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authorLinus Torvalds <torvalds@linux-foundation.org>2018-04-06 15:01:25 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-06 15:01:25 -0700
commit6ad11bdd57ad31182850a54235f0e947cbfd5ad0 (patch)
tree298074cee5a8af7ac9f885f7b30d04830031312a /kernel/audit.c
parent69824bcc4b4e1427ac18a76057d592ec9028f2fe (diff)
parentea841bafda3f7f9aa8b06a09f0f3e41c207af84f (diff)
Merge tag 'audit-pr-20180403' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit
Pull audit updates from Paul Moore: "We didn't have anything to send for v4.16, but we're back with a little more than usual for v4.17. Eleven patches in total, most fall into the small fix category, but there are three non-trivial changes worth calling out: - the audit entry filter is being removed after deprecating it for quite a while (years of no one really using it because it turns out to be not very practical) - created our own version of "__mutex_owner()" because the locking folks were upset we were using theirs - improved our handling of kernel command line parameters to make them more forgiving - we fixed auditing of symlink operations Everything passes the audit-testsuite and as of a few minutes ago it merges well with your tree" * tag 'audit-pr-20180403' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit: audit: add refused symlink to audit_names audit: remove path param from link denied function audit: link denied should not directly generate PATH record audit: make ANOM_LINK obey audit_enabled and audit_dummy_context audit: do not panic on invalid boot parameter audit: track the owner of the command mutex ourselves audit: return on memory error to avoid null pointer dereference audit: bail before bug check if audit disabled audit: deprecate the AUDIT_FILTER_ENTRY filter audit: session ID should not set arch quick field pointer audit: update bugtracker and source URIs
Diffstat (limited to 'kernel/audit.c')
-rw-r--r--kernel/audit.c108
1 files changed, 76 insertions, 32 deletions
diff --git a/kernel/audit.c b/kernel/audit.c
index d97e8f0f73ca..670665c6e2a6 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -38,7 +38,8 @@
* 6) Support low-overhead kernel-based filtering to minimize the
* information that must be passed to user-space.
*
- * Example user-space utilities: http://people.redhat.com/sgrubb/audit/
+ * Audit userspace, documentation, tests, and bug/issue trackers:
+ * https://github.com/linux-audit
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -180,9 +181,21 @@ static char *audit_feature_names[2] = {
"loginuid_immutable",
};
-
-/* Serialize requests from userspace. */
-DEFINE_MUTEX(audit_cmd_mutex);
+/**
+ * struct audit_ctl_mutex - serialize requests from userspace
+ * @lock: the mutex used for locking
+ * @owner: the task which owns the lock
+ *
+ * Description:
+ * This is the lock struct used to ensure we only process userspace requests
+ * in an orderly fashion. We can't simply use a mutex/lock here because we
+ * need to track lock ownership so we don't end up blocking the lock owner in
+ * audit_log_start() or similar.
+ */
+static struct audit_ctl_mutex {
+ struct mutex lock;
+ void *owner;
+} audit_cmd_mutex;
/* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
* audit records. Since printk uses a 1024 byte buffer, this buffer
@@ -227,6 +240,36 @@ int auditd_test_task(struct task_struct *task)
}
/**
+ * audit_ctl_lock - Take the audit control lock
+ */
+void audit_ctl_lock(void)
+{
+ mutex_lock(&audit_cmd_mutex.lock);
+ audit_cmd_mutex.owner = current;
+}
+
+/**
+ * audit_ctl_unlock - Drop the audit control lock
+ */
+void audit_ctl_unlock(void)
+{
+ audit_cmd_mutex.owner = NULL;
+ mutex_unlock(&audit_cmd_mutex.lock);
+}
+
+/**
+ * audit_ctl_owner_current - Test to see if the current task owns the lock
+ *
+ * Description:
+ * Return true if the current task owns the audit control lock, false if it
+ * doesn't own the lock.
+ */
+static bool audit_ctl_owner_current(void)
+{
+ return (current == audit_cmd_mutex.owner);
+}
+
+/**
* auditd_pid_vnr - Return the auditd PID relative to the namespace
*
* Description:
@@ -860,8 +903,8 @@ int audit_send_list(void *_dest)
struct sock *sk = audit_get_sk(dest->net);
/* wait for parent to finish and send an ACK */
- mutex_lock(&audit_cmd_mutex);
- mutex_unlock(&audit_cmd_mutex);
+ audit_ctl_lock();
+ audit_ctl_unlock();
while ((skb = __skb_dequeue(&dest->q)) != NULL)
netlink_unicast(sk, skb, dest->portid, 0);
@@ -902,8 +945,8 @@ static int audit_send_reply_thread(void *arg)
struct audit_reply *reply = (struct audit_reply *)arg;
struct sock *sk = audit_get_sk(reply->net);
- mutex_lock(&audit_cmd_mutex);
- mutex_unlock(&audit_cmd_mutex);
+ audit_ctl_lock();
+ audit_ctl_unlock();
/* Ignore failure. It'll only happen if the sender goes away,
because our timeout is set to infinite. */
@@ -1058,6 +1101,8 @@ static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature
return;
ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_FEATURE_CHANGE);
+ if (!ab)
+ return;
audit_log_task_info(ab, current);
audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
audit_feature_names[which], !!old_feature, !!new_feature,
@@ -1466,7 +1511,7 @@ static void audit_receive(struct sk_buff *skb)
nlh = nlmsg_hdr(skb);
len = skb->len;
- mutex_lock(&audit_cmd_mutex);
+ audit_ctl_lock();
while (nlmsg_ok(nlh, len)) {
err = audit_receive_msg(skb, nlh);
/* if err or if this message says it wants a response */
@@ -1475,7 +1520,7 @@ static void audit_receive(struct sk_buff *skb)
nlh = nlmsg_next(nlh, &len);
}
- mutex_unlock(&audit_cmd_mutex);
+ audit_ctl_unlock();
}
/* Run custom bind function on netlink socket group connect or bind requests. */
@@ -1547,6 +1592,9 @@ static int __init audit_init(void)
for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
INIT_LIST_HEAD(&audit_inode_hash[i]);
+ mutex_init(&audit_cmd_mutex.lock);
+ audit_cmd_mutex.owner = NULL;
+
pr_info("initializing netlink subsys (%s)\n",
audit_default ? "enabled" : "disabled");
register_pernet_subsys(&audit_net_ops);
@@ -1567,19 +1615,26 @@ static int __init audit_init(void)
}
postcore_initcall(audit_init);
-/* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
+/*
+ * Process kernel command-line parameter at boot time.
+ * audit={0|off} or audit={1|on}.
+ */
static int __init audit_enable(char *str)
{
- long val;
-
- if (kstrtol(str, 0, &val))
- panic("audit: invalid 'audit' parameter value (%s)\n", str);
- audit_default = (val ? AUDIT_ON : AUDIT_OFF);
+ if (!strcasecmp(str, "off") || !strcmp(str, "0"))
+ audit_default = AUDIT_OFF;
+ else if (!strcasecmp(str, "on") || !strcmp(str, "1"))
+ audit_default = AUDIT_ON;
+ else {
+ pr_err("audit: invalid 'audit' parameter value (%s)\n", str);
+ audit_default = AUDIT_ON;
+ }
if (audit_default == AUDIT_OFF)
audit_initialized = AUDIT_DISABLED;
if (audit_set_enabled(audit_default))
- panic("audit: error setting audit state (%d)\n", audit_default);
+ pr_err("audit: error setting audit state (%d)\n",
+ audit_default);
pr_info("%s\n", audit_default ?
"enabled (after initialization)" : "disabled (until reboot)");
@@ -1710,8 +1765,7 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
* using a PID anchored in the caller's namespace
* 2. generator holding the audit_cmd_mutex - we don't want to block
* while holding the mutex */
- if (!(auditd_test_task(current) ||
- (current == __mutex_owner(&audit_cmd_mutex)))) {
+ if (!(auditd_test_task(current) || audit_ctl_owner_current())) {
long stime = audit_backlog_wait_time;
while (audit_backlog_limit &&
@@ -2254,33 +2308,23 @@ EXPORT_SYMBOL(audit_log_task_info);
/**
* audit_log_link_denied - report a link restriction denial
* @operation: specific link operation
- * @link: the path that triggered the restriction
*/
-void audit_log_link_denied(const char *operation, const struct path *link)
+void audit_log_link_denied(const char *operation)
{
struct audit_buffer *ab;
- struct audit_names *name;
- name = kzalloc(sizeof(*name), GFP_NOFS);
- if (!name)
+ if (!audit_enabled || audit_dummy_context())
return;
/* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */
ab = audit_log_start(current->audit_context, GFP_KERNEL,
AUDIT_ANOM_LINK);
if (!ab)
- goto out;
+ return;
audit_log_format(ab, "op=%s", operation);
audit_log_task_info(ab, current);
audit_log_format(ab, " res=0");
audit_log_end(ab);
-
- /* Generate AUDIT_PATH record with object. */
- name->type = AUDIT_TYPE_NORMAL;
- audit_copy_inode(name, link->dentry, d_backing_inode(link->dentry));
- audit_log_name(current->audit_context, name, link, 0, NULL);
-out:
- kfree(name);
}
/**