quota: do not allow setting of quota limits to too high values

We should check whether quota limits set via Q_SETQUOTA are not exceeding
limits which quota format is able to handle.

Signed-off-by: Andrew Perepechko <andrew.perepechko@sun.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/dquot.c

@@ -1709,10 +1709,19 @@ int vfs_get_dqblk(struct super_block *sb, int type, qid_t id, struct if_dqblk *d
 }
 
 /* Generic routine for setting common part of quota structure */
-static void do_set_dqblk(struct dquot *dquot, struct if_dqblk *di)
+static int do_set_dqblk(struct dquot *dquot, struct if_dqblk *di)
 {
 	struct mem_dqblk *dm = &dquot->dq_dqb;
 	int check_blim = 0, check_ilim = 0;
+	struct mem_dqinfo *dqi = &sb_dqopt(dquot->dq_sb)->info[dquot->dq_type];
+
+	if ((di->dqb_valid & QIF_BLIMITS &&
+	     (di->dqb_bhardlimit > dqi->dqi_maxblimit ||
+	      di->dqb_bsoftlimit > dqi->dqi_maxblimit)) ||
+	    (di->dqb_valid & QIF_ILIMITS &&
+	     (di->dqb_ihardlimit > dqi->dqi_maxilimit ||
+	      di->dqb_isoftlimit > dqi->dqi_maxilimit)))
+		return -ERANGE;
 
 	spin_lock(&dq_data_lock);
 	if (di->dqb_valid & QIF_SPACE) {
@@ -1744,7 +1753,7 @@ static void do_set_dqblk(struct dquot *dquot, struct if_dqblk *di)
 			clear_bit(DQ_BLKS_B, &dquot->dq_flags);
 		}
 		else if (!(di->dqb_valid & QIF_BTIME))	/* Set grace only if user hasn't provided his own... */
-			dm->dqb_btime = get_seconds() + sb_dqopt(dquot->dq_sb)->info[dquot->dq_type].dqi_bgrace;
+			dm->dqb_btime = get_seconds() + dqi->dqi_bgrace;
 	}
 	if (check_ilim) {
 		if (!dm->dqb_isoftlimit || dm->dqb_curinodes < dm->dqb_isoftlimit) {
@@ -1752,7 +1761,7 @@ static void do_set_dqblk(struct dquot *dquot, struct if_dqblk *di)
 			clear_bit(DQ_INODES_B, &dquot->dq_flags);
 		}
 		else if (!(di->dqb_valid & QIF_ITIME))	/* Set grace only if user hasn't provided his own... */
-			dm->dqb_itime = get_seconds() + sb_dqopt(dquot->dq_sb)->info[dquot->dq_type].dqi_igrace;
+			dm->dqb_itime = get_seconds() + dqi->dqi_igrace;
 	}
 	if (dm->dqb_bhardlimit || dm->dqb_bsoftlimit || dm->dqb_ihardlimit || dm->dqb_isoftlimit)
 		clear_bit(DQ_FAKE_B, &dquot->dq_flags);
@@ -1760,21 +1769,24 @@ static void do_set_dqblk(struct dquot *dquot, struct if_dqblk *di)
 		set_bit(DQ_FAKE_B, &dquot->dq_flags);
 	spin_unlock(&dq_data_lock);
 	mark_dquot_dirty(dquot);
+
+	return 0;
 }
 
 int vfs_set_dqblk(struct super_block *sb, int type, qid_t id, struct if_dqblk *di)
 {
 	struct dquot *dquot;
+	int rc;
 
 	mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
 	if (!(dquot = dqget(sb, id, type))) {
 		mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
 		return -ESRCH;
 	}
-	do_set_dqblk(dquot, di);
+	rc = do_set_dqblk(dquot, di);
 	dqput(dquot);
 	mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
-	return 0;
+	return rc;
 }
 
 /* Generic routine for getting common part of quota file information */

fs/quota_v1.c

@@ -139,6 +139,9 @@ static int v1_read_file_info(struct super_block *sb, int type)
 		goto out;
 	}
 	ret = 0;
+	/* limits are stored as unsigned 32-bit data */
+	dqopt->info[type].dqi_maxblimit = 0xffffffff;
+	dqopt->info[type].dqi_maxilimit = 0xffffffff;
 	dqopt->info[type].dqi_igrace = dqblk.dqb_itime ? dqblk.dqb_itime : MAX_IQ_TIME;
 	dqopt->info[type].dqi_bgrace = dqblk.dqb_btime ? dqblk.dqb_btime : MAX_DQ_TIME;
 out:

fs/quota_v2.c

@@ -59,6 +59,9 @@ static int v2_read_file_info(struct super_block *sb, int type)
 			sb->s_id);
 		return -1;
 	}
+	/* limits are stored as unsigned 32-bit data */
+	info->dqi_maxblimit = 0xffffffff;
+	info->dqi_maxilimit = 0xffffffff;
 	info->dqi_bgrace = le32_to_cpu(dinfo.dqi_bgrace);
 	info->dqi_igrace = le32_to_cpu(dinfo.dqi_igrace);
 	info->dqi_flags = le32_to_cpu(dinfo.dqi_flags);

include/linux/quota.h

@@ -206,6 +206,8 @@ struct mem_dqinfo {
 	unsigned long dqi_flags;
 	unsigned int dqi_bgrace;
 	unsigned int dqi_igrace;
+	qsize_t dqi_maxblimit;
+	qsize_t dqi_maxilimit;
 	union {
 		struct v1_mem_dqinfo v1_i;
 		struct v2_mem_dqinfo v2_i;