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6266 harden dtrace_difo_chunksize() with respect to malicious DIF

Reviewed by: Alex Wilson <alex.wilson@joyent.com>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Approved by: Garrett D'Amore <garrett@damore.org>
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bcantrill authored and rmustacc committed Sep 29, 2015
1 parent 6a9ca70 commit 395c7a3dcfc66b8b671dc4b3c4a2f0ca26449922
@@ -0,0 +1,112 @@
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source. A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright (c) 2015, Joyent, Inc. All rights reserved.
+#
+
+err=/tmp/err.$$
+
+ppriv -s A=basic,dtrace_user $$
+
+#
+# When we lack dtrace_kernel, we expect to not be able to get at kernel memory
+# via any subroutine or other vector.
+#
+# trace(func((void *)&\`utsname)); }
+/usr/sbin/dtrace -wq -Cs /dev/stdin 2> $err <<EOF
+
+#define FAIL \
+ printf("able to read kernel memory via %s!\n", badsubr); \
+ exit(2);
+
+#define CANTREAD1(func) \
+ BEGIN { badsubr = "func()"; func((void *)&\`utsname); FAIL }
+
+#define CANTREAD2(func, arg1) \
+ BEGIN { badsubr = "func()"; func((void *)&\`utsname, arg1); FAIL }
+
+#define CANTREAD2ARG1(func, arg0) \
+ BEGIN { badsubr = "func() (arg1)"; func(arg0, (void *)&\`utsname); FAIL }
+
+#define CANTREAD3(func, arg1, arg2) \
+ BEGIN { badsubr = "func()"; func((void *)&\`utsname, arg1, arg2); FAIL }
+
+CANTREAD1(mutex_owned)
+CANTREAD1(mutex_owner)
+CANTREAD1(mutex_type_adaptive)
+CANTREAD1(mutex_type_spin)
+CANTREAD1(rw_read_held)
+CANTREAD1(rw_write_held)
+CANTREAD1(rw_iswriter)
+CANTREAD3(bcopy, alloca(1), 1)
+CANTREAD1(msgsize)
+CANTREAD1(msgdsize)
+CANTREAD1(strlen)
+CANTREAD2(strchr, '!')
+CANTREAD2(strrchr, '!')
+CANTREAD2(strstr, "doogle")
+CANTREAD2ARG1(strstr, "doogle")
+CANTREAD2(index, "bagnoogle")
+CANTREAD2ARG1(index, "bagnoogle")
+CANTREAD2(rindex, "bagnoogle")
+CANTREAD2ARG1(rindex, "bagnoogle")
+CANTREAD2(strtok, "doogle")
+CANTREAD2ARG1(strtok, "doogle")
+CANTREAD2(json, "doogle")
+CANTREAD2ARG1(json, "doogle")
+CANTREAD1(toupper)
+CANTREAD1(tolower)
+CANTREAD2(ddi_pathname, 1)
+CANTREAD2(strjoin, "doogle")
+CANTREAD2ARG1(strjoin, "doogle")
+CANTREAD1(strtoll)
+CANTREAD1(dirname)
+CANTREAD1(basename)
+CANTREAD1(cleanpath)
+
+#if defined(__amd64)
+CANTREAD3(copyout, uregs[R_R9], 1)
+CANTREAD3(copyoutstr, uregs[R_R9], 1)
+#else
+#if defined(__i386)
+CANTREAD3(copyout, uregs[R_ESP], 1)
+CANTREAD3(copyoutstr, uregs[R_ESP], 1)
+#endif
+#endif
+
+BEGIN
+{
+ exit(0);
+}
+
+ERROR
+/arg4 != DTRACEFLT_KPRIV/
+{
+ printf("bad error code via %s (expected %d, found %d)\n",
+ badsubr, DTRACEFLT_KPRIV, arg4);
+ exit(3);
+}
+
+ERROR
+/arg4 == DTRACEFLT_KPRIV/
+{
+ printf("illegal kernel access properly prevented from %s\n", badsubr);
+}
+EOF
+
+status=$?
+
+if [[ $status -eq 1 ]]; then
+ cat $err
+fi
+
+exit $status
@@ -0,0 +1,26 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source. A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright (c) 2015, Joyent, Inc. All rights reserved.
+ */
+
+struct mrbig {
+ char toomany[100000];
+};
+
+struct mrbig mrbig;
+
+BEGIN
+{
+ mrbig.toomany[0] = '!';
+ exit(0);
+}
@@ -0,0 +1,26 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source. A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright (c) 2015, Joyent, Inc. All rights reserved.
+ */
+
+struct mrbig {
+ char toomany[100000];
+};
+
+this struct mrbig mrbig;
+
+BEGIN
+{
+ this->mrbig.toomany[0] = '!';
+ exit(0);
+}
@@ -1393,6 +1393,7 @@ file path=opt/SUNWdtrt/tst/common/printf/tst.wp.d.out mode=0444
file path=opt/SUNWdtrt/tst/common/privs/tst.fds.ksh mode=0444
file path=opt/SUNWdtrt/tst/common/privs/tst.func_access.ksh mode=0444
file path=opt/SUNWdtrt/tst/common/privs/tst.getf.ksh mode=0444
+file path=opt/SUNWdtrt/tst/common/privs/tst.kpriv.ksh mode=0444
file path=opt/SUNWdtrt/tst/common/privs/tst.noprivdrop.ksh mode=0444
file path=opt/SUNWdtrt/tst/common/privs/tst.noprivrestrict.ksh mode=0444
file path=opt/SUNWdtrt/tst/common/privs/tst.op_access.ksh mode=0444
@@ -1572,6 +1573,8 @@ file path=opt/SUNWdtrt/tst/common/scalars/err.D_OP_INCOMPAT.dupltype.d \
file path=opt/SUNWdtrt/tst/common/scalars/err.D_OP_INCOMPAT.dupttype.d \
mode=0444
file path=opt/SUNWdtrt/tst/common/scalars/err.D_SYNTAX.declare.d mode=0444
+file path=opt/SUNWdtrt/tst/common/scalars/err.bigglobal.d mode=0444
+file path=opt/SUNWdtrt/tst/common/scalars/err.biglocal.d mode=0444
file path=opt/SUNWdtrt/tst/common/scalars/tst.basicvar.d mode=0444
file path=opt/SUNWdtrt/tst/common/scalars/tst.basicvar.d.out mode=0444
file path=opt/SUNWdtrt/tst/common/scalars/tst.localvar.d mode=0444
@@ -118,7 +118,7 @@ int dtrace_destructive_disallow = 0;
dtrace_optval_t dtrace_nonroot_maxsize = (16 * 1024 * 1024);
size_t dtrace_difo_maxsize = (256 * 1024);
dtrace_optval_t dtrace_dof_maxsize = (8 * 1024 * 1024);
-size_t dtrace_global_maxsize = (16 * 1024);
+size_t dtrace_statvar_maxsize = (16 * 1024);
size_t dtrace_actions_max = (16 * 1024);
size_t dtrace_retain_max = 1024;
dtrace_optval_t dtrace_helper_actions_max = 1024;
@@ -592,13 +592,33 @@ dtrace_canstore_statvar(uint64_t addr, size_t sz,
dtrace_statvar_t **svars, int nsvars)
{
int i;
+ size_t maxglobalsize, maxlocalsize;
+
+ if (nsvars == 0)
+ return (0);
+
+ maxglobalsize = dtrace_statvar_maxsize;
+ maxlocalsize = (maxglobalsize + sizeof (uint64_t)) * NCPU;
for (i = 0; i < nsvars; i++) {
dtrace_statvar_t *svar = svars[i];
+ uint8_t scope;
+ size_t size;
- if (svar == NULL || svar->dtsv_size == 0)
+ if (svar == NULL || (size = svar->dtsv_size) == 0)
continue;
+ scope = svar->dtsv_var.dtdv_scope;
+
+ /*
+ * We verify that our size is valid in the spirit of providing
+ * defense in depth: we want to prevent attackers from using
+ * DTrace to escalate an orthogonal kernel heap corruption bug
+ * into the ability to store to arbitrary locations in memory.
+ */
+ VERIFY((scope == DIFV_SCOPE_GLOBAL && size < maxglobalsize) ||
+ (scope == DIFV_SCOPE_LOCAL && size < maxlocalsize));
+
if (DTRACE_INRANGE(addr, sz, svar->dtsv_data, svar->dtsv_size))
return (1);
}
@@ -4165,7 +4185,8 @@ dtrace_dif_subr(uint_t subr, uint_t rd, uint64_t *regs,
if (!dtrace_destructive_disallow &&
dtrace_priv_proc_control(state, mstate) &&
- !dtrace_istoxic(kaddr, size)) {
+ !dtrace_istoxic(kaddr, size) &&
+ dtrace_canload(kaddr, size, mstate, vstate)) {
DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
dtrace_copyout(kaddr, uaddr, size, flags);
DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
@@ -4180,7 +4201,8 @@ dtrace_dif_subr(uint_t subr, uint_t rd, uint64_t *regs,
if (!dtrace_destructive_disallow &&
dtrace_priv_proc_control(state, mstate) &&
- !dtrace_istoxic(kaddr, size)) {
+ !dtrace_istoxic(kaddr, size) &&
+ dtrace_strcanload(kaddr, size, mstate, vstate)) {
DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
dtrace_copyoutstr(kaddr, uaddr, size, flags);
DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
@@ -6078,6 +6100,11 @@ dtrace_dif_emulate(dtrace_difo_t *difo, dtrace_mstate_t *mstate,
regs[r2] ? regs[r2] :
dtrace_strsize_default) + 1;
} else {
+ if (regs[r2] > LONG_MAX) {
+ *flags |= CPU_DTRACE_ILLOP;
+ break;
+ }
+
tupregs[ttop].dttk_size = regs[r2];
}
@@ -9344,9 +9371,10 @@ dtrace_difo_validate(dtrace_difo_t *dp, dtrace_vstate_t *vstate, uint_t nregs,
break;
}
- if (v->dtdv_scope == DIFV_SCOPE_GLOBAL &&
- vt->dtdt_size > dtrace_global_maxsize) {
- err += efunc(i, "oversized by-ref global\n");
+ if ((v->dtdv_scope == DIFV_SCOPE_GLOBAL ||
+ v->dtdv_scope == DIFV_SCOPE_LOCAL) &&
+ vt->dtdt_size > dtrace_statvar_maxsize) {
+ err += efunc(i, "oversized by-ref static\n");
break;
}
}
@@ -9683,6 +9711,9 @@ dtrace_difo_chunksize(dtrace_difo_t *dp, dtrace_vstate_t *vstate)
if (srd == 0)
return;
+ if (sval > LONG_MAX)
+ return;
+
tupregs[ttop++].dttk_size = sval;
}
@@ -9744,6 +9775,19 @@ dtrace_difo_chunksize(dtrace_difo_t *dp, dtrace_vstate_t *vstate)
*/
size = P2ROUNDUP(size, sizeof (uint64_t));
+ /*
+ * Before setting the chunk size, check that we're not going
+ * to set it to a negative value...
+ */
+ if (size > LONG_MAX)
+ return;
+
+ /*
+ * ...and make certain that we didn't badly overflow.
+ */
+ if (size < ksize || size < sizeof (dtrace_dynvar_t))
+ return;
+
if (size > vstate->dtvs_dynvars.dtds_chunksize)
vstate->dtvs_dynvars.dtds_chunksize = size;
}
@@ -13184,6 +13228,8 @@ dtrace_dstate_init(dtrace_dstate_t *dstate, size_t size)
if ((dstate->dtds_chunksize = chunksize) == 0)
dstate->dtds_chunksize = DTRACE_DYNVAR_CHUNKSIZE;
+ VERIFY(dstate->dtds_chunksize < LONG_MAX);
+
if (size < (min = dstate->dtds_chunksize + sizeof (dtrace_dynhash_t)))
size = min;
@@ -13224,6 +13270,9 @@ dtrace_dstate_init(dtrace_dstate_t *dstate, size_t size)
((uintptr_t)base + hashsize * sizeof (dtrace_dynhash_t));
limit = (uintptr_t)base + size;
+ VERIFY((uintptr_t)start < limit);
+ VERIFY((uintptr_t)start >= (uintptr_t)base);
+
maxper = (limit - (uintptr_t)start) / NCPU;
maxper = (maxper / dstate->dtds_chunksize) * dstate->dtds_chunksize;
@@ -13245,7 +13294,7 @@ dtrace_dstate_init(dtrace_dstate_t *dstate, size_t size)
start = (dtrace_dynvar_t *)limit;
}
- ASSERT(limit <= (uintptr_t)base + size);
+ VERIFY(limit <= (uintptr_t)base + size);
for (;;) {
next = (dtrace_dynvar_t *)((uintptr_t)dvar +
@@ -13254,6 +13303,8 @@ dtrace_dstate_init(dtrace_dstate_t *dstate, size_t size)
if ((uintptr_t)next + dstate->dtds_chunksize >= limit)
break;
+ VERIFY((uintptr_t)dvar >= (uintptr_t)base &&
+ (uintptr_t)dvar <= (uintptr_t)base + size);
dvar->dtdv_next = next;
dvar = next;
}
@@ -1290,16 +1290,19 @@ extern void dtrace_copystr(uintptr_t, uintptr_t, size_t, volatile uint16_t *);
/*
* DTrace Assertions
*
- * DTrace calls ASSERT from probe context. To assure that a failed ASSERT
- * does not induce a markedly more catastrophic failure (e.g., one from which
- * a dump cannot be gleaned), DTrace must define its own ASSERT to be one that
- * may safely be called from probe context. This header file must thus be
- * included by any DTrace component that calls ASSERT from probe context, and
- * _only_ by those components. (The only exception to this is kernel
- * debugging infrastructure at user-level that doesn't depend on calling
- * ASSERT.)
+ * DTrace calls ASSERT and VERIFY from probe context. To assure that a failed
+ * ASSERT or VERIFY does not induce a markedly more catastrophic failure (e.g.,
+ * one from which a dump cannot be gleaned), DTrace must define its own ASSERT
+ * and VERIFY macros to be ones that may safely be called from probe context.
+ * This header file must thus be included by any DTrace component that calls
+ * ASSERT and/or VERIFY from probe context, and _only_ by those components.
+ * (The only exception to this is kernel debugging infrastructure at user-level
+ * that doesn't depend on calling ASSERT.)
*/
#undef ASSERT
+#undef VERIFY
+#define VERIFY(EX) ((void)((EX) || \
+ dtrace_assfail(#EX, __FILE__, __LINE__)))
#ifdef DEBUG
#define ASSERT(EX) ((void)((EX) || \
dtrace_assfail(#EX, __FILE__, __LINE__)))

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