On 2017-03-21 14:58, Paul Moore wrote: > From: Paul Moore <paul(a)paul-moore.com&gt; > > There is no reason to have both of these functions, combine the two. > > Signed-off-by: Paul Moore <paul(a)paul-moore.com&gt; Reviewed-by: Richard Guy Briggs <rgb(a)redhat.com&gt;

> --- > kernel/audit.c | 19 ++++++++----------- > 1 file changed, 8 insertions(+), 11 deletions(-) > > diff --git a/kernel/audit.c b/kernel/audit.c > index 2f4964cfde0b..4037869b4b64 100644 > --- a/kernel/audit.c > +++ b/kernel/audit.c > @@ -1381,11 +1381,14 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) > return err < 0 ? err : 0; > } > > -/* > - * Get message from skb. Each message is processed by audit_receive_msg. > - * Malformed skbs with wrong length are discarded silently. > +/** > + * audit_receive - receive messages from a netlink control socket > + * @skb: the message buffer > + * > + * Parse the provided skb and deal with any messages that may be present, > + * malformed skbs are discarded. > */ > -static void audit_receive_skb(struct sk_buff *skb) > +static void audit_receive(struct sk_buff *skb) > { > struct nlmsghdr *nlh; > /* > @@ -1398,6 +1401,7 @@ static void audit_receive_skb(struct sk_buff *skb) > nlh = nlmsg_hdr(skb); > len = skb->len; > > + mutex_lock(&audit_cmd_mutex); > while (nlmsg_ok(nlh, len)) { > err = audit_receive_msg(skb, nlh); > /* if err or if this message says it wants a response */ > @@ -1406,13 +1410,6 @@ static void audit_receive_skb(struct sk_buff *skb) > > nlh = nlmsg_next(nlh, &len); > } > -} > - > -/* Receive messages from netlink socket. */ > -static void audit_receive(struct sk_buff *skb) > -{ > - mutex_lock(&audit_cmd_mutex); > - audit_receive_skb(skb); > mutex_unlock(&audit_cmd_mutex); > } > > > -- > Linux-audit mailing list > Linux-audit(a)redhat.com > https://www.redhat.com/mailman/listinfo/linux-audit - RGB -- Richard Guy Briggs <rgb(a)redhat.com&gt; Sr. S/W Engineer, Kernel Security, Base Operating Systems Remote, Ottawa, Red Hat Canada IRC: rgb, SunRaycer Voice: +1.647.777.2635, Internal: (81) 32635 -- Linux-audit mailing list Linux-audit(a)redhat.com https://www.redhat.com/mailman/listinfo/linux-audit

From: Paul Moore <paul(a)paul-moore.com&gt; We were setting the portid incorrectly in the netlink message headers, fix that to always be 0 (nlmsg_pid = 0). Signed-off-by: Paul Moore <paul(a)paul-moore.com&gt;

--- include/linux/audit.h | 3 +-- kernel/audit.c | 23 ++++++----------------- kernel/audit.h | 3 +-- kernel/auditfilter.c | 14 ++++++-------- 4 files changed, 14 insertions(+), 29 deletions(-) diff --git a/include/linux/audit.h b/include/linux/audit.h index 504e784b7ffa..cc0497c39472 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -163,8 +163,7 @@ extern void audit_log_task_info(struct audit_buffer *ab, extern int audit_update_lsm_rules(void); /* Private API (for audit.c only) */ -extern int audit_rule_change(int type, __u32 portid, int seq, - void *data, size_t datasz); +extern int audit_rule_change(int type, int seq, void *data, size_t datasz); extern int audit_list_rules_send(struct sk_buff *request_skb, int seq); extern u32 audit_enabled; diff --git a/kernel/audit.c b/kernel/audit.c index 4037869b4b64..6cbf47a372e8 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -251,14 +251,6 @@ static struct sock *audit_get_sk(const struct net *net) return aunet->sk; } -static void audit_set_portid(struct audit_buffer *ab, __u32 portid) -{ - if (ab) { - struct nlmsghdr *nlh = nlmsg_hdr(ab->skb); - nlh->nlmsg_pid = portid; - } -} - void audit_panic(const char *message) { switch (audit_failure) { @@ -819,7 +811,7 @@ int audit_send_list(void *_dest) return 0; } -struct sk_buff *audit_make_reply(__u32 portid, int seq, int type, int done, +struct sk_buff *audit_make_reply(int seq, int type, int done, int multi, const void *payload, int size) { struct sk_buff *skb; @@ -832,7 +824,7 @@ struct sk_buff *audit_make_reply(__u32 portid, int seq, int type, int done, if (!skb) return NULL; - nlh = nlmsg_put(skb, portid, seq, t, size, flags); + nlh = nlmsg_put(skb, 0, seq, t, size, flags); if (!nlh) goto out_kfree_skb; data = nlmsg_data(nlh); @@ -876,7 +868,6 @@ static int audit_send_reply_thread(void *arg) static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done, int multi, const void *payload, int size) { - u32 portid = NETLINK_CB(request_skb).portid; struct net *net = sock_net(NETLINK_CB(request_skb).sk); struct sk_buff *skb; struct task_struct *tsk; @@ -886,12 +877,12 @@ static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int if (!reply) return; - skb = audit_make_reply(portid, seq, type, done, multi, payload, size); + skb = audit_make_reply(seq, type, done, multi, payload, size); if (!skb) goto out; reply->net = get_net(net); - reply->portid = portid; + reply->portid = NETLINK_CB(request_skb).portid; reply->skb = skb; tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply"); @@ -1075,7 +1066,7 @@ static int audit_replace(pid_t pid) { struct sk_buff *skb; - skb = audit_make_reply(0, 0, AUDIT_REPLACE, 0, 0, &pid, sizeof(pid)); + skb = audit_make_reply(0, AUDIT_REPLACE, 0, 0, &pid, sizeof(pid)); if (!skb) return -ENOMEM; return auditd_send_unicast_skb(skb); @@ -1245,7 +1236,6 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) size--; audit_log_n_untrustedstring(ab, data, size); } - audit_set_portid(ab, NETLINK_CB(skb).portid); audit_log_end(ab); } break; @@ -1259,8 +1249,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) audit_log_end(ab); return -EPERM; } - err = audit_rule_change(msg_type, NETLINK_CB(skb).portid, - seq, data, nlmsg_len(nlh)); + err = audit_rule_change(msg_type, seq, data, nlmsg_len(nlh)); break; case AUDIT_LIST_RULES: err = audit_list_rules_send(skb, seq); diff --git a/kernel/audit.h b/kernel/audit.h index 0f1cf6d1878a..c21b74dd7ff2 100644 --- a/kernel/audit.h +++ b/kernel/audit.h @@ -237,8 +237,7 @@ extern int audit_uid_comparator(kuid_t left, u32 op, kuid_t right); extern int audit_gid_comparator(kgid_t left, u32 op, kgid_t right); extern int parent_len(const char *path); extern int audit_compare_dname_path(const char *dname, const char *path, int plen); -extern struct sk_buff *audit_make_reply(__u32 portid, int seq, int type, - int done, int multi, +extern struct sk_buff *audit_make_reply(int seq, int type, int done, int multi, const void *payload, int size); extern void audit_panic(const char *message); diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c index 880519d6cf2a..81cdf8d8f319 100644 --- a/kernel/auditfilter.c +++ b/kernel/auditfilter.c @@ -1033,7 +1033,7 @@ int audit_del_rule(struct audit_entry *entry) } /* List rules using struct audit_rule_data. */ -static void audit_list_rules(__u32 portid, int seq, struct sk_buff_head *q) +static void audit_list_rules(int seq, struct sk_buff_head *q) { struct sk_buff *skb; struct audit_krule *r; @@ -1048,15 +1048,15 @@ static void audit_list_rules(__u32 portid, int seq, struct sk_buff_head *q) data = audit_krule_to_data(r); if (unlikely(!data)) break; - skb = audit_make_reply(portid, seq, AUDIT_LIST_RULES, - 0, 1, data, + skb = audit_make_reply(seq, AUDIT_LIST_RULES, 0, 1, + data, sizeof(*data) + data->buflen); if (skb) skb_queue_tail(q, skb); kfree(data); } } - skb = audit_make_reply(portid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0); + skb = audit_make_reply(seq, AUDIT_LIST_RULES, 1, 1, NULL, 0); if (skb) skb_queue_tail(q, skb); } @@ -1085,13 +1085,11 @@ static void audit_log_rule_change(char *action, struct audit_krule *rule, int re /** * audit_rule_change - apply all rules to the specified message type * @type: audit message type - * @portid: target port id for netlink audit messages * @seq: netlink audit message sequence (serial) number * @data: payload data * @datasz: size of payload data */ -int audit_rule_change(int type, __u32 portid, int seq, void *data, - size_t datasz) +int audit_rule_change(int type, int seq, void *data, size_t datasz) { int err = 0; struct audit_entry *entry; @@ -1150,7 +1148,7 @@ int audit_list_rules_send(struct sk_buff *request_skb, int seq) skb_queue_head_init(&dest->q); mutex_lock(&audit_filter_mutex); - audit_list_rules(portid, seq, &dest->q); + audit_list_rules(seq, &dest->q); mutex_unlock(&audit_filter_mutex); tsk = kthread_run(audit_send_list, dest, "audit_send_list"); -- Linux-audit mailing list Linux-audit(a)redhat.com https://www.redhat.com/mailman/listinfo/linux-audit

On 2017-03-21 14:59, Paul Moore wrote: > From: Paul Moore <paul(a)paul-moore.com&gt; > > This is arguably the right thing to do, and will make it easier when > we start supporting multiple audit daemons in different namespaces. I had tried this several years ago inspired by Eric Biederman's work for the same reasons: https://www.redhat.com/archives/linux-audit/2014-February/msg00116.html A lot has changed since then... A couple of comments in-line... > Signed-off-by: Paul Moore <paul(a)paul-moore.com&gt; > --- > kernel/audit.c | 84 ++++++++++++++++++++++++++++++++++++++------------------ > kernel/audit.h | 2 + > 2 files changed, 58 insertions(+), 28 deletions(-) > > diff --git a/kernel/audit.c b/kernel/audit.c > index 6cbf47a372e8..b718bf3a73f8 100644 > --- a/kernel/audit.c > +++ b/kernel/audit.c > @@ -58,6 +58,7 @@ > #include <linux/rcupdate.h> > #include <linux/mutex.h> > #include <linux/gfp.h> > +#include <linux/pid.h> > > #include <linux/audit.h> > > @@ -117,7 +118,7 @@ struct audit_net { > * or the included spinlock for writing. > */ > static struct auditd_connection { > - int pid; > + struct pid *pid; > u32 portid; > struct net *net; > spinlock_t lock; > @@ -221,18 +222,41 @@ struct audit_reply { > * Description: > * Return 1 if the task is a registered audit daemon, 0 otherwise. > */ > -int auditd_test_task(const struct task_struct *task) > +int auditd_test_task(struct task_struct *task) Does the compiler complain if this is left as const?

Reviewed-by: Richard Guy Briggs <rgb(a)redhat.com&gt;

From: Paul Moore <paul(a)paul-moore.com&gt; The audit subsystem implemented its own buffer cache mechanism which is a bit silly these days when we could use the kmem_cache construct. Some credit is due to Florian Westphal for originally proposing that we remove the audit cache implementation in favor of simple kmalloc()/kfree() calls, but I would rather have a dedicated slab cache to ease debugging and future stats/performance work. Cc: Florian Westphal <fw(a)strlen.de&gt; Signed-off-by: Paul Moore <paul(a)paul-moore.com&gt; --- kernel/audit.c | 66 ++++++++++++++------------------------------------------ 1 file changed, 17 insertions(+), 49 deletions(-) diff --git a/kernel/audit.c b/kernel/audit.c index b718bf3a73f8..f78cdd75a4d2 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -59,6 +59,7 @@ #include <linux/mutex.h> #include <linux/gfp.h> #include <linux/pid.h> +#include <linux/slab.h> #include <linux/audit.h> @@ -152,12 +153,7 @@ static atomic_t audit_lost = ATOMIC_INIT(0); /* Hash for inode-based rules */ struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS]; -/* The audit_freelist is a list of pre-allocated audit buffers (if more - * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of - * being placed on the freelist). */ -static DEFINE_SPINLOCK(audit_freelist_lock); -static int audit_freelist_count; -static LIST_HEAD(audit_freelist); +static struct kmem_cache *audit_buffer_cache; /* queue msgs to send via kauditd_task */ static struct sk_buff_head audit_queue; @@ -193,17 +189,12 @@ DEFINE_MUTEX(audit_cmd_mutex); * should be at least that large. */ #define AUDIT_BUFSIZ 1024 -/* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the - * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */ -#define AUDIT_MAXFREE (2*NR_CPUS) - /* The audit_buffer is used when formatting an audit record. The caller * locks briefly to get the record off the freelist or to allocate the * buffer, and locks briefly to send the buffer to the netlink layer or * to place it on a transmit queue. Multiple audit_buffers can be in * use simultaneously. */ struct audit_buffer { - struct list_head list; struct sk_buff *skb; /* formatted skb ready to send */ struct audit_context *ctx; /* NULL or associated context */ gfp_t gfp_mask; @@ -1489,6 +1480,10 @@ static int __init audit_init(void) if (audit_initialized == AUDIT_DISABLED) return 0; + audit_buffer_cache = kmem_cache_create("audit_buffer", + sizeof(struct audit_buffer), + 0, SLAB_PANIC, NULL); + memset(&auditd_conn, 0, sizeof(auditd_conn)); spin_lock_init(&auditd_conn.lock); @@ -1557,60 +1552,33 @@ __setup("audit_backlog_limit=", audit_backlog_limit_set); static void audit_buffer_free(struct audit_buffer *ab) { - unsigned long flags; - if (!ab) return; kfree_skb(ab->skb); - spin_lock_irqsave(&audit_freelist_lock, flags); - if (audit_freelist_count > AUDIT_MAXFREE) - kfree(ab); - else { - audit_freelist_count++; - list_add(&ab->list, &audit_freelist); - } - spin_unlock_irqrestore(&audit_freelist_lock, flags); + kmem_cache_free(audit_buffer_cache, ab); } -static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, - gfp_t gfp_mask, int type) +static struct audit_buffer *audit_buffer_alloc(struct audit_context *ctx, + gfp_t gfp_mask, int type) { - unsigned long flags; - struct audit_buffer *ab = NULL; - struct nlmsghdr *nlh; - - spin_lock_irqsave(&audit_freelist_lock, flags); - if (!list_empty(&audit_freelist)) { - ab = list_entry(audit_freelist.next, - struct audit_buffer, list); - list_del(&ab->list); - --audit_freelist_count; - } - spin_unlock_irqrestore(&audit_freelist_lock, flags); - - if (!ab) { - ab = kmalloc(sizeof(*ab), gfp_mask); - if (!ab) - goto err; - } + struct audit_buffer *ab; - ab->ctx = ctx; - ab->gfp_mask = gfp_mask; + ab = kmem_cache_alloc(audit_buffer_cache, gfp_mask); + if (!ab) + return NULL; ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask); if (!ab->skb) goto err; + if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0)) + goto err; - nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0); - if (!nlh) - goto out_kfree_skb; + ab->ctx = ctx; + ab->gfp_mask = gfp_mask; return ab; -out_kfree_skb: - kfree_skb(ab->skb); - ab->skb = NULL; err: audit_buffer_free(ab); return NULL; -- Linux-audit mailing list Linux-audit(a)redhat.com https://www.redhat.com/mailman/listinfo/linux-audit

On 2017-03-21 14:59, Paul Moore wrote: > From: Paul Moore <paul(a)paul-moore.com&gt; > The audit subsystem implemented its own buffer cache mechanism which > is a bit silly these days when we could use the kmem_cache construct. > > Some credit is due to Florian Westphal for originally proposing that > we remove the audit cache implementation in favor of simple > kmalloc()/kfree() calls, but I would rather have a dedicated slab > cache to ease debugging and future stats/performance work. > > Cc: Florian Westphal <fw(a)strlen.de&gt; > Signed-off-by: Paul Moore <paul(a)paul-moore.com&gt; > --- > kernel/audit.c | 66 ++++++++++++++------------------------------------------ > 1 file changed, 17 insertions(+), 49 deletions(-) > > diff --git a/kernel/audit.c b/kernel/audit.c > index b718bf3a73f8..f78cdd75a4d2 100644 > --- a/kernel/audit.c > +++ b/kernel/audit.c > @@ -59,6 +59,7 @@ > #include <linux/mutex.h> > #include <linux/gfp.h> > #include <linux/pid.h> > +#include <linux/slab.h> > > #include <linux/audit.h> > > @@ -152,12 +153,7 @@ static atomic_t audit_lost = ATOMIC_INIT(0); > /* Hash for inode-based rules */ > struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS]; > > -/* The audit_freelist is a list of pre-allocated audit buffers (if more > - * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of > - * being placed on the freelist). */ > -static DEFINE_SPINLOCK(audit_freelist_lock); > -static int audit_freelist_count; > -static LIST_HEAD(audit_freelist); > +static struct kmem_cache *audit_buffer_cache; > > /* queue msgs to send via kauditd_task */ > static struct sk_buff_head audit_queue; > @@ -193,17 +189,12 @@ DEFINE_MUTEX(audit_cmd_mutex); > * should be at least that large. */ > #define AUDIT_BUFSIZ 1024 > > -/* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the > - * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */ > -#define AUDIT_MAXFREE (2*NR_CPUS) > - > /* The audit_buffer is used when formatting an audit record. The caller > * locks briefly to get the record off the freelist or to allocate the > * buffer, and locks briefly to send the buffer to the netlink layer or > * to place it on a transmit queue. Multiple audit_buffers can be in > * use simultaneously. */ > struct audit_buffer { > - struct list_head list; > struct sk_buff *skb; /* formatted skb ready to send */ > struct audit_context *ctx; /* NULL or associated context */ > gfp_t gfp_mask; > @@ -1489,6 +1480,10 @@ static int __init audit_init(void) > if (audit_initialized == AUDIT_DISABLED) > return 0; > > + audit_buffer_cache = kmem_cache_create("audit_buffer", > + sizeof(struct audit_buffer), > + 0, SLAB_PANIC, NULL); > + > memset(&auditd_conn, 0, sizeof(auditd_conn)); > spin_lock_init(&auditd_conn.lock); > > @@ -1557,60 +1552,33 @@ __setup("audit_backlog_limit=", audit_backlog_limit_set); > > static void audit_buffer_free(struct audit_buffer *ab) > { > - unsigned long flags; > - > if (!ab) > return; > > kfree_skb(ab->skb); > - spin_lock_irqsave(&audit_freelist_lock, flags); > - if (audit_freelist_count > AUDIT_MAXFREE) > - kfree(ab); > - else { > - audit_freelist_count++; > - list_add(&ab->list, &audit_freelist); > - } > - spin_unlock_irqrestore(&audit_freelist_lock, flags); > + kmem_cache_free(audit_buffer_cache, ab); > } > > -static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, > - gfp_t gfp_mask, int type) > +static struct audit_buffer *audit_buffer_alloc(struct audit_context *ctx, > + gfp_t gfp_mask, int type) > { > - unsigned long flags; > - struct audit_buffer *ab = NULL; > - struct nlmsghdr *nlh; > - > - spin_lock_irqsave(&audit_freelist_lock, flags); > - if (!list_empty(&audit_freelist)) { > - ab = list_entry(audit_freelist.next, > - struct audit_buffer, list); > - list_del(&ab->list); > - --audit_freelist_count; > - } > - spin_unlock_irqrestore(&audit_freelist_lock, flags); > - > - if (!ab) { > - ab = kmalloc(sizeof(*ab), gfp_mask); > - if (!ab) > - goto err; > - } > + struct audit_buffer *ab; > > - ab->ctx = ctx; > - ab->gfp_mask = gfp_mask; > + ab = kmem_cache_alloc(audit_buffer_cache, gfp_mask); > + if (!ab) > + return NULL; > > ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask); > if (!ab->skb) > goto err; > + if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0)) > + goto err; > > - nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0); > - if (!nlh) > - goto out_kfree_skb; Is there a reason to care about an error returned from nlmsg_put() if you aren't going to free the skb that was allocated? If you think nlmsg_put() can't fail due to extremely simple calling arguments then there is no need to check its return code. If nlmsg_new() succeeds, it has allocated an skb. If nlmsg_put() fails, you free the audit_buffer and the skb is now a memory leak. Have I read this correctly?

Otherwise, I like the intent of this simplification. > + ab->ctx = ctx; > + ab->gfp_mask = gfp_mask; > > return ab; > > -out_kfree_skb: > - kfree_skb(ab->skb); > - ab->skb = NULL; > err: > audit_buffer_free(ab); > return NULL; - RGB -- Richard Guy Briggs <rgb(a)redhat.com&gt; Sr. S/W Engineer, Kernel Security, Base Operating Systems Remote, Ottawa, Red Hat Canada IRC: rgb, SunRaycer Voice: +1.647.777.2635, Internal: (81) 32635 -- Linux-audit mailing list Linux-audit(a)redhat.com https://www.redhat.com/mailman/listinfo/linux-audit

On 2017-04-11 16:07, Paul Moore wrote: > On Mon, Apr 10, 2017 at 12:04 AM, Richard Guy Briggs <rgb(a)redhat.com&gt; wrote: > > On 2017-03-21 14:59, Paul Moore wrote: > >> From: Paul Moore <paul(a)paul-moore.com&gt; > >> The audit subsystem implemented its own buffer cache mechanism which > >> is a bit silly these days when we could use the kmem_cache construct. > >> > >> Some credit is due to Florian Westphal for originally proposing that > >> we remove the audit cache implementation in favor of simple > >> kmalloc()/kfree() calls, but I would rather have a dedicated slab > >> cache to ease debugging and future stats/performance work. > >> > >> Cc: Florian Westphal <fw(a)strlen.de&gt; > >> Signed-off-by: Paul Moore <paul(a)paul-moore.com&gt; > >> --- > >> kernel/audit.c | 66 ++++++++++++++------------------------------------------ > >> 1 file changed, 17 insertions(+), 49 deletions(-) > >> > >> diff --git a/kernel/audit.c b/kernel/audit.c > >> index b718bf3a73f8..f78cdd75a4d2 100644 > >> --- a/kernel/audit.c > >> +++ b/kernel/audit.c > >> @@ -59,6 +59,7 @@ > >> #include <linux/mutex.h> > >> #include <linux/gfp.h> > >> #include <linux/pid.h> > >> +#include <linux/slab.h> > >> > >> #include <linux/audit.h> > >> > >> @@ -152,12 +153,7 @@ static atomic_t audit_lost = ATOMIC_INIT(0); > >> /* Hash for inode-based rules */ > >> struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS]; > >> > >> -/* The audit_freelist is a list of pre-allocated audit buffers (if more > >> - * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of > >> - * being placed on the freelist). */ > >> -static DEFINE_SPINLOCK(audit_freelist_lock); > >> -static int audit_freelist_count; > >> -static LIST_HEAD(audit_freelist); > >> +static struct kmem_cache *audit_buffer_cache; > >> > >> /* queue msgs to send via kauditd_task */ > >> static struct sk_buff_head audit_queue; > >> @@ -193,17 +189,12 @@ DEFINE_MUTEX(audit_cmd_mutex); > >> * should be at least that large. */ > >> #define AUDIT_BUFSIZ 1024 > >> > >> -/* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the > >> - * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */ > >> -#define AUDIT_MAXFREE (2*NR_CPUS) > >> - > >> /* The audit_buffer is used when formatting an audit record. The caller > >> * locks briefly to get the record off the freelist or to allocate the > >> * buffer, and locks briefly to send the buffer to the netlink layer or > >> * to place it on a transmit queue. Multiple audit_buffers can be in > >> * use simultaneously. */ > >> struct audit_buffer { > >> - struct list_head list; > >> struct sk_buff *skb; /* formatted skb ready to send */ > >> struct audit_context *ctx; /* NULL or associated context */ > >> gfp_t gfp_mask; > >> @@ -1489,6 +1480,10 @@ static int __init audit_init(void) > >> if (audit_initialized == AUDIT_DISABLED) > >> return 0; > >> > >> + audit_buffer_cache = kmem_cache_create("audit_buffer", > >> + sizeof(struct audit_buffer), > >> + 0, SLAB_PANIC, NULL); > >> + > >> memset(&auditd_conn, 0, sizeof(auditd_conn)); > >> spin_lock_init(&auditd_conn.lock); > >> > >> @@ -1557,60 +1552,33 @@ __setup("audit_backlog_limit=", audit_backlog_limit_set); > >> > >> static void audit_buffer_free(struct audit_buffer *ab) > >> { > >> - unsigned long flags; > >> - > >> if (!ab) > >> return; > >> > >> kfree_skb(ab->skb); > >> - spin_lock_irqsave(&audit_freelist_lock, flags); > >> - if (audit_freelist_count > AUDIT_MAXFREE) > >> - kfree(ab); > >> - else { > >> - audit_freelist_count++; > >> - list_add(&ab->list, &audit_freelist); > >> - } > >> - spin_unlock_irqrestore(&audit_freelist_lock, flags); > >> + kmem_cache_free(audit_buffer_cache, ab); > >> } > >> > >> -static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, > >> - gfp_t gfp_mask, int type) > >> +static struct audit_buffer *audit_buffer_alloc(struct audit_context *ctx, > >> + gfp_t gfp_mask, int type) > >> { > >> - unsigned long flags; > >> - struct audit_buffer *ab = NULL; > >> - struct nlmsghdr *nlh; > >> - > >> - spin_lock_irqsave(&audit_freelist_lock, flags); > >> - if (!list_empty(&audit_freelist)) { > >> - ab = list_entry(audit_freelist.next, > >> - struct audit_buffer, list); > >> - list_del(&ab->list); > >> - --audit_freelist_count; > >> - } > >> - spin_unlock_irqrestore(&audit_freelist_lock, flags); > >> - > >> - if (!ab) { > >> - ab = kmalloc(sizeof(*ab), gfp_mask); > >> - if (!ab) > >> - goto err; > >> - } > >> + struct audit_buffer *ab; > >> > >> - ab->ctx = ctx; > >> - ab->gfp_mask = gfp_mask; > >> + ab = kmem_cache_alloc(audit_buffer_cache, gfp_mask); > >> + if (!ab) > >> + return NULL; > >> > >> ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask); > >> if (!ab->skb) > >> goto err; > >> + if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0)) > >> + goto err; > >> > >> - nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0); > >> - if (!nlh) > >> - goto out_kfree_skb; > > > > Is there a reason to care about an error returned from nlmsg_put() if > > you aren't going to free the skb that was allocated? If you think > > nlmsg_put() can't fail due to extremely simple calling arguments then > > there is no need to check its return code. > > > > If nlmsg_new() succeeds, it has allocated an skb. If nlmsg_put() fails, > > you free the audit_buffer and the skb is now a memory leak. > > > > Have I read this correctly? > > Check my math, but in the patched code if the nlmsg_put() call fails > then we jump to "err" which calls audit_buffer_free() which in turn > calls kfree_skb() on ab->skb so I don't believe we have a memory leak > on error ... I'll hold off on merging this in case I'm missing > something, but I'm pretty sure we're okay here. Ok, yes, you're right. This is ringing a bell... I think there was another place recently that the extra free_skb() was dropped and I had missed audit_buffer_free() doing the right thing then. > > Otherwise, I like the intent of this simplification. Looks good, Reviewed-by: Richard Guy Briggs <rgb(a)redhat.com&gt;