Hi Richard,
On 04/13/2016 04:25 PM, Richard Guy Briggs wrote:
 The tty field was missing from AUDIT_LOGIN events.
 
 Refactor code to create a new function audit_get_tty(), using it to
 replace the call in audit_log_task_info() and to add it to
 audit_log_set_loginuid().
 
 Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com>
 ---
  include/linux/audit.h |   18 ++++++++++++++++++
  kernel/audit.c        |   11 +----------
  kernel/auditsc.c      |    5 +++--
  3 files changed, 22 insertions(+), 12 deletions(-)
 
 diff --git a/include/linux/audit.h b/include/linux/audit.h
 index b40ed5d..20c6649 100644
 --- a/include/linux/audit.h
 +++ b/include/linux/audit.h
 @@ -26,6 +26,7 @@
  #include <linux/sched.h>
  #include <linux/ptrace.h>
  #include <uapi/linux/audit.h>
 +#include <linux/tty.h>
  
  #define AUDIT_INO_UNSET ((unsigned long)-1)
  #define AUDIT_DEV_UNSET ((dev_t)-1)
 @@ -343,6 +344,19 @@ static inline unsigned int audit_get_sessionid(struct task_struct
*tsk)
  	return tsk->sessionid;
  }
  
 +static inline char *audit_get_tty(struct task_struct *tsk)
 +{
 +	char *tty;
 +
 +	spin_lock_irq(&tsk->sighand->siglock);
 +	if (tsk->signal && tsk->signal->tty &&
tsk->signal->tty->name)
 +		tty = tsk->signal->tty->name;
 +	else
 +		tty = "(none)";
 +	spin_unlock_irq(&tsk->sighand->siglock); 
This is unsafe because the tty could be immediately torn down after the
siglock is dropped, and return a dangling ptr.
 +	return tty;
 +}
 +
  extern void __audit_ipc_obj(struct kern_ipc_perm *ipcp);
  extern void __audit_ipc_set_perm(unsigned long qbytes, uid_t uid, gid_t gid, umode_t
mode);
  extern void __audit_bprm(struct linux_binprm *bprm);
 @@ -500,6 +514,10 @@ static inline unsigned int audit_get_sessionid(struct task_struct
*tsk)
  {
  	return -1;
  }
 +static inline char *audit_get_tty(struct task_struct *tsk)
 +{
 +	return "(invalid)";
 +}
  static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp)
  { }
  static inline void audit_ipc_set_perm(unsigned long qbytes, uid_t uid,
 diff --git a/kernel/audit.c b/kernel/audit.c
 index 3a3e5de..fae11df 100644
 --- a/kernel/audit.c
 +++ b/kernel/audit.c
 @@ -64,7 +64,6 @@
  #include <linux/security.h>
  #endif
  #include <linux/freezer.h>
 -#include <linux/tty.h>
  #include <linux/pid_namespace.h>
  #include <net/netns/generic.h>
  
 @@ -1873,7 +1872,6 @@ void audit_log_task_info(struct audit_buffer *ab, struct
task_struct *tsk)
  {
  	const struct cred *cred;
  	char comm[sizeof(tsk->comm)];
 -	char *tty; 
	struct tty_struct *tty;
  
  	if (!ab)
  		return;
 @@ -1881,13 +1879,6 @@ void audit_log_task_info(struct audit_buffer *ab, struct
task_struct *tsk)
  	/* tsk == current */
  	cred = current_cred();
  
 -	spin_lock_irq(&tsk->sighand->siglock);
 -	if (tsk->signal && tsk->signal->tty &&
tsk->signal->tty->name)
 -		tty = tsk->signal->tty->name;
 -	else
 -		tty = "(none)";
 -	spin_unlock_irq(&tsk->sighand->siglock); 
	tty = get_current_tty();
	
 -
  	audit_log_format(ab,
  			 " ppid=%d pid=%d auid=%u uid=%u gid=%u"
  			 " euid=%u suid=%u fsuid=%u"
 @@ -1903,7 +1894,7 @@ void audit_log_task_info(struct audit_buffer *ab, struct
task_struct *tsk)
  			 from_kgid(&init_user_ns, cred->egid),
  			 from_kgid(&init_user_ns, cred->sgid),
  			 from_kgid(&init_user_ns, cred->fsgid),
 -			 tty, audit_get_sessionid(tsk));
 +			 audit_get_tty(tsk), audit_get_sessionid(tsk)); 
			tty_name(tty), ....);
			^^^^^^^^^^
			returns "NULL tty" if tty == NULL
	tty_kref_put(tty);
  
  	audit_log_format(ab, " comm=");
  	audit_log_untrustedstring(ab, get_task_comm(comm, tsk));
 diff --git a/kernel/auditsc.c b/kernel/auditsc.c
 index 195ffae..a0467fb 100644
 --- a/kernel/auditsc.c
 +++ b/kernel/auditsc.c
 @@ -1993,8 +1993,9 @@ static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t
kloginuid,
  		return;
  	audit_log_format(ab, "pid=%d uid=%u", task_pid_nr(current), uid);
  	audit_log_task_context(ab);
 -	audit_log_format(ab, " old-auid=%u auid=%u old-ses=%u ses=%u res=%d",
 -			 oldloginuid, loginuid, oldsessionid, sessionid, !rc); 
	tty = get_current_tty();
 +	audit_log_format(ab, " old-auid=%u auid=%u tty=%s old-ses=%u
ses=%u res=%d",
 +			 oldloginuid, loginuid, audit_get_tty(current), 
			......., tty_name(tty),
 +			 oldsessionid, sessionid, !rc); 
	tty_kref_put(tty);
Regards,
Peter Hurley
  	audit_log_end(ab);
  }