From nobody Tue Aug 29 18:12:05 2023 X-Original-To: current@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 4RZwVx5jMzz4s3TF for ; Tue, 29 Aug 2023 18:12:09 +0000 (UTC) (envelope-from dchagin@heemeyer.club) Received: from heemeyer.club (heemeyer.club [195.93.173.158]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4RZwVw5k0yz4Lsg for ; Tue, 29 Aug 2023 18:12:08 +0000 (UTC) (envelope-from dchagin@heemeyer.club) Authentication-Results: mx1.freebsd.org; dkim=none; spf=none (mx1.freebsd.org: domain of dchagin@heemeyer.club has no SPF policy when checking 195.93.173.158) smtp.mailfrom=dchagin@heemeyer.club; dmarc=none Received: from heemeyer.club (localhost [127.0.0.1]) by heemeyer.club (8.17.2/8.16.1) with ESMTP id 37TIC5Oi072256 for ; Tue, 29 Aug 2023 21:12:05 +0300 (MSK) (envelope-from dchagin@heemeyer.club) Received: (from dchagin@localhost) by heemeyer.club (8.17.2/8.16.1/Submit) id 37TIC5M6072255 for current@freebsd.org; Tue, 29 Aug 2023 21:12:05 +0300 (MSK) (envelope-from dchagin) Date: Tue, 29 Aug 2023 21:12:05 +0300 From: Dmitry Chagin To: current@freebsd.org Subject: Re: Possible issue with linux xattr support? Message-ID: References: List-Id: Discussions about the use of FreeBSD-current List-Archive: https://lists.freebsd.org/archives/freebsd-current List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-current@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spamd-Bar: / X-Spamd-Result: default: False [-0.52 / 15.00]; SUBJECT_ENDS_QUESTION(1.00)[]; AUTH_NA(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-0.99)[-0.994]; NEURAL_HAM_SHORT(-0.72)[-0.722]; FORGED_SENDER(0.30)[dchagin@freebsd.org,dchagin@heemeyer.club]; MIME_GOOD(-0.10)[text/plain]; MLMMJ_DEST(0.00)[current@freebsd.org]; TO_DOM_EQ_FROM_DOM(0.00)[]; MIME_TRACE(0.00)[0:+]; R_SPF_NA(0.00)[no SPF record]; R_DKIM_NA(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DMARC_NA(0.00)[freebsd.org]; RCVD_TLS_LAST(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; FREEFALL_USER(0.00)[dchagin]; ARC_NA(0.00)[]; FROM_NEQ_ENVFROM(0.00)[dchagin@freebsd.org,dchagin@heemeyer.club]; FROM_HAS_DN(0.00)[]; PREVIOUSLY_DELIVERED(0.00)[current@freebsd.org]; TO_MATCH_ENVRCPT_ALL(0.00)[]; TO_DN_NONE(0.00)[]; ASN(0.00)[asn:61400, ipnet:195.93.173.0/24, country:RU] X-Rspamd-Queue-Id: 4RZwVw5k0yz4Lsg On Tue, Aug 29, 2023 at 07:02:22PM +0200, Felix Palmen wrote: > * Dmitry Chagin [20230829 17:45]: > > On Tue, Aug 29, 2023 at 12:59:11PM +0200, Felix Palmen wrote: > > > Thanks, I can confirm this avoids the issue in both cases I experienced > > > (install from GNU coreutils and python). > > > > > thanks, this is the first half of the fix, it works for you due to you > > are running tools under unprivileged user, afaiu. The second I have > > tested by myself :) > > Sure, poudriere is running all builds as "nobody" by default. > > > > If I understand this patch correctly, it completely avoids EPERM, > > > masking it as not supported, so callers should consider it non-fatal, > > > allowing to silently ignore writing of "system" attributes while still > > > keeping other functionality? > > > > > system namespace is accessible only for privileged user, for others Linux > > returns ENOTSUP. So many tools ignores this error, eg ls. > > > > the second: https://people.freebsd.org/~dchagin/sea_jailed.patch > > Ok, I did some tests in a poudriere jail using Linux bash, as root. > First, with only the first patch: > > | bash-5.2# getfattr -d /bin/sh > | getfattr: /bin/sh: Operation not supported > | bash-5.2# setfattr -n user.foo -v bar /bin/sh > | bash-5.2# getfattr -n user.foo /bin/sh > | getfattr: Removing leading '/' from absolute path names > | # file: bin/sh > | user.foo="bar" > | bash-5.2# setfattr -x user.foo /bin/sh > | bash-5.2# setfattr -x system.foo /bin/sh > | setfattr: /bin/sh: Operation not supported > > So, using user.* works, using system.* doesn't, and maybe a bit > surprising(?), dumping all attributes which by default excludes the > system namespace doesn't work either. > As expected, the second patch intended to allow access to system namespace in jailed env. > Then with the second patch applied as well: > > | bash-5.2# getfattr -d /bin/sh > | bash-5.2# setfattr -n system.foo -v bar /bin/sh > | bash-5.2# getfattr -d /bin/sh -m- > | getfattr: Removing leading '/' from absolute path names > | # file: bin/sh > | system.foo="bar" > | > | bash-5.2# setfattr -x system.foo /bin/sh > | bash-5.2# getfattr -d /bin/sh -m- > | bash-5.2# > > This looks perfectly fine, thanks a lot! > > I still wonder, is the first patch needed anyways? Maybe I fail to > understand something here. Won't it map *every* EPERM to ENOSUP and > can't this be an issue? > fine, thanks. Gnu tools running under unprivileged user will fail, eg ls, which uses getfattr() to get the posix acl > Cheers, Felix > > -- > Felix Palmen {private} felix@palmen-it.de > -- ports committer -- {web} http://palmen-it.de > {pgp public key} http://palmen-it.de/pub.txt > {pgp fingerprint} 6936 13D5 5BBF 4837 B212 3ACC 54AD E006 9879 F231