diff options
author | rwatson <rwatson@FreeBSD.org> | 2006-03-19 16:03:43 +0000 |
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committer | rwatson <rwatson@FreeBSD.org> | 2006-03-19 16:03:43 +0000 |
commit | 6163ee5a7b865b66b1dd7f437ade09ea314d0b68 (patch) | |
tree | 173cc554d449ea6a66fc0846695d99861630c1a9 /sys/security/audit/audit_worker.c | |
parent | b20083fef62523a15daa2c86699c513b7adaa0e7 (diff) | |
download | FreeBSD-src-6163ee5a7b865b66b1dd7f437ade09ea314d0b68.zip FreeBSD-src-6163ee5a7b865b66b1dd7f437ade09ea314d0b68.tar.gz |
Merge Perforce changes 93512, 93514, 93515 from TrustedBSD audit3
branch:
Integrate audit.c to audit_worker.c, so as to migrate the worker
thread implementation to its own .c file.
Populate audit_worker.c using parts now removed from audit.c:
- Move audit rotation global variables.
- Move audit_record_write(), audit_worker_rotate(),
audit_worker_drain(), audit_worker(), audit_rotate_vnode().
- Create audit_worker_init() from relevant parts of audit_init(),
which now calls this routine.
- Recreate audit_free(), which wraps uma_zfree() so that
audit_record_zone can be static to audit.c.
- Unstaticize various types and variables relating to the audit
record queue so that audit_worker can get to them. We may want
to wrap these in accessor methods at some point.
- Move AUDIT_PRINTF() to audit_private.h.
Addition of audit_worker.c to kernel configuration, missed in
earlier submit.
Obtained from: TrustedBSD Project
Diffstat (limited to 'sys/security/audit/audit_worker.c')
-rw-r--r-- | sys/security/audit/audit_worker.c | 558 |
1 files changed, 558 insertions, 0 deletions
diff --git a/sys/security/audit/audit_worker.c b/sys/security/audit/audit_worker.c new file mode 100644 index 0000000..f975800 --- /dev/null +++ b/sys/security/audit/audit_worker.c @@ -0,0 +1,558 @@ +/* + * Copyright (c) 1999-2005 Apple Computer, Inc. + * Copyright (c) 2006 Robert N. M. Watson + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of + * its contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR + * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING + * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + * $FreeBSD$ + */ + +#include <sys/param.h> +#include <sys/condvar.h> +#include <sys/conf.h> +#include <sys/file.h> +#include <sys/filedesc.h> +#include <sys/fcntl.h> +#include <sys/ipc.h> +#include <sys/kernel.h> +#include <sys/kthread.h> +#include <sys/malloc.h> +#include <sys/mount.h> +#include <sys/namei.h> +#include <sys/proc.h> +#include <sys/queue.h> +#include <sys/socket.h> +#include <sys/socketvar.h> +#include <sys/protosw.h> +#include <sys/domain.h> +#include <sys/sysproto.h> +#include <sys/sysent.h> +#include <sys/systm.h> +#include <sys/ucred.h> +#include <sys/uio.h> +#include <sys/un.h> +#include <sys/unistd.h> +#include <sys/vnode.h> + +#include <bsm/audit.h> +#include <bsm/audit_internal.h> +#include <bsm/audit_kevents.h> + +#include <netinet/in.h> +#include <netinet/in_pcb.h> + +#include <security/audit/audit.h> +#include <security/audit/audit_private.h> + +#include <vm/uma.h> + +/* + * Worker thread that will schedule disk I/O, etc. + */ +static struct proc *audit_thread; + +/* + * When an audit log is rotated, the actual rotation must be performed + * by the audit worker thread, as it may have outstanding writes on the + * current audit log. audit_replacement_vp holds the vnode replacing + * the current vnode. We can't let more than one replacement occur + * at a time, so if more than one thread requests a replacement, only + * one can have the replacement "in progress" at any given moment. If + * a thread tries to replace the audit vnode and discovers a replacement + * is already in progress (i.e., audit_replacement_flag != 0), then it + * will sleep on audit_replacement_cv waiting its turn to perform a + * replacement. When a replacement is completed, this cv is signalled + * by the worker thread so a waiting thread can start another replacement. + * We also store a credential to perform audit log write operations with. + * + * The current credential and vnode are thread-local to audit_worker. + */ +static struct cv audit_replacement_cv; + +static int audit_replacement_flag; +static struct vnode *audit_replacement_vp; +static struct ucred *audit_replacement_cred; + +/* + * Flags related to Kernel->user-space communication. + */ +static int audit_file_rotate_wait; + +/* + * XXXAUDIT: Should adjust comments below to make it clear that we get to + * this point only if we believe we have storage, so not having space here + * is a violation of invariants derived from administrative procedures. + * I.e., someone else has written to the audit partition, leaving less space + * than we accounted for. + */ +static int +audit_record_write(struct vnode *vp, struct kaudit_record *ar, + struct ucred *cred, struct thread *td) +{ + int ret; + long temp; + struct au_record *bsm; + struct vattr vattr; + struct statfs *mnt_stat = &vp->v_mount->mnt_stat; + int vfslocked; + + vfslocked = VFS_LOCK_GIANT(vp->v_mount); + + /* + * First, gather statistics on the audit log file and file system + * so that we know how we're doing on space. In both cases, + * if we're unable to perform the operation, we drop the record + * and return. However, this is arguably an assertion failure. + * XXX Need a FreeBSD equivalent. + */ + ret = VFS_STATFS(vp->v_mount, mnt_stat, td); + if (ret) + goto out; + + vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); + ret = VOP_GETATTR(vp, &vattr, cred, td); + VOP_UNLOCK(vp, 0, td); + if (ret) + goto out; + + /* update the global stats struct */ + audit_fstat.af_currsz = vattr.va_size; + + /* + * XXX Need to decide what to do if the trigger to the audit daemon + * fails. + */ + + /* + * If we fall below minimum free blocks (hard limit), tell the audit + * daemon to force a rotation off of the file system. We also stop + * writing, which means this audit record is probably lost. + * If we fall below the minimum percent free blocks (soft limit), + * then kindly suggest to the audit daemon to do something. + */ + if (mnt_stat->f_bfree < AUDIT_HARD_LIMIT_FREE_BLOCKS) { + (void)send_trigger(AUDIT_TRIGGER_NO_SPACE); + /* Hopefully userspace did something about all the previous + * triggers that were sent prior to this critical condition. + * If fail-stop is set, then we're done; goodnight Gracie. + */ + if (audit_fail_stop) + panic("Audit log space exhausted and fail-stop set."); + else { + audit_suspended = 1; + ret = ENOSPC; + goto out; + } + } else + /* + * Send a message to the audit daemon that disk space + * is getting low. + * + * XXXAUDIT: Check math and block size calculation here. + */ + if (audit_qctrl.aq_minfree != 0) { + temp = mnt_stat->f_blocks / (100 / + audit_qctrl.aq_minfree); + if (mnt_stat->f_bfree < temp) + (void)send_trigger(AUDIT_TRIGGER_LOW_SPACE); + } + + /* Check if the current log file is full; if so, call for + * a log rotate. This is not an exact comparison; we may + * write some records over the limit. If that's not + * acceptable, then add a fudge factor here. + */ + if ((audit_fstat.af_filesz != 0) && + (audit_file_rotate_wait == 0) && + (vattr.va_size >= audit_fstat.af_filesz)) { + audit_file_rotate_wait = 1; + (void)send_trigger(AUDIT_TRIGGER_OPEN_NEW); + } + + /* + * If the estimated amount of audit data in the audit event queue + * (plus records allocated but not yet queued) has reached the + * amount of free space on the disk, then we need to go into an + * audit fail stop state, in which we do not permit the + * allocation/committing of any new audit records. We continue to + * process packets but don't allow any activities that might + * generate new records. In the future, we might want to detect + * when space is available again and allow operation to continue, + * but this behavior is sufficient to meet fail stop requirements + * in CAPP. + */ + if (audit_fail_stop && + (unsigned long) + ((audit_q_len + audit_pre_q_len + 1) * MAX_AUDIT_RECORD_SIZE) / + mnt_stat->f_bsize >= (unsigned long)(mnt_stat->f_bfree)) { + printf("audit_record_write: free space below size of audit " + "queue, failing stop\n"); + audit_in_failure = 1; + } + + /* + * If there is a user audit record attached to the kernel record, + * then write the user record. + */ + /* XXX Need to decide a few things here: IF the user audit + * record is written, but the write of the kernel record fails, + * what to do? Should the kernel record come before or after the + * user record? For now, we write the user record first, and + * we ignore errors. + */ + if (ar->k_ar_commit & AR_COMMIT_USER) { + /* + * Try submitting the record to any active audit pipes. + */ + audit_pipe_submit((void *)ar->k_udata, ar->k_ulen); + + /* + * And to disk. + */ + ret = vn_rdwr(UIO_WRITE, vp, (void *)ar->k_udata, ar->k_ulen, + (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, cred, NULL, + NULL, td); + if (ret) + goto out; + } + + /* + * Convert the internal kernel record to BSM format and write it + * out if everything's OK. + */ + if (!(ar->k_ar_commit & AR_COMMIT_KERNEL)) { + ret = 0; + goto out; + } + + /* + * XXXAUDIT: Should we actually allow this conversion to fail? With + * sleeping memory allocation and invariants checks, perhaps not. + */ + ret = kaudit_to_bsm(ar, &bsm); + if (ret == BSM_NOAUDIT) { + ret = 0; + goto out; + } + + /* + * XXX: We drop the record on BSM conversion failure, but really + * this is an assertion failure. + */ + if (ret == BSM_FAILURE) { + AUDIT_PRINTF(("BSM conversion failure\n")); + ret = EINVAL; + goto out; + } + + /* + * Try submitting the record to any active audit pipes. + */ + audit_pipe_submit((void *)bsm->data, bsm->len); + + /* + * XXX + * We should break the write functionality away from the BSM record + * generation and have the BSM generation done before this function + * is called. This function will then take the BSM record as a + * parameter. + */ + ret = (vn_rdwr(UIO_WRITE, vp, (void *)bsm->data, bsm->len, + (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, cred, NULL, NULL, td)); + + kau_free(bsm); + +out: + /* + * When we're done processing the current record, we have to + * check to see if we're in a failure mode, and if so, whether + * this was the last record left to be drained. If we're done + * draining, then we fsync the vnode and panic. + */ + if (audit_in_failure && + audit_q_len == 0 && audit_pre_q_len == 0) { + VOP_LOCK(vp, LK_DRAIN | LK_INTERLOCK, td); + (void)VOP_FSYNC(vp, MNT_WAIT, td); + VOP_UNLOCK(vp, 0, td); + panic("Audit store overflow; record queue drained."); + } + + VFS_UNLOCK_GIANT(vfslocked); + + return (ret); +} + +/* + * If an appropriate signal has been received rotate the audit log based on + * the global replacement variables. Signal consumers as needed that the + * rotation has taken place. + * + * XXXRW: The global variables and CVs used to signal the audit_worker to + * perform a rotation are essentially a message queue of depth 1. It would + * be much nicer to actually use a message queue. + */ +static void +audit_worker_rotate(struct ucred **audit_credp, struct vnode **audit_vpp, + struct thread *audit_td) +{ + int do_replacement_signal, vfslocked; + struct ucred *old_cred; + struct vnode *old_vp; + + mtx_assert(&audit_mtx, MA_OWNED); + + do_replacement_signal = 0; + while (audit_replacement_flag != 0) { + old_cred = *audit_credp; + old_vp = *audit_vpp; + *audit_credp = audit_replacement_cred; + *audit_vpp = audit_replacement_vp; + audit_replacement_cred = NULL; + audit_replacement_vp = NULL; + audit_replacement_flag = 0; + + audit_enabled = (*audit_vpp != NULL); + + /* + * XXX: What to do about write failures here? + */ + if (old_vp != NULL) { + AUDIT_PRINTF(("Closing old audit file\n")); + mtx_unlock(&audit_mtx); + vfslocked = VFS_LOCK_GIANT(old_vp->v_mount); + vn_close(old_vp, AUDIT_CLOSE_FLAGS, old_cred, + audit_td); + VFS_UNLOCK_GIANT(vfslocked); + crfree(old_cred); + mtx_lock(&audit_mtx); + old_cred = NULL; + old_vp = NULL; + AUDIT_PRINTF(("Audit file closed\n")); + } + if (*audit_vpp != NULL) { + AUDIT_PRINTF(("Opening new audit file\n")); + } + do_replacement_signal = 1; + } + + /* + * Signal that replacement have occurred to wake up and + * start any other replacements started in parallel. We can + * continue about our business in the mean time. We + * broadcast so that both new replacements can be inserted, + * but also so that the source(s) of replacement can return + * successfully. + */ + if (do_replacement_signal) + cv_broadcast(&audit_replacement_cv); +} + +/* + * Drain the audit commit queue and free the records. Used if there are + * records present, but no audit log target. + */ +static void +audit_worker_drain(void) +{ + struct kaudit_record *ar; + + while ((ar = TAILQ_FIRST(&audit_q))) { + TAILQ_REMOVE(&audit_q, ar, k_q); + audit_free(ar); + audit_q_len--; + } +} + +/* + * The audit_worker thread is responsible for watching the event queue, + * dequeueing records, converting them to BSM format, and committing them to + * disk. In order to minimize lock thrashing, records are dequeued in sets + * to a thread-local work queue. In addition, the audit_work performs the + * actual exchange of audit log vnode pointer, as audit_vp is a thread-local + * variable. + */ +static void +audit_worker(void *arg) +{ + TAILQ_HEAD(, kaudit_record) ar_worklist; + struct kaudit_record *ar; + struct ucred *audit_cred; + struct thread *audit_td; + struct vnode *audit_vp; + int error, lowater_signal; + + AUDIT_PRINTF(("audit_worker starting\n")); + + /* + * These are thread-local variables requiring no synchronization. + */ + TAILQ_INIT(&ar_worklist); + audit_cred = NULL; + audit_td = curthread; + audit_vp = NULL; + + mtx_lock(&audit_mtx); + while (1) { + mtx_assert(&audit_mtx, MA_OWNED); + + /* + * Wait for record or rotation events. + */ + while (!audit_replacement_flag && TAILQ_EMPTY(&audit_q)) { + AUDIT_PRINTF(("audit_worker waiting\n")); + cv_wait(&audit_cv, &audit_mtx); + AUDIT_PRINTF(("audit_worker woken up\n")); + AUDIT_PRINTF(("audit_worker: new vp = %p; value of " + "flag %d\n", audit_replacement_vp, + audit_replacement_flag)); + } + + /* + * First priority: replace the audit log target if requested. + */ + audit_worker_rotate(&audit_cred, &audit_vp, audit_td); + + /* + * If we have records, but there's no active vnode to write + * to, drain the record queue. Generally, we prevent the + * unnecessary allocation of records elsewhere, but we need + * to allow for races between conditional allocation and + * queueing. Go back to waiting when we're done. + */ + if (audit_vp == NULL) { + audit_worker_drain(); + continue; + } + + /* + * We have both records to write and an active vnode to write + * to. Dequeue a record, and start the write. Eventually, + * it might make sense to dequeue several records and perform + * our own clustering, if the lower layers aren't doing it + * automatically enough. + */ + lowater_signal = 0; + while ((ar = TAILQ_FIRST(&audit_q))) { + TAILQ_REMOVE(&audit_q, ar, k_q); + audit_q_len--; + if (audit_q_len == audit_qctrl.aq_lowater) + lowater_signal++; + TAILQ_INSERT_TAIL(&ar_worklist, ar, k_q); + } + if (lowater_signal) + cv_broadcast(&audit_commit_cv); + + mtx_unlock(&audit_mtx); + while ((ar = TAILQ_FIRST(&ar_worklist))) { + TAILQ_REMOVE(&ar_worklist, ar, k_q); + if (audit_vp != NULL) { + error = audit_record_write(audit_vp, ar, + audit_cred, audit_td); + if (error && audit_panic_on_write_fail) + panic("audit_worker: write error %d\n", + error); + else if (error) + printf("audit_worker: write error %d\n", + error); + } + audit_free(ar); + } + mtx_lock(&audit_mtx); + } +} + +/* + * audit_rotate_vnode() is called by a user or kernel thread to configure or + * de-configure auditing on a vnode. The arguments are the replacement + * credential and vnode to substitute for the current credential and vnode, + * if any. If either is set to NULL, both should be NULL, and this is used + * to indicate that audit is being disabled. The real work is done in the + * audit_worker thread, but audit_rotate_vnode() waits synchronously for that + * to complete. + * + * The vnode should be referenced and opened by the caller. The credential + * should be referenced. audit_rotate_vnode() will own both references as of + * this call, so the caller should not release either. + * + * XXXAUDIT: Review synchronize communication logic. Really, this is a + * message queue of depth 1. + * + * XXXAUDIT: Enhance the comments below to indicate that we are basically + * acquiring ownership of the communications queue, inserting our message, + * and waiting for an acknowledgement. + */ +void +audit_rotate_vnode(struct ucred *cred, struct vnode *vp) +{ + + /* + * If other parallel log replacements have been requested, we wait + * until they've finished before continuing. + */ + mtx_lock(&audit_mtx); + while (audit_replacement_flag != 0) { + AUDIT_PRINTF(("audit_rotate_vnode: sleeping to wait for " + "flag\n")); + cv_wait(&audit_replacement_cv, &audit_mtx); + AUDIT_PRINTF(("audit_rotate_vnode: woken up (flag %d)\n", + audit_replacement_flag)); + } + audit_replacement_cred = cred; + audit_replacement_flag = 1; + audit_replacement_vp = vp; + + /* + * Wake up the audit worker to perform the exchange once we + * release the mutex. + */ + cv_signal(&audit_cv); + + /* + * Wait for the audit_worker to broadcast that a replacement has + * taken place; we know that once this has happened, our vnode + * has been replaced in, so we can return successfully. + */ + AUDIT_PRINTF(("audit_rotate_vnode: waiting for news of " + "replacement\n")); + cv_wait(&audit_replacement_cv, &audit_mtx); + AUDIT_PRINTF(("audit_rotate_vnode: change acknowledged by " + "audit_worker (flag " "now %d)\n", audit_replacement_flag)); + mtx_unlock(&audit_mtx); + + audit_file_rotate_wait = 0; /* We can now request another rotation */ +} + +void +audit_worker_init(void) +{ + int error; + + cv_init(&audit_replacement_cv, "audit_replacement_cv"); + error = kthread_create(audit_worker, NULL, &audit_thread, RFHIGHPID, + 0, "audit_worker"); + if (error) + panic("audit_worker_init: kthread_create returned %d", error); +} |