diff options
Diffstat (limited to 'drivers/tty/tty_audit.c')
| -rw-r--r-- | drivers/tty/tty_audit.c | 351 |
1 files changed, 351 insertions, 0 deletions
diff --git a/drivers/tty/tty_audit.c b/drivers/tty/tty_audit.c new file mode 100644 index 000000000..90ca08293 --- /dev/null +++ b/drivers/tty/tty_audit.c @@ -0,0 +1,351 @@ +/* + * 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/slab.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, + unsigned icanon) +{ + struct tty_audit_buf *buf; + + buf = kmalloc(sizeof(*buf), GFP_KERNEL); + if (!buf) + goto err; + buf->data = kmalloc(N_TTY_BUF_SIZE, 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); + kfree(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); +} + +static void tty_audit_log(const char *description, int major, int minor, + unsigned char *data, size_t size) +{ + struct audit_buffer *ab; + struct task_struct *tsk = current; + pid_t pid = task_pid_nr(tsk); + uid_t uid = from_kuid(&init_user_ns, task_uid(tsk)); + uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(tsk)); + unsigned int sessionid = audit_get_sessionid(tsk); + + ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY); + if (ab) { + char name[sizeof(tsk->comm)]; + + audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d" + " minor=%d comm=", description, pid, uid, + loginuid, sessionid, major, minor); + get_task_comm(name, tsk); + audit_log_untrustedstring(ab, name); + audit_log_format(ab, " data="); + audit_log_n_hex(ab, data, size); + audit_log_end(ab); + } +} + +/** + * tty_audit_buf_push - 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(struct tty_audit_buf *buf) +{ + if (buf->valid == 0) + return; + if (audit_enabled == 0) { + buf->valid = 0; + return; + } + tty_audit_log("tty", buf->major, buf->minor, buf->data, buf->valid); + buf->valid = 0; +} + +/** + * 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; + + buf = current->signal->tty_audit_buf; + current->signal->tty_audit_buf = NULL; + if (!buf) + return; + + mutex_lock(&buf->mutex); + tty_audit_buf_push(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) +{ + sig->audit_tty = current->signal->audit_tty; + sig->audit_tty_log_passwd = current->signal->audit_tty_log_passwd; +} + +/** + * tty_audit_tiocsti - Log TIOCSTI + */ +void tty_audit_tiocsti(struct tty_struct *tty, char ch) +{ + struct tty_audit_buf *buf; + int major, minor, should_audit; + unsigned long flags; + + spin_lock_irqsave(¤t->sighand->siglock, flags); + should_audit = current->signal->audit_tty; + buf = current->signal->tty_audit_buf; + if (buf) + atomic_inc(&buf->count); + spin_unlock_irqrestore(¤t->sighand->siglock, flags); + + major = tty->driver->major; + minor = tty->driver->minor_start + tty->index; + if (buf) { + mutex_lock(&buf->mutex); + if (buf->major == major && buf->minor == minor) + tty_audit_buf_push(buf); + mutex_unlock(&buf->mutex); + tty_audit_buf_put(buf); + } + + if (should_audit && audit_enabled) { + kuid_t auid; + unsigned int sessionid; + + auid = audit_get_loginuid(current); + sessionid = audit_get_sessionid(current); + tty_audit_log("ioctl=TIOCSTI", major, minor, &ch, 1); + } +} + +/** + * tty_audit_push_current - Flush current's pending audit data + * + * Try to lock sighand and get a reference to the tty audit buffer if available. + * Flush the buffer or return an appropriate error code. + */ +int tty_audit_push_current(void) +{ + struct tty_audit_buf *buf = ERR_PTR(-EPERM); + struct task_struct *tsk = current; + unsigned long flags; + + if (!lock_task_sighand(tsk, &flags)) + return -ESRCH; + + if (tsk->signal->audit_tty) { + buf = tsk->signal->tty_audit_buf; + if (buf) + atomic_inc(&buf->count); + } + unlock_task_sighand(tsk, &flags); + + /* + * Return 0 when signal->audit_tty set + * but tsk->signal->tty_audit_buf == NULL. + */ + if (!buf || IS_ERR(buf)) + return PTR_ERR(buf); + + mutex_lock(&buf->mutex); + tty_audit_buf_push(buf); + mutex_unlock(&buf->mutex); + + tty_audit_buf_put(buf); + return 0; +} + +/** + * 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, + unsigned icanon) +{ + struct tty_audit_buf *buf, *buf2; + unsigned long flags; + + buf = NULL; + buf2 = NULL; + spin_lock_irqsave(¤t->sighand->siglock, flags); + if (likely(!current->signal->audit_tty)) + goto out; + buf = current->signal->tty_audit_buf; + if (buf) { + atomic_inc(&buf->count); + goto out; + } + spin_unlock_irqrestore(¤t->sighand->siglock, flags); + + buf2 = tty_audit_buf_alloc(tty->driver->major, + tty->driver->minor_start + tty->index, + icanon); + if (buf2 == NULL) { + audit_log_lost("out of memory in TTY auditing"); + return NULL; + } + + spin_lock_irqsave(¤t->sighand->siglock, flags); + 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_irqrestore(¤t->sighand->siglock, flags); + 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, unsigned icanon) +{ + struct tty_audit_buf *buf; + int major, minor; + int audit_log_tty_passwd; + unsigned long flags; + + if (unlikely(size == 0)) + return; + + spin_lock_irqsave(¤t->sighand->siglock, flags); + audit_log_tty_passwd = current->signal->audit_tty_log_passwd; + spin_unlock_irqrestore(¤t->sighand->siglock, flags); + if (!audit_log_tty_passwd && icanon && !L_ECHO(tty)) + return; + + if (tty->driver->type == TTY_DRIVER_TYPE_PTY + && tty->driver->subtype == PTY_TYPE_MASTER) + return; + + buf = tty_audit_buf_get(tty, icanon); + 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 != icanon) { + tty_audit_buf_push(buf); + buf->major = major; + buf->minor = minor; + buf->icanon = 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(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; + unsigned long flags; + + spin_lock_irqsave(¤t->sighand->siglock, flags); + if (likely(!current->signal->audit_tty)) { + spin_unlock_irqrestore(¤t->sighand->siglock, flags); + return; + } + buf = current->signal->tty_audit_buf; + if (buf) + atomic_inc(&buf->count); + spin_unlock_irqrestore(¤t->sighand->siglock, flags); + + 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(buf); + mutex_unlock(&buf->mutex); + tty_audit_buf_put(buf); + } +} |