linux/drivers/tty/tty_audit.c, branch v4.9

tty: audit: remove unused variable

2016-03-08T00:11:14Z

While building with W=1 we were getting build warning: drivers/tty/tty_audit.c:149:16: warning: variable 'sessionid' set but not used The local variable sessionid was only assigned the value of current->sessionid but was never reused. On further inspection it turned out that there is no need of audit_get_loginuid() also. Signed-off-by: Sudip Mukherjee Reviewed-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: audit: Poison tty_audit_buf while process exits

2016-01-28T00:41:04Z

Warn if tty_audit_buf use is attempted after tty_audit_exit() has already freed it. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: audit: Always push audit buffer before TIOCSTI

2016-01-28T00:41:04Z

The data read from another tty may be relevant to the action of the TIOCSTI ioctl; log the audit buffer immediately. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: audit: Check audit enable first

2016-01-28T00:41:04Z

Audit is unlikely to be enabled; check first to exit asap. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: audit: Simplify first-use allocation

2016-01-28T00:41:04Z

The first-use tty audit buffer allocation is a potential race amongst multiple attempts at 'first-use'; only one 'winner' is acceptable. The successful buffer assignment occurs if tty_audit_buf == NULL (which will also be the return from cmpxchg()); otherwise, another racer 'won' and this buffer allocation is freed. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: audit: Remove tty_audit_buf reference counting

2016-01-28T00:41:04Z

When tty_audit_exit() is called from do_exit(), the process is single-threaded. Since the tty_audit_buf is only shared by threads of a process, no other thread can be concurrently accessing the tty_audit_buf during or after tty_audit_exit(). Thus, no other thread can be holding an extra tty_audit_buf reference which would prevent tty_audit_exit() from freeing the tty_audit_buf. As that is the only purpose of the ref counting, remove the reference counting and free the tty_audit_buf directly. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: audit: Remove false memory optimization

2016-01-28T00:41:04Z

The tty audit buffer is allocated at first use and not freed until the process exits. If tty audit is turned off after the audit buffer has been allocated, no effort is made to release the buffer. So re-checking if tty audit has just been turned off when tty audit was just on is false optimization; the likelihood of triggering this condition is exceedingly small. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: audit: Handle tty audit enable atomically

2016-01-28T00:41:04Z

The audit_tty and audit_tty_log_passwd fields are actually bool values, so merge into single memory location to access atomically. NB: audit log operations may still occur after tty audit is disabled which is consistent with the existing functionality Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: audit: Track tty association with dev_t

2016-01-28T00:41:04Z

Use dev_t instead of separate major/minor fields to track tty audit buffer association. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: audit: Combine push functions

2016-01-28T00:41:04Z

tty_audit_push() and tty_audit_push_current() perform identical tasks; eliminate the tty_audit_push() implementation and the tty_audit_push_current() name. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman