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binder: read pre-translated fds from sender buffer

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This patch is to prepare for an up coming patch where we read
pre-translated fds from the sender buffer and translate them before
copying them to the target.  It does not change run time.

The patch adds two new parameters to binder_translate_fd_array() to
hold the sender buffer and sender buffer parent.  These parameters let
us call copy_from_user() directly from the sender instead of using
binder_alloc_copy_from_buffer() to copy from the target.  Also the patch
adds some new alignment checks.  Previously the alignment checks would
have been done in a different place, but this lets us print more
useful error messages.

Reviewed-by: Martijn Coenen <maco@android.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Todd Kjos <tkjos@google.com>
Link: https://lore.kernel.org/r/20211130185152.437403-4-tkjos@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Todd Kjos 2021-11-30 10:51:51 -08:00 committed by Greg Kroah-Hartman
parent 6d98eb95b4
commit 656e01f3ab
1 changed files with 32 additions and 7 deletions
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39
drivers/android/binder.c
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@ -2234,15 +2234,17 @@ err_fd_not_accepted:
}
static int binder_translate_fd_array(struct binder_fd_array_object *fda,
const void __user *sender_ubuffer,
struct binder_buffer_object *parent,
struct binder_buffer_object *sender_uparent,
struct binder_transaction *t,
struct binder_thread *thread,
struct binder_transaction *in_reply_to)
{
binder_size_t fdi, fd_buf_size;
binder_size_t fda_offset;
const void __user *sender_ufda_base;
struct binder_proc *proc = thread->proc;
struct binder_proc *target_proc = t->to_proc;
fd_buf_size = sizeof(u32) * fda->num_fds;
if (fda->num_fds >= SIZE_MAX / sizeof(u32)) {
@ -2266,7 +2268,10 @@ static int binder_translate_fd_array(struct binder_fd_array_object *fda,
*/
fda_offset = (parent->buffer - (uintptr_t)t->buffer->user_data) +
fda->parent_offset;
if (!IS_ALIGNED((unsigned long)fda_offset, sizeof(u32))) {
sender_ufda_base = (void __user *)sender_uparent->buffer + fda->parent_offset;
if (!IS_ALIGNED((unsigned long)fda_offset, sizeof(u32)) ||
!IS_ALIGNED((unsigned long)sender_ufda_base, sizeof(u32))) {
binder_user_error("%d:%d parent offset not aligned correctly.\n",
proc->pid, thread->pid);
return -EINVAL;
@ -2275,10 +2280,9 @@ static int binder_translate_fd_array(struct binder_fd_array_object *fda,
u32 fd;
int ret;
binder_size_t offset = fda_offset + fdi * sizeof(fd);
binder_size_t sender_uoffset = fdi * sizeof(fd);
ret = binder_alloc_copy_from_buffer(&target_proc->alloc,
&fd, t->buffer,
offset, sizeof(fd));
ret = copy_from_user(&fd, sender_ufda_base + sender_uoffset, sizeof(fd));
if (!ret)
ret = binder_translate_fd(fd, offset, t, thread,
in_reply_to);
@ -2951,6 +2955,8 @@ static void binder_transaction(struct binder_proc *proc,
case BINDER_TYPE_FDA: {
struct binder_object ptr_object;
binder_size_t parent_offset;
struct binder_object user_object;
size_t user_parent_size;
struct binder_fd_array_object *fda =
to_binder_fd_array_object(hdr);
size_t num_valid = (buffer_offset - off_start_offset) /
@ -2982,8 +2988,27 @@ static void binder_transaction(struct binder_proc *proc,
return_error_line = __LINE__;
goto err_bad_parent;
}
ret = binder_translate_fd_array(fda, parent, t, thread,
in_reply_to);
/*
* We need to read the user version of the parent
* object to get the original user offset
*/
user_parent_size =
binder_get_object(proc, user_buffer, t->buffer,
parent_offset, &user_object);
if (user_parent_size != sizeof(user_object.bbo)) {
binder_user_error("%d:%d invalid ptr object size: %zd vs %zd\n",
proc->pid, thread->pid,
user_parent_size,
sizeof(user_object.bbo));
return_error = BR_FAILED_REPLY;
return_error_param = -EINVAL;
return_error_line = __LINE__;
goto err_bad_parent;
}
ret = binder_translate_fd_array(fda, user_buffer,
parent,
&user_object.bbo, t,
thread, in_reply_to);
if (!ret)
ret = binder_alloc_copy_to_buffer(&target_proc->alloc,
t->buffer,