Fix crgetgroups out-of-bound and misc cred fix

init_groups has 0 nblocks, therefore calling the current crgetgroups with
init_groups would result in out-of-bound access. We fix this by returning NULL
when nblocks is 0.

Cap crgetngroups to NGROUPS_PER_BLOCK, since crgetgroups will only return
blocks[0].

Also, remove all get_group_info. The cred already holds reference on the
group_info, and cred is not mutable. So there's no reason to hold extra
reference, if we hold cred.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes #556
This commit is contained in:
Chunwei Chen 2016-10-18 15:52:30 -07:00 committed by Brian Behlendorf
parent 0d26756665
commit 9ba3c01923

View File

@ -62,19 +62,17 @@ cr_groups_search(const struct group_info *group_info, gid_t grp)
return 0;
}
/* Hold a reference on the credential and group info */
/* Hold a reference on the credential */
void
crhold(cred_t *cr)
{
(void)get_cred((const cred_t *)cr);
(void)get_group_info(cr->group_info);
}
/* Free a reference on the credential and group info */
/* Free a reference on the credential */
void
crfree(cred_t *cr)
{
put_group_info(cr->group_info);
put_cred((const cred_t *)cr);
}
@ -85,28 +83,32 @@ crgetngroups(const cred_t *cr)
struct group_info *gi;
int rc;
gi = get_group_info(cr->group_info);
gi = cr->group_info;
rc = gi->ngroups;
put_group_info(gi);
/*
* crgetgroups will only returns gi->blocks[0], which contains only
* the first NGROUPS_PER_BLOCK groups.
*/
if (rc > NGROUPS_PER_BLOCK) {
WARN_ON_ONCE(1);
rc = NGROUPS_PER_BLOCK;
}
return rc;
}
/*
* Return an array of supplemental gids. The returned address is safe
* to use as long as the caller has taken a reference with crhold().
* The caller is responsible for releasing the reference with crfree().
*/
gid_t *
crgetgroups(const cred_t *cr)
{
struct group_info *gi;
gid_t *gids;
gi = get_group_info(cr->group_info);
gids = KGIDP_TO_SGIDP(gi->blocks[0]);
put_group_info(gi);
gid_t *gids = NULL;
gi = cr->group_info;
if (gi->nblocks > 0)
gids = KGIDP_TO_SGIDP(gi->blocks[0]);
return gids;
}
@ -117,9 +119,8 @@ groupmember(gid_t gid, const cred_t *cr)
struct group_info *gi;
int rc;
gi = get_group_info(cr->group_info);
gi = cr->group_info;
rc = cr_groups_search(gi, SGID_TO_KGID(gid));
put_group_info(gi);
return rc;
}