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 <[email protected]>
> ---
> 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);
> }
>
>
