Commit bdcf0a42 authored by Thiago Rafael Becker's avatar Thiago Rafael Becker Committed by Linus Torvalds

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.comSigned-off-by: 's avatarThiago Rafael Becker <thiago.becker@gmail.com>
Reviewed-by: 's avatarMatthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: 's avatarNeilBrown <neilb@suse.com>
Acked-by: 's avatar"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: 's avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1f704fd0
......@@ -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);
......
......@@ -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);
......
......@@ -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
......
......@@ -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);
......
......@@ -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);
......
......@@ -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:
......
......@@ -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);
......
......@@ -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;
......
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