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authorEric W. Biederman <ebiederm@xmission.com>2016-06-30 16:31:01 -0500
committerEric W. Biederman <ebiederm@xmission.com>2016-07-05 15:12:05 -0500
commitd49d37624a1931c2f3b5d0cbe95bd5181cbdc279 (patch)
treef81e4129a5a393df64b6b674ed9aae83a404f707 /fs/quota/dquot.c
parent036d523641c66bef713042894a17f4335f199e49 (diff)
quota: Ensure qids map to the filesystem
Introduce the helper qid_has_mapping and use it to ensure that the quota system only considers qids that map to the filesystems s_user_ns. In practice for quota supporting filesystems today this is the exact same check as qid_valid. As only 0xffffffff aka (qid_t)-1 does not map into init_user_ns. Replace the qid_valid calls with qid_has_mapping as values come in from userspace. This is harmless today and it prepares the quota system to work on filesystems with quotas but mounted by unprivileged users. Call qid_has_mapping from dqget. This ensures the passed in qid has a prepresentation on the underlying filesystem. Previously this was unnecessary as filesystesm never had qids that could not map. With the introduction of filesystems outside of s_user_ns this will not remain true. All of this ensures the quota code never has to deal with qids that don't map to the underlying filesystem. Cc: Jan Kara <jack@suse.cz> Acked-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'fs/quota/dquot.c')
-rw-r--r--fs/quota/dquot.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index ff21980d0119..74706b6aa747 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -841,6 +841,9 @@ struct dquot *dqget(struct super_block *sb, struct kqid qid)
unsigned int hashent = hashfn(sb, qid);
struct dquot *dquot, *empty = NULL;
+ if (!qid_has_mapping(sb->s_user_ns, qid))
+ return ERR_PTR(-EINVAL);
+
if (!sb_has_quota_active(sb, qid.type))
return ERR_PTR(-ESRCH);
we_slept: