From 654d6151efe9808d293d4cd396bebfb7aba31a20 Mon Sep 17 00:00:00 2001 From: Shawn Webb Date: Sat, 11 Feb 2017 16:37:22 -0500 Subject: [PATCH] Introduce HardenedBSD's procfs hardening. OPNsense doesn't use procfs by default, but in case users try to use it, prevent an interesting attack where an attacker can abuse procfs to modify application execution state. This commit also introduces the PAX_HARDENING kernel option. Signed-off-by: Shawn Webb --- sys/conf/NOTES | 1 + sys/conf/files | 1 + sys/conf/options | 1 + sys/fs/procfs/procfs_dbregs.c | 12 ++- sys/fs/procfs/procfs_fpregs.c | 12 ++- sys/fs/procfs/procfs_mem.c | 7 ++ sys/fs/procfs/procfs_regs.c | 12 ++- sys/hardenedbsd/hbsd_pax_hardening.c | 115 +++++++++++++++++++++++++++ sys/sys/pax.h | 3 + 9 files changed, 158 insertions(+), 6 deletions(-) create mode 100644 sys/hardenedbsd/hbsd_pax_hardening.c diff --git a/sys/conf/NOTES b/sys/conf/NOTES index ef77f23bb6e..ea402378acb 100644 --- a/sys/conf/NOTES +++ b/sys/conf/NOTES @@ -3061,6 +3061,7 @@ options GZIO # PAX and HardenedBSD related knobs options PAX # Enable the PAX framework options PAX_ASLR # Address Space Layout Randomization +options PAX_HARDENING # Other hardening features options PAX_SEGVGUARD # ASLR bruteforce protection options HBSD_DEBUG diff --git a/sys/conf/files b/sys/conf/files index 45058eb7483..c20593770ff 100644 --- a/sys/conf/files +++ b/sys/conf/files @@ -3219,6 +3219,7 @@ fs/ext2fs/ext2_vfsops.c optional ext2fs fs/ext2fs/ext2_vnops.c optional ext2fs # hardenedbsd/hbsd_pax_common.c optional pax +hardenedbsd/hbsd_pax_hardening.c optional pax pax_hardening hardenedbsd/hbsd_pax_log.c optional pax hardenedbsd/hbsd_pax_aslr.c optional pax pax_aslr hardenedbsd/hbsd_pax_segvguard.c optional pax pax_segvguard diff --git a/sys/conf/options b/sys/conf/options index 12bd8740546..3db152789fc 100644 --- a/sys/conf/options +++ b/sys/conf/options @@ -968,6 +968,7 @@ RCTL opt_global.h # PaX-inspired hardening features PAX opt_pax.h PAX_ASLR opt_pax.h +PAX_HARDENING opt_pax.h PAX_SEGVGUARD opt_pax.h PAX_SYSCTLS opt_pax.h HBSD_DEBUG opt_pax.h diff --git a/sys/fs/procfs/procfs_dbregs.c b/sys/fs/procfs/procfs_dbregs.c index 1598443bce9..4c5f25bb4d4 100644 --- a/sys/fs/procfs/procfs_dbregs.c +++ b/sys/fs/procfs/procfs_dbregs.c @@ -44,11 +44,13 @@ */ #include "opt_compat.h" +#include "opt_pax.h" #include #include #include #include +#include #include #include #include @@ -121,11 +123,17 @@ procfs_doprocdbregs(PFS_FILL_ARGS) PROC_LOCK(p); } if (error == 0 && uio->uio_rw == UIO_WRITE) { - if (!P_SHOULDSTOP(p)) /* XXXKSE should be P_TRACED? */ + if (!P_SHOULDSTOP(p)) /* XXXKSE should be P_TRACED? */ { error = EBUSY; - else + } +#ifdef PAX_HARDENING + else if ((error = pax_procfs_harden(td2)) == 0) { +#else + else { +#endif /* XXXKSE: */ error = PROC(write, dbregs, td2, &r); + } } PROC_UNLOCK(p); diff --git a/sys/fs/procfs/procfs_fpregs.c b/sys/fs/procfs/procfs_fpregs.c index d2f01535eb5..a7a01a51e53 100644 --- a/sys/fs/procfs/procfs_fpregs.c +++ b/sys/fs/procfs/procfs_fpregs.c @@ -38,11 +38,13 @@ */ #include "opt_compat.h" +#include "opt_pax.h" #include #include #include #include +#include #include #include #include @@ -120,11 +122,17 @@ procfs_doprocfpregs(PFS_FILL_ARGS) PROC_LOCK(p); } if (error == 0 && uio->uio_rw == UIO_WRITE) { - if (!P_SHOULDSTOP(p)) + if (!P_SHOULDSTOP(p)) { error = EBUSY; - else + } +#ifdef PAX_HARDENING + else if ((error = pax_procfs_harden(td2)) == 0) { +#else + else { +#endif /* XXXKSE: */ error = PROC(write, fpregs, td2, &r); + } } PROC_UNLOCK(p); diff --git a/sys/fs/procfs/procfs_mem.c b/sys/fs/procfs/procfs_mem.c index d4a789635b0..1a8e4314d54 100644 --- a/sys/fs/procfs/procfs_mem.c +++ b/sys/fs/procfs/procfs_mem.c @@ -36,9 +36,12 @@ * $FreeBSD$ */ +#include "opt_pax.h" + #include #include #include +#include #include #include #include @@ -63,6 +66,10 @@ procfs_doprocmem(PFS_FILL_ARGS) PROC_LOCK(p); error = p_candebug(td, p); +#ifdef PAX_HARDENING + if (error == 0) + error = pax_procfs_harden(td); +#endif PROC_UNLOCK(p); if (error == 0) error = proc_rwmem(p, uio); diff --git a/sys/fs/procfs/procfs_regs.c b/sys/fs/procfs/procfs_regs.c index 3f784782d89..83c198b2629 100644 --- a/sys/fs/procfs/procfs_regs.c +++ b/sys/fs/procfs/procfs_regs.c @@ -38,11 +38,13 @@ */ #include "opt_compat.h" +#include "opt_pax.h" #include #include #include #include +#include #include #include #include @@ -120,11 +122,17 @@ procfs_doprocregs(PFS_FILL_ARGS) PROC_LOCK(p); } if (error == 0 && uio->uio_rw == UIO_WRITE) { - if (!P_SHOULDSTOP(p)) + if (!P_SHOULDSTOP(p)) { error = EBUSY; - else + } +#ifdef PAX_HARDENING + else if ((error = pax_procfs_harden(td2)) == 0) { +#else + else { +#endif /* XXXKSE: */ error = PROC(write, regs, td2, &r); + } } PROC_UNLOCK(p); diff --git a/sys/hardenedbsd/hbsd_pax_hardening.c b/sys/hardenedbsd/hbsd_pax_hardening.c new file mode 100644 index 00000000000..d84d6996357 --- /dev/null +++ b/sys/hardenedbsd/hbsd_pax_hardening.c @@ -0,0 +1,115 @@ +/*- + * Copyright (c) 2014, by Shawn Webb + * Copyright (c) 2014-2016, by Oliver Pinter + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * $FreeBSD$ + */ + +#include +__FBSDID("$FreeBSD$"); + +#include "opt_compat.h" +#include "opt_pax.h" + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "hbsd_pax_internal.h" + +FEATURE(hbsd_hardening, "Various hardening features."); + +static int pax_procfs_harden_global = PAX_FEATURE_SIMPLE_ENABLED; + +TUNABLE_INT("hardening.procfs_harden", &pax_procfs_harden_global); + +#ifdef PAX_SYSCTLS +SYSCTL_HBSD_2STATE(pax_procfs_harden_global, pr_hbsd.hardening.procfs_harden, + _hardening, procfs_harden, + CTLTYPE_INT|CTLFLAG_RWTUN|CTLFLAG_SECURE, + "Harden procfs, disabling write of /proc/pid/mem"); +#endif + +static void +pax_hardening_sysinit(void) +{ + + switch (pax_procfs_harden_global) { + case PAX_FEATURE_SIMPLE_DISABLED: + case PAX_FEATURE_SIMPLE_ENABLED: + break; + default: + printf("[HBSD HARDENING] WARNING, invalid settings in loader.conf!" + " (hardening.procfs_harden = %d)\n", pax_procfs_harden_global); + pax_procfs_harden_global = PAX_FEATURE_SIMPLE_ENABLED; + } + printf("[HBSD HARDENING] procfs hardening: %s\n", + pax_status_simple_str[pax_procfs_harden_global]); +} +SYSINIT(pax_hardening, SI_SUB_PAX, SI_ORDER_SECOND, pax_hardening_sysinit, NULL); + +void +pax_hardening_init_prison(struct prison *pr) +{ + struct prison *pr_p; + + CTR2(KTR_PAX, "%s: Setting prison %s PaX variables\n", + __func__, pr->pr_name); + + if (pr == &prison0) { + /* prison0 has no parent, use globals */ + pr->pr_hbsd.hardening.procfs_harden = + pax_procfs_harden_global; + } else { + KASSERT(pr->pr_parent != NULL, + ("%s: pr->pr_parent == NULL", __func__)); + pr_p = pr->pr_parent; + + pr->pr_hbsd.hardening.procfs_harden = + pr_p->pr_hbsd.hardening.procfs_harden; + } +} + +int +pax_procfs_harden(struct thread *td) +{ + struct prison *pr; + + pr = pax_get_prison_td(td); + + return (pr->pr_hbsd.hardening.procfs_harden ? EPERM : 0); +} diff --git a/sys/sys/pax.h b/sys/sys/pax.h index fd54d561f91..3dee76fc242 100644 --- a/sys/sys/pax.h +++ b/sys/sys/pax.h @@ -49,6 +49,9 @@ struct hbsd_features { int log; /* (p) Per-jail logging status */ int ulog; /* (p) Per-jail user visible logging status */ } log; + struct hbsd_hardening { + int procfs_harden; /* (p) Harden procfs */ + } hardening; }; #endif