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https://github.com/torvalds/linux
synced 2024-09-06 09:51:23 +00:00
AUDIT: expand audit tmp buffer as needed
Introduce audit_expand and make the audit_buffer use a dynamic buffer which can be resized. When audit buffer is moved to skb it will not be fragmented across skb's, so we can eliminate the sklist in the audit_buffer. During audit_log_move, we simply copy the full buffer into a single skb, and then audit_log_drain sends it on. Signed-off-by: Chris Wright <chrisw@osdl.org> Signed-off-by: David Woodhouse <dwmw2@infradead.org>
This commit is contained in:
parent
16e1904e69
commit
8fc6115c2a
139
kernel/audit.c
139
kernel/audit.c
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@ -136,14 +136,11 @@ static DECLARE_MUTEX(audit_netlink_sem);
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* use simultaneously. */
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struct audit_buffer {
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struct list_head list;
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struct sk_buff_head sklist; /* formatted skbs ready to send */
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struct sk_buff *skb; /* formatted skb ready to send */
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struct audit_context *ctx; /* NULL or associated context */
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int len; /* used area of tmp */
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char tmp[AUDIT_BUFSIZ];
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/* Pointer to header and contents */
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struct nlmsghdr *nlh;
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int total;
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int size; /* size of tmp */
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char *tmp;
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int type;
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int pid;
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};
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@ -488,55 +485,47 @@ static void audit_receive(struct sock *sk, int length)
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static void audit_log_move(struct audit_buffer *ab)
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{
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struct sk_buff *skb;
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struct nlmsghdr *nlh;
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char *start;
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int extra = ab->nlh ? 0 : NLMSG_SPACE(0);
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int len = NLMSG_SPACE(0) + ab->len + 1;
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/* possible resubmission */
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if (ab->len == 0)
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if (ab->skb)
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return;
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skb = skb_peek_tail(&ab->sklist);
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if (!skb || skb_tailroom(skb) <= ab->len + extra) {
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skb = alloc_skb(2 * ab->len + extra, GFP_ATOMIC);
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if (!skb) {
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ab->len = 0; /* Lose information in ab->tmp */
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audit_log_lost("out of memory in audit_log_move");
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return;
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}
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__skb_queue_tail(&ab->sklist, skb);
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if (!ab->nlh)
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ab->nlh = (struct nlmsghdr *)skb_put(skb,
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NLMSG_SPACE(0));
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skb = alloc_skb(len, GFP_ATOMIC);
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if (!skb) {
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/* Lose information in ab->tmp */
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audit_log_lost("out of memory in audit_log_move");
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return;
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}
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ab->skb = skb;
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nlh = (struct nlmsghdr *)skb_put(skb, NLMSG_SPACE(0));
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nlh->nlmsg_type = ab->type;
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nlh->nlmsg_len = ab->len;
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nlh->nlmsg_flags = 0;
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nlh->nlmsg_pid = ab->pid;
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nlh->nlmsg_seq = 0;
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start = skb_put(skb, ab->len);
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memcpy(start, ab->tmp, ab->len);
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ab->len = 0;
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}
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/* Iterate over the skbuff in the audit_buffer, sending their contents
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* to user space. */
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static inline int audit_log_drain(struct audit_buffer *ab)
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{
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struct sk_buff *skb;
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struct sk_buff *skb = ab->skb;
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while ((skb = skb_dequeue(&ab->sklist))) {
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if (skb) {
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int retval = 0;
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if (audit_pid) {
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if (ab->nlh) {
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ab->nlh->nlmsg_len = ab->total;
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ab->nlh->nlmsg_type = ab->type;
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ab->nlh->nlmsg_flags = 0;
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ab->nlh->nlmsg_seq = 0;
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ab->nlh->nlmsg_pid = ab->pid;
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}
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skb_get(skb); /* because netlink_* frees */
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retval = netlink_unicast(audit_sock, skb, audit_pid,
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MSG_DONTWAIT);
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}
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if (retval == -EAGAIN &&
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(atomic_read(&audit_backlog)) < audit_backlog_limit) {
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skb_queue_head(&ab->sklist, skb);
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audit_log_end_irq(ab);
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return 1;
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}
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@ -550,13 +539,12 @@ static inline int audit_log_drain(struct audit_buffer *ab)
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audit_log_lost("netlink socket too busy");
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}
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if (!audit_pid) { /* No daemon */
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int offset = ab->nlh ? NLMSG_SPACE(0) : 0;
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int offset = NLMSG_SPACE(0);
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int len = skb->len - offset;
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skb->data[offset + len] = '\0';
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printk(KERN_ERR "%s\n", skb->data + offset);
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}
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kfree_skb(skb);
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ab->nlh = NULL;
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}
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return 0;
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}
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@ -624,6 +612,10 @@ static void audit_buffer_free(struct audit_buffer *ab)
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{
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unsigned long flags;
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if (!ab)
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return;
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kfree(ab->tmp);
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atomic_dec(&audit_backlog);
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spin_lock_irqsave(&audit_freelist_lock, flags);
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if (++audit_freelist_count > AUDIT_MAXFREE)
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@ -633,7 +625,8 @@ static void audit_buffer_free(struct audit_buffer *ab)
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spin_unlock_irqrestore(&audit_freelist_lock, flags);
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}
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static struct audit_buffer * audit_buffer_alloc(int gfp_mask)
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static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
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int gfp_mask)
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{
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unsigned long flags;
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struct audit_buffer *ab = NULL;
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@ -650,11 +643,24 @@ static struct audit_buffer * audit_buffer_alloc(int gfp_mask)
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if (!ab) {
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ab = kmalloc(sizeof(*ab), GFP_ATOMIC);
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if (!ab)
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goto out;
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goto err;
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}
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atomic_inc(&audit_backlog);
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out:
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ab->tmp = kmalloc(AUDIT_BUFSIZ, GFP_ATOMIC);
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if (!ab->tmp)
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goto err;
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ab->skb = NULL;
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ab->ctx = ctx;
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ab->len = 0;
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ab->size = AUDIT_BUFSIZ;
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ab->type = AUDIT_KERNEL;
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ab->pid = 0;
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return ab;
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err:
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audit_buffer_free(ab);
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return NULL;
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}
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/* Obtain an audit buffer. This routine does locking to obtain the
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@ -684,21 +690,12 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx)
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return NULL;
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}
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ab = audit_buffer_alloc(GFP_ATOMIC);
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ab = audit_buffer_alloc(ctx, GFP_ATOMIC);
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if (!ab) {
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audit_log_lost("out of memory in audit_log_start");
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return NULL;
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}
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skb_queue_head_init(&ab->sklist);
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ab->ctx = ctx;
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ab->len = 0;
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ab->nlh = NULL;
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ab->total = 0;
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ab->type = AUDIT_KERNEL;
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ab->pid = 0;
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#ifdef CONFIG_AUDITSYSCALL
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if (ab->ctx)
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audit_get_stamp(ab->ctx, &t, &serial);
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@ -713,6 +710,27 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx)
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return ab;
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}
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/**
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* audit_expand - expand tmp buffer in the audit buffer
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* @ab: audit_buffer
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*
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* Returns 0 (no space) on failed expansion, or available space if
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* successful.
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*/
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static inline int audit_expand(struct audit_buffer *ab)
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{
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char *tmp;
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int len = ab->size + AUDIT_BUFSIZ;
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tmp = kmalloc(len, GFP_ATOMIC);
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if (!tmp)
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return 0;
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memcpy(tmp, ab->tmp, ab->len);
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kfree(ab->tmp);
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ab->tmp = tmp;
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ab->size = len;
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return ab->size - ab->len;
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}
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/* Format an audit message into the audit buffer. If there isn't enough
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* room in the audit buffer, more room will be allocated and vsnprint
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@ -726,22 +744,25 @@ static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
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if (!ab)
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return;
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avail = sizeof(ab->tmp) - ab->len;
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avail = ab->size - ab->len;
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if (avail <= 0) {
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audit_log_move(ab);
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avail = sizeof(ab->tmp) - ab->len;
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avail = audit_expand(ab);
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if (!avail)
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goto out;
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}
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len = vsnprintf(ab->tmp + ab->len, avail, fmt, args);
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len = vsnprintf(ab->tmp + ab->len, avail, fmt, args);
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if (len >= avail) {
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/* The printk buffer is 1024 bytes long, so if we get
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* here and AUDIT_BUFSIZ is at least 1024, then we can
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* log everything that printk could have logged. */
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audit_log_move(ab);
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avail = sizeof(ab->tmp) - ab->len;
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len = vsnprintf(ab->tmp + ab->len, avail, fmt, args);
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avail = audit_expand(ab);
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if (!avail)
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goto out;
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len = vsnprintf(ab->tmp + ab->len, avail, fmt, args);
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}
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ab->len += (len < avail) ? len : avail;
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ab->total += (len < avail) ? len : avail;
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out:
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return;
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}
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/* Format a message into the audit buffer. All the work is done in
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@ -789,21 +810,19 @@ void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
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char *p;
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int len, avail;
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if (prefix) audit_log_format(ab, " %s", prefix);
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if (prefix)
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audit_log_format(ab, " %s", prefix);
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if (ab->len > 128)
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audit_log_move(ab);
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avail = sizeof(ab->tmp) - ab->len;
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avail = ab->size - ab->len;
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p = d_path(dentry, vfsmnt, ab->tmp + ab->len, avail);
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if (IS_ERR(p)) {
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/* FIXME: can we save some information here? */
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audit_log_format(ab, "<toolong>");
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} else {
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/* path isn't at start of buffer */
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len = (ab->tmp + sizeof(ab->tmp) - 1) - p;
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len = (ab->tmp + ab->size - 1) - p;
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memmove(ab->tmp + ab->len, p, len);
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ab->len += len;
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ab->total += len;
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}
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}
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