From e6b1105e27317b97ff0dbf4104f081767e742fee Mon Sep 17 00:00:00 2001 From: Todd Kjos Date: Mon, 14 Jan 2019 09:10:21 -0800 Subject: [PATCH] FROMGIT: 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 Reviewed-by: Joel Fernandes (Google) Signed-off-by: Greg Kroah-Hartman (cherry picked from commit ec74136ded792deed80780a2f8baf3521eeb72f9 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master) Change-Id: I44496546e2d0dc0022f818a45cd52feb1c1a92cb Signed-off-by: Todd Kjos --- drivers/android/binder.c | 105 ++++++++++++++++++++++------ include/uapi/linux/android/binder.h | 19 +++++ 2 files changed, 101 insertions(+), 23 deletions(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index e1284f51d60..2afba981c74 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -367,6 +367,7 @@ struct binder_error { * @min_priority: minimum scheduling priority * (invariant after initialized) * @inherit_rt: inherit RT scheduling policy from caller + * @txn_security_ctx: require sender's security context * (invariant after initialized) * @async_todo: list of async work items * (protected by @proc->inner_lock) @@ -406,6 +407,7 @@ struct binder_node { u8 sched_policy:2; u8 inherit_rt:1; u8 accept_fds:1; + u8 txn_security_ctx:1; u8 min_priority; }; bool has_async_transaction; @@ -663,6 +665,7 @@ struct binder_transaction { struct binder_priority saved_priority; bool set_priority_called; kuid_t sender_euid; + binder_uintptr_t security_ctx; /** * @lock: protects @from, @to_proc, and @to_thread * @@ -1372,6 +1375,7 @@ static struct binder_node *binder_init_node_ilocked( node->min_priority = to_kernel_prio(node->sched_policy, priority); node->accept_fds = !!(flags & FLAT_BINDER_FLAG_ACCEPTS_FDS); node->inherit_rt = !!(flags & FLAT_BINDER_FLAG_INHERIT_RT); + node->txn_security_ctx = !!(flags & FLAT_BINDER_FLAG_TXN_SECURITY_CTX); spin_lock_init(&node->lock); INIT_LIST_HEAD(&node->work.entry); INIT_LIST_HEAD(&node->async_todo); @@ -2904,6 +2908,8 @@ static void binder_transaction(struct binder_proc *proc, binder_size_t last_fixup_min_off = 0; struct binder_context *context = proc->context; int t_debug_id = atomic_inc_return(&binder_last_id); + char *secctx = NULL; + u32 secctx_sz = 0; e = binder_transaction_log_add(&binder_transaction_log); e->debug_id = t_debug_id; @@ -3127,6 +3133,20 @@ static void binder_transaction(struct binder_proc *proc, t->priority = target_proc->default_priority; } + if (target_node && target_node->txn_security_ctx) { + u32 secid; + + security_task_getsecid(proc->tsk, &secid); + ret = security_secid_to_secctx(secid, &secctx, &secctx_sz); + if (ret) { + return_error = BR_FAILED_REPLY; + return_error_param = ret; + return_error_line = __LINE__; + goto err_get_secctx_failed; + } + extra_buffers_size += ALIGN(secctx_sz, sizeof(u64)); + } + trace_binder_transaction(reply, t, target_node); t->buffer = binder_alloc_new_buf(&target_proc->alloc, tr->data_size, @@ -3143,6 +3163,19 @@ static void binder_transaction(struct binder_proc *proc, t->buffer = NULL; goto err_binder_alloc_buf_failed; } + if (secctx) { + size_t buf_offset = ALIGN(tr->data_size, sizeof(void *)) + + ALIGN(tr->offsets_size, sizeof(void *)) + + ALIGN(extra_buffers_size, sizeof(void *)) - + ALIGN(secctx_sz, sizeof(u64)); + char *kptr = t->buffer->data + buf_offset; + + t->security_ctx = (uintptr_t)kptr + + binder_alloc_get_user_buffer_offset(&target_proc->alloc); + memcpy(kptr, secctx, secctx_sz); + security_release_secctx(secctx, secctx_sz); + secctx = NULL; + } t->buffer->debug_id = t->debug_id; t->buffer->transaction = t; t->buffer->target_node = target_node; @@ -3413,6 +3446,9 @@ err_copy_data_failed: t->buffer->transaction = NULL; binder_alloc_free_buf(&target_proc->alloc, t->buffer); err_binder_alloc_buf_failed: + if (secctx) + security_release_secctx(secctx, secctx_sz); +err_get_secctx_failed: kfree(tcomplete); binder_stats_deleted(BINDER_STAT_TRANSACTION_COMPLETE); err_alloc_tcomplete_failed: @@ -4059,11 +4095,13 @@ retry: while (1) { uint32_t cmd; - struct binder_transaction_data tr; + struct binder_transaction_data_secctx tr; + struct binder_transaction_data *trd = &tr.transaction_data; struct binder_work *w = NULL; struct list_head *list = NULL; struct binder_transaction *t = NULL; struct binder_thread *t_from; + size_t trsize = sizeof(*trd); binder_inner_proc_lock(proc); if (!binder_worklist_empty_ilocked(&thread->todo)) @@ -4258,41 +4296,47 @@ retry: struct binder_node *target_node = t->buffer->target_node; struct binder_priority node_prio; - tr.target.ptr = target_node->ptr; - tr.cookie = target_node->cookie; + trd->target.ptr = target_node->ptr; + trd->cookie = target_node->cookie; node_prio.sched_policy = target_node->sched_policy; node_prio.prio = target_node->min_priority; binder_transaction_priority(current, t, node_prio, target_node->inherit_rt); cmd = BR_TRANSACTION; } else { - tr.target.ptr = 0; - tr.cookie = 0; + trd->target.ptr = 0; + trd->cookie = 0; cmd = BR_REPLY; } - tr.code = t->code; - tr.flags = t->flags; - tr.sender_euid = from_kuid(current_user_ns(), t->sender_euid); + trd->code = t->code; + trd->flags = t->flags; + trd->sender_euid = from_kuid(current_user_ns(), t->sender_euid); t_from = binder_get_txn_from(t); if (t_from) { struct task_struct *sender = t_from->proc->tsk; - tr.sender_pid = task_tgid_nr_ns(sender, - task_active_pid_ns(current)); + trd->sender_pid = + task_tgid_nr_ns(sender, + task_active_pid_ns(current)); } else { - tr.sender_pid = 0; + trd->sender_pid = 0; } - tr.data_size = t->buffer->data_size; - tr.offsets_size = t->buffer->offsets_size; - tr.data.ptr.buffer = (binder_uintptr_t) + trd->data_size = t->buffer->data_size; + trd->offsets_size = t->buffer->offsets_size; + trd->data.ptr.buffer = (binder_uintptr_t) ((uintptr_t)t->buffer->data + binder_alloc_get_user_buffer_offset(&proc->alloc)); - tr.data.ptr.offsets = tr.data.ptr.buffer + + trd->data.ptr.offsets = trd->data.ptr.buffer + ALIGN(t->buffer->data_size, sizeof(void *)); + tr.secctx = t->security_ctx; + if (t->security_ctx) { + cmd = BR_TRANSACTION_SEC_CTX; + trsize = sizeof(tr); + } if (put_user(cmd, (uint32_t __user *)ptr)) { if (t_from) binder_thread_dec_tmpref(t_from); @@ -4303,7 +4347,7 @@ retry: return -EFAULT; } ptr += sizeof(uint32_t); - if (copy_to_user(ptr, &tr, sizeof(tr))) { + if (copy_to_user(ptr, &tr, trsize)) { if (t_from) binder_thread_dec_tmpref(t_from); @@ -4312,7 +4356,7 @@ retry: return -EFAULT; } - ptr += sizeof(tr); + ptr += trsize; trace_binder_transaction_received(t); binder_stat_br(proc, thread, cmd); @@ -4320,16 +4364,18 @@ retry: "%d:%d %s %d %d:%d, cmd %d size %zd-%zd ptr %016llx-%016llx\n", proc->pid, thread->pid, (cmd == BR_TRANSACTION) ? "BR_TRANSACTION" : - "BR_REPLY", + (cmd == BR_TRANSACTION_SEC_CTX) ? + "BR_TRANSACTION_SEC_CTX" : "BR_REPLY", t->debug_id, t_from ? t_from->proc->pid : 0, t_from ? t_from->pid : 0, cmd, t->buffer->data_size, t->buffer->offsets_size, - (u64)tr.data.ptr.buffer, (u64)tr.data.ptr.offsets); + (u64)trd->data.ptr.buffer, + (u64)trd->data.ptr.offsets); if (t_from) binder_thread_dec_tmpref(t_from); t->buffer->allow_user_free = 1; - if (cmd == BR_TRANSACTION && !(t->flags & TF_ONE_WAY)) { + if (cmd != BR_REPLY && !(t->flags & TF_ONE_WAY)) { binder_inner_proc_lock(thread->proc); t->to_parent = thread->transaction_stack; t->to_thread = thread; @@ -4672,7 +4718,8 @@ out: return ret; } -static int binder_ioctl_set_ctx_mgr(struct file *filp) +static int binder_ioctl_set_ctx_mgr(struct file *filp, + struct flat_binder_object *fbo) { int ret = 0; struct binder_proc *proc = filp->private_data; @@ -4701,7 +4748,7 @@ static int binder_ioctl_set_ctx_mgr(struct file *filp) } else { context->binder_context_mgr_uid = curr_euid; } - new_node = binder_new_node(proc, NULL); + new_node = binder_new_node(proc, fbo); if (!new_node) { ret = -ENOMEM; goto out; @@ -4823,8 +4870,20 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) binder_inner_proc_unlock(proc); break; } + case BINDER_SET_CONTEXT_MGR_EXT: { + struct flat_binder_object fbo; + + if (copy_from_user(&fbo, ubuf, sizeof(fbo))) { + ret = -EINVAL; + goto err; + } + ret = binder_ioctl_set_ctx_mgr(filp, &fbo); + if (ret) + goto err; + break; + } case BINDER_SET_CONTEXT_MGR: - ret = binder_ioctl_set_ctx_mgr(filp); + ret = binder_ioctl_set_ctx_mgr(filp, NULL); if (ret) goto err; break; diff --git a/include/uapi/linux/android/binder.h b/include/uapi/linux/android/binder.h index 2ff6b15ac91..d5ba82daefe 100644 --- a/include/uapi/linux/android/binder.h +++ b/include/uapi/linux/android/binder.h @@ -86,6 +86,14 @@ enum flat_binder_object_flags { * scheduling policy from the caller (for synchronous transactions). */ FLAT_BINDER_FLAG_INHERIT_RT = 0x800, + + /** + * @FLAT_BINDER_FLAG_TXN_SECURITY_CTX: request security contexts + * + * Only when set, causes senders to include their security + * context + */ + FLAT_BINDER_FLAG_TXN_SECURITY_CTX = 0x1000, }; #ifdef BINDER_IPC_32BIT @@ -261,6 +269,7 @@ struct binder_node_info_for_ref { #define BINDER_VERSION _IOWR('b', 9, struct binder_version) #define BINDER_GET_NODE_DEBUG_INFO _IOWR('b', 11, struct binder_node_debug_info) #define BINDER_GET_NODE_INFO_FOR_REF _IOWR('b', 12, struct binder_node_info_for_ref) +#define BINDER_SET_CONTEXT_MGR_EXT _IOW('b', 13, struct flat_binder_object) /* * NOTE: Two special error codes you should check for when calling @@ -319,6 +328,11 @@ struct binder_transaction_data { } data; }; +struct binder_transaction_data_secctx { + struct binder_transaction_data transaction_data; + binder_uintptr_t secctx; +}; + struct binder_transaction_data_sg { struct binder_transaction_data transaction_data; binder_size_t buffers_size; @@ -354,6 +368,11 @@ enum binder_driver_return_protocol { BR_OK = _IO('r', 1), /* No parameters! */ + BR_TRANSACTION_SEC_CTX = _IOR('r', 2, + struct binder_transaction_data_secctx), + /* + * binder_transaction_data_secctx: the received command. + */ BR_TRANSACTION = _IOR('r', 2, struct binder_transaction_data), BR_REPLY = _IOR('r', 3, struct binder_transaction_data), /* -- 2.20.1