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-rw-r--r--fs/quota/netlink.c17
-rw-r--r--include/uapi/linux/genetlink.h1
-rw-r--r--net/netlink/genetlink.c10
3 files changed, 24 insertions, 4 deletions
diff --git a/fs/quota/netlink.c b/fs/quota/netlink.c
index 16e8abb..aa22fe0 100644
--- a/fs/quota/netlink.c
+++ b/fs/quota/netlink.c
@@ -11,13 +11,23 @@
/* Netlink family structure for quota */
static struct genl_family quota_genl_family = {
- .id = GENL_ID_GENERATE,
+ /*
+ * Needed due to multicast group ID abuse - old code assumed
+ * the family ID was also a valid multicast group ID (which
+ * isn't true) and userspace might thus rely on it. Assign a
+ * static ID for this group to make dealing with that easier.
+ */
+ .id = GENL_ID_VFS_DQUOT,
.hdrsize = 0,
.name = "VFS_DQUOT",
.version = 1,
.maxattr = QUOTA_NL_A_MAX,
};
+static struct genl_multicast_group quota_mcgrp = {
+ .name = "events",
+};
+
/**
* quota_send_warning - Send warning to userspace about exceeded quota
* @type: The quota type: USRQQUOTA, GRPQUOTA,...
@@ -78,7 +88,7 @@ void quota_send_warning(struct kqid qid, dev_t dev,
goto attr_err_out;
genlmsg_end(skb, msg_head);
- genlmsg_multicast(skb, 0, quota_genl_family.id, GFP_NOFS);
+ genlmsg_multicast(skb, 0, quota_mcgrp.id, GFP_NOFS);
return;
attr_err_out:
printk(KERN_ERR "VFS: Not enough space to compose quota message!\n");
@@ -92,6 +102,9 @@ static int __init quota_init(void)
if (genl_register_family(&quota_genl_family) != 0)
printk(KERN_ERR
"VFS: Failed to create quota netlink interface.\n");
+ if (genl_register_mc_group(&quota_genl_family, &quota_mcgrp))
+ printk(KERN_ERR
+ "VFS: Failed to register quota mcast group.\n");
return 0;
};
diff --git a/include/uapi/linux/genetlink.h b/include/uapi/linux/genetlink.h
index c880a41..1af72d8 100644
--- a/include/uapi/linux/genetlink.h
+++ b/include/uapi/linux/genetlink.h
@@ -27,6 +27,7 @@ struct genlmsghdr {
*/
#define GENL_ID_GENERATE 0
#define GENL_ID_CTRL NLMSG_MIN_TYPE
+#define GENL_ID_VFS_DQUOT (NLMSG_MIN_TYPE + 1)
/**************************************************************************
* Controller
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 353909d..bee91a7 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -69,8 +69,11 @@ static struct list_head family_ht[GENL_FAM_TAB_SIZE];
* abuses the API and thinks it can statically use group 1.
* That group will typically conflict with other groups that
* any proper users use.
+ * Bit 17 is marked as already used since the VFS quota code
+ * also abused this API and relied on family == group ID, we
+ * cater to that by giving it a static family and group ID.
*/
-static unsigned long mc_group_start = 0x3;
+static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_VFS_DQUOT);
static unsigned long *mc_groups = &mc_group_start;
static unsigned long mc_groups_longs = 1;
@@ -130,7 +133,8 @@ static u16 genl_generate_id(void)
int i;
for (i = 0; i <= GENL_MAX_ID - GENL_MIN_ID; i++) {
- if (!genl_family_find_byid(id_gen_idx))
+ if (id_gen_idx != GENL_ID_VFS_DQUOT &&
+ !genl_family_find_byid(id_gen_idx))
return id_gen_idx;
if (++id_gen_idx > GENL_MAX_ID)
id_gen_idx = GENL_MIN_ID;
@@ -169,6 +173,8 @@ int genl_register_mc_group(struct genl_family *family,
id = GENL_ID_CTRL;
else if (strcmp(family->name, "NET_DM") == 0)
id = 1;
+ else if (strcmp(family->name, "VFS_DQUOT") == 0)
+ id = GENL_ID_VFS_DQUOT;
else
id = find_first_zero_bit(mc_groups,
mc_groups_longs * BITS_PER_LONG);
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