Date: Tue, 27 Jan 2015 16:08:28 -0800 From: Devin Teske <dteske@FreeBSD.org> To: Baptiste Daroussin <bapt@FreeBSD.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, Bruce Evans <brde@optusnet.com.au>, Slawa Olhovchenkov <slw@zxy.spb.ru>, svn-src-head@freebsd.org, Devin Teske <dteske@FreeBSD.org> Subject: Re: svn commit: r277652 - in head/usr.sbin/pw: . tests Message-ID: <AD40C8A5-3ACC-468C-8BB0-A0B466098328@FreeBSD.org> In-Reply-To: <20150127234420.GB84622@ivaldir.etoilebsd.net> References: <201501241913.t0OJD4xT039188@svn.freebsd.org> <20150125155254.V1007@besplex.bde.org> <20150125142148.GA76051@zxy.spb.ru> <20150126014336.P2572@besplex.bde.org> <5D58B34B-8647-4B69-8D90-E7D37C98D4AD@FreeBSD.org> <20150127234420.GB84622@ivaldir.etoilebsd.net>
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> On Jan 27, 2015, at 3:44 PM, Baptiste Daroussin <bapt@FreeBSD.org> = wrote: >=20 > On Mon, Jan 26, 2015 at 01:20:28PM -0800, Devin Teske wrote: >>=20 >>> On Jan 25, 2015, at 7:31 AM, Bruce Evans <brde@optusnet.com.au> = wrote: >>>=20 >>> On Sun, 25 Jan 2015, Slawa Olhovchenkov wrote: >>>=20 >>>> On Sun, Jan 25, 2015 at 04:56:24PM +1100, Bruce Evans wrote: >>>>=20 >>>>> Negative ids have historical abuses in places like mountd. >>=20 >> Which paves the way for the =E2=80=9Caccepted practice=E2=80=9D = argument >> and backed up by =E2=80=9Cin-the-field usage=E2=80=9D statement(s). >>=20 >>=20 >>=20 >>>>> mountd still >>>>> hard-codes -2 and -2 for the default uid and gid of an = unprivileged user. >>>>> It at least casts these values to uid_t and gid_t before using = them. >>>>> This gives the ids the non-random values of UINT32_MAX-1 if uid_t = and >>>>> gid_t are uint32_t. (If uid_t and gid_t were signed, then it = would >>>>> leave the values as negative, so invalid.) These magic values may = work >>>>> better than when ids were 16 bits, since there is less risk of = them >>>>> conflicting with a normal id. However, the non-conflict is = probably >>>>> a bug. FreeBSD uses the magic ids of 65534 for user nobody: group >>>>> nobody. These would have been (id_t)-2 with 16-bit ids. They no >>>>> longer match, so ls displays (id_t)-2 numerically. FreeBSD also = has >>>>> a group nogroup =3D 65553 that doesn't match the nfs usage. = However2, >>>>> in FreeBSD-1 wher ids were 16-bits, nobody was 32767 and nogroup = was >>>>> 32766. so they didn't match nfs for other reasons. The 2 = non-groups >>>>> now seem to be just a bug -- FreeBSD-1 didn't have group nobody. >>>>> 4.4BSD-Lite2 has the same values as FreeBSD-1. >>>>=20 >>>> This is not full true for ZFS case. >>>> On ZFS nobody is 2^32-2. >>>=20 >>> File systems don't get to decide this. >>=20 >> +1 (and thanks for the historical account, bruce =E2=80=94 sincerely) >>=20 >> However, I still want to make the argument that: >>=20 >> a. Because we=E2=80=99ve supported mapping negative inputs to = unsigned values in pw *for over a decade*, that=E2=80=A6 >>=20 >> b. We should either revert or make a relnotes submission to note that = we=E2=80=99re changing the long-standing accepted practice. >>=20 >> Changing the accepted practice broke code internally, it would have = likely broken some external code as well =E2=80=94 and people deserve to = know about said change else we should continue to support accepted = practice that is decade(s) old. >=20 > It has never been accepted by pw(8) it was just not checked Those are indistinguishable from each other by an end-user (someone not reading the code; and even still there is the =E2=80=9Cspirit=E2=80=9D = of the code and the =E2=80=9Cletter of the code"). > as a result it was > accepting *anything* and passed it unchecked directly to atoi(3) = resulting in > for example pw groupdel -u plop removing wheel... or pw userdel -u = something > trying to delete root. (was this an accepted behaviour for a decade as = well?) >=20 The erroneous deletion was inherently wrong. I do not want to see that = bug resurface (and I thank you very much for fixing it). However, I=E2=80=99m sure you know that said erroneous deletion was a = side-effect of lacking error-checks. Again, thank you fixing the PR itemizing the erroneous deletion of = users/groups. Please note that Bruce sent me a private e-mail with some historical = background, to which I replied and we=E2=80=99re working out some logic on the side. = There shouldn=E2=80=99t be much more to this thread =E2=80=94 I envision that we=E2=80=99ll be = approaching a solid agree- meant that should lead to some commits (can=E2=80=99t say yet what = direction it will go as I=E2=80=99m looking forward to Bruce=E2=80=99s touch-points). =E2=80=94=20 Devin=
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