diff options
Diffstat (limited to 'kernel/fs/quota/netlink.c')
| -rw-r--r-- | kernel/fs/quota/netlink.c | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/kernel/fs/quota/netlink.c b/kernel/fs/quota/netlink.c new file mode 100644 index 000000000..bb2869f5d --- /dev/null +++ b/kernel/fs/quota/netlink.c @@ -0,0 +1,109 @@ + +#include <linux/cred.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/quotaops.h> +#include <linux/sched.h> +#include <linux/slab.h> +#include <net/netlink.h> +#include <net/genetlink.h> + +static const struct genl_multicast_group quota_mcgrps[] = { + { .name = "events", }, +}; + +/* Netlink family structure for quota */ +static struct genl_family quota_genl_family = { + /* + * 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, + .mcgrps = quota_mcgrps, + .n_mcgrps = ARRAY_SIZE(quota_mcgrps), +}; + +/** + * quota_send_warning - Send warning to userspace about exceeded quota + * @qid: The kernel internal quota identifier. + * @dev: The device on which the fs is mounted (sb->s_dev) + * @warntype: The type of the warning: QUOTA_NL_... + * + * This can be used by filesystems (including those which don't use + * dquot) to send a message to userspace relating to quota limits. + * + */ + +void quota_send_warning(struct kqid qid, dev_t dev, + const char warntype) +{ + static atomic_t seq; + struct sk_buff *skb; + void *msg_head; + int ret; + int msg_size = 4 * nla_total_size(sizeof(u32)) + + 2 * nla_total_size(sizeof(u64)); + + /* We have to allocate using GFP_NOFS as we are called from a + * filesystem performing write and thus further recursion into + * the fs to free some data could cause deadlocks. */ + skb = genlmsg_new(msg_size, GFP_NOFS); + if (!skb) { + printk(KERN_ERR + "VFS: Not enough memory to send quota warning.\n"); + return; + } + msg_head = genlmsg_put(skb, 0, atomic_add_return(1, &seq), + "a_genl_family, 0, QUOTA_NL_C_WARNING); + if (!msg_head) { + printk(KERN_ERR + "VFS: Cannot store netlink header in quota warning.\n"); + goto err_out; + } + ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, qid.type); + if (ret) + goto attr_err_out; + ret = nla_put_u64(skb, QUOTA_NL_A_EXCESS_ID, + from_kqid_munged(&init_user_ns, qid)); + if (ret) + goto attr_err_out; + ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype); + if (ret) + goto attr_err_out; + ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MAJOR, MAJOR(dev)); + if (ret) + goto attr_err_out; + ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev)); + if (ret) + goto attr_err_out; + ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID, + from_kuid_munged(&init_user_ns, current_uid())); + if (ret) + goto attr_err_out; + genlmsg_end(skb, msg_head); + + genlmsg_multicast("a_genl_family, skb, 0, 0, GFP_NOFS); + return; +attr_err_out: + printk(KERN_ERR "VFS: Not enough space to compose quota message!\n"); +err_out: + kfree_skb(skb); +} +EXPORT_SYMBOL(quota_send_warning); + +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"); + return 0; +}; + +module_init(quota_init); |