Date: Wed, 30 Sep 2015 03:30:26 +0000 (UTC) From: Mark Johnston <markj@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-vendor@freebsd.org Subject: svn commit: r288408 - vendor-sys/illumos/dist/uts/common/dtrace vendor-sys/illumos/dist/uts/common/sys vendor/illumos/dist/cmd/dtrace/test/tst/common/privs vendor/illumos/dist/cmd/dtrace/test/tst/c... Message-ID: <201509300330.t8U3UQDx042363@repo.freebsd.org>
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Author: markj Date: Wed Sep 30 03:30:24 2015 New Revision: 288408 URL: https://svnweb.freebsd.org/changeset/base/288408 Log: 6266 harden dtrace_difo_chunksize() with respect to malicious DIF illumos/illumos-gate@395c7a3dcfc66b8b671dc4b3c4a2f0ca26449922 Reviewed by: Alex Wilson <alex.wilson@joyent.com> Reviewed by: Dan McDonald <danmcd@omniti.com> Approved by: Garrett D'Amore <garrett@damore.org> Author: Bryan Cantrill <bryan@joyent.com> Modified: vendor-sys/illumos/dist/uts/common/dtrace/dtrace.c vendor-sys/illumos/dist/uts/common/sys/dtrace_impl.h Changes in other areas also in this revision: Added: vendor/illumos/dist/cmd/dtrace/test/tst/common/privs/tst.kpriv.ksh vendor/illumos/dist/cmd/dtrace/test/tst/common/scalars/err.bigglobal.d (contents, props changed) vendor/illumos/dist/cmd/dtrace/test/tst/common/scalars/err.biglocal.d (contents, props changed) Modified: vendor-sys/illumos/dist/uts/common/dtrace/dtrace.c ============================================================================== --- vendor-sys/illumos/dist/uts/common/dtrace/dtrace.c Wed Sep 30 00:11:06 2015 (r288407) +++ vendor-sys/illumos/dist/uts/common/dtrace/dtrace.c Wed Sep 30 03:30:24 2015 (r288408) @@ -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, s 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, 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, 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, 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, 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, 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, */ 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 *dsta 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 *dsta ((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 *dsta 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 *dsta 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; } Modified: vendor-sys/illumos/dist/uts/common/sys/dtrace_impl.h ============================================================================== --- vendor-sys/illumos/dist/uts/common/sys/dtrace_impl.h Wed Sep 30 00:11:06 2015 (r288407) +++ vendor-sys/illumos/dist/uts/common/sys/dtrace_impl.h Wed Sep 30 03:30:24 2015 (r288408) @@ -1290,16 +1290,19 @@ extern void dtrace_copystr(uintptr_t, ui /* * 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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