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Bug 821403 - sys-apps/sandbox-3.0: handing off children to new tracer fails w/yama.ptrace_scope=1: ptrace(PTRACE_ATTACH): Operation not permitted
Summary: sys-apps/sandbox-3.0: handing off children to new tracer fails w/yama.ptrace_...
Status: CONFIRMED
Alias: None
Product: Portage Development
Classification: Unclassified
Component: Sandbox (show other bugs)
Hardware: All Linux
: Normal normal (vote)
Assignee: Sandbox Maintainers
URL:
Whiteboard:
Keywords:
Depends on: 821499 879087
Blocks:
  Show dependency tree
 
Reported: 2021-11-03 02:32 UTC by Sam James
Modified: 2022-11-02 00:50 UTC (History)
3 users (show)

See Also:
Package list:
Runtime testing required: ---


Attachments
build.log (killed after it hanged) (file_821403.txt,21.46 KB, text/plain)
2021-11-03 02:32 UTC, Sam James
Details
.config (5.10.76) (file_821403.txt,229.07 KB, text/plain)
2021-11-03 03:43 UTC, Sam James
Details
`cargo --version; rustc +stable` with sandbox debugging on (file_821403.txt,7.80 KB, text/plain)
2021-11-03 03:59 UTC, Sam James
Details
ps faux (file_821403.txt,2.53 KB, text/plain)
2021-11-03 04:06 UTC, Sam James
Details
strace -f sandbox file -L /usr/bin/rust (with debug, killed) (file_821403.txt,51.98 KB, text/plain)
2021-11-03 04:11 UTC, Sam James
Details
strace -f -o log rustc +stable (within sandbox) (file_821403.txt,9.71 KB, text/plain)
2021-11-03 04:14 UTC, Sam James
Details
strace -f -o log sandbox rustc (file_821403.txt,68.05 KB, text/plain)
2021-11-03 04:15 UTC, Sam James
Details
strace -f -o log rustc (no sandbox) (file_821403.txt,24.35 KB, text/plain)
2021-11-03 04:16 UTC, Sam James
Details
rustc (rustc,394.36 KB, application/x-sharedlib)
2021-11-03 04:17 UTC, Sam James
Details

Note You need to log in before you can comment on or make changes to this bug.
Description Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-11-03 02:32:06 UTC
0:05.13 checking for cargo... /usr/bin/cargo
 * /var/tmp/portage/sys-apps/sandbox-3.0/work/sandbox-3.0/libsandbox/trace.c:_do_ptrace():83: failure (Operation not permitted):
 * ISE:_do_ptrace: ptrace(PTRACE_ATTACH, ..., 0x0000000000000000, 0x0000000000000000): Operation not permitted

----
Portage 3.0.28 (python 3.10.0-final-0, default/linux/amd64/17.1/desktop/plasma/systemd, gcc-11.2.0, glibc-2.34, 5.10.76-gentoo-dist-hardened x86_64)
=================================================================
System uname: Linux-5.10.76-gentoo-dist-hardened-x86_64-AMD_Ryzen_9_3950X_16-Core_Processor-with-glibc2.34
KiB Mem:    16365060 total,   1672992 free
KiB Swap:   16777212 total,  16436988 free
Timestamp of repository gentoo: Wed, 03 Nov 2021 02:21:30 +0000
Head commit of repository gentoo: 0546a8d10ef977033b71485c917697b741fce29a

Timestamp of repository kde: Tue, 02 Nov 2021 14:21:06 +0000
Head commit of repository kde: f1949c88c6fb67373cdf79e3cd7ac7a76711206d

Timestamp of repository qt: Sun, 31 Oct 2021 19:53:12 +0000
Head commit of repository qt: ac9d3dde2e0467974b2692f0f83c18ea00850c26

Timestamp of repository steam-overlay: Sun, 31 Oct 2021 19:53:14 +0000
Head commit of repository steam-overlay: 89b2827ea35ef220c165a9adfb5b5187c2f3da9d

sh dash 0.5.11.5
ld GNU ld (Gentoo 2.37_p1 p1) 2.37
ccache version 4.4.2 [disabled]
app-shells/bash:          5.1_p8::gentoo
dev-lang/perl:            5.34.0-r5::gentoo
dev-lang/python:          2.7.18_p13::gentoo, 3.8.12_p1::gentoo, 3.9.7_p1::gentoo, 3.10.0_p1::gentoo
dev-lang/rust-bin:        1.56.1::gentoo
dev-util/ccache:          4.4.2::gentoo
dev-util/cmake:           3.21.4::gentoo
sys-apps/baselayout:      2.8::gentoo
sys-apps/sandbox:         3.0::gentoo
sys-devel/autoconf:       2.13-r1::gentoo, 2.71-r1::gentoo
sys-devel/automake:       1.16.5::gentoo
sys-devel/binutils:       2.37_p1-r1::gentoo
sys-devel/gcc:            9.4.0::gentoo, 10.3.0-r2::gentoo, 11.2.0::gentoo
sys-devel/gcc-config:     2.4::gentoo
sys-devel/libtool:        2.4.6-r6::gentoo
sys-devel/make:           4.3::gentoo
sys-kernel/linux-headers: 5.15::gentoo (virtual/os-headers)
sys-libs/glibc:           2.34::gentoo
Repositories:

gentoo
    location: /var/db/repos/gentoo
    sync-type: git
    sync-uri: https://github.com/gentoo-mirror/gentoo.git
    priority: -1000
    eclass-overrides: sam_c
    sync-git-verify-commit-signature: yes
    sync-git-clone-extra-opts: -b stable -c gc.reflogExpire=0 -c gc.reflogExpireUnreachable=0 -c gc.rerereresolved=0 -c gc.rerereunresolved=0 -c gc.pruneExpire=now

crossdev
    location: /var/db/repos/crossdev
    masters: gentoo
    eclass-overrides: sam_c

kde
    location: /var/db/repos/kde
    sync-type: git
    sync-uri: https://github.com/gentoo-mirror/kde.git
    masters: gentoo
    eclass-overrides: sam_c

qt
    location: /var/db/repos/qt
    sync-type: git
    sync-uri: https://github.com/gentoo-mirror/qt.git
    masters: gentoo
    eclass-overrides: sam_c

sam_c
    location: /home/sam/git/overlay
    masters: gentoo
    eclass-overrides: sam_c

steam-overlay
    location: /var/db/repos/steam-overlay
    sync-type: git
    sync-uri: https://github.com/gentoo-mirror/steam-overlay.git
    masters: gentoo
    eclass-overrides: sam_c

ACCEPT_KEYWORDS="amd64 ~amd64"
ACCEPT_LICENSE="@FREE"
CBUILD="x86_64-pc-linux-gnu"
CFLAGS="-O2 -pipe -march=native -fdiagnostics-color=always -frecord-gcc-switches"
CHOST="x86_64-pc-linux-gnu"
CONFIG_PROTECT="/etc /usr/lib64/libreoffice/program/sofficerc /usr/share/config /usr/share/gnupg/qualified.txt"
CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/dconf /etc/env.d /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo /etc/texmf/language.dat.d /etc/texmf/language.def.d /etc/texmf/updmap.d /etc/texmf/web2c"
CXXFLAGS="-O2 -pipe -march=native -fdiagnostics-color=always -frecord-gcc-switches"
DISTDIR="/var/cache/distfiles"
EMERGE_DEFAULT_OPTS="--keep-going --with-bdeps=y --complete-graph --deep --changed-deps-report=y"
ENV_UNSET="CARGO_HOME DBUS_SESSION_BUS_ADDRESS DISPLAY GOBIN GOPATH PERL5LIB PERL5OPT PERLPREFIX PERL_CORE PERL_MB_OPT PERL_MM_OPT XAUTHORITY XDG_CACHE_HOME XDG_CONFIG_HOME XDG_DATA_HOME XDG_RUNTIME_DIR"
FCFLAGS="-O2 -pipe -march=native -fdiagnostics-color=always -frecord-gcc-switches"
FEATURES="assume-digests binpkg-docompress binpkg-dostrip binpkg-logs cgroup config-protect-if-modified distlocks ebuild-locks fixlafiles ipc-sandbox mount-sandbox multilib-strict network-sandbox news parallel-fetch parallel-install pid-sandbox preserve-libs protect-owned qa-unresolved-soname-deps sandbox sfperms strict unknown-features-warn unmerge-logs unmerge-orphans userfetch userpriv usersandbox usersync xattr"
FFLAGS="-O2 -pipe -march=native -fdiagnostics-color=always -frecord-gcc-switches"
GENTOO_MIRRORS="http://mirror.bytemark.co.uk/gentoo/ http://www.mirrorservice.org/sites/distfiles.gentoo.org/ http://mirrors.soeasyto.com/distfiles.gentoo.org/ http://mirrors.gethosted.online/gentoo"
LANG="en_GB.UTF-8"
LDFLAGS="-Wl,-O1 -Wl,--as-needed -Wl,--defsym=__gentoo_check_ldflags__=0"
LINGUAS="en en_GB"
MAKEOPTS="-j24"
PKGDIR="/var/cache/binpkgs"
PORTAGE_CONFIGROOT="/"
PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --omit-dir-times --compress --force --whole-file --delete --stats --human-readable --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages --exclude=/.git"
PORTAGE_TMPDIR="/var/tmp"
USE="PIC X a52 aac acl acpi activities aes alsa amd64 avx avx2 bash-completion bluetooth branding bzip2 cairo caps cdda cdr cli crypt dbus declarative dist-kernel dri dts dvd dvdr emacs emboss encode exif f16c filecaps firewalld flac fma3 fortran gdbm gif gmp gpm graphite gtk gui hardened hunspell iconv icu ipv6 jit jpeg kde kdesu kipi kwallet lcms libglvnd libnotify libtirpc llvm-libunwind mad mmx mmxext mng mp3 mp4 mpeg multilib ncurses nls nptl ogg opengl openmp pam pango pclmul pcre pdf pgo pie plasma png policykit popcnt ppds pulseaudio qml qt5 rdrand readline sdl seccomp semantic-desktop sha spell split-usr sse sse2 sse3 sse4_1 sse4_2 sse4a ssl ssse3 startup-notification svg system-av1 system-binutils system-boost system-bootstrap system-cairo system-clang system-digest system-ffmpeg system-harfbuzz system-heimdal system-icu system-jpeg system-leveldb system-libevent system-libs system-libvpx system-libyaml system-lz4 system-mitkrb5 system-sqlite system-ssl system-tbb system-uulib system-webp system-zlib systemd threads tiff truetype udev udisks unicode upower usb verify-sig vorbis vulkan wayland widgets wxwidgets x264 xattr xcb xml xv xvid zfs zlib zsh-completion" ABI_X86="32 64" ADA_TARGET="gnat_2019" APACHE2_MODULES="authn_core authz_core socache_shmcb unixd actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache cgi cgid dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" CALLIGRA_FEATURES="karbon sheets words" COLLECTD_PLUGINS="df interface irq load memory rrdtool swap syslog" CPU_FLAGS_X86="aes avx avx2 f16c fma3 mmx mmxext pclmul popcnt rdrand sha sse sse2 sse3 sse4_1 sse4_2 sse4a ssse3" ELIBC="glibc" GPSD_PROTOCOLS="ashtech aivdm earthmate evermore fv18 garmin garmintxt gpsclock greis isync itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf skytraq superstar2 timing tsip tripmate tnt ublox ubx" INPUT_DEVICES="libinput" KERNEL="linux" L10N="en en-GB" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LIBREOFFICE_EXTENSIONS="presenter-console presenter-minimizer" LUA_SINGLE_TARGET="lua5-1" LUA_TARGETS="lua5-1" OFFICE_IMPLEMENTATION="libreoffice" PHP_TARGETS="php7-3 php7-4" POSTGRES_TARGETS="postgres12 postgres13" PYTHON_SINGLE_TARGET="python3_9" PYTHON_TARGETS="python3_9 python3_10 python3_8" RUBY_TARGETS="ruby26 ruby27" USERLAND="GNU" VIDEO_CARDS="amdgpu radeonsi radeon" XTABLES_ADDONS="quota2 psd pknock lscan length2 ipv4options ipset ipp2p iface geoip fuzzy condition tee tarpit sysrq proto steal rawnat logmark ipmark dhcpmac delude chaos account"
Unset:  CC, CPPFLAGS, CTARGET, CXX, INSTALL_MASK, LC_ALL, PORTAGE_BINHOST, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS, RUSTFLAGS
Comment 1 Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-11-03 02:32:44 UTC
Created attachment 748131 [details]
build.log (killed after it hanged)
Comment 2 Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-11-03 02:33:30 UTC
I didn't get this error/hang wiht sandbox-2.29.
Comment 3 SpanKY gentoo-dev 2021-11-03 03:37:22 UTC
building firefox is working for me w/sandbox-3.0.  so can't explain this.

we seem to have comparable FEATURES & USE settings.  but the failure itself looks pretty basic -- it's just running cargo.  do you have YAMA LSM stuff enabled in the kernel ?

can you reproduce this directly ?
  sandbox
  rustc +stable
  cargo +stable
  rustc --version --verbose
  cargo --version --verbose

rustc & cargo are dynamically linked on my system too, so not sure why your system is running these programs through the ptrace code path.
Comment 4 Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-11-03 03:43:34 UTC
Created attachment 748140 [details]
.config (5.10.76)

(In reply to SpanKY from comment #3)
> building firefox is working for me w/sandbox-3.0.  so can't explain this.
> 
> we seem to have comparable FEATURES & USE settings.  but the failure itself
> looks pretty basic -- it's just running cargo.  do you have YAMA LSM stuff
> enabled in the kernel ?

No, not intentionally anyway. Attached config but I'm not aware of having done anything weird. Note that everything works with 2.29 and I feel like I would've noticed if YAMA was messing with ptrace in general before now?

$ sysctl kernel.yama.ptrace_scope
kernel.yama.ptrace_scope = 1

Let me know if I can grab any other info.

> 
> can you reproduce this directly ?
>   sandbox
>   rustc +stable
>   cargo +stable
>   rustc --version --verbose
>   cargo --version --verbose
> 

Good idea, and yes, I can!

```
sam@mop ~ $ sandbox
============================= Gentoo path sandbox ==============================
Detection of the support files.
Verification of the required files.
Setting up the required environment variables.
The protected environment has been started.
--------------------------------------------------------------------------------
Process being started in forked instance.
sam@mop ~ $ rustc +stable
 * /var/tmp/portage/sys-apps/sandbox-3.0/work/sandbox-3.0/libsandbox/trace.c:_do_ptrace():83: failure (Operation not permitted):
 * ISE:_do_ptrace: ptrace(PTRACE_ATTACH, ..., 0x0000000000000000, 0x0000000000000000): Operation not permitted
```

> rustc & cargo are dynamically linked on my system too, so not sure why your
> system is running these programs through the ptrace code path.

This is what threw me straight away, I don't get why ptrace is even involved.

$ file -L /usr/bin/cargo
/usr/bin/cargo: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.18, stripped
Comment 5 Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-11-03 03:46:04 UTC
No idea if this is interesting or relevant but even if I temporarily set SANDBOX_METHOD (wasn't set before this, just trying it for fun), ptrace is used?

sam@mop ~ $ grep SANDBOX_METHOD /etc/sandbox.conf
# SANDBOX_METHOD
SANDBOX_METHOD="preload"
sam@mop ~ $ rustc +stable
 * /var/tmp/portage/sys-apps/sandbox-3.0/work/sandbox-3.0/libsandbox/trace.c:_do_ptrace():83: failure (Operation not permitted):
 * ISE:_do_ptrace: ptrace(PTRACE_ATTACH, ..., 0x0000000000000000, 0x0000000000000000): Operation not permitted
Comment 6 Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-11-03 03:51:00 UTC
(In reply to Sam James from comment #5)

Again, might be completely useless, but weirdly it works when run inside of gdb.

$ gdb --args sandbox rustc +stable
[...]
Reading symbols from sandbox...
Reading symbols from /usr/lib/debug//usr/bin/sandbox.debug...
(gdb) r
Starting program: /usr/bin/sandbox rustc +stable
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
[Detaching after fork from child process 9419]
error: couldn't read +stable: No such file or directory (os error 2)

error: aborting due to previous error

[Inferior 1 (process 9415) exited with code 01]
Comment 7 SpanKY gentoo-dev 2021-11-03 03:55:29 UTC
great that we can isolate from firefox

try running `export SANDBOX_{VERBOSE,DEBUG}=yes` inside of `sandbox` and before running `cargo --version`.  see if that has anything interesting in it.
Comment 8 Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-11-03 03:59:19 UTC
Created attachment 748143 [details]
`cargo --version; rustc +stable` with sandbox debugging on

Attached the full thing although none of it looks that interesting?
Comment 9 SpanKY gentoo-dev 2021-11-03 04:03:59 UTC
(In reply to Sam James from comment #8)
>  * tracing: /usr/bin/rustc

assuming `file -L /usr/bin/rustc` says it's dynamically linked, that shouldn't have happened.  can you compress+attach that here ?

also can you run (outside of sandbox) `strace -f -o log rustc +stable` and attach that here too.

i'm guessing this behavior didn't start with 3.0, it just got worse because the only diff between 2.29 & 3.0 is that we trace children of traced processes.
Comment 10 Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-11-03 04:06:12 UTC
Created attachment 748146 [details]
ps faux

(In reply to Sam James from comment #8)
> Created attachment 748143 [details]
> `cargo --version; rustc +stable` with sandbox debugging on
> 
> Attached the full thing although none of it looks that interesting?

fwiw, rustc +stable is the only thing from the list which triggers it, which is weird, but think I was slightly misled here, it doesn't hang when calling cargo, but rustc (obvious from the above).

portage    36634  3.3  0.2  47048 41832 pts/2    SN   04:04   0:01                      |                                       \_ /var/tmp/portage/www-client/firefox-94.0/work/firefox_build/_virtualenvs/build/bin/python /var/tmp/portage/www-client/firefox-94.0/work/firefox-94.0/configure.py
portage    36838  0.0  0.2  47048 36972 pts/2    SN   04:04   0:00                      |                                           \_ /var/tmp/portage/www-client/firefox-94.0/work/firefox_build/_virtualenvs/build/bin/python /var/tmp/portage/www-client/firefox-94.0/work/firefox-94.0/configure.py
portage    36839  0.0  0.1 168968 26264 pts/2    SNl  04:04   0:00                      |                                               \_ /usr/bin/rustc +stable
portage    36841  0.1  0.0      0     0 pts/2    ZN   04:04   0:00                      |                                               \_ [python] <defunct>
Comment 11 Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-11-03 04:11:16 UTC
Created attachment 748149 [details]
strace -f sandbox file -L /usr/bin/rust (with debug, killed)

(In reply to SpanKY from comment #9)

Attach what, sorry? Just stracing it inside of sandbox?

That's really dull both ways:
```
 $ strace -f -o log sandbox rustc +stable
 * absolute_path: /proc/self/statm
 * resolved_path: /proc/39340/statm
 * ACCESS ALLOWED:  open_rd:       /proc/self/statm
 * absolute_path: /opt/rust-bin-1.56.1/lib/rustlib/x86_64-unknown-linux-gnu/lib
 * resolved_path: /opt/rust-bin-1.56.1/lib/rustlib/x86_64-unknown-linux-gnu/lib
 * ACCESS ALLOWED:  opendir:       /opt/rust-bin-1.56.1/lib/rustlib/x86_64-unknown-linux-gnu/lib
 * EARLY FAIL: open64(+stable): No such file or directory
error: couldn't read +stable: Invalid argument (os error 22)

error: aborting due to previous error
```

```
sam@mop ~ $ sandbox strace -f -o log rustc +stable
 * absolute_path: /proc/sys/kernel/pid_max
 * resolved_path: /proc/sys/kernel/pid_max
 * ACCESS ALLOWED:  open_rd:       /proc/sys/kernel/pid_max
 * absolute_path: /home/sam/log
 * resolved_path: /home/sam/log
 * ACCESS PREDICTED:  fopen_wr:      /home/sam/log
strace: Can't fopen 'log': Permission denied
```

But this is fun:

sam@mop ~ $ export SANDBOX_{VERBOSE,DEBUG}=yes
sam@mop ~ $ file -L /usr/bin/rustc
 * absolute_path: /usr/bin/file
 * resolved_path: /usr/bin/file
 * ACCESS ALLOWED:  execve:        /usr/bin/file
 * absolute_path: /usr/share/misc/magic.mgc
Bad system call

Only happens when debugging is enabled and probably a distraction.
Comment 12 Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-11-03 04:14:24 UTC
Created attachment 748152 [details]
strace -f -o log rustc +stable (within sandbox)
Comment 13 SpanKY gentoo-dev 2021-11-03 04:15:29 UTC
(In reply to Sam James from comment #11)

attach the rustc binary itself (not the symlink) so i can analyze it

attach the strace of running rustc *outside* of the sandbox so i can compare it to your log running inside

i know about the file SIGSYS crash.  it's unrelated, and only happens inside of file.  i added a fsync() call to libsandbox which file's seccomp bpf filter is not expecting.  it's safe to ignore for this bug.
Comment 14 Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-11-03 04:15:34 UTC
Created attachment 748155 [details]
strace -f -o log sandbox rustc
Comment 15 Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-11-03 04:16:32 UTC
Created attachment 748158 [details]
strace -f -o log rustc (no sandbox)
Comment 16 Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-11-03 04:17:14 UTC
Created attachment 748161 [details]
rustc
Comment 17 SpanKY gentoo-dev 2021-11-03 04:34:54 UTC
oh, i see why now.  this rustc you have implements its own set of memory hooks that do not play safely with an in-process sandbox.  see http://crbug.com/586444 for gory details.

did you compile this yourself ?  or is it a prebuilt ?

i can reproduce the SANDBOX_METHOD=preload not being respected, so let me fix that too while we're here.
Comment 18 Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-11-03 04:37:55 UTC
(In reply to SpanKY from comment #17)
> did you compile this yourself ?  or is it a prebuilt ?

pre-built:

dev-lang/rust-bin-1.56.1::gentoo was built with the following:
USE="verify-sig -clippy -doc (-prefix) -rls -rustfmt" ABI_X86="32 (64) (-x32)" CPU_FLAGS_X86="sse2"

> 
> i can reproduce the SANDBOX_METHOD=preload not being respected, so let me
> fix that too while we're here.

cheers! opened tab for reading of the tcmalloc bug later too. heading off for a bit now but it sounds like you've got enough to work with atm.
Comment 19 Larry the Git Cow gentoo-dev 2021-11-03 04:55:28 UTC
The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/proj/sandbox.git/commit/?id=373c81e05db464d82d9f667871d682b36804de15

commit 373c81e05db464d82d9f667871d682b36804de15
Author:     Mike Frysinger <vapier@gentoo.org>
AuthorDate: 2021-11-03 04:50:10 +0000
Commit:     Mike Frysinger <vapier@gentoo.org>
CommitDate: 2021-11-03 04:50:10 +0000

    sandbox: fix passing of config env vars down
    
    This code has been buggy since it was first added years ago -- it
    would read the right value out of the config file, but then always
    just set $SANDBOX_VERBOSE to it instead of the right env var.  This
    prevented the basic loading of sandbox settings from sandbox.conf.
    
    Bug: https://bugs.gentoo.org/821403
    Signed-off-by: Mike Frysinger <vapier@gentoo.org>

 src/environ.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
Comment 20 Larry the Git Cow gentoo-dev 2021-11-03 04:59:17 UTC
The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/proj/sandbox.git/commit/?id=7c92fad8b8e613ada5b4ce951829ed420a4aaac7

commit 7c92fad8b8e613ada5b4ce951829ed420a4aaac7
Author:     Mike Frysinger <vapier@gentoo.org>
AuthorDate: 2021-11-03 04:56:17 +0000
Commit:     Mike Frysinger <vapier@gentoo.org>
CommitDate: 2021-11-03 04:56:17 +0000

    libsbutil: drop fsync when logging
    
    This was added as part of running multiple tracers in parallel in the
    hopes (hack) it would make logs less intermingled.  Unfortunately, it
    didn't really accomplish that, and it upsets `file` when verbose output
    is enabled due to file's own seccomp filter (which doesn't have fsync).
    We could add this to file's seccomp filter (since it's a pretty benign
    syscall), but easier to just drop it at this point since it's not all
    that useful.
    
    Bug: https://bugs.gentoo.org/821403
    Signed-off-by: Mike Frysinger <vapier@gentoo.org>

 libsbutil/sb_efuncs.c | 1 -
 1 file changed, 1 deletion(-)
Comment 21 SpanKY gentoo-dev 2021-11-03 05:00:41 UTC
ok, we've fixed the side bugs, but we still have the original one here to contend with.  why is the ptrace hand off failing with EPERM ?

let me try installing the prebuilt to see if i can reproduce that failure.
Comment 22 SpanKY gentoo-dev 2021-11-03 05:06:52 UTC
i was afraid installing rust-bin was going to take a while due to conflicts, but i guess these install in parallel fine.

that said, it's working for me :/.

$ sandbox
$ rustc --version
rustc 1.56.1 (59eed8a2a 2021-11-01)
$ export SANDBOX_{DEBUG,VERBOSE}=yes
$ rustc --version
 * absolute_path: /usr/bin/rustc
 * resolved_path: /opt/rust-bin-1.56.1/bin/rustc-bin-1.56.1
 * ACCESS ALLOWED:  execve:        /usr/bin/rustc
 * tracing: /usr/bin/rustc
...

i don't have YAMA enabled in my kernel though, so let me try that next.
Comment 23 SpanKY gentoo-dev 2021-11-03 05:54:45 UTC
ok, rebuilding my kernel with extra options didn't help.  so i went back and just read the code harder.

i think i have a handle on where it's going wrong, and i think i can force it to fail in the same way as you.
Comment 24 SpanKY gentoo-dev 2021-11-03 06:16:29 UTC
ok, i lied a bit.  the issue does seem to be yama related.  the default for yama/ptrace_scope is 1.  if i set that to 0, i can't make it fail anymore.

i can't reproduce with the rust prebuilt, but i can with some custom test case.

yama is a common setting i think, so i'll have to figure out how to make this work.  in the mean time, i'll have the children tracing auto-disable if yama is greater than 1, and get a sandbox-3.1 out with that mitigation in place.
Comment 25 Marek Bartosiewicz 2021-11-03 06:38:24 UTC
firefox-94 compilation fails for me with funny sandbox violation.

ACCESS DENIED:  open_wr:       /usr/share/fonts/nerd-fonts

Do you need any logs/help from me?

[ebuild   R    ] sys-apps/sandbox-3.0::gentoo  USE="nnp" ABI_X86="(32) (64) (-x32)" 0 KiB
[ebuild   R    ] dev-lang/rust-1.56.1:stable/1.56::gentoo  USE="rustfmt system-bootstrap system-llvm -clippy -debug -doc -miri -nightly (-parallel-compiler) -rls -test -verify-sig -wasm" ABI_X86="(64) -32 (-x32)" CPU_FLAGS_X86="sse2" LLVM_TARGETS="AMDGPU (X86) -AArch64 -ARM -AVR -BPF -Hexagon -Lanai -MSP430 -Mips -NVPTX -PowerPC -RISCV -Sparc -SystemZ -WebAssembly -XCore" 0 KiB
[ebuild     U  ] www-client/firefox-94.0:0/94::gentoo [93.0:0/93::gentoo] USE="clang dbus gmp-autoupdate hwaccel lto openh264 pgo pulseaudio screencast system-av1 system-harfbuzz system-icu system-jpeg system-libevent system-libvpx system-webp wayland -debug -eme-free -geckodriver -hardened -jack (-selinux) -sndio -wifi" L10N="en-GB pl -ach -af -an -ar -ast -az -be -bg -bn -br -bs -ca -ca-valencia -cak -cs -cy -da -de -dsb -el -en-CA -eo -es-AR -es-CL -es-ES -es-MX -et -eu -fa -ff -fi -fr -fy -ga -gd -gl -gn -gu -he -hi -hr -hsb -hu -hy -ia -id -is -it -ja -ka -kab -kk -km -kn -ko -lij -lt -lv -mk -mr -ms -my -nb -ne -nl -nn -oc -pa -pt-BR -pt-PT -rm -ro -ru -sco -si -sk -sl -son -sq -sr -sv -szl -ta -te -th -tl -tr -trs -uk -ur -uz -vi -xh -zh-CN -zh-TW" 0 KiB
Comment 26 Larry the Git Cow gentoo-dev 2021-11-03 06:59:24 UTC
The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/proj/sandbox.git/commit/?id=746d68ae5972575d5fd87b7bd82e318d56352d9e

commit 746d68ae5972575d5fd87b7bd82e318d56352d9e
Author:     Mike Frysinger <vapier@gentoo.org>
AuthorDate: 2021-11-03 06:40:08 +0000
Commit:     Mike Frysinger <vapier@gentoo.org>
CommitDate: 2021-11-03 06:40:08 +0000

    libsandbox: add YAMA checks and skip ptrace when active
    
    The YAMA ptrace_scope knob restricts access to different ptrace calls
    depending on the capabilities the current process holds.  For now, do
    not try to ptrace processes when the YAMA level is incompatible with
    the capabilities that we have.
    
    This means we basically cannot protect against processes when they
    get into this state, so for now, we release them rather than abort.
    
    Bug: https://bugs.gentoo.org/771360
    Bug: https://bugs.gentoo.org/821403
    Signed-off-by: Mike Frysinger <vapier@gentoo.org>

 libsandbox/trace.c | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)
Comment 27 Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-11-03 15:04:58 UTC
(In reply to Marek Bartosiewicz from comment #25)
> firefox-94 compilation fails for me with funny sandbox violation.
> 
> ACCESS DENIED:  open_wr:       /usr/share/fonts/nerd-fonts
> 
> Do you need any logs/help from me?
>

Please file a new bug for this with the full logs as this is something else.
Comment 28 SpanKY gentoo-dev 2021-11-03 16:53:33 UTC
i think current FEATURES set factors in too.  if it's all building as root (i.e. full caps), then this wouldn't be a problem.  but if we have FEATURES="userpriv usersandbox", i think that's when this situation shows up.

it could be made to work by having the tracer inject a syscall into the tracee such that it calls prctl(PR_SET_PTRACER) on the new tracer.  then we'd be able to attach.

if we update portage to pass ambient caps to us that include ptrace, then we'd be able to run fine too.  that would prob be easier to do right now.

it wouldn't be an issue if i went with a one-tracer-to-many-tracees design, but based on what i've seen in other projects that used that design, the performance tanks pretty quickly since the single tracer process becomes a huge bottleneck.  use of ptrace seccomp would make the scale better, but not go away.

i don't know if making it threaded changes the equation or security checks.  the docs talk about PIDs, not TIDs, but that might be an oversight.  would have to dig into the kernel implementation to find out.
Comment 29 Larry the Git Cow gentoo-dev 2021-11-04 00:32:37 UTC
The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=0410a141e0a13133097d422078f5edaf2894dc1a

commit 0410a141e0a13133097d422078f5edaf2894dc1a
Author:     Sam James <sam@gentoo.org>
AuthorDate: 2021-11-04 00:31:20 +0000
Commit:     Sam James <sam@gentoo.org>
CommitDate: 2021-11-04 00:32:13 +0000

    profiles: mask newer sandbox versions w/ ptrace issues
    
    Masking for now to avoid duplicate reports of known issues;
    hangs when emerging e.g. Firefox and seemingly anything Go
    based are nasty.
    
    One of the bugs (821403) should be OK now but tagging
    anyway for reference.
    
    Bug: https://bugs.gentoo.org/821532
    Bug: https://bugs.gentoo.org/821523
    Bug: https://bugs.gentoo.org/821403
    Signed-off-by: Sam James <sam@gentoo.org>

 profiles/package.mask | 8 ++++++++
 1 file changed, 8 insertions(+)