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kernel: make groups_sort calling a responsibility group_info allocators

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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>
This commit is contained in:
Thiago Rafael Becker 2017-12-14 15:33:12 -08:00 committed by Greg Kroah-Hartman
parent d1698dc8a5
commit 58330ec2fe
8 changed files with 13 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/s390/kernel/compat_linux.c
View File

@ -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);

3
fs/nfsd/auth.c
View File

@ -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);

1
include/linux/cred.h
View File

@ -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) \

5
kernel/groups.c
View File

@ -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);

1
kernel/uid16.c
View File

@ -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);

1
net/sunrpc/auth_gss/gss_rpc_xdr.c
View File

@ -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:

1
net/sunrpc/auth_gss/svcauth_gss.c
View File

@ -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);

2
net/sunrpc/svcauth_unix.c
View File

@ -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;