userns: Convert qutoactl

Update the quotactl user space interface to successfull compile with
user namespaces support enabled and to hand off quota identifiers to
lower layers of the kernel in struct kqid instead of type and qid
pairs.

The quota on function is not converted because while it takes a quota
type and an id.  The id is the on disk quota format to use, which
is something completely different.

The signature of two struct quotactl_ops methods were changed to take
struct kqid argumetns get_dqblk and set_dqblk.

The dquot, xfs, and ocfs2 implementations of get_dqblk and set_dqblk
are minimally changed so that the code continues to work with
the change in parameter type.

This is the first in a series of changes to always store quota
identifiers in the kernel in struct kqid and only use raw type and qid
values when interacting with on disk structures or userspace.  Always
using struct kqid internally makes it hard to miss places that need
conversion to or from the kernel internal values.

Cc: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Ben Myers <bpm@sgi.com>
Cc: Alex Elder <elder@kernel.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

2 files changed, 26 insertions, 10 deletions

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 36a29b753c79..7714b169d646 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2376,12 +2376,12 @@ static void do_get_dqblk(struct dquot *dquot, struct fs_disk_quota *di)
         spin_unlock(&dq_data_lock);
 }
 
-int dquot_get_dqblk(struct super_block *sb, int type, qid_t id,
+int dquot_get_dqblk(struct super_block *sb, struct kqid qid,
                     struct fs_disk_quota *di)
 {
         struct dquot *dquot;
 
-        dquot = dqget(sb, id, type);
+        dquot = dqget(sb, qid.type, from_kqid(&init_user_ns, qid));
         if (!dquot)
                 return -ESRCH;
         do_get_dqblk(dquot, di);
@@ -2488,13 +2488,13 @@ static int do_set_dqblk(struct dquot *dquot, struct fs_disk_quota *di)
         return 0;
 }
 
-int dquot_set_dqblk(struct super_block *sb, int type, qid_t id,
+int dquot_set_dqblk(struct super_block *sb, struct kqid qid,
                   struct fs_disk_quota *di)
 {
         struct dquot *dquot;
         int rc;
 
-        dquot = dqget(sb, id, type);
+        dquot = dqget(sb, qid.type, from_kqid(&init_user_ns, qid));
         if (!dquot) {
                 rc = -ESRCH;
                 goto out;
diff --git a/fs/quota/quota.c b/fs/quota/quota.c
index 6f155788cbc6..ff0135d6bc51 100644
--- a/fs/quota/quota.c
+++ b/fs/quota/quota.c
@@ -32,8 +32,8 @@ static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
         /* allow to query information for dquots we "own" */
         case Q_GETQUOTA:
         case Q_XGETQUOTA:
-                if ((type == USRQUOTA && current_euid() == id) ||
-                    (type == GRPQUOTA && in_egroup_p(id)))
+                if ((type == USRQUOTA && uid_eq(current_euid(), make_kuid(current_user_ns(), id))) ||
+                    (type == GRPQUOTA && in_egroup_p(make_kgid(current_user_ns(), id))))
                         break;
                 /*FALLTHROUGH*/
         default:
@@ -130,13 +130,17 @@ static void copy_to_if_dqblk(struct if_dqblk *dst, struct fs_disk_quota *src)
 static int quota_getquota(struct super_block *sb, int type, qid_t id,
                           void __user *addr)
 {
+        struct kqid qid;
         struct fs_disk_quota fdq;
         struct if_dqblk idq;
         int ret;
 
         if (!sb->s_qcop->get_dqblk)
                 return -ENOSYS;
-        ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
+        qid = make_kqid(current_user_ns(), type, id);
+        if (!qid_valid(qid))
+                return -EINVAL;
+        ret = sb->s_qcop->get_dqblk(sb, qid, &fdq);
         if (ret)
                 return ret;
         copy_to_if_dqblk(&idq, &fdq);
@@ -176,13 +180,17 @@ static int quota_setquota(struct super_block *sb, int type, qid_t id,
 {
         struct fs_disk_quota fdq;
         struct if_dqblk idq;
+        struct kqid qid;
 
         if (copy_from_user(&idq, addr, sizeof(idq)))
                 return -EFAULT;
         if (!sb->s_qcop->set_dqblk)
                 return -ENOSYS;
+        qid = make_kqid(current_user_ns(), type, id);
+        if (!qid_valid(qid))
+                return -EINVAL;
         copy_from_if_dqblk(&fdq, &idq);
-        return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
+        return sb->s_qcop->set_dqblk(sb, qid, &fdq);
 }
 
 static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
@@ -213,23 +221,31 @@ static int quota_setxquota(struct super_block *sb, int type, qid_t id,
                            void __user *addr)
 {
         struct fs_disk_quota fdq;
+        struct kqid qid;
 
         if (copy_from_user(&fdq, addr, sizeof(fdq)))
                 return -EFAULT;
         if (!sb->s_qcop->set_dqblk)
                 return -ENOSYS;
-        return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
+        qid = make_kqid(current_user_ns(), type, id);
+        if (!qid_valid(qid))
+                return -EINVAL;
+        return sb->s_qcop->set_dqblk(sb, qid, &fdq);
 }
 
 static int quota_getxquota(struct super_block *sb, int type, qid_t id,
                            void __user *addr)
 {
         struct fs_disk_quota fdq;
+        struct kqid qid;
         int ret;
 
         if (!sb->s_qcop->get_dqblk)
                 return -ENOSYS;
-        ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
+        qid = make_kqid(current_user_ns(), type, id);
+        if (!qid_valid(qid))
+                return -EINVAL;
+        ret = sb->s_qcop->get_dqblk(sb, qid, &fdq);
         if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
                 return -EFAULT;
         return ret;