From: Li Li <dualli@google.com> It's a known issue that neither the frozen processes nor the system administration process of the OS can correctly deal with failed binder transactions. The reason is that there's no reliable way for the user space administration process to fetch the binder errors from the kernel binder driver. Android is such an OS suffering from this issue. Since cgroup freezer was used to freeze user applications to save battery, innocent frozen apps have to be killed when they receive sync binder transactions or when their async binder buffer is running out. This patch introduces the Linux generic netlink messages into the binder driver so that the Linux/Android system administration process can listen to important events and take corresponding actions, like stopping a broken app from attacking the OS by sending huge amount of spamming binder transactiions. The 1st version uses a global generic netlink for all binder contexts, raising potential security concerns. There were a few other feedbacks like request to kernel docs and test code. The thread can be found at https://lore.kernel.org/lkml/20240812211844.4107494-1-dualli@chromium.org/ The 2nd version fixes those issues and has been tested on the latest version of AOSP. See https://r.android.com/3305462 for how userspace is going to use this feature and the test code. It can be found at https://lore.kernel.org/lkml/20241011064427.1565287-1-dualli@chromium.org/ The 3rd version replaces the handcrafted netlink source code with the netlink protocal specs in YAML. It also fixes the documentation issues. https://lore.kernel.org/lkml/20241021182821.1259487-1-dualli@chromium.org/ The 4th version just containsi trivial fixes, making the subject of the patch aligned with the subject of the cover letter. https://lore.kernel.org/lkml/20241021191233.1334897-1-dualli@chromium.org/ The 5th version incorporates the suggested fixes to the kernel doc and the init function. It also removes the unsupported uapi-header in YAML that contains "/" for subdirectory. https://lore.kernel.org/lkml/20241025075102.1785960-1-dualli@chromium.org/ The 6th version has some trivial kernel doc fixes, without modifying any other source code. https://lore.kernel.org/lkml/20241028101952.775731-1-dualli@chromium.org/ The 7th version breaks the binary struct netlink message into individual attributes to better support automatic error checking. Thanks Jakub for improving ynl-gen. v1: add a global binder genl socket for all contexts v2: change to per-context binder genl for security reason replace the new ioctl with a netlink command add corresponding doc Documentation/admin-guide/binder_genl.rst add user space test code in AOSP v3: use YNL spec (./tools/net/ynl/ynl-regen.sh) fix documentation index v4: change the subject of the patch and remove unsed #if 0 v5: improve the kernel doc and the init function remove unsupported uapi-header in YAML v6: fix some trivial kernel doc issues v7: break the binary struct binder_report into individual attributes Jakub Kicinski (1): tools: ynl-gen: allow uapi headers in sub-dirs Li Li (1): binder: report txn errors via generic netlink Documentation/admin-guide/binder_genl.rst | 93 ++++++ Documentation/admin-guide/index.rst | 1 + Documentation/netlink/specs/binder_genl.yaml | 114 +++++++ drivers/android/Kconfig | 1 + drivers/android/Makefile | 2 +- drivers/android/binder.c | 313 ++++++++++++++++++- drivers/android/binder_genl.c | 38 +++ drivers/android/binder_genl.h | 18 ++ drivers/android/binder_internal.h | 22 ++ drivers/android/binder_trace.h | 35 +++ drivers/android/binderfs.c | 4 + include/uapi/linux/android/binder.h | 31 ++ include/uapi/linux/android/binder_genl.h | 56 ++++ tools/net/ynl/ynl-gen-c.py | 1 + 14 files changed, 721 insertions(+), 8 deletions(-) create mode 100644 Documentation/admin-guide/binder_genl.rst create mode 100644 Documentation/netlink/specs/binder_genl.yaml create mode 100644 drivers/android/binder_genl.c create mode 100644 drivers/android/binder_genl.h create mode 100644 include/uapi/linux/android/binder_genl.h base-commit: d30b56c8666d2543112152dd5d93d052eafd6bc2 -- 2.47.0.163.g1226f6d8fa-goog From: Jakub Kicinski <kuba@kernel.org> Binder places its headers under include/uapi/linux/android/ Make sure replace / with _ in the uAPI header guard, the c_upper() is more strict and only converts - to _. This is likely a good constraint to have, to enforce sane naming in enums etc. But paths may include /. Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Li Li <dualli@google.com> --- tools/net/ynl/ynl-gen-c.py | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/net/ynl/ynl-gen-c.py b/tools/net/ynl/ynl-gen-c.py index XXXXXXX..XXXXXXX 100755 --- a/tools/net/ynl/ynl-gen-c.py +++ b/tools/net/ynl/ynl-gen-c.py @@ -XXX,XX +XXX,XX @@ def uapi_enum_start(family, cw, obj, ckey='', enum_name='enum-name'): def render_uapi(family, cw): hdr_prot = f"_UAPI_LINUX_{c_upper(family.uapi_header_name)}_H" + hdr_prot = hdr_prot.replace('/', '_') cw.p('#ifndef ' + hdr_prot) cw.p('#define ' + hdr_prot) cw.nl() -- 2.47.0.163.g1226f6d8fa-goog From: Li Li <dualli@google.com> Frozen tasks can't process binder transactions, so sync binder transactions will fail with BR_FROZEN_REPLY and async binder transactions will be queued in the kernel async binder buffer. As these queued async transactions accumulates over time, the async buffer will eventually be running out, denying all new transactions after that with BR_FAILED_REPLY. In addition to the above cases, different kinds of binder error codes might be returned to the sender. However, the core Linux, or Android, system administration process never knows what's actually happening. Introduce generic netlink messages into the binder driver so that the Linux/Android system administration process can listen to important events and take corresponding actions, like stopping a broken app from attacking the OS by sending huge amount of spamming binder transactions. The new binder genl sources and headers are automatically generated from the corresponding binder_genl YAML spec. Don't modify them directly. Signed-off-by: Li Li <dualli@google.com> --- Documentation/admin-guide/binder_genl.rst | 93 ++++++ Documentation/admin-guide/index.rst | 1 + Documentation/netlink/specs/binder_genl.yaml | 114 +++++++ drivers/android/Kconfig | 1 + drivers/android/Makefile | 2 +- drivers/android/binder.c | 313 ++++++++++++++++++- drivers/android/binder_genl.c | 38 +++ drivers/android/binder_genl.h | 18 ++ drivers/android/binder_internal.h | 22 ++ drivers/android/binder_trace.h | 35 +++ drivers/android/binderfs.c | 4 + include/uapi/linux/android/binder.h | 31 ++ include/uapi/linux/android/binder_genl.h | 56 ++++ 13 files changed, 720 insertions(+), 8 deletions(-) create mode 100644 Documentation/admin-guide/binder_genl.rst create mode 100644 Documentation/netlink/specs/binder_genl.yaml create mode 100644 drivers/android/binder_genl.c create mode 100644 drivers/android/binder_genl.h create mode 100644 include/uapi/linux/android/binder_genl.h diff --git a/Documentation/admin-guide/binder_genl.rst b/Documentation/admin-guide/binder_genl.rst new file mode 100644 index XXXXXXX..XXXXXXX --- /dev/null +++ b/Documentation/admin-guide/binder_genl.rst @@ -XXX,XX +XXX,XX @@ +.. SPDX-License-Identifier: GPL-2.0 + +=========================================================== +Generic Netlink for the Android Binder Driver (Binder Genl) +=========================================================== + +The Generic Netlink subsystem in the Linux kernel provides a generic way for +the Linux kernel to communicate to the user space applications via binder +driver. It is used to report various kinds of binder transactions to user +space administration process. The driver allows multiple binder devices and +their corresponding binder contexts. Each context has an independent Generic +Netlink for security reason. To prevent untrusted user applications from +accessing the netlink data, the kernel driver uses unicast mode instead of +multicast. + +Basically, the user space code uses the "set" command to request what kind +of binder transactions reported by the kernel binder driver. The driver then +uses "reply" command to acknowledge the request. The "set" command also +registers the current user space process to receive the reports. When the +user space process exits, the previous request will be reset to prevent any +potential leaks. + +Currently the driver can report binder transactions that "failed" to reach +the target process, or that are "delayed" due to the target process being +frozen by cgroup freezer, or that are considered "spam" according to existing +logic in binder_alloc.c. + +When the specified binder transactions happen, the driver uses the "report" +command to send a generic netlink message to the registered process, +containing the payload struct binder_report. + +More details about the flags, attributes and operations can be found at the +the doc sections in Documentations/netlink/specs/binder_genl.yaml and the +kernel-doc comments of the new source code in binder.{h|c}. + +Using Binder Genl +----------------- + +The Binder Genl can be used in the same way as any other generic netlink +drivers. Userspace application uses a raw netlink socket to send commands +to and receive packets from the kernel driver. + +.. note:: + If the userspace application that talks to the driver exits, the kernel + driver will automatically reset the configuration to the default and + stop sending more reports to prevent leaking memory. + +Usage example (user space pseudo code): + +:: + + // open netlink socket + int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC); + + // bind netlink socket + bind(fd, struct socketaddr); + + // get the family id of the binder genl + send(fd, CTRL_CMD_GETFAMILY, CTRL_ATTR_FAMILY_NAME, "binder"); + void *data = recv(CTRL_CMD_NEWFAMILY); + __u16 id = nla(data)[CTRL_ATTR_FAMILY_ID]; + + // enable per-context binder report + send(fd, id, BINDER_GENL_CMD_SET, 0, BINDER_GENL_FLAG_FAILED | + BINDER_GENL_FLAG_DELAYED); + + // confirm the per-context configuration + void *data = recv(fd, BINDER_GENL_CMD_REPLY); + __u32 pid = nla(data)[BINDER_GENL_A_CMD_PID]; + __u32 flags = nla(data)[BINDER_GENL_A_CMD_FLAGS]; + + // set optional per-process report, overriding the per-context one + send(fd, id, BINDER_GENL_CMD_SET, getpid(), + BINDER_GENL_FLAG_SPAM | BINDER_REPORT_OVERRIDE); + + // confirm the optional per-process configuration + void *data = recv(fd, BINDER_GENL_CMD_REPLY); + __u32 pid = nla(data)[BINDER_GENL_A_CMD_PID]; + __u32 flags = nla(data)[BINDER_GENL_A_CMD_FLAGS]; + + // wait and read all binder reports + while (running) { + void *data = recv(fd, BINDER_GENL_CMD_REPORT); + u32 *attr = nla(data)[BINDER_GENL_A_REPORT_XXX]; + + // process binder report + do_something(*attr); + } + + // clean up + send(fd, id, BINDER_GENL_CMD_SET, 0, 0); + send(fd, id, BINDER_GENL_CMD_SET, getpid(), 0); + close(fd); diff --git a/Documentation/admin-guide/index.rst b/Documentation/admin-guide/index.rst index XXXXXXX..XXXXXXX 100644 --- a/Documentation/admin-guide/index.rst +++ b/Documentation/admin-guide/index.rst @@ -XXX,XX +XXX,XX @@ configure specific aspects of kernel behavior to your liking. aoe/index auxdisplay/index bcache + binder_genl binderfs binfmt-misc blockdev/index diff --git a/Documentation/netlink/specs/binder_genl.yaml b/Documentation/netlink/specs/binder_genl.yaml new file mode 100644 index XXXXXXX..XXXXXXX --- /dev/null +++ b/Documentation/netlink/specs/binder_genl.yaml @@ -XXX,XX +XXX,XX @@ +# SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) + +name: binder_genl +protocol: genetlink +uapi-header: linux/android/binder_genl.h +doc: Netlink protocol to report binder transaction errors and warnings. + +definitions: + - + type: flags + name: flag + doc: | + Used with "set" and "reply" command below, defining what kind of binder + transactions reported to the user space administration process. + value-start: 0 + entries: [ failed, delayed, spam, override ] + +attribute-sets: + - + name: cmd + doc: The supported attributes of "set" and "reply" commands + attributes: + - + name: pid + type: u32 + doc: | + What binder proc or context to enable binder genl report, + used by "set" and "reply" command below. + - + name: flags + type: u32 + doc: | + What kind of binder transactions reported via binder genl, + used by "set" and "reply" command below. + - + name: report + doc: The supported attributes of "report" command + attributes: + - + name: err + type: u32 + doc: | + Copy of binder_driver_return_protocol returned to the sender, + used by "report" command below. + - + name: from_pid + type: u32 + doc: | + Sender pid of the corresponding binder transaction + used by "report" command below. + - + name: from_tid + type: u32 + doc: | + Sender tid of the corresponding binder transaction + used by "report" command below. + - + name: to_pid + type: u32 + doc: | + Target pid of the corresponding binder transaction + used by "report" command below. + - + name: to_tid + type: u32 + doc: | + Target tid of the corresponding binder transaction + used by "report" command below. + - + name: reply + type: u32 + doc: | + 1 means the transaction is a reply, 0 otherwise + used by "report" command below. + - + name: flags + type: u32 + doc: | + Copy of binder_transaction_data->flags + used by "report" command below. + - + name: code + type: u32 + doc: | + Copy of binder_transaction_data->code + used by "report" command below. + - + name: data_size + type: u32 + doc: | + Copy of binder_transaction_data->data_size + used by "report" command below. + +operations: + list: + - + name: set + doc: | + Set flags from user space, requesting what kinds of binder + transactions to report. + attribute-set: cmd + + do: + request: &params + attributes: + - pid + - flags + reply: *params + - + name: reply + doc: Acknowledge the above "set" request, echoing the same params. + - + name: report + doc: Send the requested binder transaction reports to user space. diff --git a/drivers/android/Kconfig b/drivers/android/Kconfig index XXXXXXX..XXXXXXX 100644 --- a/drivers/android/Kconfig +++ b/drivers/android/Kconfig @@ -XXX,XX +XXX,XX @@ menu "Android" config ANDROID_BINDER_IPC bool "Android Binder IPC Driver" depends on MMU + depends on NET default n help Binder is used in Android for both communication between processes, diff --git a/drivers/android/Makefile b/drivers/android/Makefile index XXXXXXX..XXXXXXX 100644 --- a/drivers/android/Makefile +++ b/drivers/android/Makefile @@ -XXX,XX +XXX,XX @@ ccflags-y += -I$(src) # needed for trace events obj-$(CONFIG_ANDROID_BINDERFS) += binderfs.o -obj-$(CONFIG_ANDROID_BINDER_IPC) += binder.o binder_alloc.o +obj-$(CONFIG_ANDROID_BINDER_IPC) += binder.o binder_alloc.o binder_genl.o obj-$(CONFIG_ANDROID_BINDER_IPC_SELFTEST) += binder_alloc_selftest.o diff --git a/drivers/android/binder.c b/drivers/android/binder.c index XXXXXXX..XXXXXXX 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -XXX,XX +XXX,XX @@ #include <linux/cacheflush.h> +#include "binder_genl.h" #include "binder_internal.h" #include "binder_trace.h" @@ -XXX,XX +XXX,XX @@ static void binder_set_txn_from_error(struct binder_transaction *t, int id, binder_thread_dec_tmpref(from); } +/** + * binder_find_proc() - set binder report flags + * @pid: the target process + */ +static struct binder_proc *binder_find_proc(int pid) +{ + struct binder_proc *proc; + + mutex_lock(&binder_procs_lock); + hlist_for_each_entry(proc, &binder_procs, proc_node) { + if (proc->pid == pid) { + mutex_unlock(&binder_procs_lock); + return proc; + } + } + mutex_unlock(&binder_procs_lock); + + return NULL; +} + +/** + * binder_genl_set_report() - set binder report flags + * @context: the binder context to set the flags + * @pid: the target process + * @flags: the flags to set + * + * If pid is 0, the flags are applied to the whole binder context. + * Otherwise, the flags are applied to the specific process only. + */ +static int binder_genl_set_report(struct binder_context *context, u32 pid, + u32 flags) +{ + struct binder_proc *proc; + + if (flags != (flags & (BINDER_GENL_FLAG_OVERRIDE + | BINDER_GENL_FLAG_FAILED + | BINDER_GENL_FLAG_DELAYED + | BINDER_GENL_FLAG_SPAM))) { + pr_err("Invalid binder report flags: %u\n", flags); + return -EINVAL; + } + + if (!pid) { + /* Set the global flags for the whole binder context */ + context->report_flags = flags; + } else { + /* Set the per-process flags */ + proc = binder_find_proc(pid); + if (!proc) { + pr_err("Invalid binder report pid %u\n", pid); + return -EINVAL; + } + + proc->report_flags = flags; + } + + return 0; +} + +/** + * binder_genl_report_enabled() - check if binder genl reports are enabled + * @proc: the binder_proc to check + * @mask: the categories of binder genl reports + * + * Returns true if certain binder genl reports are enabled for this binder + * proc (when per-process overriding takes effect) or context. + */ +static bool binder_genl_report_enabled(struct binder_proc *proc, u32 mask) +{ + struct binder_context *context = proc->context; + + if (!context->report_portid) + return false; + + if (proc->report_flags & BINDER_GENL_FLAG_OVERRIDE) + return (proc->report_flags & mask) != 0; + else + return (context->report_flags & mask) != 0; +} + +/** + * binder_genl_send_report() - send one binder genl report + * @context: the binder context + * @err: copy of binder_driver_return_protocol returned to the sender + * @pid: sender process + * @tid: sender thread + * @to_pid: target process + * @to_tid: target thread + * @reply: whether the binder transaction is a reply + * @tr: the binder transaction data + * + * Packs the report data into a "report" binder genl message and send it. + */ +static void binder_genl_send_report(struct binder_context *context, u32 err, + u32 pid, u32 tid, u32 to_pid, u32 to_tid, + u32 reply, + struct binder_transaction_data *tr) +{ + int payload; + int ret; + struct sk_buff *skb; + void *hdr; + + trace_binder_send_report(context->name, err, pid, tid, to_pid, to_tid, + reply, tr); + + payload = nla_total_size(sizeof(u32)) * BINDER_GENL_A_REPORT_MAX; + skb = genlmsg_new(payload + GENL_HDRLEN, GFP_KERNEL); + if (!skb) { + pr_err("Failed to alloc binder genl message\n"); + return; + } + + hdr = genlmsg_put(skb, 0, atomic_inc_return(&context->report_seq), + &context->genl_family, 0, BINDER_GENL_CMD_REPORT); + if (!hdr) + goto free_skb; + + if (nla_put_u32(skb, BINDER_GENL_A_REPORT_ERR, err)) + goto cancel_skb; + + if (nla_put_u32(skb, BINDER_GENL_A_REPORT_FROM_PID, pid)) + goto cancel_skb; + + if (nla_put_u32(skb, BINDER_GENL_A_REPORT_FROM_TID, tid)) + goto cancel_skb; + + if (nla_put_u32(skb, BINDER_GENL_A_REPORT_TO_PID, to_pid)) + goto cancel_skb; + + if (nla_put_u32(skb, BINDER_GENL_A_REPORT_TO_TID, to_tid)) + goto cancel_skb; + + if (nla_put_u32(skb, BINDER_GENL_A_REPORT_REPLY, reply)) + goto cancel_skb; + + if (nla_put_u32(skb, BINDER_GENL_A_REPORT_FLAGS, tr->flags)) + goto cancel_skb; + + if (nla_put_u32(skb, BINDER_GENL_A_REPORT_CODE, tr->code)) + goto cancel_skb; + + if (nla_put_u32(skb, BINDER_GENL_A_REPORT_DATA_SIZE, tr->data_size)) + goto cancel_skb; + + genlmsg_end(skb, hdr); + + ret = genlmsg_unicast(&init_net, skb, context->report_portid); + if (ret < 0) + pr_err("Failed to send binder genl message to %d: %d\n", + context->report_portid, ret); + return; + +cancel_skb: + pr_err("Failed to add report attributes to binder genl message\n"); + genlmsg_cancel(skb, hdr); +free_skb: + pr_err("Free binder genl report message on error\n"); + nlmsg_free(skb); +} + static void binder_transaction(struct binder_proc *proc, struct binder_thread *thread, struct binder_transaction_data *tr, int reply, @@ -XXX,XX +XXX,XX @@ static void binder_transaction(struct binder_proc *proc, return_error_line = __LINE__; goto err_copy_data_failed; } - if (t->buffer->oneway_spam_suspect) + if (t->buffer->oneway_spam_suspect) { tcomplete->type = BINDER_WORK_TRANSACTION_ONEWAY_SPAM_SUSPECT; - else + if (binder_genl_report_enabled(proc, BINDER_GENL_FLAG_SPAM)) + binder_genl_send_report(context, + BR_ONEWAY_SPAM_SUSPECT, + proc->pid, thread->pid, + target_proc ? target_proc->pid : 0, + target_thread ? target_thread->pid : 0, + reply, tr); + } else { tcomplete->type = BINDER_WORK_TRANSACTION_COMPLETE; + } t->work.type = BINDER_WORK_TRANSACTION; if (reply) { @@ -XXX,XX +XXX,XX @@ static void binder_transaction(struct binder_proc *proc, * process and is put in a pending queue, waiting for the target * process to be unfrozen. */ - if (return_error == BR_TRANSACTION_PENDING_FROZEN) + if (return_error == BR_TRANSACTION_PENDING_FROZEN) { tcomplete->type = BINDER_WORK_TRANSACTION_PENDING; + if (binder_genl_report_enabled(proc, BINDER_GENL_FLAG_DELAYED)) + binder_genl_send_report(context, return_error, + proc->pid, thread->pid, + target_proc ? target_proc->pid : 0, + target_thread ? target_thread->pid : 0, + reply, tr); + } binder_enqueue_thread_work(thread, tcomplete); if (return_error && return_error != BR_TRANSACTION_PENDING_FROZEN) @@ -XXX,XX +XXX,XX @@ static void binder_transaction(struct binder_proc *proc, binder_dec_node_tmpref(target_node); } + if (binder_genl_report_enabled(proc, BINDER_GENL_FLAG_FAILED)) + binder_genl_send_report(context, return_error, + proc->pid, thread->pid, + target_proc ? target_proc->pid : 0, + target_thread ? target_thread->pid : 0, + reply, tr); + binder_debug(BINDER_DEBUG_FAILED_TRANSACTION, "%d:%d transaction %s to %d:%d failed %d/%d/%d, size %lld-%lld line %d\n", proc->pid, thread->pid, reply ? "reply" : @@ -XXX,XX +XXX,XX @@ static int binder_release(struct inode *nodp, struct file *filp) binder_defer_work(proc, BINDER_DEFERRED_RELEASE); + if (proc->pid == proc->context->report_portid) { + proc->context->report_portid = 0; + proc->context->report_flags = 0; + } + return 0; } @@ -XXX,XX +XXX,XX @@ binder_defer_work(struct binder_proc *proc, enum binder_deferred_state defer) mutex_unlock(&binder_deferred_lock); } +/** + * binder_genl_nl_set_doit() - .doit handler for BINDER_GENL_CMD_SET + * @skb: the metadata struct passed from netlink driver + * @info: the generic netlink struct passed from netlink driver + * + * Implements the .doit function to process binder genl commands. + */ +int binder_genl_nl_set_doit(struct sk_buff *skb, struct genl_info *info) +{ + int payload; + int portid; + u32 pid; + u32 flags; + void *hdr; + struct binder_context *context; + + /* Both attributes are required for BINDER_GENL_CMD_SET */ + if (!info->attrs[BINDER_GENL_A_CMD_PID] || !info->attrs[BINDER_GENL_A_CMD_FLAGS]) { + pr_err("Attributes not set\n"); + return -EINVAL; + } + + portid = nlmsg_hdr(skb)->nlmsg_pid; + pid = nla_get_u32(info->attrs[BINDER_GENL_A_CMD_PID]); + flags = nla_get_u32(info->attrs[BINDER_GENL_A_CMD_FLAGS]); + context = container_of(info->family, struct binder_context, + genl_family); + + if (context->report_portid && context->report_portid != portid) { + pr_err("No permission to set report flags from %u\n", portid); + return -EPERM; + } + + if (binder_genl_set_report(context, pid, flags) < 0) { + pr_err("Failed to set report flags %u for %u\n", flags, pid); + return -EINVAL; + } + + payload = nla_total_size(sizeof(pid)) + nla_total_size(sizeof(flags)); + skb = genlmsg_new(payload + GENL_HDRLEN, GFP_KERNEL); + if (!skb) { + pr_err("Failed to alloc binder genl reply message\n"); + return -ENOMEM; + } + + hdr = genlmsg_put_reply(skb, info, info->family, 0, + BINDER_GENL_CMD_REPLY); + if (!hdr) + goto free_skb; + + if (nla_put_u32(skb, BINDER_GENL_A_CMD_PID, pid)) + goto cancel_skb; + + if (nla_put_u32(skb, BINDER_GENL_A_CMD_FLAGS, flags)) + goto cancel_skb; + + genlmsg_end(skb, hdr); + + if (genlmsg_reply(skb, info)) { + pr_err("Failed to send binder genl reply message\n"); + return -EFAULT; + } + + if (!context->report_portid) + context->report_portid = portid; + + return 0; + +cancel_skb: + pr_err("Failed to add reply attributes to binder genl message\n"); + genlmsg_cancel(skb, hdr); +free_skb: + pr_err("Free binder genl reply message on error\n"); + nlmsg_free(skb); + return -EMSGSIZE; +} + static void print_binder_transaction_ilocked(struct seq_file *m, struct binder_proc *proc, const char *prefix, @@ -XXX,XX +XXX,XX @@ const struct binder_debugfs_entry binder_debugfs_entries[] = { {} /* terminator */ }; +/** + * binder_genl_init() - initialize binder generic netlink + * @family: the generic netlink family + * @name: the binder device name + * + * Registers the binder generic netlink family. + */ +int binder_genl_init(struct genl_family *family, const char *name) +{ + int ret; + + memcpy(family, &binder_genl_nl_family, sizeof(*family)); + strscpy(family->name, name, GENL_NAMSIZ); + ret = genl_register_family(family); + if (ret) { + pr_err("Failed to register binder genl: %s\n", name); + return ret; + } + + return 0; +} + static int __init init_binder_device(const char *name) { int ret; @@ -XXX,XX +XXX,XX @@ static int __init init_binder_device(const char *name) mutex_init(&binder_device->context.context_mgr_node_lock); ret = misc_register(&binder_device->miscdev); - if (ret < 0) { - kfree(binder_device); - return ret; - } + if (ret < 0) + goto err_free_dev; + + binder_device->context.report_seq = (atomic_t)ATOMIC_INIT(0); + ret = binder_genl_init(&binder_device->context.genl_family, name); + if (ret < 0) + goto err_misc_deregister; hlist_add_head(&binder_device->hlist, &binder_devices); + return ret; + +err_misc_deregister: + misc_deregister(&binder_device->miscdev); + +err_free_dev: + kfree(binder_device); + return ret; } diff --git a/drivers/android/binder_genl.c b/drivers/android/binder_genl.c new file mode 100644 index XXXXXXX..XXXXXXX --- /dev/null +++ b/drivers/android/binder_genl.c @@ -XXX,XX +XXX,XX @@ +// SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) +/* Do not edit directly, auto-generated from: */ +/* Documentation/netlink/specs/binder_genl.yaml */ +/* YNL-GEN kernel source */ + +#include <net/netlink.h> +#include <net/genetlink.h> + +#include "binder_genl.h" + +#include <uapi/linux/android/binder_genl.h> + +/* BINDER_GENL_CMD_SET - do */ +static const struct nla_policy binder_genl_set_nl_policy[BINDER_GENL_A_CMD_FLAGS + 1] = { + [BINDER_GENL_A_CMD_PID] = { .type = NLA_U32, }, + [BINDER_GENL_A_CMD_FLAGS] = { .type = NLA_U32, }, +}; + +/* Ops table for binder_genl */ +static const struct genl_split_ops binder_genl_nl_ops[] = { + { + .cmd = BINDER_GENL_CMD_SET, + .doit = binder_genl_nl_set_doit, + .policy = binder_genl_set_nl_policy, + .maxattr = BINDER_GENL_A_CMD_FLAGS, + .flags = GENL_CMD_CAP_DO, + }, +}; + +struct genl_family binder_genl_nl_family __ro_after_init = { + .name = BINDER_GENL_FAMILY_NAME, + .version = BINDER_GENL_FAMILY_VERSION, + .netnsok = true, + .parallel_ops = true, + .module = THIS_MODULE, + .split_ops = binder_genl_nl_ops, + .n_split_ops = ARRAY_SIZE(binder_genl_nl_ops), +}; diff --git a/drivers/android/binder_genl.h b/drivers/android/binder_genl.h new file mode 100644 index XXXXXXX..XXXXXXX --- /dev/null +++ b/drivers/android/binder_genl.h @@ -XXX,XX +XXX,XX @@ +/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) */ +/* Do not edit directly, auto-generated from: */ +/* Documentation/netlink/specs/binder_genl.yaml */ +/* YNL-GEN kernel header */ + +#ifndef _LINUX_BINDER_GENL_GEN_H +#define _LINUX_BINDER_GENL_GEN_H + +#include <net/netlink.h> +#include <net/genetlink.h> + +#include <uapi/linux/android/binder_genl.h> + +int binder_genl_nl_set_doit(struct sk_buff *skb, struct genl_info *info); + +extern struct genl_family binder_genl_nl_family; + +#endif /* _LINUX_BINDER_GENL_GEN_H */ diff --git a/drivers/android/binder_internal.h b/drivers/android/binder_internal.h index XXXXXXX..XXXXXXX 100644 --- a/drivers/android/binder_internal.h +++ b/drivers/android/binder_internal.h @@ -XXX,XX +XXX,XX @@ #include <linux/stddef.h> #include <linux/types.h> #include <linux/uidgid.h> +#include <net/genetlink.h> #include <uapi/linux/android/binderfs.h> #include "binder_alloc.h" #include "dbitmap.h" +/** + * struct binder_context - information about a binder domain + * @binder_context_mgr_node: the context manager + * @context_mgr_node_lock: the lock protecting the above context manager node + * @binder_context_mgr_uid: the uid of the above context manager + * @name: the name of the binder device + * @genl_family: the generic netlink family + * @report_portid: the netlink socket to receive binder reports + * @report_flags: the categories of binder transactions that would + * be reported (see enum binder_report_flag). + * @report_seq: the seq number of the generic netlink report + */ struct binder_context { struct binder_node *binder_context_mgr_node; struct mutex context_mgr_node_lock; kuid_t binder_context_mgr_uid; const char *name; + struct genl_family genl_family; + u32 report_portid; + u32 report_flags; + atomic_t report_seq; }; /** @@ -XXX,XX +XXX,XX @@ struct binder_ref { * @binderfs_entry: process-specific binderfs log file * @oneway_spam_detection_enabled: process enabled oneway spam detection * or not + * @report_flags: the categories of binder transactions that would + * be reported (see enum binder_report_flag). * * Bookkeeping structure for binder processes */ @@ -XXX,XX +XXX,XX @@ struct binder_proc { spinlock_t outer_lock; struct dentry *binderfs_entry; bool oneway_spam_detection_enabled; + u32 report_flags; }; /** @@ -XXX,XX +XXX,XX @@ struct binder_object { }; }; +int binder_genl_init(struct genl_family *family, const char *name); + #endif /* _LINUX_BINDER_INTERNAL_H */ diff --git a/drivers/android/binder_trace.h b/drivers/android/binder_trace.h index XXXXXXX..XXXXXXX 100644 --- a/drivers/android/binder_trace.h +++ b/drivers/android/binder_trace.h @@ -XXX,XX +XXX,XX @@ TRACE_EVENT(binder_return, "unknown") ); +TRACE_EVENT(binder_send_report, + TP_PROTO(const char *name, u32 err, u32 pid, u32 tid, u32 to_pid, + u32 to_tid, u32 reply, struct binder_transaction_data *tr), + TP_ARGS(name, err, pid, tid, to_pid, to_tid, reply, tr), + TP_STRUCT__entry( + __field(const char *, name) + __field(u32, err) + __field(u32, pid) + __field(u32, tid) + __field(u32, to_pid) + __field(u32, to_tid) + __field(u32, reply) + __field(u32, flags) + __field(u32, code) + __field(binder_size_t, data_size) + ), + TP_fast_assign( + __entry->name = name; + __entry->err = err; + __entry->pid = pid; + __entry->tid = tid; + __entry->to_pid = to_pid; + __entry->to_tid = to_tid; + __entry->reply = reply; + __entry->flags = tr->flags; + __entry->code = tr->code; + __entry->data_size = tr->data_size; + ), + TP_printk("%s: %d %d:%d -> %d:%d %s flags=0x08%x code=%d %llu", + __entry->name, __entry->err, __entry->pid, __entry->tid, + __entry->to_pid, __entry->to_tid, + __entry->reply ? "reply" : "", + __entry->flags, __entry->code, __entry->data_size) +); + #endif /* _BINDER_TRACE_H */ #undef TRACE_INCLUDE_PATH diff --git a/drivers/android/binderfs.c b/drivers/android/binderfs.c index XXXXXXX..XXXXXXX 100644 --- a/drivers/android/binderfs.c +++ b/drivers/android/binderfs.c @@ -XXX,XX +XXX,XX @@ static int binderfs_binder_device_create(struct inode *ref_inode, fsnotify_create(root->d_inode, dentry); inode_unlock(d_inode(root)); + ret = binder_genl_init(&device->context.genl_family, name); + if (ret < 0) + goto err; + return 0; err: diff --git a/include/uapi/linux/android/binder.h b/include/uapi/linux/android/binder.h index XXXXXXX..XXXXXXX 100644 --- a/include/uapi/linux/android/binder.h +++ b/include/uapi/linux/android/binder.h @@ -XXX,XX +XXX,XX @@ enum binder_driver_command_protocol { */ }; +/* + * struct binder_report - reports an abnormal binder transaction + * @err: copy of binder_driver_return_protocol returned to the sender + * @from_pid: sender pid of the corresponding binder transaction + * @from_tid: sender tid of the corresponding binder transaction + * @to_pid: target pid of the corresponding binder transaction + * @to_tid: target tid of the corresponding binder transaction + * @reply: 1 means the txn is a reply, 0 otherwise + * @flags: copy of binder_transaction_data->flags + * @code: copy of binder_transaction_data->code + * @data_size: copy of binder_transaction_data->data_size + * + * When a binder transaction fails to reach the target process or is not + * delivered on time, an error command BR_XXX is returned from the kernel + * binder driver to the user space sender. This is considered an abnormal + * binder transaction. The most important information about this abnormal + * binder transaction will be packed into this binder_report struct and sent + * to the registered user space administration process via generic netlink. + */ +struct binder_report { + __u32 err; + __u32 from_pid; + __u32 from_tid; + __u32 to_pid; + __u32 to_tid; + __u32 reply; + __u32 flags; + __u32 code; + binder_size_t data_size; +}; + #endif /* _UAPI_LINUX_BINDER_H */ diff --git a/include/uapi/linux/android/binder_genl.h b/include/uapi/linux/android/binder_genl.h new file mode 100644 index XXXXXXX..XXXXXXX --- /dev/null +++ b/include/uapi/linux/android/binder_genl.h @@ -XXX,XX +XXX,XX @@ +/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) */ +/* Do not edit directly, auto-generated from: */ +/* Documentation/netlink/specs/binder_genl.yaml */ +/* YNL-GEN uapi header */ + +#ifndef _UAPI_LINUX_ANDROID_BINDER_GENL_H +#define _UAPI_LINUX_ANDROID_BINDER_GENL_H + +#define BINDER_GENL_FAMILY_NAME "binder_genl" +#define BINDER_GENL_FAMILY_VERSION 1 + +/** + * enum binder_genl_flag - Used with "set" and "reply" command below, defining + * what kind of binder transactions reported to the user space administration + * process. + */ +enum binder_genl_flag { + BINDER_GENL_FLAG_FAILED = 1, + BINDER_GENL_FLAG_DELAYED = 2, + BINDER_GENL_FLAG_SPAM = 4, + BINDER_GENL_FLAG_OVERRIDE = 8, +}; + +enum { + BINDER_GENL_A_CMD_PID = 1, + BINDER_GENL_A_CMD_FLAGS, + + __BINDER_GENL_A_CMD_MAX, + BINDER_GENL_A_CMD_MAX = (__BINDER_GENL_A_CMD_MAX - 1) +}; + +enum { + BINDER_GENL_A_REPORT_ERR = 1, + BINDER_GENL_A_REPORT_FROM_PID, + BINDER_GENL_A_REPORT_FROM_TID, + BINDER_GENL_A_REPORT_TO_PID, + BINDER_GENL_A_REPORT_TO_TID, + BINDER_GENL_A_REPORT_REPLY, + BINDER_GENL_A_REPORT_FLAGS, + BINDER_GENL_A_REPORT_CODE, + BINDER_GENL_A_REPORT_DATA_SIZE, + + __BINDER_GENL_A_REPORT_MAX, + BINDER_GENL_A_REPORT_MAX = (__BINDER_GENL_A_REPORT_MAX - 1) +}; + +enum { + BINDER_GENL_CMD_SET = 1, + BINDER_GENL_CMD_REPLY, + BINDER_GENL_CMD_REPORT, + + __BINDER_GENL_CMD_MAX, + BINDER_GENL_CMD_MAX = (__BINDER_GENL_CMD_MAX - 1) +}; + +#endif /* _UAPI_LINUX_ANDROID_BINDER_GENL_H */ -- 2.47.0.163.g1226f6d8fa-goog From: Li Li <dualli@google.com> It's a known issue that neither the frozen processes nor the system administration process of the OS can correctly deal with failed binder transactions. The reason is that there's no reliable way for the user space administration process to fetch the binder errors from the kernel binder driver. Android is such an OS suffering from this issue. Since cgroup freezer was used to freeze user applications to save battery, innocent frozen apps have to be killed when they receive sync binder transactions or when their async binder buffer is running out. This patch introduces the Linux generic netlink messages into the binder driver so that the Linux/Android system administration process can listen to important events and take corresponding actions, like stopping a broken app from attacking the OS by sending huge amount of spamming binder transactiions. The 1st version uses a global generic netlink for all binder contexts, raising potential security concerns. There were a few other feedbacks like request to kernel docs and test code. The thread can be found at https://lore.kernel.org/lkml/20240812211844.4107494-1-dualli@chromium.org/ The 2nd version fixes those issues and has been tested on the latest version of AOSP. See https://r.android.com/3305462 for how userspace is going to use this feature and the test code. It can be found at https://lore.kernel.org/lkml/20241011064427.1565287-1-dualli@chromium.org/ The 3rd version replaces the handcrafted netlink source code with the netlink protocal specs in YAML. It also fixes the documentation issues. https://lore.kernel.org/lkml/20241021182821.1259487-1-dualli@chromium.org/ The 4th version just containsi trivial fixes, making the subject of the patch aligned with the subject of the cover letter. https://lore.kernel.org/lkml/20241021191233.1334897-1-dualli@chromium.org/ The 5th version incorporates the suggested fixes to the kernel doc and the init function. It also removes the unsupported uapi-header in YAML that contains "/" for subdirectory. https://lore.kernel.org/lkml/20241025075102.1785960-1-dualli@chromium.org/ The 6th version has some trivial kernel doc fixes, without modifying any other source code. https://lore.kernel.org/lkml/20241028101952.775731-1-dualli@chromium.org/ The 7th version breaks the binary struct netlink message into individual attributes to better support automatic error checking. Thanks Jakub for improving ynl-gen. https://lore.kernel.org/all/20241031092504.840708-1-dualli@chromium.org/ The 8th version solves the multi-genl-family issue by demuxing the messages based on a new context attribute. It also improves the YAML spec to be consistent with netlink tradition. A Huge 'Thank You' to Jakub who taught me a lot about the netlink protocol! https://lore.kernel.org/all/20241113193239.2113577-1-dualli@chromium.org/ The 9th version only contains a few trivial fixes, removing a redundant pr_err and unnecessary payload check. The ynl-gen patch to allow uapi header in sub-dirs has been merged so it's no longer included in this patch set. v1: add a global binder genl socket for all contexts v2: change to per-context binder genl for security reason replace the new ioctl with a netlink command add corresponding doc Documentation/admin-guide/binder_genl.rst add user space test code in AOSP v3: use YNL spec (./tools/net/ynl/ynl-regen.sh) fix documentation index v4: change the subject of the patch and remove unsed #if 0 v5: improve the kernel doc and the init function remove unsupported uapi-header in YAML v6: fix some trivial kernel doc issues v7: break the binary struct binder_report into individual attributes v8: use multiplex netlink message in a unified netlink family improve the YAML spec to be consistent with netlink tradition v9: remove unnecessary check to netlink flags and message payloads. Li Li (1): binder: report txn errors via generic netlink Documentation/admin-guide/binder_genl.rst | 96 +++++++ Documentation/admin-guide/index.rst | 1 + Documentation/netlink/specs/binder_genl.yaml | 108 ++++++++ drivers/android/Kconfig | 1 + drivers/android/Makefile | 2 +- drivers/android/binder.c | 277 ++++++++++++++++++- drivers/android/binder_genl.c | 39 +++ drivers/android/binder_genl.h | 18 ++ drivers/android/binder_internal.h | 27 +- drivers/android/binder_trace.h | 35 +++ drivers/android/binderfs.c | 2 + include/uapi/linux/android/binder_genl.h | 55 ++++ 12 files changed, 655 insertions(+), 6 deletions(-) create mode 100644 Documentation/admin-guide/binder_genl.rst create mode 100644 Documentation/netlink/specs/binder_genl.yaml create mode 100644 drivers/android/binder_genl.c create mode 100644 drivers/android/binder_genl.h create mode 100644 include/uapi/linux/android/binder_genl.h base-commit: 6145fefc1e42c1895c0c1c2c8593de2c085d8c56 -- 2.47.0.338.g60cca15819-goog From: Li Li <dualli@google.com> Frozen tasks can't process binder transactions, so sync binder transactions will fail with BR_FROZEN_REPLY and async binder transactions will be queued in the kernel async binder buffer. As these queued async transactions accumulates over time, the async buffer will eventually be running out, denying all new transactions after that with BR_FAILED_REPLY. In addition to the above cases, different kinds of binder error codes might be returned to the sender. However, the core Linux, or Android, system administration process never knows what's actually happening. Introduce generic netlink messages into the binder driver so that the Linux/Android system administration process can listen to important events and take corresponding actions, like stopping a broken app from attacking the OS by sending huge amount of spamming binder transactions. The new binder genl sources and headers are automatically generated from the corresponding binder_genl YAML spec. Don't modify them directly. Signed-off-by: Li Li <dualli@google.com> --- Documentation/admin-guide/binder_genl.rst | 96 +++++++ Documentation/admin-guide/index.rst | 1 + Documentation/netlink/specs/binder_genl.yaml | 108 ++++++++ drivers/android/Kconfig | 1 + drivers/android/Makefile | 2 +- drivers/android/binder.c | 277 ++++++++++++++++++- drivers/android/binder_genl.c | 39 +++ drivers/android/binder_genl.h | 18 ++ drivers/android/binder_internal.h | 27 +- drivers/android/binder_trace.h | 35 +++ drivers/android/binderfs.c | 2 + include/uapi/linux/android/binder_genl.h | 55 ++++ 12 files changed, 655 insertions(+), 6 deletions(-) create mode 100644 Documentation/admin-guide/binder_genl.rst create mode 100644 Documentation/netlink/specs/binder_genl.yaml create mode 100644 drivers/android/binder_genl.c create mode 100644 drivers/android/binder_genl.h create mode 100644 include/uapi/linux/android/binder_genl.h diff --git a/Documentation/admin-guide/binder_genl.rst b/Documentation/admin-guide/binder_genl.rst new file mode 100644 index XXXXXXX..XXXXXXX --- /dev/null +++ b/Documentation/admin-guide/binder_genl.rst @@ -XXX,XX +XXX,XX @@ +.. SPDX-License-Identifier: GPL-2.0 + +=========================================================== +Generic Netlink for the Android Binder Driver (Binder Genl) +=========================================================== + +The Generic Netlink subsystem in the Linux kernel provides a generic way for +the Linux kernel to communicate to the user space applications via binder +driver. It is used to report various kinds of binder transactions to user +space administration process. The driver allows multiple binder devices and +their corresponding binder contexts. Each context has an independent Generic +Netlink for security reason. To prevent untrusted user applications from +accessing the netlink data, the kernel driver uses unicast mode instead of +multicast. + +Basically, the user space code uses the "set" command to request what kind +of binder transactions should be reported by the kernel binder driver. The +driver then echoes the attributes in a reply message to acknowledge the +request. The "set" command also registers the current user space process to +receive the reports. When the user space process exits, the previous request +will be reset to prevent any potential leaks. + +Currently the driver can report binder transactions that "failed" to reach +the target process, or that are "delayed" due to the target process being +frozen by cgroup freezer, or that are considered "spam" according to existing +logic in binder_alloc.c. + +When the specified binder transactions happen, the driver uses the "report" +command to send a generic netlink message to the registered process, +containing the payload struct binder_report. + +More details about the flags, attributes and operations can be found at the +the doc sections in Documentations/netlink/specs/binder_genl.yaml and the +kernel-doc comments of the new source code in binder.{h|c}. + +Using Binder Genl +----------------- + +The Binder Genl can be used in the same way as any other generic netlink +drivers. Userspace application uses a raw netlink socket to send commands +to and receive packets from the kernel driver. + +.. note:: + If the userspace application that talks to the driver exits, the kernel + driver will automatically reset the configuration to the default and + stop sending more reports to prevent leaking memory. + +Usage example (user space pseudo code): + +:: + + // open netlink socket + int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC); + + // bind netlink socket + bind(fd, struct socketaddr); + + // get the family id of the binder genl + send(fd, CTRL_CMD_GETFAMILY, CTRL_ATTR_FAMILY_NAME, + BINDER_GENL_FAMILY_NAME); + void *data = recv(CTRL_CMD_NEWFAMILY); + __u16 id = nla(data)[CTRL_ATTR_FAMILY_ID]; + + // enable per-context binder report + send(fd, id, BINDER_GENL_CMD_SET, "binder", 0, BINDER_GENL_FLAG_FAILED | + BINDER_GENL_FLAG_DELAYED); + + // confirm the per-context configuration + data = recv(fd, BINDER_GENL_CMD_REPLY); + char *context = nla(data)[BINDER_GENL_A_CMD_CONTEXT]; + __u32 pid = nla(data)[BINDER_GENL_A_CMD_PID]; + __u32 flags = nla(data)[BINDER_GENL_A_CMD_FLAGS]; + + // set optional per-process report, overriding the per-context one + send(fd, id, BINDER_GENL_CMD_SET, "binder", getpid(), + BINDER_GENL_FLAG_SPAM | BINDER_REPORT_OVERRIDE); + + // confirm the optional per-process configuration + data = recv(fd, BINDER_GENL_CMD_REPLY); + context = nla(data)[BINDER_GENL_A_CMD_CONTEXT]; + pid = nla(data)[BINDER_GENL_A_CMD_PID]; + flags = nla(data)[BINDER_GENL_A_CMD_FLAGS]; + + // wait and read all binder reports + while (running) { + data = recv(fd, BINDER_GENL_CMD_REPORT); + auto *attr = nla(data)[BINDER_GENL_A_REPORT_XXX]; + + // process binder report + do_something(*attr); + } + + // clean up + send(fd, id, BINDER_GENL_CMD_SET, 0, 0); + send(fd, id, BINDER_GENL_CMD_SET, getpid(), 0); + close(fd); diff --git a/Documentation/admin-guide/index.rst b/Documentation/admin-guide/index.rst index XXXXXXX..XXXXXXX 100644 --- a/Documentation/admin-guide/index.rst +++ b/Documentation/admin-guide/index.rst @@ -XXX,XX +XXX,XX @@ configure specific aspects of kernel behavior to your liking. aoe/index auxdisplay/index bcache + binder_genl binderfs binfmt-misc blockdev/index diff --git a/Documentation/netlink/specs/binder_genl.yaml b/Documentation/netlink/specs/binder_genl.yaml new file mode 100644 index XXXXXXX..XXXXXXX --- /dev/null +++ b/Documentation/netlink/specs/binder_genl.yaml @@ -XXX,XX +XXX,XX @@ +# SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) + +name: binder_genl +protocol: genetlink +uapi-header: linux/android/binder_genl.h +doc: Netlink protocol to report binder transaction errors and warnings. + +definitions: + - + type: flags + name: flag + doc: Define what kind of binder transactions should be reported. + entries: [ failed, delayed, spam, override ] + +attribute-sets: + - + name: cmd + doc: The supported attributes of "set" and "reply" commands + attributes: + - + name: context + type: string + doc: The binder context to enable binder genl report. + - + name: pid + type: u32 + doc: The binder proc to enable binder genl report. + - + name: flags + type: u32 + enum: flag + doc: What kind of binder transactions should be reported. + - + name: report + doc: The supported attributes of "report" command + attributes: + - + name: context + type: string + doc: The binder context where the binder genl report happens. + - + name: err + type: u32 + doc: Copy of binder_driver_return_protocol returned to the sender. + - + name: from_pid + type: u32 + doc: Sender pid of the corresponding binder transaction. + - + name: from_tid + type: u32 + doc: Sender tid of the corresponding binder transaction. + - + name: to_pid + type: u32 + doc: Target pid of the corresponding binder transaction. + - + name: to_tid + type: u32 + doc: Target tid of the corresponding binder transaction. + - + name: reply + type: u32 + doc: 1 means the transaction is a reply, 0 otherwise. + - + name: flags + type: u32 + doc: Copy of binder_transaction_data->flags. + - + name: code + type: u32 + doc: Copy of binder_transaction_data->code. + - + name: data_size + type: u32 + doc: Copy of binder_transaction_data->data_size. + +operations: + list: + - + name: set + doc: Set flags from user space. + attribute-set: cmd + + do: + request: &params + attributes: + - context + - pid + - flags + reply: *params + - + name: report + doc: Send the requested reports to user space. + attribute-set: report + + event: + attributes: + - context + - err + - from_pid + - from_tid + - to_pid + - to_tid + - reply + - flags + - code + - data_size diff --git a/drivers/android/Kconfig b/drivers/android/Kconfig index XXXXXXX..XXXXXXX 100644 --- a/drivers/android/Kconfig +++ b/drivers/android/Kconfig @@ -XXX,XX +XXX,XX @@ menu "Android" config ANDROID_BINDER_IPC bool "Android Binder IPC Driver" depends on MMU + depends on NET default n help Binder is used in Android for both communication between processes, diff --git a/drivers/android/Makefile b/drivers/android/Makefile index XXXXXXX..XXXXXXX 100644 --- a/drivers/android/Makefile +++ b/drivers/android/Makefile @@ -XXX,XX +XXX,XX @@ ccflags-y += -I$(src) # needed for trace events obj-$(CONFIG_ANDROID_BINDERFS) += binderfs.o -obj-$(CONFIG_ANDROID_BINDER_IPC) += binder.o binder_alloc.o +obj-$(CONFIG_ANDROID_BINDER_IPC) += binder.o binder_alloc.o binder_genl.o obj-$(CONFIG_ANDROID_BINDER_IPC_SELFTEST) += binder_alloc_selftest.o diff --git a/drivers/android/binder.c b/drivers/android/binder.c index XXXXXXX..XXXXXXX 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -XXX,XX +XXX,XX @@ #include <linux/cacheflush.h> +#include "binder_genl.h" #include "binder_internal.h" #include "binder_trace.h" @@ -XXX,XX +XXX,XX @@ static void binder_set_txn_from_error(struct binder_transaction *t, int id, binder_thread_dec_tmpref(from); } +/** + * binder_find_proc() - set binder report flags + * @pid: the target process + */ +static struct binder_proc *binder_find_proc(int pid) +{ + struct binder_proc *proc; + + mutex_lock(&binder_procs_lock); + hlist_for_each_entry(proc, &binder_procs, proc_node) { + if (proc->pid == pid) { + mutex_unlock(&binder_procs_lock); + return proc; + } + } + mutex_unlock(&binder_procs_lock); + + return NULL; +} + +/** + * binder_genl_set_report() - set binder report flags + * @context: the binder context to set the flags + * @pid: the target process + * @flags: the flags to set + * + * If pid is 0, the flags are applied to the whole binder context. + * Otherwise, the flags are applied to the specific process only. + */ +static int binder_genl_set_report(struct binder_context *context, u32 pid, + u32 flags) +{ + struct binder_proc *proc; + + if (flags != (flags & (BINDER_GENL_FLAG_OVERRIDE + | BINDER_GENL_FLAG_FAILED + | BINDER_GENL_FLAG_DELAYED + | BINDER_GENL_FLAG_SPAM))) { + pr_err("Invalid binder report flags: %u\n", flags); + return -EINVAL; + } + + if (!pid) { + /* Set the global flags for the whole binder context */ + context->report_flags = flags; + } else { + /* Set the per-process flags */ + proc = binder_find_proc(pid); + if (!proc) { + pr_err("Invalid binder report pid %u\n", pid); + return -EINVAL; + } + + proc->report_flags = flags; + } + + return 0; +} + +/** + * binder_genl_report_enabled() - check if binder genl reports are enabled + * @proc: the binder_proc to check + * @mask: the categories of binder genl reports + * + * Returns true if certain binder genl reports are enabled for this binder + * proc (when per-process overriding takes effect) or context. + */ +static bool binder_genl_report_enabled(struct binder_proc *proc, u32 mask) +{ + struct binder_context *context = proc->context; + + if (!context->report_portid) + return false; + + if (proc->report_flags & BINDER_GENL_FLAG_OVERRIDE) + return (proc->report_flags & mask) != 0; + else + return (context->report_flags & mask) != 0; +} + +/** + * binder_genl_send_report() - send one binder genl report + * @context: the binder context + * @err: copy of binder_driver_return_protocol returned to the sender + * @pid: sender process + * @tid: sender thread + * @to_pid: target process + * @to_tid: target thread + * @reply: whether the binder transaction is a reply + * @tr: the binder transaction data + * + * Packs the report data into a "report" binder genl message and send it. + */ +static void binder_genl_send_report(struct binder_context *context, u32 err, + u32 pid, u32 tid, u32 to_pid, u32 to_tid, + u32 reply, + struct binder_transaction_data *tr) +{ + int ret; + struct sk_buff *skb; + void *hdr; + + trace_binder_send_report(context->name, err, pid, tid, to_pid, to_tid, + reply, tr); + + skb = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL); + if (!skb) { + pr_err("Failed to alloc binder genl message\n"); + return; + } + + hdr = genlmsg_put(skb, 0, atomic_inc_return(&context->report_seq), + &binder_genl_nl_family, 0, BINDER_GENL_CMD_REPORT); + if (!hdr) + goto free_skb; + + if (nla_put_string(skb, BINDER_GENL_A_REPORT_CONTEXT, context->name) || + nla_put_u32(skb, BINDER_GENL_A_REPORT_ERR, err) || + nla_put_u32(skb, BINDER_GENL_A_REPORT_FROM_PID, pid) || + nla_put_u32(skb, BINDER_GENL_A_REPORT_FROM_TID, tid) || + nla_put_u32(skb, BINDER_GENL_A_REPORT_TO_PID, to_pid) || + nla_put_u32(skb, BINDER_GENL_A_REPORT_TO_TID, to_tid) || + nla_put_u32(skb, BINDER_GENL_A_REPORT_REPLY, reply) || + nla_put_u32(skb, BINDER_GENL_A_REPORT_FLAGS, tr->flags) || + nla_put_u32(skb, BINDER_GENL_A_REPORT_CODE, tr->code) || + nla_put_u32(skb, BINDER_GENL_A_REPORT_DATA_SIZE, tr->data_size)) + goto cancel_skb; + + genlmsg_end(skb, hdr); + + ret = genlmsg_unicast(&init_net, skb, context->report_portid); + if (ret < 0) + pr_err("Failed to send binder genl message to %d: %d\n", + context->report_portid, ret); + return; + +cancel_skb: + pr_err("Failed to add report attributes to binder genl message\n"); + genlmsg_cancel(skb, hdr); +free_skb: + pr_err("Free binder genl report message on error\n"); + nlmsg_free(skb); +} + static void binder_transaction(struct binder_proc *proc, struct binder_thread *thread, struct binder_transaction_data *tr, int reply, @@ -XXX,XX +XXX,XX @@ static void binder_transaction(struct binder_proc *proc, return_error_line = __LINE__; goto err_copy_data_failed; } - if (t->buffer->oneway_spam_suspect) + if (t->buffer->oneway_spam_suspect) { tcomplete->type = BINDER_WORK_TRANSACTION_ONEWAY_SPAM_SUSPECT; - else + if (binder_genl_report_enabled(proc, BINDER_GENL_FLAG_SPAM)) + binder_genl_send_report(context, + BR_ONEWAY_SPAM_SUSPECT, + proc->pid, thread->pid, + target_proc ? target_proc->pid : 0, + target_thread ? target_thread->pid : 0, + reply, tr); + } else { tcomplete->type = BINDER_WORK_TRANSACTION_COMPLETE; + } t->work.type = BINDER_WORK_TRANSACTION; if (reply) { @@ -XXX,XX +XXX,XX @@ static void binder_transaction(struct binder_proc *proc, * process and is put in a pending queue, waiting for the target * process to be unfrozen. */ - if (return_error == BR_TRANSACTION_PENDING_FROZEN) + if (return_error == BR_TRANSACTION_PENDING_FROZEN) { tcomplete->type = BINDER_WORK_TRANSACTION_PENDING; + if (binder_genl_report_enabled(proc, BINDER_GENL_FLAG_DELAYED)) + binder_genl_send_report(context, return_error, + proc->pid, thread->pid, + target_proc ? target_proc->pid : 0, + target_thread ? target_thread->pid : 0, + reply, tr); + } binder_enqueue_thread_work(thread, tcomplete); if (return_error && return_error != BR_TRANSACTION_PENDING_FROZEN) @@ -XXX,XX +XXX,XX @@ static void binder_transaction(struct binder_proc *proc, binder_dec_node_tmpref(target_node); } + if (binder_genl_report_enabled(proc, BINDER_GENL_FLAG_FAILED)) + binder_genl_send_report(context, return_error, + proc->pid, thread->pid, + target_proc ? target_proc->pid : 0, + target_thread ? target_thread->pid : 0, + reply, tr); + binder_debug(BINDER_DEBUG_FAILED_TRANSACTION, "%d:%d transaction %s to %d:%d failed %d/%d/%d, size %lld-%lld line %d\n", proc->pid, thread->pid, reply ? "reply" : @@ -XXX,XX +XXX,XX @@ static int binder_release(struct inode *nodp, struct file *filp) binder_defer_work(proc, BINDER_DEFERRED_RELEASE); + if (proc->pid == proc->context->report_portid) { + proc->context->report_portid = 0; + proc->context->report_flags = 0; + } + return 0; } @@ -XXX,XX +XXX,XX @@ binder_defer_work(struct binder_proc *proc, enum binder_deferred_state defer) mutex_unlock(&binder_deferred_lock); } +/** + * binder_genl_nl_set_doit() - .doit handler for BINDER_GENL_CMD_SET + * @skb: the metadata struct passed from netlink driver + * @info: the generic netlink struct passed from netlink driver + * + * Implements the .doit function to process binder genl commands. + */ +int binder_genl_nl_set_doit(struct sk_buff *skb, struct genl_info *info) +{ + int portid; + u32 pid; + u32 flags; + void *hdr; + struct binder_device *device; + struct binder_context *context = NULL; + + hlist_for_each_entry(device, &binder_devices, hlist) { + if (!nla_strcmp(info->attrs[BINDER_GENL_A_CMD_CONTEXT], + device->context.name)) { + context = &device->context; + break; + } + } + + if (!context) { + NL_SET_ERR_MSG(info->extack, "Unknown binder context\n"); + return -EINVAL; + } + + portid = nlmsg_hdr(skb)->nlmsg_pid; + pid = nla_get_u32(info->attrs[BINDER_GENL_A_CMD_PID]); + flags = nla_get_u32(info->attrs[BINDER_GENL_A_CMD_FLAGS]); + + if (context->report_portid && context->report_portid != portid) { + NL_SET_ERR_MSG_FMT(info->extack, + "No permission to set flags from %d\n", + portid); + return -EPERM; + } + + if (binder_genl_set_report(context, pid, flags) < 0) { + pr_err("Failed to set report flags %u for %u\n", flags, pid); + return -EINVAL; + } + + skb = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL); + if (!skb) { + pr_err("Failed to alloc binder genl reply message\n"); + return -ENOMEM; + } + + hdr = genlmsg_iput(skb, info); + if (!hdr) + goto free_skb; + + if (nla_put_string(skb, BINDER_GENL_A_CMD_CONTEXT, context->name) || + nla_put_u32(skb, BINDER_GENL_A_CMD_PID, pid) || + nla_put_u32(skb, BINDER_GENL_A_CMD_FLAGS, flags)) + goto cancel_skb; + + genlmsg_end(skb, hdr); + + if (genlmsg_reply(skb, info)) { + pr_err("Failed to send binder genl reply message\n"); + return -EFAULT; + } + + if (!context->report_portid) + context->report_portid = portid; + + return 0; + +cancel_skb: + pr_err("Failed to add reply attributes to binder genl message\n"); + genlmsg_cancel(skb, hdr); +free_skb: + pr_err("Free binder genl reply message on error\n"); + nlmsg_free(skb); + return -EMSGSIZE; +} + static void print_binder_transaction_ilocked(struct seq_file *m, struct binder_proc *proc, const char *prefix, @@ -XXX,XX +XXX,XX @@ const struct binder_debugfs_entry binder_debugfs_entries[] = { {} /* terminator */ }; +/** + * Add a binder device to binder_devices + * @device: the new binder device to add to the global list + * + * Not reentrant as the list is not protected by any locks + */ +void binder_add_device(struct binder_device *device) +{ + hlist_add_head(&device->hlist, &binder_devices); +} + static int __init init_binder_device(const char *name) { int ret; @@ -XXX,XX +XXX,XX @@ static int __init init_binder_device(const char *name) } hlist_add_head(&binder_device->hlist, &binder_devices); + binder_device->context.report_seq = (atomic_t)ATOMIC_INIT(0); return ret; } @@ -XXX,XX +XXX,XX @@ static int __init binder_init(void) if (ret) goto err_init_binder_device_failed; + ret = genl_register_family(&binder_genl_nl_family); + if (ret) { + pr_err("Failed to register binder genl family\n"); + goto err_init_binder_device_failed; + } + return ret; err_init_binder_device_failed: diff --git a/drivers/android/binder_genl.c b/drivers/android/binder_genl.c new file mode 100644 index XXXXXXX..XXXXXXX --- /dev/null +++ b/drivers/android/binder_genl.c @@ -XXX,XX +XXX,XX @@ +// SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) +/* Do not edit directly, auto-generated from: */ +/* Documentation/netlink/specs/binder_genl.yaml */ +/* YNL-GEN kernel source */ + +#include <net/netlink.h> +#include <net/genetlink.h> + +#include "binder_genl.h" + +#include <uapi/linux/android/binder_genl.h> + +/* BINDER_GENL_CMD_SET - do */ +static const struct nla_policy binder_genl_set_nl_policy[BINDER_GENL_A_CMD_FLAGS + 1] = { + [BINDER_GENL_A_CMD_CONTEXT] = { .type = NLA_NUL_STRING, }, + [BINDER_GENL_A_CMD_PID] = { .type = NLA_U32, }, + [BINDER_GENL_A_CMD_FLAGS] = NLA_POLICY_MASK(NLA_U32, 0xf), +}; + +/* Ops table for binder_genl */ +static const struct genl_split_ops binder_genl_nl_ops[] = { + { + .cmd = BINDER_GENL_CMD_SET, + .doit = binder_genl_nl_set_doit, + .policy = binder_genl_set_nl_policy, + .maxattr = BINDER_GENL_A_CMD_FLAGS, + .flags = GENL_CMD_CAP_DO, + }, +}; + +struct genl_family binder_genl_nl_family __ro_after_init = { + .name = BINDER_GENL_FAMILY_NAME, + .version = BINDER_GENL_FAMILY_VERSION, + .netnsok = true, + .parallel_ops = true, + .module = THIS_MODULE, + .split_ops = binder_genl_nl_ops, + .n_split_ops = ARRAY_SIZE(binder_genl_nl_ops), +}; diff --git a/drivers/android/binder_genl.h b/drivers/android/binder_genl.h new file mode 100644 index XXXXXXX..XXXXXXX --- /dev/null +++ b/drivers/android/binder_genl.h @@ -XXX,XX +XXX,XX @@ +/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) */ +/* Do not edit directly, auto-generated from: */ +/* Documentation/netlink/specs/binder_genl.yaml */ +/* YNL-GEN kernel header */ + +#ifndef _LINUX_BINDER_GENL_GEN_H +#define _LINUX_BINDER_GENL_GEN_H + +#include <net/netlink.h> +#include <net/genetlink.h> + +#include <uapi/linux/android/binder_genl.h> + +int binder_genl_nl_set_doit(struct sk_buff *skb, struct genl_info *info); + +extern struct genl_family binder_genl_nl_family; + +#endif /* _LINUX_BINDER_GENL_GEN_H */ diff --git a/drivers/android/binder_internal.h b/drivers/android/binder_internal.h index XXXXXXX..XXXXXXX 100644 --- a/drivers/android/binder_internal.h +++ b/drivers/android/binder_internal.h @@ -XXX,XX +XXX,XX @@ #include <linux/stddef.h> #include <linux/types.h> #include <linux/uidgid.h> +#include <net/genetlink.h> #include <uapi/linux/android/binderfs.h> #include "binder_alloc.h" #include "dbitmap.h" +/** + * struct binder_context - information about a binder domain + * @binder_context_mgr_node: the context manager + * @context_mgr_node_lock: the lock protecting the above context manager node + * @binder_context_mgr_uid: the uid of the above context manager + * @name: the name of the binder device + * @report_portid: the netlink socket to receive binder reports + * @report_flags: the categories of binder transactions that would + * be reported (see enum binder_report_flag). + * @report_seq: the seq number of the generic netlink report + */ struct binder_context { struct binder_node *binder_context_mgr_node; struct mutex context_mgr_node_lock; kuid_t binder_context_mgr_uid; const char *name; + u32 report_portid; + u32 report_flags; + atomic_t report_seq; }; /** * struct binder_device - information about a binder device node - * @hlist: list of binder devices (only used for devices requested via - * CONFIG_ANDROID_BINDER_DEVICES) + * @hlist: list of binder devices * @miscdev: information about a binder character device node * @context: binder context information * @binderfs_inode: This is the inode of the root dentry of the super block @@ -XXX,XX +XXX,XX @@ struct binder_ref { * @binderfs_entry: process-specific binderfs log file * @oneway_spam_detection_enabled: process enabled oneway spam detection * or not + * @report_flags: the categories of binder transactions that would + * be reported (see enum binder_genl_flag). * * Bookkeeping structure for binder processes */ @@ -XXX,XX +XXX,XX @@ struct binder_proc { spinlock_t outer_lock; struct dentry *binderfs_entry; bool oneway_spam_detection_enabled; + u32 report_flags; }; /** @@ -XXX,XX +XXX,XX @@ struct binder_object { }; }; +/** + * Add a binder device to binder_devices + * @device: the new binder device to add to the global list + */ +void binder_add_device(struct binder_device *device); + #endif /* _LINUX_BINDER_INTERNAL_H */ diff --git a/drivers/android/binder_trace.h b/drivers/android/binder_trace.h index XXXXXXX..XXXXXXX 100644 --- a/drivers/android/binder_trace.h +++ b/drivers/android/binder_trace.h @@ -XXX,XX +XXX,XX @@ TRACE_EVENT(binder_return, "unknown") ); +TRACE_EVENT(binder_send_report, + TP_PROTO(const char *name, u32 err, u32 pid, u32 tid, u32 to_pid, + u32 to_tid, u32 reply, struct binder_transaction_data *tr), + TP_ARGS(name, err, pid, tid, to_pid, to_tid, reply, tr), + TP_STRUCT__entry( + __field(const char *, name) + __field(u32, err) + __field(u32, pid) + __field(u32, tid) + __field(u32, to_pid) + __field(u32, to_tid) + __field(u32, reply) + __field(u32, flags) + __field(u32, code) + __field(binder_size_t, data_size) + ), + TP_fast_assign( + __entry->name = name; + __entry->err = err; + __entry->pid = pid; + __entry->tid = tid; + __entry->to_pid = to_pid; + __entry->to_tid = to_tid; + __entry->reply = reply; + __entry->flags = tr->flags; + __entry->code = tr->code; + __entry->data_size = tr->data_size; + ), + TP_printk("%s: %d %d:%d -> %d:%d %s flags=0x08%x code=%d %llu", + __entry->name, __entry->err, __entry->pid, __entry->tid, + __entry->to_pid, __entry->to_tid, + __entry->reply ? "reply" : "", + __entry->flags, __entry->code, __entry->data_size) +); + #endif /* _BINDER_TRACE_H */ #undef TRACE_INCLUDE_PATH diff --git a/drivers/android/binderfs.c b/drivers/android/binderfs.c index XXXXXXX..XXXXXXX 100644 --- a/drivers/android/binderfs.c +++ b/drivers/android/binderfs.c @@ -XXX,XX +XXX,XX @@ static int binderfs_binder_device_create(struct inode *ref_inode, fsnotify_create(root->d_inode, dentry); inode_unlock(d_inode(root)); + binder_add_device(device); + return 0; err: diff --git a/include/uapi/linux/android/binder_genl.h b/include/uapi/linux/android/binder_genl.h new file mode 100644 index XXXXXXX..XXXXXXX --- /dev/null +++ b/include/uapi/linux/android/binder_genl.h @@ -XXX,XX +XXX,XX @@ +/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) */ +/* Do not edit directly, auto-generated from: */ +/* Documentation/netlink/specs/binder_genl.yaml */ +/* YNL-GEN uapi header */ + +#ifndef _UAPI_LINUX_ANDROID_BINDER_GENL_H +#define _UAPI_LINUX_ANDROID_BINDER_GENL_H + +#define BINDER_GENL_FAMILY_NAME "binder_genl" +#define BINDER_GENL_FAMILY_VERSION 1 + +/* + * Define what kind of binder transactions should be reported. + */ +enum binder_genl_flag { + BINDER_GENL_FLAG_FAILED = 1, + BINDER_GENL_FLAG_DELAYED = 2, + BINDER_GENL_FLAG_SPAM = 4, + BINDER_GENL_FLAG_OVERRIDE = 8, +}; + +enum { + BINDER_GENL_A_CMD_CONTEXT = 1, + BINDER_GENL_A_CMD_PID, + BINDER_GENL_A_CMD_FLAGS, + + __BINDER_GENL_A_CMD_MAX, + BINDER_GENL_A_CMD_MAX = (__BINDER_GENL_A_CMD_MAX - 1) +}; + +enum { + BINDER_GENL_A_REPORT_CONTEXT = 1, + BINDER_GENL_A_REPORT_ERR, + BINDER_GENL_A_REPORT_FROM_PID, + BINDER_GENL_A_REPORT_FROM_TID, + BINDER_GENL_A_REPORT_TO_PID, + BINDER_GENL_A_REPORT_TO_TID, + BINDER_GENL_A_REPORT_REPLY, + BINDER_GENL_A_REPORT_FLAGS, + BINDER_GENL_A_REPORT_CODE, + BINDER_GENL_A_REPORT_DATA_SIZE, + + __BINDER_GENL_A_REPORT_MAX, + BINDER_GENL_A_REPORT_MAX = (__BINDER_GENL_A_REPORT_MAX - 1) +}; + +enum { + BINDER_GENL_CMD_SET = 1, + BINDER_GENL_CMD_REPORT, + + __BINDER_GENL_CMD_MAX, + BINDER_GENL_CMD_MAX = (__BINDER_GENL_CMD_MAX - 1) +}; + +#endif /* _UAPI_LINUX_ANDROID_BINDER_GENL_H */ -- 2.47.0.338.g60cca15819-goog