From c8802aac28470714ec204d00342f6ecbca45908f Mon Sep 17 00:00:00 2001 From: Darren Tucker Date: Tue, 8 Dec 2009 13:39:48 +1100 Subject: [PATCH] - (dtucker) Bug #1470: Disable OOM-killing of the listening sshd on Linux, based on a patch from Vaclav Ovsik and Colin Watson. ok djm. --- ChangeLog | 4 +++ configure.ac | 5 +-- openbsd-compat/port-linux.c | 63 +++++++++++++++++++++++++++++++++++-- openbsd-compat/port-linux.h | 7 ++++- platform.c | 14 ++++++++- platform.h | 3 +- sshd.c | 1 + 7 files changed, 90 insertions(+), 7 deletions(-) diff --git a/ChangeLog b/ChangeLog index 53d89c905..7f95697f4 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,7 @@ +20091208 + - (dtucker) Bug #1470: Disable OOM-killing of the listening sshd on Linux, + based on a patch from Vaclav Ovsik and Colin Watson. ok djm. + 20091207 - (dtucker) Bug #1160: use pkg-config for opensc config if it's available. Tested by Martin Paljak. diff --git a/configure.ac b/configure.ac index 88a248fb5..94f049fc6 100644 --- a/configure.ac +++ b/configure.ac @@ -1,4 +1,4 @@ -# $Id: configure.ac,v 1.431 2009/12/07 00:15:43 dtucker Exp $ +# $Id: configure.ac,v 1.432 2009/12/08 02:39:48 dtucker Exp $ # # Copyright (c) 1999-2004 Damien Miller # @@ -15,7 +15,7 @@ # OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. AC_INIT(OpenSSH, Portable, openssh-unix-dev@mindrot.org) -AC_REVISION($Revision: 1.431 $) +AC_REVISION($Revision: 1.432 $) AC_CONFIG_SRCDIR([ssh.c]) AC_CONFIG_HEADER(config.h) @@ -589,6 +589,7 @@ main() { if (NSVersionOfRunTimeLibrary("System") >= (60 << 16)) if it doesn't return EOPNOTSUPP.]) AC_DEFINE(_PATH_BTMP, "/var/log/btmp", [log for bad login attempts]) AC_DEFINE(USE_BTMP) + AC_DEFINE(LINUX_OOM_ADJUST, 1, [Adjust Linux out-of-memory killer]) inet6_default_4in6=yes case `uname -r` in 1.*|2.0.*) diff --git a/openbsd-compat/port-linux.c b/openbsd-compat/port-linux.c index 88c601e20..cda751dea 100644 --- a/openbsd-compat/port-linux.c +++ b/openbsd-compat/port-linux.c @@ -1,4 +1,4 @@ -/* $Id: port-linux.c,v 1.6 2009/10/24 04:04:13 dtucker Exp $ */ +/* $Id: port-linux.c,v 1.7 2009/12/08 02:39:48 dtucker Exp $ */ /* * Copyright (c) 2005 Daniel Walsh @@ -23,15 +23,17 @@ #include "includes.h" +#if defined(WITH_SELINUX) || defined(LINUX_OOM_ADJUST) #include #include #include +#include -#ifdef WITH_SELINUX #include "log.h" #include "xmalloc.h" #include "port-linux.h" +#ifdef WITH_SELINUX #include #include #include @@ -204,3 +206,60 @@ ssh_selinux_change_context(const char *newname) xfree(newctx); } #endif /* WITH_SELINUX */ + +#ifdef LINUX_OOM_ADJUST +#define OOM_ADJ_PATH "/proc/self/oom_adj" +/* + * The magic "don't kill me", as documented in eg: + * http://lxr.linux.no/#linux+v2.6.32/Documentation/filesystems/proc.txt + */ +#define OOM_ADJ_NOKILL -17 + +static int oom_adj_save = INT_MIN; + +/* + * Tell the kernel's out-of-memory killer to avoid sshd. + * Returns the previous oom_adj value or zero. + */ +void +oom_adjust_setup(void) +{ + FILE *fp; + + debug3("%s", __func__); + if ((fp = fopen(OOM_ADJ_PATH, "r+")) != NULL) { + if (fscanf(fp, "%d", &oom_adj_save) != 1) + logit("error reading %s: %s", OOM_ADJ_PATH, strerror(errno)); + else { + rewind(fp); + if (fprintf(fp, "%d\n", OOM_ADJ_NOKILL) <= 0) + logit("error writing %s: %s", + OOM_ADJ_PATH, strerror(errno)); + else + verbose("Set %s from %d to %d", + OOM_ADJ_PATH, oom_adj_save, OOM_ADJ_NOKILL); + } + fclose(fp); + } +} + +/* Restore the saved OOM adjustment */ +void +oom_adjust_restore(void) +{ + FILE *fp; + + debug3("%s", __func__); + if (oom_adj_save == INT_MIN || (fp = fopen(OOM_ADJ_PATH, "w")) == NULL) + return; + + if (fprintf(fp, "%d\n", oom_adj_save) <= 0) + logit("error writing %s: %s", OOM_ADJ_PATH, strerror(errno)); + else + verbose("Set %s to %d", OOM_ADJ_PATH, oom_adj_save); + + fclose(fp); + return; +} +#endif /* LINUX_OOM_ADJUST */ +#endif /* WITH_SELINUX || LINUX_OOM_ADJUST */ diff --git a/openbsd-compat/port-linux.h b/openbsd-compat/port-linux.h index 6ad4a49f6..209d9a7a2 100644 --- a/openbsd-compat/port-linux.h +++ b/openbsd-compat/port-linux.h @@ -1,4 +1,4 @@ -/* $Id: port-linux.h,v 1.3 2009/10/24 04:04:13 dtucker Exp $ */ +/* $Id: port-linux.h,v 1.4 2009/12/08 02:39:48 dtucker Exp $ */ /* * Copyright (c) 2006 Damien Miller @@ -26,4 +26,9 @@ void ssh_selinux_setup_exec_context(char *); void ssh_selinux_change_context(const char *); #endif +#ifdef LINUX_OOM_ADJUST +void oom_adjust_restore(void); +void oom_adjust_setup(void); +#endif + #endif /* ! _PORT_LINUX_H */ diff --git a/platform.c b/platform.c index aee4b01e7..2dc4352f4 100644 --- a/platform.c +++ b/platform.c @@ -1,4 +1,4 @@ -/* $Id: platform.c,v 1.1 2006/08/30 17:24:41 djm Exp $ */ +/* $Id: platform.c,v 1.2 2009/12/08 02:39:48 dtucker Exp $ */ /* * Copyright (c) 2006 Darren Tucker. All rights reserved. @@ -21,6 +21,15 @@ #include "openbsd-compat/openbsd-compat.h" +void +platform_pre_listen(void) +{ +#ifdef LINUX_OOM_ADJUST + /* Adjust out-of-memory killer so listening process is not killed */ + oom_adjust_setup(); +#endif +} + void platform_pre_fork(void) { @@ -43,4 +52,7 @@ platform_post_fork_child(void) #ifdef USE_SOLARIS_PROCESS_CONTRACTS solaris_contract_post_fork_child(); #endif +#ifdef LINUX_OOM_ADJUST + oom_adjust_restore(); +#endif } diff --git a/platform.h b/platform.h index cf93bc57c..8a34e364e 100644 --- a/platform.h +++ b/platform.h @@ -1,4 +1,4 @@ -/* $Id: platform.h,v 1.1 2006/08/30 17:24:41 djm Exp $ */ +/* $Id: platform.h,v 1.2 2009/12/08 02:39:48 dtucker Exp $ */ /* * Copyright (c) 2006 Darren Tucker. All rights reserved. @@ -18,6 +18,7 @@ #include +void platform_pre_listen(void); void platform_pre_fork(void); void platform_post_fork_parent(pid_t child_pid); void platform_post_fork_child(void); diff --git a/sshd.c b/sshd.c index 04d8f9fa0..38aaa1820 100644 --- a/sshd.c +++ b/sshd.c @@ -1656,6 +1656,7 @@ main(int ac, char **av) if (inetd_flag) { server_accept_inetd(&sock_in, &sock_out); } else { + platform_pre_listen(); server_listen(); if (options.protocol & SSH_PROTO_1)