|
| 1 | +/*------------------------------------------------------------------------- |
| 2 | + * |
| 3 | + * signalfuncs.c |
| 4 | + * Functions for signalling backends |
| 5 | + * |
| 6 | + * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group |
| 7 | + * Portions Copyright (c) 1994, Regents of the University of California |
| 8 | + * |
| 9 | + * |
| 10 | + * IDENTIFICATION |
| 11 | + * src/backend/storage/ipc/signalfuncs.c |
| 12 | + * |
| 13 | + *------------------------------------------------------------------------- |
| 14 | + */ |
| 15 | +#include"postgres.h" |
| 16 | + |
| 17 | +#include<signal.h> |
| 18 | + |
| 19 | +#include"catalog/pg_authid.h" |
| 20 | +#include"miscadmin.h" |
| 21 | +#include"postmaster/syslogger.h" |
| 22 | +#include"storage/pmsignal.h" |
| 23 | +#include"storage/proc.h" |
| 24 | +#include"storage/procarray.h" |
| 25 | +#include"utils/acl.h" |
| 26 | +#include"utils/builtins.h" |
| 27 | + |
| 28 | + |
| 29 | +/* |
| 30 | + * Send a signal to another backend. |
| 31 | + * |
| 32 | + * The signal is delivered if the user is either a superuser or the same |
| 33 | + * role as the backend being signaled. For "dangerous" signals, an explicit |
| 34 | + * check for superuser needs to be done prior to calling this function. |
| 35 | + * |
| 36 | + * Returns 0 on success, 1 on general failure, 2 on normal permission error |
| 37 | + * and 3 if the caller needs to be a superuser. |
| 38 | + * |
| 39 | + * In the event of a general failure (return code 1), a warning message will |
| 40 | + * be emitted. For permission errors, doing that is the responsibility of |
| 41 | + * the caller. |
| 42 | + */ |
| 43 | +#defineSIGNAL_BACKEND_SUCCESS 0 |
| 44 | +#defineSIGNAL_BACKEND_ERROR 1 |
| 45 | +#defineSIGNAL_BACKEND_NOPERMISSION 2 |
| 46 | +#defineSIGNAL_BACKEND_NOSUPERUSER 3 |
| 47 | +staticint |
| 48 | +pg_signal_backend(intpid,intsig) |
| 49 | +{ |
| 50 | +PGPROC*proc=BackendPidGetProc(pid); |
| 51 | + |
| 52 | +/* |
| 53 | + * BackendPidGetProc returns NULL if the pid isn't valid; but by the time |
| 54 | + * we reach kill(), a process for which we get a valid proc here might |
| 55 | + * have terminated on its own. There's no way to acquire a lock on an |
| 56 | + * arbitrary process to prevent that. But since so far all the callers of |
| 57 | + * this mechanism involve some request for ending the process anyway, that |
| 58 | + * it might end on its own first is not a problem. |
| 59 | + */ |
| 60 | +if (proc==NULL) |
| 61 | +{ |
| 62 | +/* |
| 63 | + * This is just a warning so a loop-through-resultset will not abort |
| 64 | + * if one backend terminated on its own during the run. |
| 65 | + */ |
| 66 | +ereport(WARNING, |
| 67 | +(errmsg("PID %d is not a PostgreSQL server process",pid))); |
| 68 | +returnSIGNAL_BACKEND_ERROR; |
| 69 | +} |
| 70 | + |
| 71 | +/* Only allow superusers to signal superuser-owned backends. */ |
| 72 | +if (superuser_arg(proc->roleId)&& !superuser()) |
| 73 | +returnSIGNAL_BACKEND_NOSUPERUSER; |
| 74 | + |
| 75 | +/* Users can signal backends they have role membership in. */ |
| 76 | +if (!has_privs_of_role(GetUserId(),proc->roleId)&& |
| 77 | +!has_privs_of_role(GetUserId(),DEFAULT_ROLE_SIGNAL_BACKENDID)) |
| 78 | +returnSIGNAL_BACKEND_NOPERMISSION; |
| 79 | + |
| 80 | +/* |
| 81 | + * Can the process we just validated above end, followed by the pid being |
| 82 | + * recycled for a new process, before reaching here? Then we'd be trying |
| 83 | + * to kill the wrong thing. Seems near impossible when sequential pid |
| 84 | + * assignment and wraparound is used. Perhaps it could happen on a system |
| 85 | + * where pid re-use is randomized. That race condition possibility seems |
| 86 | + * too unlikely to worry about. |
| 87 | + */ |
| 88 | + |
| 89 | +/* If we have setsid(), signal the backend's whole process group */ |
| 90 | +#ifdefHAVE_SETSID |
| 91 | +if (kill(-pid,sig)) |
| 92 | +#else |
| 93 | +if (kill(pid,sig)) |
| 94 | +#endif |
| 95 | +{ |
| 96 | +/* Again, just a warning to allow loops */ |
| 97 | +ereport(WARNING, |
| 98 | +(errmsg("could not send signal to process %d: %m",pid))); |
| 99 | +returnSIGNAL_BACKEND_ERROR; |
| 100 | +} |
| 101 | +returnSIGNAL_BACKEND_SUCCESS; |
| 102 | +} |
| 103 | + |
| 104 | +/* |
| 105 | + * Signal to cancel a backend process. This is allowed if you are a member of |
| 106 | + * the role whose process is being canceled. |
| 107 | + * |
| 108 | + * Note that only superusers can signal superuser-owned processes. |
| 109 | + */ |
| 110 | +Datum |
| 111 | +pg_cancel_backend(PG_FUNCTION_ARGS) |
| 112 | +{ |
| 113 | +intr=pg_signal_backend(PG_GETARG_INT32(0),SIGINT); |
| 114 | + |
| 115 | +if (r==SIGNAL_BACKEND_NOSUPERUSER) |
| 116 | +ereport(ERROR, |
| 117 | +(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), |
| 118 | + (errmsg("must be a superuser to cancel superuser query")))); |
| 119 | + |
| 120 | +if (r==SIGNAL_BACKEND_NOPERMISSION) |
| 121 | +ereport(ERROR, |
| 122 | +(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), |
| 123 | + (errmsg("must be a member of the role whose query is being canceled or member of pg_signal_backend")))); |
| 124 | + |
| 125 | +PG_RETURN_BOOL(r==SIGNAL_BACKEND_SUCCESS); |
| 126 | +} |
| 127 | + |
| 128 | +/* |
| 129 | + * Signal to terminate a backend process. This is allowed if you are a member |
| 130 | + * of the role whose process is being terminated. |
| 131 | + * |
| 132 | + * Note that only superusers can signal superuser-owned processes. |
| 133 | + */ |
| 134 | +Datum |
| 135 | +pg_terminate_backend(PG_FUNCTION_ARGS) |
| 136 | +{ |
| 137 | +intr=pg_signal_backend(PG_GETARG_INT32(0),SIGTERM); |
| 138 | + |
| 139 | +if (r==SIGNAL_BACKEND_NOSUPERUSER) |
| 140 | +ereport(ERROR, |
| 141 | +(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), |
| 142 | + (errmsg("must be a superuser to terminate superuser process")))); |
| 143 | + |
| 144 | +if (r==SIGNAL_BACKEND_NOPERMISSION) |
| 145 | +ereport(ERROR, |
| 146 | +(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), |
| 147 | + (errmsg("must be a member of the role whose process is being terminated or member of pg_signal_backend")))); |
| 148 | + |
| 149 | +PG_RETURN_BOOL(r==SIGNAL_BACKEND_SUCCESS); |
| 150 | +} |
| 151 | + |
| 152 | +/* |
| 153 | + * Signal to reload the database configuration |
| 154 | + * |
| 155 | + * Permission checking for this function is managed through the normal |
| 156 | + * GRANT system. |
| 157 | + */ |
| 158 | +Datum |
| 159 | +pg_reload_conf(PG_FUNCTION_ARGS) |
| 160 | +{ |
| 161 | +if (kill(PostmasterPid,SIGHUP)) |
| 162 | +{ |
| 163 | +ereport(WARNING, |
| 164 | +(errmsg("failed to send signal to postmaster: %m"))); |
| 165 | +PG_RETURN_BOOL(false); |
| 166 | +} |
| 167 | + |
| 168 | +PG_RETURN_BOOL(true); |
| 169 | +} |
| 170 | + |
| 171 | + |
| 172 | +/* |
| 173 | + * Rotate log file |
| 174 | + * |
| 175 | + * This function is kept to support adminpack 1.0. |
| 176 | + */ |
| 177 | +Datum |
| 178 | +pg_rotate_logfile(PG_FUNCTION_ARGS) |
| 179 | +{ |
| 180 | +if (!superuser()) |
| 181 | +ereport(ERROR, |
| 182 | +(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), |
| 183 | + (errmsg("must be superuser to rotate log files with adminpack 1.0"), |
| 184 | +errhint("Consider using pg_logfile_rotate(), which is part of core, instead.")))); |
| 185 | + |
| 186 | +if (!Logging_collector) |
| 187 | +{ |
| 188 | +ereport(WARNING, |
| 189 | +(errmsg("rotation not possible because log collection not active"))); |
| 190 | +PG_RETURN_BOOL(false); |
| 191 | +} |
| 192 | + |
| 193 | +SendPostmasterSignal(PMSIGNAL_ROTATE_LOGFILE); |
| 194 | +PG_RETURN_BOOL(true); |
| 195 | +} |
| 196 | + |
| 197 | +/* |
| 198 | + * Rotate log file |
| 199 | + * |
| 200 | + * Permission checking for this function is managed through the normal |
| 201 | + * GRANT system. |
| 202 | + */ |
| 203 | +Datum |
| 204 | +pg_rotate_logfile_v2(PG_FUNCTION_ARGS) |
| 205 | +{ |
| 206 | +if (!Logging_collector) |
| 207 | +{ |
| 208 | +ereport(WARNING, |
| 209 | +(errmsg("rotation not possible because log collection not active"))); |
| 210 | +PG_RETURN_BOOL(false); |
| 211 | +} |
| 212 | + |
| 213 | +SendPostmasterSignal(PMSIGNAL_ROTATE_LOGFILE); |
| 214 | +PG_RETURN_BOOL(true); |
| 215 | +} |