| Message ID | 20171211151420.18655-1-thiago.becker@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Dec 11, 2017 at 01:14:20PM -0200, 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 <thiago.becker@gmail.com> Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com> -- 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
ACK. (Assuming somebody else takes it--Andrew? Al? Or I can take it through the nfsd tree. I'm not sure who owns the stuff under kernel/.) --b. On Mon, Dec 11, 2017 at 01:14:20PM -0200, 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 <thiago.becker@gmail.com> > --- > 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_linux.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, gidsetsize, u16 __user *, grouplis > return retval; > } > > + groups_sort(group_info); > retval = set_current_groups(group_info); > put_group_info(group_info); > > 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_export *exp) > gi->gid[i] = exp->ex_anon_gid; > else > gi->gid[i] = rqgi->gid[i]; > + > + /* Each thread allocates its own gi, no race */ > + groups_sort(gi); > } > } else { > gi = 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 *); > > /* > * 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); > } > > -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); > > /* 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 = group_info; > } > @@ -206,6 +206,7 @@ SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist) > return retval; > } > > + groups_sort(group_info); > retval = set_current_groups(group_info); > put_group_info(group_info); > > 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; > } > > + groups_sort(group_info); > retval = set_current_groups(group_info); > put_group_info(group_info); > > 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 *xdr, > goto out_free_groups; > creds->cr_group_info->gid[i] = kgid; > } > + groups_sort(creds->cr_group_info); > > return 0; > out_free_groups: > diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_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] = kgid; > } > + groups_sort(rsci.cred.cr_group_info); > > /* mech name */ > len = 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] = kgid; > } > > + groups_sort(ug.gi); > ugp = unix_gid_lookup(cd, uid); > if (ugp) { > struct cache_head *ch; > @@ -819,6 +820,7 @@ svcauth_unix_accept(struct svc_rqst *rqstp, __be32 *authp) > kgid_t kgid = make_kgid(&init_user_ns, svc_getnl(argv)); > cred->cr_group_info->gid[i] = kgid; > } > + groups_sort(cred->cr_group_info); > if (svc_getu32(argv) != htonl(RPC_AUTH_NULL) || svc_getu32(argv) != 0) { > *authp = rpc_autherr_badverf; > return SVC_DENIED; > -- > 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 -- 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
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 <thiago.becker@gmail.com> Reviewed-by: NeilBrown <neilb@suse.com> 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 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_linux.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, gidsetsize, u16 __user *, grouplis > return retval; > } > > + groups_sort(group_info); > retval = set_current_groups(group_info); > put_group_info(group_info); > > 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_export *exp) > gi->gid[i] = exp->ex_anon_gid; > else > gi->gid[i] = rqgi->gid[i]; > + > + /* Each thread allocates its own gi, no race */ > + groups_sort(gi); > } > } else { > gi = 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 *); > > /* > * 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); > } > > -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); > > /* 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 = group_info; > } > @@ -206,6 +206,7 @@ SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist) > return retval; > } > > + groups_sort(group_info); > retval = set_current_groups(group_info); > put_group_info(group_info); > > 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; > } > > + groups_sort(group_info); > retval = set_current_groups(group_info); > put_group_info(group_info); > > 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 *xdr, > goto out_free_groups; > creds->cr_group_info->gid[i] = kgid; > } > + groups_sort(creds->cr_group_info); > > return 0; > out_free_groups: > diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_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] = kgid; > } > + groups_sort(rsci.cred.cr_group_info); > > /* mech name */ > len = 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] = kgid; > } > > + groups_sort(ug.gi); > ugp = unix_gid_lookup(cd, uid); > if (ugp) { > struct cache_head *ch; > @@ -819,6 +820,7 @@ svcauth_unix_accept(struct svc_rqst *rqstp, __be32 *authp) > kgid_t kgid = make_kgid(&init_user_ns, svc_getnl(argv)); > cred->cr_group_info->gid[i] = kgid; > } > + groups_sort(cred->cr_group_info); > if (svc_getu32(argv) != htonl(RPC_AUTH_NULL) || svc_getu32(argv) != 0) { > *authp = rpc_autherr_badverf; > return SVC_DENIED; > -- > 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
NeilBrown <neilb@suse.com> wrote: > 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? Please update it. Thanks, David -- 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
diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.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, gidsetsize, u16 __user *, grouplis return retval; } + groups_sort(group_info); retval = set_current_groups(group_info); put_group_info(group_info); 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_export *exp) gi->gid[i] = exp->ex_anon_gid; else gi->gid[i] = rqgi->gid[i]; + + /* Each thread allocates its own gi, no race */ + groups_sort(gi); } } else { gi = 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 *); /* * 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); } -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); /* 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 = group_info; } @@ -206,6 +206,7 @@ SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist) return retval; } + groups_sort(group_info); retval = set_current_groups(group_info); put_group_info(group_info); 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; } + groups_sort(group_info); retval = set_current_groups(group_info); put_group_info(group_info); 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 *xdr, goto out_free_groups; creds->cr_group_info->gid[i] = kgid; } + groups_sort(creds->cr_group_info); return 0; out_free_groups: diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_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] = kgid; } + groups_sort(rsci.cred.cr_group_info); /* mech name */ len = 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] = kgid; } + groups_sort(ug.gi); ugp = unix_gid_lookup(cd, uid); if (ugp) { struct cache_head *ch; @@ -819,6 +820,7 @@ svcauth_unix_accept(struct svc_rqst *rqstp, __be32 *authp) kgid_t kgid = make_kgid(&init_user_ns, svc_getnl(argv)); cred->cr_group_info->gid[i] = kgid; } + groups_sort(cred->cr_group_info); if (svc_getu32(argv) != htonl(RPC_AUTH_NULL) || svc_getu32(argv) != 0) { *authp = rpc_autherr_badverf; return SVC_DENIED;
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 <thiago.becker@gmail.com> --- 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(-)