diff options
Diffstat (limited to 'kernel/audit.c')
| -rw-r--r-- | kernel/audit.c | 114 |
1 files changed, 79 insertions, 35 deletions
diff --git a/kernel/audit.c b/kernel/audit.c index 227db99b0f19..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: @@ -443,15 +486,15 @@ static int audit_set_failure(u32 state) * Drop any references inside the auditd connection tracking struct and free * the memory. */ - static void auditd_conn_free(struct rcu_head *rcu) - { +static void auditd_conn_free(struct rcu_head *rcu) +{ struct auditd_connection *ac; ac = container_of(rcu, struct auditd_connection, rcu); put_pid(ac->pid); put_net(ac->net); kfree(ac); - } +} /** * auditd_set - Set/Reset the auditd connection state @@ -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); } /** |