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binder: create node flag to request sender's security context
To allow servers to verify client identity, allow a node flag to be set that causes the sender's security context to be delivered with the transaction. The BR_TRANSACTION command is extended in BR_TRANSACTION_SEC_CTX to contain a pointer to the security context string. Signed-off-by: Todd Kjos <tkjos@google.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Todd Kjos
Greg Kroah-Hartman
parent
8fdf906265
commit
ec74136ded
2 changed files with 102 additions and 23 deletions
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@ -329,6 +329,8 @@ struct binder_error {
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* (invariant after initialized)
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* @min_priority: minimum scheduling priority
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* (invariant after initialized)
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* @txn_security_ctx: require sender's security context
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* (invariant after initialized)
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* @async_todo: list of async work items
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* (protected by @proc->inner_lock)
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*
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@ -365,6 +367,7 @@ struct binder_node {
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* invariant after initialization
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*/
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u8 accept_fds:1;
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u8 txn_security_ctx:1;
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u8 min_priority;
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};
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bool has_async_transaction;
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@ -615,6 +618,7 @@ struct binder_transaction {
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long saved_priority;
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kuid_t sender_euid;
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struct list_head fd_fixups;
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binder_uintptr_t security_ctx;
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/**
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* @lock: protects @from, @to_proc, and @to_thread
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*
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@ -1152,6 +1156,7 @@ static struct binder_node *binder_init_node_ilocked(
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node->work.type = BINDER_WORK_NODE;
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node->min_priority = flags & FLAT_BINDER_FLAG_PRIORITY_MASK;
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node->accept_fds = !!(flags & FLAT_BINDER_FLAG_ACCEPTS_FDS);
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node->txn_security_ctx = !!(flags & FLAT_BINDER_FLAG_TXN_SECURITY_CTX);
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spin_lock_init(&node->lock);
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INIT_LIST_HEAD(&node->work.entry);
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INIT_LIST_HEAD(&node->async_todo);
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@ -2778,6 +2783,8 @@ static void binder_transaction(struct binder_proc *proc,
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binder_size_t last_fixup_min_off = 0;
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struct binder_context *context = proc->context;
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int t_debug_id = atomic_inc_return(&binder_last_id);
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char *secctx = NULL;
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u32 secctx_sz = 0;
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e = binder_transaction_log_add(&binder_transaction_log);
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e->debug_id = t_debug_id;
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@ -3020,6 +3027,20 @@ static void binder_transaction(struct binder_proc *proc,
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t->flags = tr->flags;
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t->priority = task_nice(current);
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if (target_node && target_node->txn_security_ctx) {
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u32 secid;
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security_task_getsecid(proc->tsk, &secid);
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ret = security_secid_to_secctx(secid, &secctx, &secctx_sz);
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if (ret) {
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return_error = BR_FAILED_REPLY;
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return_error_param = ret;
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return_error_line = __LINE__;
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goto err_get_secctx_failed;
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}
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extra_buffers_size += ALIGN(secctx_sz, sizeof(u64));
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}
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trace_binder_transaction(reply, t, target_node);
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t->buffer = binder_alloc_new_buf(&target_proc->alloc, tr->data_size,
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@ -3036,6 +3057,19 @@ static void binder_transaction(struct binder_proc *proc,
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t->buffer = NULL;
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goto err_binder_alloc_buf_failed;
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}
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if (secctx) {
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size_t buf_offset = ALIGN(tr->data_size, sizeof(void *)) +
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ALIGN(tr->offsets_size, sizeof(void *)) +
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ALIGN(extra_buffers_size, sizeof(void *)) -
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ALIGN(secctx_sz, sizeof(u64));
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char *kptr = t->buffer->data + buf_offset;
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t->security_ctx = (uintptr_t)kptr +
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binder_alloc_get_user_buffer_offset(&target_proc->alloc);
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memcpy(kptr, secctx, secctx_sz);
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security_release_secctx(secctx, secctx_sz);
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secctx = NULL;
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}
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t->buffer->debug_id = t->debug_id;
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t->buffer->transaction = t;
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t->buffer->target_node = target_node;
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@ -3305,6 +3339,9 @@ static void binder_transaction(struct binder_proc *proc,
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t->buffer->transaction = NULL;
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binder_alloc_free_buf(&target_proc->alloc, t->buffer);
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err_binder_alloc_buf_failed:
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if (secctx)
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security_release_secctx(secctx, secctx_sz);
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err_get_secctx_failed:
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kfree(tcomplete);
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binder_stats_deleted(BINDER_STAT_TRANSACTION_COMPLETE);
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err_alloc_tcomplete_failed:
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@ -4036,11 +4073,13 @@ static int binder_thread_read(struct binder_proc *proc,
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while (1) {
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uint32_t cmd;
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struct binder_transaction_data tr;
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struct binder_transaction_data_secctx tr;
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struct binder_transaction_data *trd = &tr.transaction_data;
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struct binder_work *w = NULL;
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struct list_head *list = NULL;
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struct binder_transaction *t = NULL;
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struct binder_thread *t_from;
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size_t trsize = sizeof(*trd);
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binder_inner_proc_lock(proc);
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if (!binder_worklist_empty_ilocked(&thread->todo))
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@ -4240,8 +4279,8 @@ static int binder_thread_read(struct binder_proc *proc,
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if (t->buffer->target_node) {
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struct binder_node *target_node = t->buffer->target_node;
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tr.target.ptr = target_node->ptr;
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tr.cookie = target_node->cookie;
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trd->target.ptr = target_node->ptr;
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trd->cookie = target_node->cookie;
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t->saved_priority = task_nice(current);
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if (t->priority < target_node->min_priority &&
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!(t->flags & TF_ONE_WAY))
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@ -4251,22 +4290,23 @@ static int binder_thread_read(struct binder_proc *proc,
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binder_set_nice(target_node->min_priority);
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cmd = BR_TRANSACTION;
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} else {
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tr.target.ptr = 0;
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tr.cookie = 0;
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trd->target.ptr = 0;
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trd->cookie = 0;
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cmd = BR_REPLY;
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}
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tr.code = t->code;
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tr.flags = t->flags;
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tr.sender_euid = from_kuid(current_user_ns(), t->sender_euid);
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trd->code = t->code;
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trd->flags = t->flags;
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trd->sender_euid = from_kuid(current_user_ns(), t->sender_euid);
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t_from = binder_get_txn_from(t);
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if (t_from) {
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struct task_struct *sender = t_from->proc->tsk;
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tr.sender_pid = task_tgid_nr_ns(sender,
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task_active_pid_ns(current));
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trd->sender_pid =
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task_tgid_nr_ns(sender,
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task_active_pid_ns(current));
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} else {
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tr.sender_pid = 0;
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trd->sender_pid = 0;
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}
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ret = binder_apply_fd_fixups(t);
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@ -4297,15 +4337,20 @@ static int binder_thread_read(struct binder_proc *proc,
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}
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continue;
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}
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tr.data_size = t->buffer->data_size;
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tr.offsets_size = t->buffer->offsets_size;
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tr.data.ptr.buffer = (binder_uintptr_t)
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trd->data_size = t->buffer->data_size;
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trd->offsets_size = t->buffer->offsets_size;
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trd->data.ptr.buffer = (binder_uintptr_t)
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((uintptr_t)t->buffer->data +
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binder_alloc_get_user_buffer_offset(&proc->alloc));
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tr.data.ptr.offsets = tr.data.ptr.buffer +
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trd->data.ptr.offsets = trd->data.ptr.buffer +
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ALIGN(t->buffer->data_size,
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sizeof(void *));
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tr.secctx = t->security_ctx;
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if (t->security_ctx) {
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cmd = BR_TRANSACTION_SEC_CTX;
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trsize = sizeof(tr);
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}
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if (put_user(cmd, (uint32_t __user *)ptr)) {
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if (t_from)
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binder_thread_dec_tmpref(t_from);
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@ -4316,7 +4361,7 @@ static int binder_thread_read(struct binder_proc *proc,
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return -EFAULT;
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}
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ptr += sizeof(uint32_t);
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if (copy_to_user(ptr, &tr, sizeof(tr))) {
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if (copy_to_user(ptr, &tr, trsize)) {
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if (t_from)
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binder_thread_dec_tmpref(t_from);
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@ -4325,7 +4370,7 @@ static int binder_thread_read(struct binder_proc *proc,
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return -EFAULT;
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}
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ptr += sizeof(tr);
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ptr += trsize;
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trace_binder_transaction_received(t);
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binder_stat_br(proc, thread, cmd);
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@ -4333,16 +4378,18 @@ static int binder_thread_read(struct binder_proc *proc,
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"%d:%d %s %d %d:%d, cmd %d size %zd-%zd ptr %016llx-%016llx\n",
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proc->pid, thread->pid,
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(cmd == BR_TRANSACTION) ? "BR_TRANSACTION" :
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"BR_REPLY",
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(cmd == BR_TRANSACTION_SEC_CTX) ?
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"BR_TRANSACTION_SEC_CTX" : "BR_REPLY",
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t->debug_id, t_from ? t_from->proc->pid : 0,
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t_from ? t_from->pid : 0, cmd,
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t->buffer->data_size, t->buffer->offsets_size,
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(u64)tr.data.ptr.buffer, (u64)tr.data.ptr.offsets);
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(u64)trd->data.ptr.buffer,
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(u64)trd->data.ptr.offsets);
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if (t_from)
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binder_thread_dec_tmpref(t_from);
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t->buffer->allow_user_free = 1;
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if (cmd == BR_TRANSACTION && !(t->flags & TF_ONE_WAY)) {
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if (cmd != BR_REPLY && !(t->flags & TF_ONE_WAY)) {
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binder_inner_proc_lock(thread->proc);
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t->to_parent = thread->transaction_stack;
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t->to_thread = thread;
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@ -4690,7 +4737,8 @@ static int binder_ioctl_write_read(struct file *filp,
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return ret;
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}
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static int binder_ioctl_set_ctx_mgr(struct file *filp)
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static int binder_ioctl_set_ctx_mgr(struct file *filp,
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struct flat_binder_object *fbo)
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{
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int ret = 0;
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struct binder_proc *proc = filp->private_data;
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@ -4719,7 +4767,7 @@ static int binder_ioctl_set_ctx_mgr(struct file *filp)
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} else {
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context->binder_context_mgr_uid = curr_euid;
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}
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new_node = binder_new_node(proc, NULL);
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new_node = binder_new_node(proc, fbo);
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if (!new_node) {
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ret = -ENOMEM;
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goto out;
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@ -4842,8 +4890,20 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
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binder_inner_proc_unlock(proc);
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break;
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}
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case BINDER_SET_CONTEXT_MGR_EXT: {
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struct flat_binder_object fbo;
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if (copy_from_user(&fbo, ubuf, sizeof(fbo))) {
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ret = -EINVAL;
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goto err;
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}
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ret = binder_ioctl_set_ctx_mgr(filp, &fbo);
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if (ret)
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goto err;
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break;
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}
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case BINDER_SET_CONTEXT_MGR:
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ret = binder_ioctl_set_ctx_mgr(filp);
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ret = binder_ioctl_set_ctx_mgr(filp, NULL);
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if (ret)
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goto err;
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break;
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@ -41,6 +41,14 @@ enum {
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enum {
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FLAT_BINDER_FLAG_PRIORITY_MASK = 0xff,
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FLAT_BINDER_FLAG_ACCEPTS_FDS = 0x100,
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/**
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* @FLAT_BINDER_FLAG_TXN_SECURITY_CTX: request security contexts
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*
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* Only when set, causes senders to include their security
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* context
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*/
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FLAT_BINDER_FLAG_TXN_SECURITY_CTX = 0x1000,
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};
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#ifdef BINDER_IPC_32BIT
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@ -218,6 +226,7 @@ struct binder_node_info_for_ref {
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#define BINDER_VERSION _IOWR('b', 9, struct binder_version)
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#define BINDER_GET_NODE_DEBUG_INFO _IOWR('b', 11, struct binder_node_debug_info)
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#define BINDER_GET_NODE_INFO_FOR_REF _IOWR('b', 12, struct binder_node_info_for_ref)
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#define BINDER_SET_CONTEXT_MGR_EXT _IOW('b', 13, struct flat_binder_object)
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/*
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* NOTE: Two special error codes you should check for when calling
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@ -276,6 +285,11 @@ struct binder_transaction_data {
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} data;
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};
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struct binder_transaction_data_secctx {
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struct binder_transaction_data transaction_data;
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binder_uintptr_t secctx;
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};
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struct binder_transaction_data_sg {
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struct binder_transaction_data transaction_data;
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binder_size_t buffers_size;
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@ -311,6 +325,11 @@ enum binder_driver_return_protocol {
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BR_OK = _IO('r', 1),
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/* No parameters! */
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BR_TRANSACTION_SEC_CTX = _IOR('r', 2,
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struct binder_transaction_data_secctx),
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/*
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* binder_transaction_data_secctx: the received command.
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*/
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BR_TRANSACTION = _IOR('r', 2, struct binder_transaction_data),
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BR_REPLY = _IOR('r', 3, struct binder_transaction_data),
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/*
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