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binder: Split flat_binder_object
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flat_binder_object is used for both handling
binder objects and file descriptors, even though
the two are mostly independent. Since we'll
have more fixup objects in binder in the future,
instead of extending flat_binder_object again,
split out file descriptors to their own object
while retaining backwards compatibility to
existing user-space clients. All binder objects
just share a header.

Cc: Greg Kroah-Hartman <[email protected]>
Cc: Martijn Coenen <[email protected]>
Cc: Arve Hjønnevåg <[email protected]>
Cc: Amit Pundir <[email protected]>
Cc: Serban Constantinescu <[email protected]>
Cc: Dmitry Shmidt <[email protected]>
Cc: Rom Lemarchand <[email protected]>
Cc: Android Kernel Team <[email protected]>
Signed-off-by: Martijn Coenen <[email protected]>
Signed-off-by: John Stultz <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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@gregkh
Martijn Coenen authored and gregkh committed Feb 10, 2017
1 parent 8fa8bea commit feba390
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Showing 2 changed files with 137 additions and 52 deletions.
158 changes: 109 additions & 49 deletions drivers/android/binder.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -145,6 +145,11 @@ module_param_call(stop_on_user_error, binder_set_stop_on_user_error,
binder_stop_on_user_error = 2; \
} while (0)

#define to_flat_binder_object(hdr) \
container_of(hdr, struct flat_binder_object, hdr)

#define to_binder_fd_object(hdr) container_of(hdr, struct binder_fd_object, hdr)

enum binder_stat_types {
BINDER_STAT_PROC,
BINDER_STAT_THREAD,
Expand Down Expand Up @@ -1240,6 +1245,47 @@ static void binder_send_failed_reply(struct binder_transaction *t,
}
}

/**
* binder_validate_object() - checks for a valid metadata object in a buffer.
* @buffer: binder_buffer that we're parsing.
* @offset: offset in the buffer at which to validate an object.
*
* Return: If there's a valid metadata object at @offset in @buffer, the
* size of that object. Otherwise, it returns zero.
*/
static size_t binder_validate_object(struct binder_buffer *buffer, u64 offset)
{
/* Check if we can read a header first */
struct binder_object_header *hdr;
size_t object_size = 0;

if (offset > buffer->data_size - sizeof(*hdr) ||
buffer->data_size < sizeof(*hdr) ||
!IS_ALIGNED(offset, sizeof(u32)))
return 0;

/* Ok, now see if we can read a complete object. */
hdr = (struct binder_object_header *)(buffer->data + offset);
switch (hdr->type) {
case BINDER_TYPE_BINDER:
case BINDER_TYPE_WEAK_BINDER:
case BINDER_TYPE_HANDLE:
case BINDER_TYPE_WEAK_HANDLE:
object_size = sizeof(struct flat_binder_object);
break;
case BINDER_TYPE_FD:
object_size = sizeof(struct binder_fd_object);
break;
default:
return 0;
}
if (offset <= buffer->data_size - object_size &&
buffer->data_size >= object_size)
return object_size;
else
return 0;
}

static void binder_transaction_buffer_release(struct binder_proc *proc,
struct binder_buffer *buffer,
binder_size_t *failed_at)
Expand All @@ -1262,21 +1308,23 @@ static void binder_transaction_buffer_release(struct binder_proc *proc,
else
off_end = (void *)offp + buffer->offsets_size;
for (; offp < off_end; offp++) {
struct flat_binder_object *fp;
struct binder_object_header *hdr;
size_t object_size = binder_validate_object(buffer, *offp);

if (*offp > buffer->data_size - sizeof(*fp) ||
buffer->data_size < sizeof(*fp) ||
!IS_ALIGNED(*offp, sizeof(u32))) {
pr_err("transaction release %d bad offset %lld, size %zd\n",
if (object_size == 0) {
pr_err("transaction release %d bad object at offset %lld, size %zd\n",
debug_id, (u64)*offp, buffer->data_size);
continue;
}
fp = (struct flat_binder_object *)(buffer->data + *offp);
switch (fp->type) {
hdr = (struct binder_object_header *)(buffer->data + *offp);
switch (hdr->type) {
case BINDER_TYPE_BINDER:
case BINDER_TYPE_WEAK_BINDER: {
struct binder_node *node = binder_get_node(proc, fp->binder);
struct flat_binder_object *fp;
struct binder_node *node;

fp = to_flat_binder_object(hdr);
node = binder_get_node(proc, fp->binder);
if (node == NULL) {
pr_err("transaction release %d bad node %016llx\n",
debug_id, (u64)fp->binder);
Expand All @@ -1285,15 +1333,17 @@ static void binder_transaction_buffer_release(struct binder_proc *proc,
binder_debug(BINDER_DEBUG_TRANSACTION,
" node %d u%016llx\n",
node->debug_id, (u64)node->ptr);
binder_dec_node(node, fp->type == BINDER_TYPE_BINDER, 0);
binder_dec_node(node, hdr->type == BINDER_TYPE_BINDER,
0);
} break;
case BINDER_TYPE_HANDLE:
case BINDER_TYPE_WEAK_HANDLE: {
struct flat_binder_object *fp;
struct binder_ref *ref;

fp = to_flat_binder_object(hdr);
ref = binder_get_ref(proc, fp->handle,
fp->type == BINDER_TYPE_HANDLE);

hdr->type == BINDER_TYPE_HANDLE);
if (ref == NULL) {
pr_err("transaction release %d bad handle %d\n",
debug_id, fp->handle);
Expand All @@ -1302,19 +1352,21 @@ static void binder_transaction_buffer_release(struct binder_proc *proc,
binder_debug(BINDER_DEBUG_TRANSACTION,
" ref %d desc %d (node %d)\n",
ref->debug_id, ref->desc, ref->node->debug_id);
binder_dec_ref(ref, fp->type == BINDER_TYPE_HANDLE);
binder_dec_ref(ref, hdr->type == BINDER_TYPE_HANDLE);
} break;

case BINDER_TYPE_FD:
case BINDER_TYPE_FD: {
struct binder_fd_object *fp = to_binder_fd_object(hdr);

binder_debug(BINDER_DEBUG_TRANSACTION,
" fd %d\n", fp->handle);
" fd %d\n", fp->fd);
if (failed_at)
task_close_fd(proc, fp->handle);
break;
task_close_fd(proc, fp->fd);
} break;

default:
pr_err("transaction release %d bad object type %x\n",
debug_id, fp->type);
debug_id, hdr->type);
break;
}
}
Expand Down Expand Up @@ -1531,28 +1583,29 @@ static void binder_transaction(struct binder_proc *proc,
off_end = (void *)offp + tr->offsets_size;
off_min = 0;
for (; offp < off_end; offp++) {
struct flat_binder_object *fp;
struct binder_object_header *hdr;
size_t object_size = binder_validate_object(t->buffer, *offp);

if (*offp > t->buffer->data_size - sizeof(*fp) ||
*offp < off_min ||
t->buffer->data_size < sizeof(*fp) ||
!IS_ALIGNED(*offp, sizeof(u32))) {
binder_user_error("%d:%d got transaction with invalid offset, %lld (min %lld, max %lld)\n",
if (object_size == 0 || *offp < off_min) {
binder_user_error("%d:%d got transaction with invalid offset (%lld, min %lld max %lld) or object.\n",
proc->pid, thread->pid, (u64)*offp,
(u64)off_min,
(u64)(t->buffer->data_size -
sizeof(*fp)));
(u64)t->buffer->data_size);
return_error = BR_FAILED_REPLY;
goto err_bad_offset;
}
fp = (struct flat_binder_object *)(t->buffer->data + *offp);
off_min = *offp + sizeof(struct flat_binder_object);
switch (fp->type) {

hdr = (struct binder_object_header *)(t->buffer->data + *offp);
off_min = *offp + object_size;
switch (hdr->type) {
case BINDER_TYPE_BINDER:
case BINDER_TYPE_WEAK_BINDER: {
struct flat_binder_object *fp;
struct binder_node *node;
struct binder_ref *ref;
struct binder_node *node = binder_get_node(proc, fp->binder);

fp = to_flat_binder_object(hdr);
node = binder_get_node(proc, fp->binder);
if (node == NULL) {
node = binder_new_node(proc, fp->binder, fp->cookie);
if (node == NULL) {
Expand Down Expand Up @@ -1580,14 +1633,14 @@ static void binder_transaction(struct binder_proc *proc,
return_error = BR_FAILED_REPLY;
goto err_binder_get_ref_for_node_failed;
}
if (fp->type == BINDER_TYPE_BINDER)
fp->type = BINDER_TYPE_HANDLE;
if (hdr->type == BINDER_TYPE_BINDER)
hdr->type = BINDER_TYPE_HANDLE;
else
fp->type = BINDER_TYPE_WEAK_HANDLE;
hdr->type = BINDER_TYPE_WEAK_HANDLE;
fp->binder = 0;
fp->handle = ref->desc;
fp->cookie = 0;
binder_inc_ref(ref, fp->type == BINDER_TYPE_HANDLE,
binder_inc_ref(ref, hdr->type == BINDER_TYPE_HANDLE,
&thread->todo);

trace_binder_transaction_node_to_ref(t, node, ref);
Expand All @@ -1598,11 +1651,12 @@ static void binder_transaction(struct binder_proc *proc,
} break;
case BINDER_TYPE_HANDLE:
case BINDER_TYPE_WEAK_HANDLE: {
struct flat_binder_object *fp;
struct binder_ref *ref;

fp = to_flat_binder_object(hdr);
ref = binder_get_ref(proc, fp->handle,
fp->type == BINDER_TYPE_HANDLE);

hdr->type == BINDER_TYPE_HANDLE);
if (ref == NULL) {
binder_user_error("%d:%d got transaction with invalid handle, %d\n",
proc->pid,
Expand All @@ -1616,13 +1670,15 @@ static void binder_transaction(struct binder_proc *proc,
goto err_binder_get_ref_failed;
}
if (ref->node->proc == target_proc) {
if (fp->type == BINDER_TYPE_HANDLE)
fp->type = BINDER_TYPE_BINDER;
if (hdr->type == BINDER_TYPE_HANDLE)
hdr->type = BINDER_TYPE_BINDER;
else
fp->type = BINDER_TYPE_WEAK_BINDER;
hdr->type = BINDER_TYPE_WEAK_BINDER;
fp->binder = ref->node->ptr;
fp->cookie = ref->node->cookie;
binder_inc_node(ref->node, fp->type == BINDER_TYPE_BINDER, 0, NULL);
binder_inc_node(ref->node,
hdr->type == BINDER_TYPE_BINDER,
0, NULL);
trace_binder_transaction_ref_to_node(t, ref);
binder_debug(BINDER_DEBUG_TRANSACTION,
" ref %d desc %d -> node %d u%016llx\n",
Expand All @@ -1639,7 +1695,9 @@ static void binder_transaction(struct binder_proc *proc,
fp->binder = 0;
fp->handle = new_ref->desc;
fp->cookie = 0;
binder_inc_ref(new_ref, fp->type == BINDER_TYPE_HANDLE, NULL);
binder_inc_ref(new_ref,
hdr->type == BINDER_TYPE_HANDLE,
NULL);
trace_binder_transaction_ref_to_ref(t, ref,
new_ref);
binder_debug(BINDER_DEBUG_TRANSACTION,
Expand All @@ -1652,25 +1710,26 @@ static void binder_transaction(struct binder_proc *proc,
case BINDER_TYPE_FD: {
int target_fd;
struct file *file;
struct binder_fd_object *fp = to_binder_fd_object(hdr);

if (reply) {
if (!(in_reply_to->flags & TF_ACCEPT_FDS)) {
binder_user_error("%d:%d got reply with fd, %d, but target does not allow fds\n",
proc->pid, thread->pid, fp->handle);
proc->pid, thread->pid, fp->fd);
return_error = BR_FAILED_REPLY;
goto err_fd_not_allowed;
}
} else if (!target_node->accept_fds) {
binder_user_error("%d:%d got transaction with fd, %d, but target does not allow fds\n",
proc->pid, thread->pid, fp->handle);
proc->pid, thread->pid, fp->fd);
return_error = BR_FAILED_REPLY;
goto err_fd_not_allowed;
}

file = fget(fp->handle);
file = fget(fp->fd);
if (file == NULL) {
binder_user_error("%d:%d got transaction with invalid fd, %d\n",
proc->pid, thread->pid, fp->handle);
proc->pid, thread->pid, fp->fd);
return_error = BR_FAILED_REPLY;
goto err_fget_failed;
}
Expand All @@ -1688,17 +1747,18 @@ static void binder_transaction(struct binder_proc *proc,
goto err_get_unused_fd_failed;
}
task_fd_install(target_proc, target_fd, file);
trace_binder_transaction_fd(t, fp->handle, target_fd);
trace_binder_transaction_fd(t, fp->fd, target_fd);
binder_debug(BINDER_DEBUG_TRANSACTION,
" fd %d -> %d\n", fp->handle, target_fd);
" fd %d -> %d\n", fp->fd,
target_fd);
/* TODO: fput? */
fp->binder = 0;
fp->handle = target_fd;
fp->pad_binder = 0;
fp->fd = target_fd;
} break;

default:
binder_user_error("%d:%d got transaction with invalid object type, %x\n",
proc->pid, thread->pid, fp->type);
proc->pid, thread->pid, hdr->type);
return_error = BR_FAILED_REPLY;
goto err_bad_object_type;
}
Expand Down
31 changes: 28 additions & 3 deletions include/uapi/linux/android/binder.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,14 @@ typedef __u64 binder_size_t;
typedef __u64 binder_uintptr_t;
#endif

/**
* struct binder_object_header - header shared by all binder metadata objects.
* @type: type of the object
*/
struct binder_object_header {
__u32 type;
};

/*
* This is the flattened representation of a Binder object for transfer
* between processes. The 'offsets' supplied as part of a binder transaction
Expand All @@ -56,9 +64,8 @@ typedef __u64 binder_uintptr_t;
* between processes.
*/
struct flat_binder_object {
/* 8 bytes for large_flat_header. */
__u32 type;
__u32 flags;
struct binder_object_header hdr;
__u32 flags;

/* 8 bytes of data. */
union {
Expand All @@ -70,6 +77,24 @@ struct flat_binder_object {
binder_uintptr_t cookie;
};

/**
* struct binder_fd_object - describes a filedescriptor to be fixed up.
* @hdr: common header structure
* @pad_flags: padding to remain compatible with old userspace code
* @pad_binder: padding to remain compatible with old userspace code
* @fd: file descriptor
* @cookie: opaque data, used by user-space
*/
struct binder_fd_object {
struct binder_object_header hdr;
__u32 pad_flags;
union {
binder_uintptr_t pad_binder;
__u32 fd;
};

binder_uintptr_t cookie;
};
/*
* On 64-bit platforms where user code may run in 32-bits the driver must
* translate the buffer (and local binder) addresses appropriately.
Expand Down

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