kernel: make groups_sort calling a responsibility group_info allocators

commit bdcf0a423ea1c40bbb40e7ee483b50fc8aa3d758 upstream.

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

Link: http://lkml.kernel.org/r/20171211151420.18655-1-thiago.becker@gmail.com
Signed-off-by: Thiago Rafael Becker <thiago.becker@gmail.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: NeilBrown <neilb@suse.com>
Acked-by: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c
index 437e611592790b0ed725998d08281be420fcf954..0176ebc97bfddd26a89b1a10d961b049498d4561 100644 (file)
--- 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 9d46a0bdd9f9aea4d882a77ac3c22454d0f2b634..a260060042ad5580f6afc3fe200b220c912d5d50 100644 (file)
--- a/fs/nfsd/auth.c
+++ b/fs/nfsd/auth.c
@@ -59,6 +59,9 @@ int nfsd_setuser(struct svc_rqst *rqstp, struct svc_export *exp)
                                GROUP_AT(gi, i) = exp->ex_anon_gid;
                        else
                                GROUP_AT(gi, i) = GROUP_AT(rqgi, 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 257db64562e54092adec7bc506b6db7325f86c3e..9e120c92551b8d92e3343d6b1380be65a4d917ce 100644 (file)
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -87,6 +87,7 @@ 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 *);
 
 /* access the groups "array" with this macro */
 #define GROUP_AT(gi, i) \

diff --git a/kernel/groups.c b/kernel/groups.c
index 74d431d252515042296bb739cb8aba456635113e..5ea9847f172fa2c0d9f5101a2c646affafd1a641 100644 (file)
--- a/kernel/groups.c
+++ b/kernel/groups.c
@@ -101,7 +101,7 @@ static int groups_from_user(struct group_info *group_info,
 }
 
 /* a simple Shell sort */
-static void groups_sort(struct group_info *group_info)
+void groups_sort(struct group_info *group_info)
 {
        int base, max, stride;
        int gidsetsize = group_info->ngroups;
@@ -128,6 +128,7 @@ static void groups_sort(struct group_info *group_info)
                stride /= 3;
        }
 }
+EXPORT_SYMBOL(groups_sort);
 
 /* a simple bsearch */
 int groups_search(const struct group_info *group_info, kgid_t grp)
@@ -159,7 +160,6 @@ 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;
 }
@@ -243,6 +243,7 @@ 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 d58cc4d8f0d1fa95c7ec0120cb408a9b4ad859e5..651aaa5221ecedb11cc6ef145bc62af2d6607c5a 100644 (file)
--- a/kernel/uid16.c
+++ b/kernel/uid16.c
@@ -190,6 +190,7 @@ 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 2410d557ae398a894d0ff382b0a53784ad9e1176..89731c9023f03b252872966dd91c95fab731a023 100644 (file)
--- 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;
                GROUP_AT(creds->cr_group_info, 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 033fec307528806c4dc77f292960b879375ad221..036bbf2b44c16174744cb364d034464b82c7de58 100644 (file)
--- 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;
                        GROUP_AT(rsci.cred.cr_group_info, 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 621ca7b4a1552e393f332fda279be25d7f082152..98db1715cb170c88579a553fdc45360176c71c1e 100644 (file)
--- 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,
                GROUP_AT(ug.gi, i) = kgid;
        }
 
+       groups_sort(ug.gi);
        ugp = unix_gid_lookup(cd, uid);
        if (ugp) {
                struct cache_head *ch;
@@ -827,6 +828,7 @@ svcauth_unix_accept(struct svc_rqst *rqstp, __be32 *authp)
                kgid_t kgid = make_kgid(&init_user_ns, svc_getnl(argv));
                GROUP_AT(cred->cr_group_info, 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;