/* * Creating audit events from TTY input. * * Copyright (C) 2007 Red Hat, Inc. All rights reserved. This copyrighted * material is made available to anyone wishing to use, modify, copy, or * redistribute it subject to the terms and conditions of the GNU General * Public License v.2. * * Authors: Miloslav Trmac <mitr@redhat.com> */ #include <linux/audit.h> #include <linux/file.h> #include <linux/fdtable.h> #include <linux/tty.h> struct tty_audit_buf { atomic_t count; struct mutex mutex; /* Protects all data below */ int major, minor; /* The TTY which the data is from */ unsigned icanon:1; size_t valid; unsigned char *data; /* Allocated size N_TTY_BUF_SIZE */ }; static struct tty_audit_buf *tty_audit_buf_alloc(int major, int minor, int icanon) { struct tty_audit_buf *buf; buf = kmalloc(sizeof(*buf), GFP_KERNEL); if (!buf) goto err; if (PAGE_SIZE != N_TTY_BUF_SIZE) buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL); else buf->data = (unsigned char *)__get_free_page(GFP_KERNEL); if (!buf->data) goto err_buf; atomic_set(&buf->count, 1); mutex_init(&buf->mutex); buf->major = major; buf->minor = minor; buf->icanon = icanon; buf->valid = 0; return buf; err_buf: kfree(buf); err: return NULL; } static void tty_audit_buf_free(struct tty_audit_buf *buf) { WARN_ON(buf->valid != 0); if (PAGE_SIZE != N_TTY_BUF_SIZE) kfree(buf->data); else free_page((unsigned long)buf->data); kfree(buf); } static void tty_audit_buf_put(struct tty_audit_buf *buf) { if (atomic_dec_and_test(&buf->count)) tty_audit_buf_free(buf); } /** * tty_audit_buf_push - Push buffered data out * * Generate an audit message from the contents of @buf, which is owned by * @tsk with @loginuid. @buf->mutex must be locked. */ static void tty_audit_buf_push(struct task_struct *tsk, uid_t loginuid, unsigned int sessionid, struct tty_audit_buf *buf) { struct audit_buffer *ab; if (buf->valid == 0) return; if (audit_enabled == 0) return; ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY); if (ab) { char name[sizeof(tsk->comm)]; audit_log_format(ab, "tty pid=%u uid=%u auid=%u ses=%u " "major=%d minor=%d comm=", tsk->pid, tsk->uid, loginuid, sessionid, buf->major, buf->minor); get_task_comm(name, tsk); audit_log_untrustedstring(ab, name); audit_log_format(ab, " data="); audit_log_n_hex(ab, buf->data, buf->valid); audit_log_end(ab); } buf->valid = 0; } /** * tty_audit_buf_push_current - Push buffered data out * * Generate an audit message from the contents of @buf, which is owned by * the current task. @buf->mutex must be locked. */ static void tty_audit_buf_push_current(struct tty_audit_buf *buf) { uid_t auid = audit_get_loginuid(current); unsigned int sessionid = audit_get_sessionid(current); tty_audit_buf_push(current, auid, sessionid, buf); } /** * tty_audit_exit - Handle a task exit * * Make sure all buffered data is written out and deallocate the buffer. * Only needs to be called if current->signal->tty_audit_buf != %NULL. */ void tty_audit_exit(void) { struct tty_audit_buf *buf; spin_lock_irq(¤t->sighand->siglock); buf = current->signal->tty_audit_buf; current->signal->tty_audit_buf = NULL; spin_unlock_irq(¤t->sighand->siglock); if (!buf) return; mutex_lock(&buf->mutex); tty_audit_buf_push_current(buf); mutex_unlock(&buf->mutex); tty_audit_buf_put(buf); } /** * tty_audit_fork - Copy TTY audit state for a new task * * Set up TTY audit state in @sig from current. @sig needs no locking. */ void tty_audit_fork(struct signal_struct *sig) { spin_lock_irq(¤t->sighand->siglock); sig->audit_tty = current->signal->audit_tty; spin_unlock_irq(¤t->sighand->siglock); sig->tty_audit_buf = NULL; } /** * tty_audit_push_task - Flush task's pending audit data */ void tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid) { struct tty_audit_buf *buf; spin_lock_irq(&tsk->sighand->siglock); buf = tsk->signal->tty_audit_buf; if (buf) atomic_inc(&buf->count); spin_unlock_irq(&tsk->sighand->siglock); if (!buf) return; mutex_lock(&buf->mutex); tty_audit_buf_push(tsk, loginuid, sessionid, buf); mutex_unlock(&buf->mutex); tty_audit_buf_put(buf); } /** * tty_audit_buf_get - Get an audit buffer. * * Get an audit buffer for @tty, allocate it if necessary. Return %NULL * if TTY auditing is disabled or out of memory. Otherwise, return a new * reference to the buffer. */ static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty) { struct tty_audit_buf *buf, *buf2; buf = NULL; buf2 = NULL; spin_lock_irq(¤t->sighand->siglock); if (likely(!current->signal->audit_tty)) goto out; buf = current->signal->tty_audit_buf; if (buf) { atomic_inc(&buf->count); goto out; } spin_unlock_irq(¤t->sighand->siglock); buf2 = tty_audit_buf_alloc(tty->driver->major, tty->driver->minor_start + tty->index, tty->icanon); if (buf2 == NULL) { audit_log_lost("out of memory in TTY auditing"); return NULL; } spin_lock_irq(¤t->sighand->siglock); if (!current->signal->audit_tty) goto out; buf = current->signal->tty_audit_buf; if (!buf) { current->signal->tty_audit_buf = buf2; buf = buf2; buf2 = NULL; } atomic_inc(&buf->count); /* Fall through */ out: spin_unlock_irq(¤t->sighand->siglock); if (buf2) tty_audit_buf_free(buf2); return buf; } /** * tty_audit_add_data - Add data for TTY auditing. * * Audit @data of @size from @tty, if necessary. */ void tty_audit_add_data(struct tty_struct *tty, unsigned char *data, size_t size) { struct tty_audit_buf *buf; int major, minor; if (unlikely(size == 0)) return; if (tty->driver->type == TTY_DRIVER_TYPE_PTY && tty->driver->subtype == PTY_TYPE_MASTER) return; buf = tty_audit_buf_get(tty); if (!buf) return; mutex_lock(&buf->mutex); major = tty->driver->major; minor = tty->driver->minor_start + tty->index; if (buf->major != major || buf->minor != minor || buf->icanon != tty->icanon) { tty_audit_buf_push_current(buf); buf->major = major; buf->minor = minor; buf->icanon = tty->icanon; } do { size_t run; run = N_TTY_BUF_SIZE - buf->valid; if (run > size) run = size; memcpy(buf->data + buf->valid, data, run); buf->valid += run; data += run; size -= run; if (buf->valid == N_TTY_BUF_SIZE) tty_audit_buf_push_current(buf); } while (size != 0); mutex_unlock(&buf->mutex); tty_audit_buf_put(buf); } /** * tty_audit_push - Push buffered data out * * Make sure no audit data is pending for @tty on the current process. */ void tty_audit_push(struct tty_struct *tty) { struct tty_audit_buf *buf; spin_lock_irq(¤t->sighand->siglock); if (likely(!current->signal->audit_tty)) { spin_unlock_irq(¤t->sighand->siglock); return; } buf = current->signal->tty_audit_buf; if (buf) atomic_inc(&buf->count); spin_unlock_irq(¤t->sighand->siglock); if (buf) { int major, minor; major = tty->driver->major; minor = tty->driver->minor_start + tty->index; mutex_lock(&buf->mutex); if (buf->major == major && buf->minor == minor) tty_audit_buf_push_current(buf); mutex_unlock(&buf->mutex); tty_audit_buf_put(buf); } }