Re: [PATCH V4] audit: add tty field to LOGIN event

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(). Lock and bump the kref to protect it, adding audit_put_tty() alias to decrement it. Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com&gt; --- V4: Add missing prototype for audit_put_tty() when audit syscall is not enabled (MIPS). V3: Introduce audit_put_tty() alias to decrement kref. V2: Use kref to protect tty signal struct while in use. --- include/linux/audit.h | 24 ++++++++++++++++++++++++ kernel/audit.c | 18 +++++------------- kernel/auditsc.c | 8 ++++++-- 3 files changed, 35 insertions(+), 15 deletions(-) diff --git a/include/linux/audit.h b/include/linux/audit.h index b40ed5d..32cdafb 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 +344,23 @@ static inline unsigned int audit_get_sessionid(struct task_struct *tsk) return tsk->sessionid; } +static inline struct tty_struct *audit_get_tty(struct task_struct *tsk) +{ + struct tty_struct *tty = NULL; + unsigned long flags; + + spin_lock_irqsave(&tsk->sighand->siglock, flags); + if (tsk->signal) + tty = tty_kref_get(tsk->signal->tty); + spin_unlock_irqrestore(&tsk->sighand->siglock, flags);

+ return tty; +} + +static inline void audit_put_tty(struct tty_struct *tty) +{ + tty_kref_put(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 +518,12 @@ static inline unsigned int audit_get_sessionid(struct task_struct *tsk) { return -1; } +static inline struct tty_struct *audit_get_tty(struct task_struct *tsk) +{ + return NULL; +} +static inline void audit_put_tty(struct tty_struct *tty) +{ } 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..7edd776 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> @@ -1873,21 +1872,14 @@ 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; /* 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 = audit_get_tty(tsk); audit_log_format(ab, " ppid=%d pid=%d auid=%u uid=%u gid=%u" " euid=%u suid=%u fsuid=%u" @@ -1903,11 +1895,11 @@ 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)); - + tty ? tty_name(tty) : "(none)", + audit_get_sessionid(tsk)); + audit_put_tty(tty); audit_log_format(ab, " comm="); audit_log_untrustedstring(ab, get_task_comm(comm, tsk)); - audit_log_d_path_exe(ab, tsk->mm); audit_log_task_context(ab); } diff --git a/kernel/auditsc.c b/kernel/auditsc.c index 195ffae..71e14d8 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -1980,6 +1980,7 @@ static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid, { struct audit_buffer *ab; uid_t uid, oldloginuid, loginuid; + struct tty_struct *tty; if (!audit_enabled) return; @@ -1987,14 +1988,17 @@ static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid, uid = from_kuid(&init_user_ns, task_uid(current)); oldloginuid = from_kuid(&init_user_ns, koldloginuid); loginuid = from_kuid(&init_user_ns, kloginuid), + tty = audit_get_tty(current); ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_LOGIN); if (!ab) 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); + audit_log_format(ab, " old-auid=%u auid=%u tty=%s old-ses=%u ses=%u res=%d", + oldloginuid, loginuid, tty ? tty_name(tty) : "(none)", + oldsessionid, sessionid, !rc); + audit_put_tty(tty); audit_log_end(ab); }