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Code Issues Releases Activity

Allow a single read(2) system call on an audit pipe to retrieve data from

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more than one audit record at a time in order to improve efficiency.

MFC after:	2 months
Sponsored by:	Apple, Inc.
This commit is contained in:
Robert Watson 2008-11-01 21:16:09 +00:00
parent 92ab0af8a3
commit a9275e0bd5
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=184534
1 changed files with 32 additions and 40 deletions
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72
sys/security/audit/audit_pipe.c
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@ -930,19 +930,8 @@ audit_pipe_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flag,
}
/*
* Audit pipe read. Pull one record off the queue and copy to user space.
* On error, the record is dropped.
*
* Providing more sophisticated behavior, such as partial reads, is tricky
* due to the potential for parallel I/O. If partial read support is
* required, it will require a per-pipe "current record being read" along
* with an offset into that trecord which has already been read. Threads
* performing partial reads will need to allocate per-thread copies of the
* data so that if another thread completes the read of the record, it can be
* freed without adding reference count logic. If this is added, a flag to
* indicate that only atomic record reads are desired would be useful, as if
* different threads are all waiting for records on the pipe, they will want
* independent record reads, which is currently the behavior.
* Audit pipe read. Read one or more partial or complete records to user
* memory.
*/
static int
audit_pipe_read(struct cdev *dev, struct uio *uio, int flag)
@ -978,40 +967,43 @@ audit_pipe_read(struct cdev *dev, struct uio *uio, int flag)
/*
* Copy as many remaining bytes from the current record to userspace
* as we can.
* as we can. Keep processing records until we run out of records in
* the queue, or until the user buffer runs out of space.
*
* Note: we rely on the SX lock to maintain ape's stability here.
*/
ap->ap_reads++;
ape = TAILQ_FIRST(&ap->ap_queue);
toread = MIN(ape->ape_record_len - ape->ape_record_offset,
uio->uio_resid);
AUDIT_PIPE_UNLOCK(ap);
error = uiomove((char *)ape->ape_record + ape->ape_record_offset,
toread, uio);
if (error) {
AUDIT_PIPE_SX_XUNLOCK(ap);
return (error);
}
while ((ape = TAILQ_FIRST(&ap->ap_queue)) != NULL &&
uio->uio_resid > 0) {
AUDIT_PIPE_LOCK_ASSERT(ap);
/*
* If the copy succeeded, update book-keeping, and if no bytes remain
* in the current record, free it.
*/
AUDIT_PIPE_LOCK(ap);
KASSERT(TAILQ_FIRST(&ap->ap_queue) == ape,
("audit_pipe_read: queue out of sync after uiomove"));
ape->ape_record_offset += toread;
if (ape->ape_record_offset == ape->ape_record_len) {
TAILQ_REMOVE(&ap->ap_queue, ape, ape_queue);
ap->ap_qlen--;
} else
ape = NULL;
toread = MIN(ape->ape_record_len - ape->ape_record_offset,
uio->uio_resid);
AUDIT_PIPE_UNLOCK(ap);
error = uiomove((char *)ape->ape_record +
ape->ape_record_offset, toread, uio);
if (error) {
AUDIT_PIPE_SX_XUNLOCK(ap);
return (error);
}
/*
* If the copy succeeded, update book-keeping, and if no
* bytes remain in the current record, free it.
*/
AUDIT_PIPE_LOCK(ap);
KASSERT(TAILQ_FIRST(&ap->ap_queue) == ape,
("audit_pipe_read: queue out of sync after uiomove"));
ape->ape_record_offset += toread;
if (ape->ape_record_offset == ape->ape_record_len) {
TAILQ_REMOVE(&ap->ap_queue, ape, ape_queue);
audit_pipe_entry_free(ape);
ap->ap_qlen--;
}
}
AUDIT_PIPE_UNLOCK(ap);
AUDIT_PIPE_SX_XUNLOCK(ap);
if (ape != NULL)
audit_pipe_entry_free(ape);
return (error);
return (0);
}
/*