, NULL } -}; - -static const char * const system_methods[][2] = { { "ClearJobs", "reboot" }, - { "CreateSnapshot", "status" }, - { "Dump", "status" }, - { "Exit", "halt" }, - { "FlushDevices", "halt" }, - { "Get", "status" }, - { "GetAll", "status" }, - { "GetJob", "status" }, - { "GetSeat", "status" }, - { "GetSession", "status" }, - { "GetSessionByPID", "status" }, - { "GetUnitByPID", "status" }, - { "GetUser", "status" }, - { "Halt", "halt" }, - { "Introspect", "status" }, - { "KExec", "reboot" }, - { "KillSession", "halt" }, - { "KillUser", "halt" }, - { "LoadUnit", "reload" }, - { "ListJobs", "status" }, - { "ListSeats", "status" }, - { "ListSessions", "status" }, - { "ListUnits", "status" }, - { "ListUnitFiles", "status" }, - { "ListUsers", "status" }, - { "LockSession", "halt" }, - { "PowerOff", "halt" }, - { "Reboot", "reboot" }, - { "Reload", "reload" }, - { "Reexecute", "reload" }, - { "ResetFailed", "reload" }, - { "Subscribe", "status" }, - { "SwithcRoot", "reboot" }, - { "SetEnvironment", "status" }, - { "SetUserLinger", "halt" }, - { "TerminateSeat", "halt" }, - { "TerminateSession", "halt" }, - { "TerminateUser", "halt" }, - { "Unsubscribe", "status" }, - { "UnsetEnvironment", "status" }, - { "UnsetAndSetEnvironment", "status" }, - { NULL, NULL } -}; - -/* - If the admin toggles the selinux enforcment mode this callback - will get called before the next access check -*/ -static int setenforce_callback(int enforcing) -{ - selinux_enforcing = enforcing; - return 0; -} - -/* This mimics dbus_bus_get_unix_user() */ static int bus_get_selinux_security_context( DBusConnection *connection, const char *name, char **scon, DBusError *error) { - DBusMessage *m = NULL, *reply = NULL; - int r; + _cleanup_dbus_message_unref_ DBusMessage *m = NULL, *reply = NULL; + DBusMessageIter iter, sub; + const char *bytes; + char *b; + int nbytes; m = dbus_message_new_method_call( DBUS_SERVICE_DBUS, @@ -165,97 +70,43 @@ static int bus_get_selinux_security_context( DBUS_INTERFACE_DBUS, "GetConnectionSELinuxSecurityContext"); if (!m) { - r = -errno; dbus_set_error_const(error, DBUS_ERROR_NO_MEMORY, NULL); - goto finish; + return -ENOMEM; } - r = dbus_message_append_args( - m, - DBUS_TYPE_STRING, &name, - DBUS_TYPE_INVALID); - if (!r) { - r = -errno; + if (!dbus_message_append_args( + m, + DBUS_TYPE_STRING, &name, + DBUS_TYPE_INVALID)) { dbus_set_error_const(error, DBUS_ERROR_NO_MEMORY, NULL); - goto finish; + return -ENOMEM; } reply = dbus_connection_send_with_reply_and_block(connection, m, -1, error); - if (!reply) { - r = -errno; - goto finish; - } + if (!reply) + return -EIO; - r = dbus_set_error_from_message(error, reply); - if (!r) { - r = -errno; - goto finish; - } + if (dbus_set_error_from_message(error, reply)) + return -EIO; - r = dbus_message_get_args( - reply, error, - DBUS_TYPE_STRING, scon, - DBUS_TYPE_INVALID); - if (!r) { - r = -errno; - goto finish; - } + if (!dbus_message_iter_init(reply, &iter)) + return -EIO; - r = 0; -finish: - if (m) - dbus_message_unref(m); + if (dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_ARRAY) + return -EIO; - if (reply) - dbus_message_unref(reply); + dbus_message_iter_recurse(&iter, &sub); + dbus_message_iter_get_fixed_array(&sub, &bytes, &nbytes); - return r; -} + b = strndup(bytes, nbytes); + if (!b) + return -ENOMEM; -static int get_cmdline(pid_t pid, char **cmdline) { - char buf[PATH_MAX]; - FILE *f; - int count; - int n; + *scon = b; - snprintf(buf, sizeof(buf), "/proc/%lu/cmdline", (unsigned long) pid); - f = fopen(buf, "re"); - if (!f) { - return -errno; - } - count = fread(buf, 1, sizeof(buf), f); - fclose(f); - if (! count) { - return -errno; - } - for (n = 0; n < count - 1; n++) - { - if (buf[n] == '\0') - buf[n] = ' '; - } - (*cmdline) = strdup(buf); - if (! (*cmdline)) { - return -errno; - } return 0; } -static int get_pid_id(pid_t pid, const char *file, uid_t *id) { - char buf[PATH_MAX]; - int r = 0; - FILE *f; - snprintf(buf, sizeof(buf), "/proc/%lu/%s", (unsigned long) pid, file); - f = fopen(buf, "re"); - if (!f) - return -errno; - fscanf(f, "%d", id); - if (ferror(f)) - r = -errno; - fclose(f); - return r; -} - -/* This mimics dbus_bus_get_unix_user() */ static int bus_get_audit_data( DBusConnection *connection, const char *name, @@ -263,88 +114,57 @@ static int bus_get_audit_data( DBusError *error) { pid_t pid; - DBusMessage *m = NULL, *reply = NULL; - int r = -1; - - m = dbus_message_new_method_call( - DBUS_SERVICE_DBUS, - DBUS_PATH_DBUS, - DBUS_INTERFACE_DBUS, - "GetConnectionUnixProcessID"); - if (!m) { - r = -errno; - dbus_set_error_const(error, DBUS_ERROR_NO_MEMORY, NULL); - goto finish; - } - - r = dbus_message_append_args( - m, - DBUS_TYPE_STRING, &name, - DBUS_TYPE_INVALID); - if (!r) { - r = -errno; - dbus_set_error_const(error, DBUS_ERROR_NO_MEMORY, NULL); - goto finish; - } - - reply = dbus_connection_send_with_reply_and_block(connection, m, -1, error); - if (!reply) { - r = -errno; - goto finish; - } + int r; - r = dbus_set_error_from_message(error, reply); - if (!r) { - r = -errno; - goto finish; - } + pid = bus_get_unix_process_id(connection, name, error); + if (pid <= 0) + return -EIO; - r = dbus_message_get_args( - reply, error, - DBUS_TYPE_UINT32, &pid, - DBUS_TYPE_INVALID); - if (!r) { - r = -errno; - goto finish; - } - - r = get_pid_id(pid, "loginuid", &(audit->loginuid)); - if (r) - goto finish; + r = audit_loginuid_from_pid(pid, &audit->loginuid); + if (r < 0) + return r; - r = get_pid_id(pid, "uid", &(audit->uid)); - if (r) - goto finish; + r = get_process_uid(pid, &audit->uid); + if (r < 0) + return r; - r = get_pid_id(pid, "gid", &(audit->gid)); - if (r) - goto finish; + r = get_process_gid(pid, &audit->gid); + if (r < 0) + return r; - r = get_cmdline(pid, &(audit->cmdline)); - if (r) - goto finish; + r = get_process_cmdline(pid, 0, true, &audit->cmdline); + if (r < 0) + return r; - r = 0; -finish: - if (m) - dbus_message_unref(m); - if (reply) - dbus_message_unref(reply); - return r; + return 0; } /* Any time an access gets denied this callback will be called with the aduit data. We then need to just copy the audit data into the msgbuf. */ -static int audit_callback(void *auditdata, security_class_t cls, - char *msgbuf, size_t msgbufsize) -{ +static int audit_callback( + void *auditdata, + security_class_t cls, + char *msgbuf, + size_t msgbufsize) { + struct auditstruct *audit = (struct auditstruct *) auditdata; + snprintf(msgbuf, msgbufsize, - "name=\"%s\" cmdline=\"%s\" auid=%d uid=%d gid=%d", - audit->path, audit->cmdline, audit->loginuid, - audit->uid, audit->gid); + "auid=%d uid=%d gid=%d%s%s%s%s%s%s", + audit->loginuid, + audit->uid, + audit->gid, + (audit->path ? " path=\"" : ""), + strempty(audit->path), + (audit->path ? "\"" : ""), + (audit->cmdline ? " cmdline=\"" : ""), + strempty(audit->cmdline), + (audit->cmdline ? "\"" : "")); + + msgbuf[msgbufsize-1] = 0; + return 0; } @@ -354,23 +174,30 @@ static int audit_callback(void *auditdata, security_class_t cls, user_avc's into the /var/log/audit/audit.log, otherwise they will be sent to syslog. */ -static int log_callback(int type, const char *fmt, ...) -{ +static int log_callback(int type, const char *fmt, ...) { va_list ap; va_start(ap, fmt); + #ifdef HAVE_AUDIT - if (audit_fd >= 0) { - char buf[LINE_MAX*2]; + if (get_audit_fd() >= 0) { + _cleanup_free_ char *buf = NULL; + int r; - vsnprintf(buf, sizeof(buf), fmt, ap); - audit_log_user_avc_message(audit_fd, AUDIT_USER_AVC, - buf, NULL, NULL, NULL, 0); - return 0; + r = vasprintf(&buf, fmt, ap); + va_end(ap); + + if (r >= 0) { + audit_log_user_avc_message(get_audit_fd(), AUDIT_USER_AVC, buf, NULL, NULL, NULL, 0); + return 0; + } + + va_start(ap, fmt); } #endif log_metav(LOG_USER | LOG_INFO, __FILE__, __LINE__, __FUNCTION__, fmt, ap); va_end(ap); + return 0; } @@ -380,104 +207,87 @@ static int log_callback(int type, const char *fmt, ...) If you want to cleanup memory you should need to call selinux_access_finish. */ static int access_init(void) { - - int r = -1; + int r; if (avc_open(NULL, 0)) { - log_full(LOG_ERR, "avc_open failed: %m\n"); + log_error("avc_open() failed: %m"); return -errno; } - selinux_set_callback(SELINUX_CB_AUDIT, (union selinux_callback) &audit_callback); - selinux_set_callback(SELINUX_CB_LOG, (union selinux_callback) &log_callback); - selinux_set_callback(SELINUX_CB_SETENFORCE, (union selinux_callback) &setenforce_callback); + selinux_set_callback(SELINUX_CB_AUDIT, (union selinux_callback) audit_callback); + selinux_set_callback(SELINUX_CB_LOG, (union selinux_callback) log_callback); - if ((r = security_getenforce()) >= 0) { - setenforce_callback(r); + if (security_getenforce() >= 0) return 0; - } + r = -errno; avc_destroy(); + return r; } -static int selinux_init(Manager *m, DBusError *error) { - +static int selinux_access_init(DBusError *error) { int r; -#ifdef HAVE_AUDIT - audit_fd = m->audit_fd; -#endif - if (!first_time) + if (initialized) return 0; - if (selinux_enabled < 0) - selinux_enabled = is_selinux_enabled() == 1; - - if (selinux_enabled) { - /* if not first time is not set, then initialize access */ + if (use_selinux()) { r = access_init(); if (r < 0) { - dbus_set_error(error, BUS_ERROR_ACCESS_DENIED, "Unable to initialize SELinux."); - + dbus_set_error(error, DBUS_ERROR_ACCESS_DENIED, "Failed to initialize SELinux."); return r; } - first_time = 0; } + initialized = true; return 0; } +void selinux_access_free(void) { + if (!initialized) + return; + + avc_destroy(); + initialized = false; +} + static int get_audit_data( - DBusConnection *connection, - DBusMessage *message, - struct auditstruct *audit, - DBusError *error) { + DBusConnection *connection, + DBusMessage *message, + struct auditstruct *audit, + DBusError *error) { const char *sender; - int r = -1; + int r, fd; + struct ucred ucred; + socklen_t len = sizeof(ucred); sender = dbus_message_get_sender(message); - if (sender) { - r = bus_get_audit_data( - connection, - sender, - audit, - error); - if (r) - goto finish; - } else { - int fd; - struct ucred ucred; - socklen_t len; - r = dbus_connection_get_unix_fd(connection, &fd); - if (!r) { - r = -EINVAL; - goto finish; - } + if (sender) + return bus_get_audit_data(connection, sender, audit, error); - r = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &ucred, &len); - if (r < 0) { - r = -errno; - log_error("Failed to determine peer credentials: %m"); - goto finish; - } - audit->uid = ucred.uid; - audit->gid = ucred.gid; - - r = get_pid_id(ucred.pid, "loginuid", &(audit->loginuid)); - if (r) - goto finish; + if (!dbus_connection_get_unix_fd(connection, &fd)) + return -EINVAL; - r = get_cmdline(ucred.pid, &(audit->cmdline)); - if (r) - goto finish; + r = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &ucred, &len); + if (r < 0) { + log_error("Failed to determine peer credentials: %m"); + return -errno; } - r = 0; + audit->uid = ucred.uid; + audit->gid = ucred.gid; -finish: - return r; + r = audit_loginuid_from_pid(ucred.pid, &audit->loginuid); + if (r < 0) + return r; + + r = get_process_cmdline(ucred.pid, 0, true, &audit->cmdline); + if (r < 0) + return r; + + return 0; } /* @@ -485,13 +295,14 @@ finish: connections. Whether it is on the bus or a local connection. */ static int get_calling_context( - DBusConnection *connection, - DBusMessage *message, - security_context_t *scon, - DBusError *error) { + DBusConnection *connection, + DBusMessage *message, + security_context_t *scon, + DBusError *error) { const char *sender; int r; + int fd; /* If sender exists then @@ -501,52 +312,25 @@ static int get_calling_context( sender = dbus_message_get_sender(message); if (sender) { r = bus_get_selinux_security_context(connection, sender, scon, error); - if (r < 0) - return -EINVAL; - } else { - int fd; - r = dbus_connection_get_unix_fd(connection, &fd); - if (! r) - return -EINVAL; - - r = getpeercon(fd, scon); - if (r < 0) - return -errno; - } - - return 0; -} + if (r >= 0) + return r; -/* - This function returns the SELinux permission to check and whether or not the - check requires a unit file. -*/ -static void selinux_perm_lookup(const char *method, const char **perm, int *require_unit) -{ - int i; - *require_unit = -1; - - for (i = 0; unit_methods[i][0]; i++) { - if (streq(method, unit_methods[i][0])) { - *perm = unit_methods[i][1]; - *require_unit = 1; - break; - } + log_error("bus_get_selinux_security_context failed: %m"); + return r; } - if (*require_unit < 0) { - for (i = 0; system_methods[i][0]; i++) { - if (streq(method, system_methods[i][0])) { - *perm = system_methods[i][1]; - *require_unit = 0; - break; - } - } + if (!dbus_connection_get_unix_fd(connection, &fd)) { + log_error("bus_connection_get_unix_fd failed %m"); + return -EINVAL; } - if (*require_unit < 0) { - *require_unit = 0; - *perm = "undefined"; + + r = getpeercon(fd, scon); + if (r < 0) { + log_error("getpeercon failed %m"); + return -errno; } + + return 0; } /* @@ -555,26 +339,49 @@ static void selinux_perm_lookup(const char *method, const char **perm, int *requ If the machine is in permissive mode it will return ok. Audit messages will still be generated if the access would be denied in enforcing mode. */ -static int selinux_access_check(DBusConnection *connection, DBusMessage *message, Manager *m, DBusError *error, const char *perm, const char *path) { - security_context_t scon = NULL; - security_context_t fcon = NULL; +int selinux_access_check( + DBusConnection *connection, + DBusMessage *message, + const char *path, + const char *permission, + DBusError *error) { + + security_context_t scon = NULL, fcon = NULL; int r = 0; const char *tclass = NULL; struct auditstruct audit; - audit.uid = audit.loginuid = audit.gid = -1; + + assert(connection); + assert(message); + assert(permission); + assert(error); + + if (!use_selinux()) + return 0; + + r = selinux_access_init(error); + if (r < 0) + return r; + + audit.uid = audit.loginuid = (uid_t) -1; + audit.gid = (gid_t) -1; audit.cmdline = NULL; audit.path = path; r = get_calling_context(connection, message, &scon, error); - if (r != 0) + if (r < 0) { + log_error("Failed to get caller's security context on: %m"); goto finish; + } if (path) { tclass = "service"; /* get the file context of the unit file */ r = getfilecon(path, &fcon); if (r < 0) { - log_full(LOG_ERR, "Failed to get security context on: %s %m\n",path); + dbus_set_error(error, DBUS_ERROR_ACCESS_DENIED, "Failed to get file context on %s.", path); + r = -errno; + log_error("Failed to get security context on %s: %m",path); goto finish; } @@ -582,61 +389,31 @@ static int selinux_access_check(DBusConnection *connection, DBusMessage *message tclass = "system"; r = getcon(&fcon); if (r < 0) { - dbus_set_error(error, BUS_ERROR_ACCESS_DENIED, "Unable to get current context, SELinux policy denies access."); + dbus_set_error(error, DBUS_ERROR_ACCESS_DENIED, "Failed to get current context."); + r = -errno; + log_error("Failed to get current process context on: %m"); goto finish; } } (void) get_audit_data(connection, message, &audit, error); - errno=0; - r = selinux_check_access(scon, fcon, tclass, perm, &audit); - if ( r < 0) { + errno = 0; + r = selinux_check_access(scon, fcon, tclass, permission, &audit); + if (r < 0) { + dbus_set_error(error, DBUS_ERROR_ACCESS_DENIED, "SELinux policy denies access."); r = -errno; - log_error("SELinux Denied \"%s\"", audit.cmdline); - - dbus_set_error(error, BUS_ERROR_ACCESS_DENIED, "SELinux policy denies access."); + log_error("SELinux policy denies access."); } - log_debug("SELinux checkaccess scon %s tcon %s tclass %s perm %s path %s: %d", scon, fcon, tclass, perm, path, r); -finish: - if (r) - r = -errno; + log_debug("SELinux access check scon=%s tcon=%s tclass=%s perm=%s path=%s cmdline=%s: %i", scon, fcon, tclass, permission, path, audit.cmdline, r); +finish: free(audit.cmdline); freecon(scon); freecon(fcon); - return r; -} - -/* - Clean up memory allocated in selinux_avc_init -*/ -void selinux_access_finish(void) { - if (!first_time) - avc_destroy(); - first_time = 1; -} - -int selinux_unit_access_check(DBusConnection *connection, DBusMessage *message, Manager *m, const char *path, DBusError *error) { - const char *perm; - int require_unit; - const char *member = dbus_message_get_member(message); - int r; - - r = selinux_init(m, error); - if (r) - return r; - - if (! selinux_enabled) - return 0; - - selinux_perm_lookup(member, &perm, &require_unit); - log_debug("SELinux dbus-unit Look %s up perm %s require_unit %d", member, perm, require_unit); - - r = selinux_access_check(connection, message, m, error, perm, path); - if ((r < 0) && (!selinux_enforcing)) { + if (r && security_getenforce() != 1) { dbus_error_init(error); r = 0; } @@ -644,67 +421,19 @@ int selinux_unit_access_check(DBusConnection *connection, DBusMessage *message, return r; } -int selinux_manager_access_check(DBusConnection *connection, DBusMessage *message, Manager *m, DBusError *error) { - int r = -1; - const char *member; - int require_unit; - const char *perm; - char *path = NULL; - - r = selinux_init(m, error); - if (r) - return r; - - if (! selinux_enabled) - return 0; - - member = dbus_message_get_member(message); - - selinux_perm_lookup(member, &perm, &require_unit); - log_debug("SELinux dbus-manager Lookup %s perm %s require_unit %d", member, perm, require_unit); - - if (require_unit) { - const char *name; - Unit *u; - - r = dbus_message_get_args( - message, - error, - DBUS_TYPE_STRING, &name, - DBUS_TYPE_INVALID); - if (!r) - goto finish; - - u = manager_get_unit(m, name); - if ( !u ) { - if ((r = manager_load_unit(m, name, NULL, error, &u)) < 0) { - r = -errno; - dbus_set_error(error, BUS_ERROR_NO_SUCH_UNIT, "Unit %s is not loaded.", name); - goto finish; - } - } - - path = (u->fragment_path ? u->fragment_path: u->source_path); - } - r = selinux_access_check(connection, message, m, error, perm, path); +#else -finish: - /* if SELinux is in permissive mode return 0 */ - if (r && (!selinux_enforcing)) { - dbus_error_init(error); - r = 0; - } - return r; -} +int selinux_access_check( + DBusConnection *connection, + DBusMessage *message, + const char *path, + const char *permission, + DBusError *error) { -#else -int selinux_unit_access_check(DBusConnection *connection, DBusMessage *message, Manager *m, const char *path, DBusError *error) { return 0; } -int selinux_manager_access_check(DBusConnection *connection, DBusMessage *message, Manager *m, DBusError *error) { - return 0; +void selinux_access_free(void) { } -void selinux_access_finish(void) {} #endif