From e615dc88c89142a1b7ecf7ba6f6f01ea59c61be5 Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Wed, 17 Nov 2021 20:25:19 +1300 Subject: [PATCH] Make EXEC_BACKEND work reliably on Linux and FreeBSD. Try to disable ASLR when building in EXEC_BACKEND mode (developer only), to avoid random memory mapping failures. Suggested-by: Andres Freund Discussion: https://postgr.es/m/20210806032944.m4tz7j2w47mant26%40alap3.anarazel.de --- configure | 2 +- configure.ac | 1 + src/bin/pg_ctl/pg_ctl.c | 4 ++++ src/common/exec.c | 32 ++++++++++++++++++++++++++++++++ src/include/pg_config.h.in | 3 +++ src/include/port.h | 11 +++++++++++ src/test/regress/pg_regress.c | 4 ++++ 7 files changed, 56 insertions(+), 1 deletion(-) diff --git a/configure b/configure index ded80be880..9b7033d7dd 100755 --- a/configure +++ b/configure @@ -13427,7 +13427,7 @@ $as_echo "#define HAVE_STDBOOL_H 1" >>confdefs.h fi -for ac_header in atomic.h copyfile.h execinfo.h getopt.h ifaddrs.h langinfo.h mbarrier.h poll.h sys/epoll.h sys/event.h sys/ipc.h sys/prctl.h sys/procctl.h sys/pstat.h sys/resource.h sys/select.h sys/sem.h sys/shm.h sys/sockio.h sys/tas.h sys/uio.h sys/un.h termios.h ucred.h wctype.h +for ac_header in atomic.h copyfile.h execinfo.h getopt.h ifaddrs.h langinfo.h mbarrier.h poll.h sys/epoll.h sys/event.h sys/ipc.h sys/personality.h sys/prctl.h sys/procctl.h sys/pstat.h sys/resource.h sys/select.h sys/sem.h sys/shm.h sys/sockio.h sys/tas.h sys/uio.h sys/un.h termios.h ucred.h wctype.h do : as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh` ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default" diff --git a/configure.ac b/configure.ac index 775e5c4436..9602b04e36 100644 --- a/configure.ac +++ b/configure.ac @@ -1376,6 +1376,7 @@ AC_CHECK_HEADERS(m4_normalize([ sys/epoll.h sys/event.h sys/ipc.h + sys/personality.h sys/prctl.h sys/procctl.h sys/pstat.h diff --git a/src/bin/pg_ctl/pg_ctl.c b/src/bin/pg_ctl/pg_ctl.c index 7fbbe7022e..eadb5c2297 100644 --- a/src/bin/pg_ctl/pg_ctl.c +++ b/src/bin/pg_ctl/pg_ctl.c @@ -451,6 +451,10 @@ start_postmaster(void) fflush(stdout); fflush(stderr); +#ifdef EXEC_BACKEND + pg_disable_aslr(); +#endif + pm_pid = fork(); if (pm_pid < 0) { diff --git a/src/common/exec.c b/src/common/exec.c index 81b810d4cf..e5d9174333 100644 --- a/src/common/exec.c +++ b/src/common/exec.c @@ -25,6 +25,14 @@ #include #include +#ifdef EXEC_BACKEND +#if defined(HAVE_SYS_PERSONALITY_H) +#include +#elif defined(HAVE_SYS_PROCCTL_H) +#include +#endif +#endif + /* * Hacky solution to allow expressing both frontend and backend error reports * in one macro call. First argument of log_error is an errcode() call of @@ -470,6 +478,30 @@ set_pglocale_pgservice(const char *argv0, const char *app) } } +#ifdef EXEC_BACKEND +/* + * For the benefit of PostgreSQL developers testing EXEC_BACKEND code paths on + * Unix systems (ie paths normally exercised only on Windows), provide a way to + * disable ASLR so that we avoid memory map in developer-only builds, if we + * know how on this platform. (See also the macOS-specific hack in + * sysv_shmem.c.) + */ +int +pg_disable_aslr(void) +{ +#if defined(HAVE_SYS_PERSONALITY_H) + return personality(ADDR_NO_RANDOMIZE); +#elif defined(HAVE_SYS_PROCCTL_H) && defined(PROC_ASLR_FORCE_DISABLE) + int data = PROC_ASLR_FORCE_DISABLE; + + return procctl(P_PID, 0, PROC_ASLR_CTL, &data); +#else + errno = ENOSYS; + return -1; +#endif +} +#endif + #ifdef WIN32 /* diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in index ca3592465e..a3d658644a 100644 --- a/src/include/pg_config.h.in +++ b/src/include/pg_config.h.in @@ -617,6 +617,9 @@ /* Define to 1 if you have the header file. */ #undef HAVE_SYS_IPC_H +/* Define to 1 if you have the header file. */ +#undef HAVE_SYS_PERSONALITY_H + /* Define to 1 if you have the header file. */ #undef HAVE_SYS_PRCTL_H diff --git a/src/include/port.h b/src/include/port.h index 49b4d38131..94b0f23837 100644 --- a/src/include/port.h +++ b/src/include/port.h @@ -42,6 +42,12 @@ typedef SOCKET pgsocket; typedef unsigned int socklen_t; #endif +#ifdef EXEC_BACKEND +#if defined(HAVE_SYS_PROCCTL_H) +#include +#endif +#endif + /* non-blocking */ extern bool pg_set_noblock(pgsocket sock); extern bool pg_set_block(pgsocket sock); @@ -140,6 +146,11 @@ extern char *pipe_read_line(char *cmd, char *line, int maxsize); /* Doesn't belong here, but this is used with find_other_exec(), so... */ #define PG_BACKEND_VERSIONSTR "postgres (PostgreSQL) " PG_VERSION "\n" +#ifdef EXEC_BACKEND +/* Disable ASLR before exec, for developer builds only (in exec.c) */ +extern int pg_disable_aslr(void); +#endif + #if defined(WIN32) || defined(__CYGWIN__) #define EXE ".exe" diff --git a/src/test/regress/pg_regress.c b/src/test/regress/pg_regress.c index 2c8a600bad..67c78bccf2 100644 --- a/src/test/regress/pg_regress.c +++ b/src/test/regress/pg_regress.c @@ -1246,6 +1246,10 @@ spawn_process(const char *cmdline) if (logfile) fflush(logfile); +#ifdef EXEC_BACKEND + pg_disable_aslr(); +#endif + pid = fork(); if (pid == -1) { -- 2.33.1