From: Thiago Rafael Becker thiago.becker@gmail.com Subject: kernel: make groups_sort calling a responsibility group_info allocators
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 ---
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 -puN arch/s390/kernel/compat_linux.c~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators arch/s390/kernel/compat_linux.c --- a/arch/s390/kernel/compat_linux.c~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators +++ a/arch/s390/kernel/compat_linux.c @@ -263,6 +263,7 @@ COMPAT_SYSCALL_DEFINE2(s390_setgroups16, return retval; }
+ groups_sort(group_info); retval = set_current_groups(group_info); put_group_info(group_info);
diff -puN fs/nfsd/auth.c~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators fs/nfsd/auth.c --- a/fs/nfsd/auth.c~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators +++ a/fs/nfsd/auth.c @@ -60,6 +60,9 @@ int nfsd_setuser(struct svc_rqst *rqstp, 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 -puN include/linux/cred.h~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators include/linux/cred.h --- a/include/linux/cred.h~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators +++ a/include/linux/cred.h @@ -83,6 +83,7 @@ extern int set_current_groups(struct gro 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 -puN kernel/groups.c~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators kernel/groups.c --- a/kernel/groups.c~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators +++ a/kernel/groups.c @@ -86,11 +86,12 @@ static int gid_cmp(const void *_a, const 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_inf 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, gidsetsi return retval; }
+ groups_sort(group_info); retval = set_current_groups(group_info); put_group_info(group_info);
diff -puN kernel/uid16.c~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators kernel/uid16.c --- a/kernel/uid16.c~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators +++ a/kernel/uid16.c @@ -192,6 +192,7 @@ SYSCALL_DEFINE2(setgroups16, int, gidset return retval; }
+ groups_sort(group_info); retval = set_current_groups(group_info); put_group_info(group_info);
diff -puN net/sunrpc/auth_gss/gss_rpc_xdr.c~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators net/sunrpc/auth_gss/gss_rpc_xdr.c --- a/net/sunrpc/auth_gss/gss_rpc_xdr.c~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators +++ a/net/sunrpc/auth_gss/gss_rpc_xdr.c @@ -231,6 +231,7 @@ static int gssx_dec_linux_creds(struct x goto out_free_groups; creds->cr_group_info->gid[i] = kgid; } + groups_sort(creds->cr_group_info);
return 0; out_free_groups: diff -puN net/sunrpc/auth_gss/svcauth_gss.c~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators net/sunrpc/auth_gss/svcauth_gss.c --- a/net/sunrpc/auth_gss/svcauth_gss.c~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators +++ a/net/sunrpc/auth_gss/svcauth_gss.c @@ -481,6 +481,7 @@ static int rsc_parse(struct cache_detail 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 -puN net/sunrpc/svcauth_unix.c~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators net/sunrpc/svcauth_unix.c --- a/net/sunrpc/svcauth_unix.c~kernel-make-groups_sort-calling-a-responsibility-group_info-allocators +++ a/net/sunrpc/svcauth_unix.c @@ -520,6 +520,7 @@ static int unix_gid_parse(struct cache_d 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 *rqs 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; _