From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752498AbdLKVoL (ORCPT ); Mon, 11 Dec 2017 16:44:11 -0500 Received: from mx2.suse.de ([195.135.220.15]:49395 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751543AbdLKVoJ (ORCPT ); Mon, 11 Dec 2017 16:44:09 -0500 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "To" From: NeilBrown To: Thiago Rafael Becker , viro@zeniv.linux.org.uk, schwidefsky@de.ibm.com, willy@infradead.org, bfields@fieldses.org To: David Howells Date: Tue, 12 Dec 2017 08:43:58 +1100 Cc: linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Thiago Rafael Becker Subject: Re: [PATCH v5] kernel: make groups_sort calling a responsibility group_info allocators In-Reply-To: <20171211151420.18655-1-thiago.becker@gmail.com> References: <20171211142708.GA23284@bombadil.infradead.org> <20171211151420.18655-1-thiago.becker@gmail.com> Message-ID: <878te9os81.fsf@notabene.neil.brown.name> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Mon, Dec 11 2017, Thiago Rafael Becker wrote: > In testing, we found that nfsd threads may call set_groups in parallel for > the same entry cached in auth.unix.gid, racing in the call of groups_sort, > corrupting the groups for that entry and leading to permission denials for > the client. > > This patch: > - Make groups_sort globally visible. > - Move the call to groups_sort to the modifiers of group_info > - Remove the call to groups_sort from set_groups > > Signed-off-by: Thiago Rafael Becker Reviewed-by: NeilBrown Thanks. I like this better as a single patch. I'd probably suggest "Cc: stable@vger.kernel.org". Less important bugfixes have gone to stable... It might be nice to enhance Documentation/security/credentials.rst=20 to explain that the groups list is always sorted, and must be sorted before set_groups() or set_current_groups() is called, but as the document doesn't mention any of this at all, this is purely an extra enhancement and doesn't need to be included in the same patch. David: do you agree that this sort of content would be appropriate in that file (which you apparently authored). Would you like to update it, or shall I? Thanks, NeilBrown > --- > arch/s390/kernel/compat_linux.c | 1 + > fs/nfsd/auth.c | 3 +++ > include/linux/cred.h | 1 + > kernel/groups.c | 5 +++-- > kernel/uid16.c | 1 + > net/sunrpc/auth_gss/gss_rpc_xdr.c | 1 + > net/sunrpc/auth_gss/svcauth_gss.c | 1 + > net/sunrpc/svcauth_unix.c | 2 ++ > 8 files changed, 13 insertions(+), 2 deletions(-) > > diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_li= nux.c > index f04db37..59eea9c 100644 > --- a/arch/s390/kernel/compat_linux.c > +++ b/arch/s390/kernel/compat_linux.c > @@ -263,6 +263,7 @@ COMPAT_SYSCALL_DEFINE2(s390_setgroups16, int, gidsets= ize, u16 __user *, grouplis > return retval; > } >=20=20 > + groups_sort(group_info); > retval =3D set_current_groups(group_info); > put_group_info(group_info); >=20=20 > diff --git a/fs/nfsd/auth.c b/fs/nfsd/auth.c > index 697f8ae..f650e47 100644 > --- a/fs/nfsd/auth.c > +++ b/fs/nfsd/auth.c > @@ -60,6 +60,9 @@ int nfsd_setuser(struct svc_rqst *rqstp, struct svc_exp= ort *exp) > gi->gid[i] =3D exp->ex_anon_gid; > else > gi->gid[i] =3D rqgi->gid[i]; > + > + /* Each thread allocates its own gi, no race */ > + groups_sort(gi); > } > } else { > gi =3D get_group_info(rqgi); > diff --git a/include/linux/cred.h b/include/linux/cred.h > index 099058e..6312865 100644 > --- a/include/linux/cred.h > +++ b/include/linux/cred.h > @@ -83,6 +83,7 @@ extern int set_current_groups(struct group_info *); > extern void set_groups(struct cred *, struct group_info *); > extern int groups_search(const struct group_info *, kgid_t); > extern bool may_setgroups(void); > +extern void groups_sort(struct group_info *); >=20=20 > /* > * The security context of a task > diff --git a/kernel/groups.c b/kernel/groups.c > index e357bc8..daae2f2 100644 > --- a/kernel/groups.c > +++ b/kernel/groups.c > @@ -86,11 +86,12 @@ static int gid_cmp(const void *_a, const void *_b) > return gid_gt(a, b) - gid_lt(a, b); > } >=20=20 > -static void groups_sort(struct group_info *group_info) > +void groups_sort(struct group_info *group_info) > { > sort(group_info->gid, group_info->ngroups, sizeof(*group_info->gid), > gid_cmp, NULL); > } > +EXPORT_SYMBOL(groups_sort); >=20=20 > /* a simple bsearch */ > int groups_search(const struct group_info *group_info, kgid_t grp) > @@ -122,7 +123,6 @@ int groups_search(const struct group_info *group_info= , kgid_t grp) > void set_groups(struct cred *new, struct group_info *group_info) > { > put_group_info(new->group_info); > - groups_sort(group_info); > get_group_info(group_info); > new->group_info =3D group_info; > } > @@ -206,6 +206,7 @@ SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __u= ser *, grouplist) > return retval; > } >=20=20 > + groups_sort(group_info); > retval =3D set_current_groups(group_info); > put_group_info(group_info); >=20=20 > diff --git a/kernel/uid16.c b/kernel/uid16.c > index ce74a49..ef1da2a 100644 > --- a/kernel/uid16.c > +++ b/kernel/uid16.c > @@ -192,6 +192,7 @@ SYSCALL_DEFINE2(setgroups16, int, gidsetsize, old_gid= _t __user *, grouplist) > return retval; > } >=20=20 > + groups_sort(group_info); > retval =3D set_current_groups(group_info); > put_group_info(group_info); >=20=20 > diff --git a/net/sunrpc/auth_gss/gss_rpc_xdr.c b/net/sunrpc/auth_gss/gss_= rpc_xdr.c > index c4778ca..444380f 100644 > --- a/net/sunrpc/auth_gss/gss_rpc_xdr.c > +++ b/net/sunrpc/auth_gss/gss_rpc_xdr.c > @@ -231,6 +231,7 @@ static int gssx_dec_linux_creds(struct xdr_stream *xd= r, > goto out_free_groups; > creds->cr_group_info->gid[i] =3D kgid; > } > + groups_sort(creds->cr_group_info); >=20=20 > return 0; > out_free_groups: > diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svca= uth_gss.c > index 5dd4e6c..2653119 100644 > --- a/net/sunrpc/auth_gss/svcauth_gss.c > +++ b/net/sunrpc/auth_gss/svcauth_gss.c > @@ -481,6 +481,7 @@ static int rsc_parse(struct cache_detail *cd, > goto out; > rsci.cred.cr_group_info->gid[i] =3D kgid; > } > + groups_sort(rsci.cred.cr_group_info); >=20=20 > /* mech name */ > len =3D qword_get(&mesg, buf, mlen); > diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c > index 740b67d..af7f28f 100644 > --- a/net/sunrpc/svcauth_unix.c > +++ b/net/sunrpc/svcauth_unix.c > @@ -520,6 +520,7 @@ static int unix_gid_parse(struct cache_detail *cd, > ug.gi->gid[i] =3D kgid; > } >=20=20 > + groups_sort(ug.gi); > ugp =3D unix_gid_lookup(cd, uid); > if (ugp) { > struct cache_head *ch; > @@ -819,6 +820,7 @@ svcauth_unix_accept(struct svc_rqst *rqstp, __be32 *a= uthp) > kgid_t kgid =3D make_kgid(&init_user_ns, svc_getnl(argv)); > cred->cr_group_info->gid[i] =3D kgid; > } > + groups_sort(cred->cr_group_info); > if (svc_getu32(argv) !=3D htonl(RPC_AUTH_NULL) || svc_getu32(argv) !=3D= 0) { > *authp =3D rpc_autherr_badverf; > return SVC_DENIED; > --=20 > 2.9.5 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEG8Yp69OQ2HB7X0l6Oeye3VZigbkFAlou/B4ACgkQOeye3VZi gbn4Cg//W2se+9COOuHRQYktquLXhW2EQZj5LZukwDgo8OZO5mOKSBcrg0BAKOp0 IByKhNV697MFLkpTAUMEXpx6To+anPry6a6xd0J14Cwbu2na9mBXoE3Q5NXzo1dA wNmkvQ2o9Vp47fm7S/p2rd0VR4DAOeBXzGHn/MRK/cmU15jOtwXvxeHx4/VNCWkp YuMuS3BOTsbNob0FVX57ediYpuMTPJbU/CQlslSvZ2s8DjnsjK22De/DhtpNUeDu NLKffcqqGHCAm5QJCnKmuwmWn59/CzTclmI2ytmbrZMeu+Wh0htXZiSYaTfsxXHK 7QpGE0ZabxngGb6NVPoCAr7LPKc9lOPjkNT0cCg2TR+cbBUzpilmjKK/GOct2+mf LyQ4yHwFWvPvk+W+u480llAt0YjmpGCdSTsFPktMlnIninwdpSmeaa9i9fyCH8Ew NIKe1OxqVIrV8F2yafehv+pDCUXH+LKbmRvkJNIB8gaSURH7ZNTA0bbMjNmcw5xt U5luJ5/9cEnQMvwTBIYVnIMAVhxg2kMfTOh+aPMeKTrU3KYuqMMixNwFCy8H4r4n ++RgkIr63j7GZVcsrr/P7z2eyeJK6nLosr5wjH63eQTXGTrfHnRwNPYyGDafSE84 Tppy5EdfmaCjmz4exKzS3Y62MabTapK43NAsEp2KWhqDYbWANyc= =vzDf -----END PGP SIGNATURE----- --=-=-=--