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Allow "-C variable" and "--describe-config" even to root users.

There's no really compelling reason to refuse to do these read-only,non-server-starting options as root, and there's at least one goodreason to allow -C: pg_ctl uses -C to find out the true data directorylocation when pointed at a config-only directory. On Windows, this isdone before dropping administrator privileges, which means that pg_ctlfails for administrators if and only if a config-only layout is used.Since the root-privilege check is done so early in startup, it's a bitawkward to check for these switches. Make the somewhat arbitrarydecision that we'll only skip the root check if -C is the first switch.This is not just to make the code a bit simpler: it also guarantees thatwe can't misinterpret a --boot mode switch. (While AuxiliaryProcessMaindoesn't currently recognize any such switch, it might have one in thefuture.) This is no particular problem for pg_ctl, and since the wholebehavior is undocumented anyhow, it's not a documentation issue either.(--describe-config only works as the first switch anyway, so this isno restriction for that case either.)Back-patch to 9.2 where pg_ctl first began to use -C.MauMau, heavily edited by me

1 parent598f303 commit7d1a0f5Copy full SHA for 7d1a0f5

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2 files changed

+28

-6

lines changed

src
- backend/main
  - main.c
- bin/pg_ctl
  - pg_ctl.c

2 files changed

+28

-6

lines changed

`‎src/backend/main/main.c‎`

Lines changed: 23 additions & 3 deletions

Original file line number	Diff line number	Diff line change
`@@ -59,6 +59,8 @@ static char get_current_username(const char progname);`
`59`	`59`	`int`
`60`	`60`	`main(intargc,char*argv[])`
`61`	`61`	`{`
	`62`	`+booldo_check_root= true;`
	`63`	`+`
`62`	`64`	`progname=get_progname(argv[0]);`
`63`	`65`
`64`	`66`	`/*`
`@@ -153,7 +155,8 @@ main(int argc, char *argv[])`
`153`	`155`	`unsetenv("LC_ALL");`
`154`	`156`
`155`	`157`	`/*`
`156`		`- * Catch standard options before doing much else`
	`158`	`+ * Catch standard options before doing much else, in particular before we`
	`159`	`+ * insist on not being root.`
`157`	`160`	`*/`
`158`	`161`	`if (argc>1)`
`159`	`162`	`{`
`@@ -167,12 +170,29 @@ main(int argc, char *argv[])`
`167`	`170`	`puts("postgres (PostgreSQL) "PG_VERSION);`
`168`	`171`	`exit(0);`
`169`	`172`	`}`
	`173`	`+`
	`174`	`+/*`
	`175`	`+ * In addition to the above, we allow "--describe-config" and "-C var"`
	`176`	`+ * to be called by root. This is reasonably safe since these are`
	`177`	`+ * read-only activities. The -C case is important because pg_ctl may`
	`178`	`+ * try to invoke it while still holding administrator privileges on`
	`179`	`+ * Windows. Note that while -C can normally be in any argv position,`
	`180`	`+ * if you wanna bypass the root check you gotta put it first. This`
	`181`	`+ * reduces the risk that we might misinterpret some other mode's -C`
	`182`	`+ * switch as being the postmaster/postgres one.`
	`183`	`+ */`
	`184`	`+if (strcmp(argv[1],"--describe-config")==0)`
	`185`	`+do_check_root= false;`
	`186`	`+elseif (argc>2&&strcmp(argv[1],"-C")==0)`
	`187`	`+do_check_root= false;`
`170`	`188`	`}`
`171`	`189`
`172`	`190`	`/*`
`173`		`- * Make sure we are not running as root.`
	`191`	`+ * Make sure we are not running as root, unless it's safe for the selected`
	`192`	`+ * option.`
`174`	`193`	`*/`
`175`		`-check_root(progname);`
	`194`	`+if (do_check_root)`
	`195`	`+check_root(progname);`
`176`	`196`
`177`	`197`	`/*`
`178`	`198`	`* Dispatch to one of various subprograms depending on first argument.`

`‎src/bin/pg_ctl/pg_ctl.c‎`

Lines changed: 5 additions & 3 deletions

Original file line number	Diff line number	Diff line change
`@@ -1962,9 +1962,11 @@ adjust_data_dir(void)`
`1962`	`1962`	`else`
`1963`	`1963`	`my_exec_path=pg_strdup(exec_path);`
`1964`	`1964`
`1965`		`-snprintf(cmd,MAXPGPATH,SYSTEMQUOTE"\"%s\" %s%s -C data_directory"SYSTEMQUOTE,`
`1966`		`-my_exec_path,pgdata_opt ?pgdata_opt :"",post_opts ?`
`1967`		`-post_opts :"");`
	`1965`	`+/* it's important for -C to be the first option, see main.c */`
	`1966`	`+snprintf(cmd,MAXPGPATH,SYSTEMQUOTE"\"%s\" -C data_directory %s%s"SYSTEMQUOTE,`
	`1967`	`+my_exec_path,`
	`1968`	`+pgdata_opt ?pgdata_opt :"",`
	`1969`	`+post_opts ?post_opts :"");`
`1968`	`1970`
`1969`	`1971`	`fd=popen(cmd,"r");`
`1970`	`1972`	`if (fd==NULL\|\|fgets(filename,sizeof(filename),fd)==NULL)`

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Commit7d1a0f5

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2 files changed

2 files changed

`‎src/backend/main/main.c‎`

`‎src/bin/pg_ctl/pg_ctl.c‎`

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