diff options
| -rw-r--r-- | fs/quota/netlink.c | 17 | ||||
| -rw-r--r-- | include/uapi/linux/genetlink.h | 1 | ||||
| -rw-r--r-- | net/netlink/genetlink.c | 10 |
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("a_genl_family) != 0) printk(KERN_ERR "VFS: Failed to create quota netlink interface.\n"); + if (genl_register_mc_group("a_genl_family, "a_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); |
