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![Christian Brauner](/assets/img/avatar_default.png)
When a binder transaction is initiated on a binder device coming from a
binderfs instance, a pointer to the name of the binder device is stashed
in the binder_transaction_log_entry's context_name member. Later on it
is used to print the name in print_binder_transaction_log_entry(). By
the time print_binder_transaction_log_entry() accesses context_name
binderfs_evict_inode() might have already freed the associated memory
thereby causing a UAF. Do the simple thing and prevent this by copying
the name of the binder device instead of stashing a pointer to it.
Reported-by: Jann Horn <jannh@google.com>
Fixes: 03e2e07e38
("binder: Make transaction_log available in binderfs")
Link: https://lore.kernel.org/r/CAG48ez14Q0-F8LqsvcNbyR2o6gPW8SHXsm4u5jmD9MpsteM2Tw@mail.gmail.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: Todd Kjos <tkjos@google.com>
Reviewed-by: Hridya Valsaraju <hridya@google.com>
Link: https://lore.kernel.org/r/20191008130159.10161-1-christian.brauner@ubuntu.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
144 lines
4 KiB
C
144 lines
4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_BINDER_INTERNAL_H
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#define _LINUX_BINDER_INTERNAL_H
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#include <linux/export.h>
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#include <linux/fs.h>
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#include <linux/list.h>
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#include <linux/miscdevice.h>
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#include <linux/mutex.h>
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#include <linux/stddef.h>
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#include <linux/types.h>
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#include <linux/uidgid.h>
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struct binder_context {
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struct binder_node *binder_context_mgr_node;
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struct mutex context_mgr_node_lock;
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kuid_t binder_context_mgr_uid;
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const char *name;
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};
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/**
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* struct binder_device - information about a binder device node
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* @hlist: list of binder devices (only used for devices requested via
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* CONFIG_ANDROID_BINDER_DEVICES)
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* @miscdev: information about a binder character device node
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* @context: binder context information
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* @binderfs_inode: This is the inode of the root dentry of the super block
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* belonging to a binderfs mount.
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*/
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struct binder_device {
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struct hlist_node hlist;
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struct miscdevice miscdev;
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struct binder_context context;
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struct inode *binderfs_inode;
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};
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/**
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* binderfs_mount_opts - mount options for binderfs
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* @max: maximum number of allocatable binderfs binder devices
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* @stats_mode: enable binder stats in binderfs.
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*/
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struct binderfs_mount_opts {
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int max;
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int stats_mode;
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};
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/**
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* binderfs_info - information about a binderfs mount
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* @ipc_ns: The ipc namespace the binderfs mount belongs to.
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* @control_dentry: This records the dentry of this binderfs mount
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* binder-control device.
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* @root_uid: uid that needs to be used when a new binder device is
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* created.
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* @root_gid: gid that needs to be used when a new binder device is
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* created.
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* @mount_opts: The mount options in use.
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* @device_count: The current number of allocated binder devices.
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* @proc_log_dir: Pointer to the directory dentry containing process-specific
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* logs.
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*/
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struct binderfs_info {
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struct ipc_namespace *ipc_ns;
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struct dentry *control_dentry;
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kuid_t root_uid;
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kgid_t root_gid;
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struct binderfs_mount_opts mount_opts;
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int device_count;
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struct dentry *proc_log_dir;
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};
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extern const struct file_operations binder_fops;
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extern char *binder_devices_param;
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#ifdef CONFIG_ANDROID_BINDERFS
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extern bool is_binderfs_device(const struct inode *inode);
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extern struct dentry *binderfs_create_file(struct dentry *dir, const char *name,
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const struct file_operations *fops,
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void *data);
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extern void binderfs_remove_file(struct dentry *dentry);
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#else
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static inline bool is_binderfs_device(const struct inode *inode)
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{
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return false;
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}
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static inline struct dentry *binderfs_create_file(struct dentry *dir,
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const char *name,
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const struct file_operations *fops,
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void *data)
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{
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return NULL;
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}
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static inline void binderfs_remove_file(struct dentry *dentry) {}
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#endif
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#ifdef CONFIG_ANDROID_BINDERFS
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extern int __init init_binderfs(void);
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#else
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static inline int __init init_binderfs(void)
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{
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return 0;
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}
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#endif
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int binder_stats_show(struct seq_file *m, void *unused);
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DEFINE_SHOW_ATTRIBUTE(binder_stats);
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int binder_state_show(struct seq_file *m, void *unused);
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DEFINE_SHOW_ATTRIBUTE(binder_state);
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int binder_transactions_show(struct seq_file *m, void *unused);
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DEFINE_SHOW_ATTRIBUTE(binder_transactions);
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int binder_transaction_log_show(struct seq_file *m, void *unused);
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DEFINE_SHOW_ATTRIBUTE(binder_transaction_log);
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struct binder_transaction_log_entry {
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int debug_id;
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int debug_id_done;
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int call_type;
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int from_proc;
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int from_thread;
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int target_handle;
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int to_proc;
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int to_thread;
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int to_node;
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int data_size;
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int offsets_size;
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int return_error_line;
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uint32_t return_error;
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uint32_t return_error_param;
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char context_name[BINDERFS_MAX_NAME + 1];
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};
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struct binder_transaction_log {
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atomic_t cur;
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bool full;
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struct binder_transaction_log_entry entry[32];
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};
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extern struct binder_transaction_log binder_transaction_log;
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extern struct binder_transaction_log binder_transaction_log_failed;
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#endif /* _LINUX_BINDER_INTERNAL_H */
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