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Add pg_ls_logdir() and pg_ls_waldir() functions. 

These functions are intended to be used by monitoring tools, and,
unlike pg_ls_dir(), access to them can be granted to non-superusers,
so that those monitoring tools can observe the principle of least
privilege.

Dave Page, revised by me, and also reviewed a bit by Thomas Munro.

Discussion: http://postgr.es/m/CA+OCxow-X=D2fWdKy+HP+vQ1LtrgbsYQ=CshzZBqyFT5jOYrFw@mail.gmail.com
This commit is contained in:
Robert Haas 2017-03-16 15:05:02 -04:00
parent b30fb56b07
commit befd73c50f
5 changed files with 147 additions and 3 deletions
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45
doc/src/sgml/func.sgml
View File

@ -19646,7 +19646,8 @@ postgres=# SELECT * FROM pg_walfile_name_offset(pg_stop_backup());
database cluster directory and the <varname>log_directory</> can be
accessed. Use a relative path for files in the cluster directory,
and a path matching the <varname>log_directory</> configuration setting
for log files. Use of these functions is restricted to superusers.
for log files. Use of these functions is restricted to superusers
except where stated otherwise.
</para>
<table id="functions-admin-genfile-table">
@ -19667,6 +19668,26 @@ postgres=# SELECT * FROM pg_walfile_name_offset(pg_stop_backup());
List the contents of a directory.
</entry>
</row>
<row>
<entry>
<literal><function>pg_ls_logdir()</function></literal>
</entry>
<entry><type>setof record</type></entry>
<entry>
List the name, size, and last modification time of files in the log
directory. Access may be granted to non-superuser roles.
</entry>
</row>
<row>
<entry>
<literal><function>pg_ls_waldir()</function></literal>
</entry>
<entry><type>setof record</type></entry>
<entry>
List the name, size, and last modification time of files in the WAL
directory. Access may be granted to non-superuser roles.
</entry>
</row>
<row>
<entry>
<literal><function>pg_read_file(<parameter>filename</> <type>text</> [, <parameter>offset</> <type>bigint</>, <parameter>length</> <type>bigint</> [, <parameter>missing_ok</> <type>boolean</>] ])</function></literal>
@ -19699,7 +19720,7 @@ postgres=# SELECT * FROM pg_walfile_name_offset(pg_stop_backup());
</table>
<para>
All of these functions take an optional <parameter>missing_ok</> parameter,
Some of these functions take an optional <parameter>missing_ok</> parameter,
which specifies the behavior when the file or directory does not exist.
If <literal>true</literal>, the function returns NULL (except
<function>pg_ls_dir</>, which returns an empty result set). If
@ -19719,6 +19740,26 @@ postgres=# SELECT * FROM pg_walfile_name_offset(pg_stop_backup());
empty directory from an non-existent directory.
</para>
<indexterm>
<primary>pg_ls_logdir</primary>
</indexterm>
<para>
<function>pg_ls_logdir</> returns the name, size, and last modified time
(mtime) of each file in the log directory. By default, only superusers
can use this function, but access may be granted to others using
<command>GRANT</command>.
</para>
<indexterm>
<primary>pg_ls_waldir</primary>
</indexterm>
<para>
<function>pg_ls_waldir</> returns the name, size, and last modified time
(mtime) of each file in the write ahead log (WAL) directory. By
default only superusers can use this function, but access may be granted
to others using <command>GRANT</command>.
</para>
<indexterm>
<primary>pg_read_file</primary>
</indexterm>

3
src/backend/catalog/system_views.sql
View File

@ -1102,3 +1102,6 @@ REVOKE EXECUTE ON FUNCTION pg_stat_reset() FROM public;
REVOKE EXECUTE ON FUNCTION pg_stat_reset_shared(text) FROM public;
REVOKE EXECUTE ON FUNCTION pg_stat_reset_single_table_counters(oid) FROM public;
REVOKE EXECUTE ON FUNCTION pg_stat_reset_single_function_counters(oid) FROM public;
REVOKE EXECUTE ON FUNCTION pg_ls_logdir() FROM public;
REVOKE EXECUTE ON FUNCTION pg_ls_waldir() FROM public;

94
src/backend/utils/adt/genfile.c
View File

@ -21,6 +21,7 @@
#include <dirent.h>
#include "access/htup_details.h"
#include "access/xlog_internal.h"
#include "catalog/pg_type.h"
#include "funcapi.h"
#include "mb/pg_wchar.h"
@ -473,3 +474,96 @@ pg_ls_dir_1arg(PG_FUNCTION_ARGS)
{
return pg_ls_dir(fcinfo);
}
/* Generic function to return a directory listing of files */
static Datum
pg_ls_dir_files(FunctionCallInfo fcinfo, char *dir)
{
FuncCallContext *funcctx;
struct dirent *de;
directory_fctx *fctx;
if (SRF_IS_FIRSTCALL())
{
MemoryContext oldcontext;
TupleDesc tupdesc;
funcctx = SRF_FIRSTCALL_INIT();
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
fctx = palloc(sizeof(directory_fctx));
tupdesc = CreateTemplateTupleDesc(3, false);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "name",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "size",
INT8OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 3, "modification",
TIMESTAMPTZOID, -1, 0);
funcctx->tuple_desc = BlessTupleDesc(tupdesc);
fctx->location = pstrdup(dir);
fctx->dirdesc = AllocateDir(fctx->location);
if (!fctx->dirdesc)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read directory \"%s\": %m",
fctx->location)));
funcctx->user_fctx = fctx;
MemoryContextSwitchTo(oldcontext);
}
funcctx = SRF_PERCALL_SETUP();
fctx = (directory_fctx *) funcctx->user_fctx;
while ((de = ReadDir(fctx->dirdesc, fctx->location)) != NULL)
{
Datum values[3];
bool nulls[3];
char path[MAXPGPATH];
struct stat attrib;
HeapTuple tuple;
/* Skip hidden files */
if (de->d_name[0] == '.')
continue;
/* Get the file info */
snprintf(path, MAXPGPATH, "%s/%s", fctx->location, de->d_name);
if (stat(path, &attrib) < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not stat directory \"%s\": %m", dir)));
/* Ignore anything but regular files */
if (!S_ISREG(attrib.st_mode))
continue;
values[0] = CStringGetTextDatum(de->d_name);
values[1] = Int64GetDatum((int64) attrib.st_size);
values[2] = TimestampTzGetDatum(time_t_to_timestamptz(attrib.st_mtime));
memset(nulls, 0, sizeof(nulls));
tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
SRF_RETURN_NEXT(funcctx, HeapTupleGetDatum(tuple));
}
FreeDir(fctx->dirdesc);
SRF_RETURN_DONE(funcctx);
}
/* Function to return the list of files in the log directory */
Datum
pg_ls_logdir(PG_FUNCTION_ARGS)
{
return pg_ls_dir_files(fcinfo, Log_directory);
}
/* Function to return the list of files in the WAL directory */
Datum
pg_ls_waldir(PG_FUNCTION_ARGS)
{
return pg_ls_dir_files(fcinfo, XLOGDIR);
}

2
src/include/catalog/catversion.h
View File

@ -53,6 +53,6 @@
*/
/* yyyymmddN */
#define CATALOG_VERSION_NO 201703151
#define CATALOG_VERSION_NO 201703161
#endif

6
src/include/catalog/pg_proc.h
View File

@ -5398,6 +5398,12 @@ DESCR("pg_controldata init state information as a function");
DATA(insert OID = 3445 ( pg_import_system_collations PGNSP PGUID 12 100 0 0 0 f f f f t f v r 2 0 2278 "16 4089" _null_ _null_ "{if_not_exists,schema}" _null_ _null_ pg_import_system_collations _null_ _null_ _null_ ));
DESCR("import collations from operating system");
/* system management/monitoring related functions */
DATA(insert OID = 3353 ( pg_ls_logdir PGNSP PGUID 12 10 20 0 0 f f f f t t v s 0 0 2249 "" "{25,20,1184}" "{o,o,o}" "{name,size,modification}" _null_ _null_ pg_ls_logdir _null_ _null_ _null_ ));
DESCR("list files in the log directory");
DATA(insert OID = 3354 ( pg_ls_waldir PGNSP PGUID 12 10 20 0 0 f f f f t t v s 0 0 2249 "" "{25,20,1184}" "{o,o,o}" "{name,size,modification}" _null_ _null_ pg_ls_waldir _null_ _null_ _null_ ));
DESCR("list of files in the WAL directory");
/*
* Symbolic values for provolatile column: these indicate whether the result
* of a function is dependent *only* on the values of its explicit arguments,