From nobody Sat Nov 13 19:09:35 2021 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 02B501848949 for ; Sat, 13 Nov 2021 19:09:43 +0000 (UTC) (envelope-from jrtc27@jrtc27.com) Received: from mail-wm1-f53.google.com (mail-wm1-f53.google.com [209.85.128.53]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1D4" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4Hs4lB6Dz1z4hCF for ; Sat, 13 Nov 2021 19:09:42 +0000 (UTC) (envelope-from jrtc27@jrtc27.com) Received: by mail-wm1-f53.google.com with SMTP id o29so10467410wms.2 for ; Sat, 13 Nov 2021 11:09:42 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=tJit0HGNBxxBQiavC9gryjS2WsDg+TFPi/Q6Tvxz6vY=; b=4gG+n+h3oyLGVc1wrvvq+q4uPakLGW0l+fYsTU+z2sXw5F3t6rybrVk6/M1cO76otr zvEZXGWk+yCboQ3pODXs8XGp6LaTVOPc4+RU6VsqgdIxBWi1DmG8754DUFrmN4cpZuHn ter2NfxwlOnph+hMXHXrawVSUmt6Qv8BOhXh41DIaghczXd8e1PVqsxuhDuuIlteuaHC egzzAgdjz/JmNCOy0WjiIPgqNbty4Zd5DOe4/Z7fvxwBELhPCprz+WKUzXoP6Y013vu9 j5cuiriT4yL263yjWr6+SdLTrbZjs7GfCsgL5/Sv0woUJr64fl2ZOCZY8T29KtNlt+H8 S/uw== X-Gm-Message-State: AOAM530aqd1YAuB8bhqbPviNl6LuFKzctE8hea7Le605G4+eeQLcS+0f +y5rTzvnP1VHnRvyoj3PDxEvnPt/rP30oQ== X-Google-Smtp-Source: ABdhPJysb//gV16ljfA61sre00HnsOOCpsKp5Ta/FKmOMctdtsr5Hmu7n16ZXGbqIjkFyEZiHNukgw== X-Received: by 2002:a05:600c:1914:: with SMTP id j20mr45544992wmq.26.1636830576411; Sat, 13 Nov 2021 11:09:36 -0800 (PST) Received: from smtpclient.apple (global-5-141.nat-2.net.cam.ac.uk. [131.111.5.141]) by smtp.gmail.com with ESMTPSA id n32sm17873670wms.1.2021.11.13.11.09.35 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Sat, 13 Nov 2021 11:09:36 -0800 (PST) Content-Type: text/plain; charset=utf-8 List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-dev-commits-src-all@freebsd.org X-BeenThere: dev-commits-src-all@freebsd.org Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.120.0.1.13\)) Subject: Re: git: 64ba1f4cf3a6 - main - rtld: Implement LD_SHOW_AUXV From: Jessica Clarke In-Reply-To: Date: Sat, 13 Nov 2021 19:09:35 +0000 Cc: "src-committers@freebsd.org" , "dev-commits-src-all@freebsd.org" , "dev-commits-src-main@freebsd.org" Content-Transfer-Encoding: quoted-printable Message-Id: References: <202111131733.1ADHXekX049248@gitrepo.freebsd.org> <37FC39AA-925D-4D75-8E0A-EA14E846E3A6@freebsd.org> <110784F6-3A7A-4F27-AAEB-E9B5A8F7CF0E@freebsd.org> <2450270B-CB98-43D0-B3BE-3C6D02F9B6FD@freebsd.org> To: Konstantin Belousov X-Mailer: Apple Mail (2.3654.120.0.1.13) X-Rspamd-Queue-Id: 4Hs4lB6Dz1z4hCF X-Spamd-Bar: ---- Authentication-Results: mx1.freebsd.org; none X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[] X-ThisMailContainsUnwantedMimeParts: N On 13 Nov 2021, at 19:06, Konstantin Belousov = wrote: > On Sat, Nov 13, 2021 at 08:59:00PM +0200, Konstantin Belousov wrote: >> On Sat, Nov 13, 2021 at 06:29:24PM +0000, Jessica Clarke wrote: >>> On 13 Nov 2021, at 17:57, Jessica Clarke wrote: >>>>=20 >>>> On 13 Nov 2021, at 17:54, Jessica Clarke = wrote: >>>>>=20 >>>>> On 13 Nov 2021, at 17:33, Konstantin Belousov = wrote: >>>>>>=20 >>>>>> The branch main has been updated by kib: >>>>>>=20 >>>>>> URL: = https://cgit.FreeBSD.org/src/commit/?id=3D64ba1f4cf3a6847a1dacf4bab0409d94= 898fa168 >>>>>>=20 >>>>>> commit 64ba1f4cf3a6847a1dacf4bab0409d94898fa168 >>>>>> Author: Konstantin Belousov >>>>>> AuthorDate: 2021-11-13 01:18:13 +0000 >>>>>> Commit: Konstantin Belousov >>>>>> CommitDate: 2021-11-13 17:33:13 +0000 >>>>>>=20 >>>>>> rtld: Implement LD_SHOW_AUXV >>>>>>=20 >>>>>> It dumps auxv as seen by interpreter, right before starting any = user >>>>>> code. >>>>>>=20 >>>>>> Copied from: glibc >>>>>> Sponsored by: The FreeBSD Foundation >>>>>> MFC after: 1 week >>>>>> --- >>>>>> libexec/rtld-elf/rtld.1 | 7 +++++- >>>>>> libexec/rtld-elf/rtld.c | 67 = +++++++++++++++++++++++++++++++++++++++++++++++++ >>>>>> 2 files changed, 73 insertions(+), 1 deletion(-) >>>>>>=20 >>>>>> diff --git a/libexec/rtld-elf/rtld.1 b/libexec/rtld-elf/rtld.1 >>>>>> index 187dc105667a..66aa2bdabd17 100644 >>>>>> --- a/libexec/rtld-elf/rtld.1 >>>>>> +++ b/libexec/rtld-elf/rtld.1 >>>>>> @@ -28,7 +28,7 @@ >>>>>> .\" >>>>>> .\" $FreeBSD$ >>>>>> .\" >>>>>> -.Dd August 15, 2021 >>>>>> +.Dd November 13, 2021 >>>>>> .Dt RTLD 1 >>>>>> .Os >>>>>> .Sh NAME >>>>>> @@ -309,6 +309,11 @@ will process the filtee dependencies of the = loaded objects immediately, >>>>>> instead of postponing it until required. >>>>>> Normally, the filtees are opened at the time of the first symbol = resolution >>>>>> from the filter object. >>>>>> +.It Ev LD_SHOW_AUXV >>>>>> +If set, causes >>>>>> +.Nm >>>>>> +to dump content of the aux vector to standard output, before = passing >>>>>> +control to any user code. >>>>>> .El >>>>>> .Sh DIRECT EXECUTION MODE >>>>>> .Nm >>>>>> diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c >>>>>> index c173c5a6e22e..0475134b0d96 100644 >>>>>> --- a/libexec/rtld-elf/rtld.c >>>>>> +++ b/libexec/rtld-elf/rtld.c >>>>>> @@ -104,6 +104,7 @@ static Obj_Entry *dlopen_object(const char = *name, int fd, Obj_Entry *refobj, >>>>>> static Obj_Entry *do_load_object(int, const char *, char *, = struct stat *, int); >>>>>> static int do_search_info(const Obj_Entry *obj, int, struct = dl_serinfo *); >>>>>> static bool donelist_check(DoneList *, const Obj_Entry *); >>>>>> +static void dump_auxv(Elf_Auxinfo **aux_info); >>>>>> static void errmsg_restore(struct dlerror_save *); >>>>>> static struct dlerror_save *errmsg_save(void); >>>>>> static void *fill_search_info(const char *, size_t, void *); >>>>>> @@ -364,6 +365,7 @@ enum { >>>>>> LD_TRACE_LOADED_OBJECTS_FMT1, >>>>>> LD_TRACE_LOADED_OBJECTS_FMT2, >>>>>> LD_TRACE_LOADED_OBJECTS_ALL, >>>>>> + LD_SHOW_AUXV, >>>>>> }; >>>>>>=20 >>>>>> struct ld_env_var_desc { >>>>>> @@ -396,6 +398,7 @@ static struct ld_env_var_desc ld_env_vars[] =3D= { >>>>>> LD_ENV_DESC(TRACE_LOADED_OBJECTS_FMT1, false), >>>>>> LD_ENV_DESC(TRACE_LOADED_OBJECTS_FMT2, false), >>>>>> LD_ENV_DESC(TRACE_LOADED_OBJECTS_ALL, false), >>>>>> + LD_ENV_DESC(SHOW_AUXV, false), >>>>>> }; >>>>>>=20 >>>>>> static const char * >>>>>> @@ -857,6 +860,9 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, = Obj_Entry **objp) >>>>>> if (rtld_verify_versions(&list_main) =3D=3D -1 && !ld_tracing) >>>>>> rtld_die(); >>>>>>=20 >>>>>> + if (ld_get_env_var(LD_SHOW_AUXV) !=3D NULL) >>>>>> + dump_auxv(aux_info); >>>>>> + >>>>>> if (ld_tracing) { /* We're done */ >>>>>> trace_loaded_objects(obj_main); >>>>>> exit(0); >>>>>> @@ -6058,6 +6064,67 @@ print_usage(const char *argv0) >>>>>> " Arguments to the executed process\n", argv0); >>>>>> } >>>>>>=20 >>>>>> +#define AUXFMT(at, xfmt) [at] =3D { .name =3D #at, .fmt =3D xfmt = } >>>>>> +static const struct auxfmt { >>>>>> + const char *name; >>>>>> + const char *fmt; >>>>>> +} auxfmts[] =3D { >>>>>> + AUXFMT(AT_NULL, NULL), >>>>>> + AUXFMT(AT_IGNORE, NULL), >>>>>> + AUXFMT(AT_EXECFD, "%d"), >>>>>> + AUXFMT(AT_PHDR, "%p"), >>>>>> + AUXFMT(AT_PHENT, "%u"), >>>>>> + AUXFMT(AT_PHNUM, "%u"), >>>>>> + AUXFMT(AT_PAGESZ, "%u"), >>>>>> + AUXFMT(AT_BASE, "%#lx"), >>>>>> + AUXFMT(AT_FLAGS, "%#lx"), >>>>>> + AUXFMT(AT_ENTRY, "%p"), >>>>>> + AUXFMT(AT_NOTELF, NULL), >>>>>> + AUXFMT(AT_UID, "%d"), >>>>>> + AUXFMT(AT_EUID, "%d"), >>>>>> + AUXFMT(AT_GID, "%d"), >>>>>> + AUXFMT(AT_EGID, "%d"), >>>>>> + AUXFMT(AT_EXECPATH, "%s"), >>>>>> + AUXFMT(AT_CANARY, "%p"), >>>>>> + AUXFMT(AT_CANARYLEN, "%u"), >>>>>> + AUXFMT(AT_OSRELDATE, "%u"), >>>>>> + AUXFMT(AT_NCPUS, "%u"), >>>>>> + AUXFMT(AT_PAGESIZES, "%p"), >>>>>> + AUXFMT(AT_PAGESIZESLEN, "%u"), >>>>>> + AUXFMT(AT_TIMEKEEP, "%p"), >>>>>> + AUXFMT(AT_STACKPROT, "%#x"), >>>>>> + AUXFMT(AT_EHDRFLAGS, "%#lx"), >>>>>> + AUXFMT(AT_HWCAP, "%#lx"), >>>>>> + AUXFMT(AT_HWCAP2, "%#lx"), >>>>>> + AUXFMT(AT_BSDFLAGS, "%#lx"), >>>>>> + AUXFMT(AT_ARGC, "%u"), >>>>>> + AUXFMT(AT_ARGV, "%p"), >>>>>> + AUXFMT(AT_ENVC, "%p"), >>>>>> + AUXFMT(AT_ENVV, "%p"), >>>>>> + AUXFMT(AT_PS_STRINGS, "%p"), >>>>>> + AUXFMT(AT_FXRNG, "%p"), >>>>>> +}; >>>>>> + >>>>>> +static void >>>>>> +dump_auxv(Elf_Auxinfo **aux_info) >>>>>> +{ >>>>>> + Elf_Auxinfo *auxp; >>>>>> + const struct auxfmt *fmt; >>>>>> + int i; >>>>>> + >>>>>> + for (i =3D 0; i < AT_COUNT; i++) { >>>>>> + auxp =3D aux_info[i]; >>>>>> + if (auxp =3D=3D NULL) >>>>>> + continue; >>>>>> + fmt =3D &auxfmts[i]; >>>>>> + if (fmt->fmt =3D=3D NULL) >>>>>> + continue; >>>>>> + rtld_fdprintf(STDOUT_FILENO, "%s:\t", = fmt->name); >>>>>> + rtld_fdprintfx(STDOUT_FILENO, fmt->fmt, = auxp->a_un.a_ptr); >>>>>> + rtld_fdprintf(STDOUT_FILENO, "\n"); >>>>>=20 >>>>> This is undefined behaviour, breaks CHERI, and totally = unnecessary. You >>>>> have a handful of cases here, just make an enum and have separate >>>>> rtld_fdprintf calls. >>>=20 >>> In particular, ignoring CHERI, unsigned ints are sign-extended to 64 >>> bits on MIPS and RISC-V. Thus by passing a 64-bit value but using a = %u, >>> you are violating the calling convention. I can=E2=80=99t currently = get GCC or >>> Clang to exploit the fact that varargs arguments are sign-extended, = but >>> on MIPS, and RISC-V GCC (Clang is currently stupid and round-trips = via >>> memory even when the va_arg calls have no branching surrounding = them, >>> rather than just grabbing from the register) there is a redundant >>> sext.w that can legally be optimised out, but would be broken by = this >>> calling convention violation. >> I might understand the argument that all non-pointer formats for auxv >> should be longs, i.e. %lu/%ld/%lx, but this is the only problem I see >> there. We do rely on having specific representations for addresses = and >> longs, and a low-level component as rtld has full rights to exercise >> this fact, same as VM subsystem or memory allocators. >>=20 >> In fact ELF spec exercises this as well. >> Our arches are either ILP32 or LP64. >>=20 >>>=20 >>> Then CHERI makes it worse because a_ptr and a_val do not have the = same >>> representation, although in practice I think passing a_ptr and = nothing >>> further does end up working on CHERI-RISC-V and Morello, just not >>> CHERI-MIPS due to being big-endian. >=20 > Ok, the following should be enough for CHERI, right? >=20 > diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c > index 0475134b0d96..cf467ae7aacd 100644 > --- a/libexec/rtld-elf/rtld.c > +++ b/libexec/rtld-elf/rtld.c > @@ -6071,33 +6071,33 @@ static const struct auxfmt { > } auxfmts[] =3D { > AUXFMT(AT_NULL, NULL), > AUXFMT(AT_IGNORE, NULL), > - AUXFMT(AT_EXECFD, "%d"), > + AUXFMT(AT_EXECFD, "%ld"), > AUXFMT(AT_PHDR, "%p"), > - AUXFMT(AT_PHENT, "%u"), > - AUXFMT(AT_PHNUM, "%u"), > - AUXFMT(AT_PAGESZ, "%u"), > + AUXFMT(AT_PHENT, "%lu"), > + AUXFMT(AT_PHNUM, "%lu"), > + AUXFMT(AT_PAGESZ, "%lu"), > AUXFMT(AT_BASE, "%#lx"), > AUXFMT(AT_FLAGS, "%#lx"), > AUXFMT(AT_ENTRY, "%p"), > AUXFMT(AT_NOTELF, NULL), > - AUXFMT(AT_UID, "%d"), > - AUXFMT(AT_EUID, "%d"), > - AUXFMT(AT_GID, "%d"), > - AUXFMT(AT_EGID, "%d"), > + AUXFMT(AT_UID, "%ld"), > + AUXFMT(AT_EUID, "%ld"), > + AUXFMT(AT_GID, "%ld"), > + AUXFMT(AT_EGID, "%ld"), > AUXFMT(AT_EXECPATH, "%s"), > AUXFMT(AT_CANARY, "%p"), > - AUXFMT(AT_CANARYLEN, "%u"), > - AUXFMT(AT_OSRELDATE, "%u"), > - AUXFMT(AT_NCPUS, "%u"), > + AUXFMT(AT_CANARYLEN, "%lu"), > + AUXFMT(AT_OSRELDATE, "%lu"), > + AUXFMT(AT_NCPUS, "%lu"), > AUXFMT(AT_PAGESIZES, "%p"), > - AUXFMT(AT_PAGESIZESLEN, "%u"), > + AUXFMT(AT_PAGESIZESLEN, "%lu"), > AUXFMT(AT_TIMEKEEP, "%p"), > - AUXFMT(AT_STACKPROT, "%#x"), > + AUXFMT(AT_STACKPROT, "%#lx"), > AUXFMT(AT_EHDRFLAGS, "%#lx"), > AUXFMT(AT_HWCAP, "%#lx"), > AUXFMT(AT_HWCAP2, "%#lx"), > AUXFMT(AT_BSDFLAGS, "%#lx"), > - AUXFMT(AT_ARGC, "%u"), > + AUXFMT(AT_ARGC, "%lu"), > AUXFMT(AT_ARGV, "%p"), > AUXFMT(AT_ENVC, "%p"), > AUXFMT(AT_ENVV, "%p"), > @@ -6105,6 +6105,15 @@ static const struct auxfmt { > AUXFMT(AT_FXRNG, "%p"), > }; >=20 > +static bool > +is_ptr_fmt(const char *fmt) > +{ > + char last; > + > + last =3D fmt[strlen(fmt) - 1]; > + return (last =3D=3D 'p' || last =3D=3D 's'); > +} > + > static void > dump_auxv(Elf_Auxinfo **aux_info) > { > @@ -6120,7 +6129,8 @@ dump_auxv(Elf_Auxinfo **aux_info) > if (fmt->fmt =3D=3D NULL) > continue; > rtld_fdprintf(STDOUT_FILENO, "%s:\t", fmt->name); > - rtld_fdprintfx(STDOUT_FILENO, fmt->fmt, = auxp->a_un.a_ptr); > + rtld_fdprintfx(STDOUT_FILENO, fmt->fmt, = is_ptr_fmt(fmt->fmt) ? > + auxp->a_un.a_ptr : auxp->a_un.a_val); > rtld_fdprintf(STDOUT_FILENO, "\n"); > } > } That should indeed work, though I=E2=80=99d argue it=E2=80=99s still not = as nice as avoiding rtld_fdprintfx entirely. Jess