Kernel Exploit 用到的结构体
kernel structs
shm_file_data
size: 0x20 kmalloc-32
struct shm_file_data {
int id;
struct ipc_namespace *ns;
struct file *file;
const struct vm_operations_struct *vm_ops;
};
seq_operations
size: 0x20 kmalloc-32
struct seq_operations {
void * (*start) (struct seq_file *m, loff_t *pos);
void (*stop) (struct seq_file *m, void *v);
void * (*next) (struct seq_file *m, void *v, loff_t *pos);
int (*show) (struct seq_file *m, void *v);
};
msg_msg
size: 0x31-0x1000 kmalloc-64以上
/* one msg_msg structure for each message */
struct msg_msg {
struct list_head m_list;
long m_type;
size_t m_ts; /* message text size */
struct msg_msgseg *next;
void *security;
/* the actual message follows immediately */
};
subprocess_info
size: 0x60 kmalloc-128
struct subprocess_info {
struct work_struct work;
struct completion *complete;
const char *path;
char **argv;
char **envp;
struct file *file;
int wait;
int retval;
pid_t pid;
int (*init)(struct subprocess_info *info, struct cred *new);
void (*cleanup)(struct subprocess_info *info);
void *data;
} __randomize_layout;
cred
size: 0xa8 kmalloc-192
alloc path:
创建进程时，folk一个cred
free path:
exploit path:
uid,gid = 0 获得root
struct cred {
atomic_t usage;
#ifdef CONFIG_DEBUG_CREDENTIALS
atomic_t subscribers; /* number of processes subscribed */
void *put_addr;
unsigned magic;
#define CRED_MAGIC 0x43736564
#define CRED_MAGIC_DEAD 0x44656144
#endif
kuid_t uid; /* real UID of the task */
kgid_t gid; /* real GID of the task */
kuid_t suid; /* saved UID of the task */
kgid_t sgid; /* saved GID of the task */
kuid_t euid; /* effective UID of the task */
kgid_t egid; /* effective GID of the task */
kuid_t fsuid; /* UID for VFS ops */
kgid_t fsgid; /* GID for VFS ops */
unsigned securebits; /* SUID-less security management */
kernel_cap_t cap_inheritable; /* caps our children can inherit */
kernel_cap_t cap_permitted; /* caps we're permitted */
kernel_cap_t cap_effective; /* caps we can actually use */
kernel_cap_t cap_bset; /* capability bounding set */
kernel_cap_t cap_ambient; /* Ambient capability set */
#ifdef CONFIG_KEYS
unsigned char jit_keyring; /* default keyring to attach requested keys to */
struct key __rcu *session_keyring; /* keyring inherited over fork */
struct key *process_keyring; /* keyring private to this process */
struct key *thread_keyring; /* keyring private to this thread */
struct key *request_key_auth; /* assumed request_key authority */
#endif
#ifdef CONFIG_SECURITY
void *security; /* subjective LSM security */
#endif
struct user_struct *user; /* real user ID subscription */
struct user_namespace *user_ns; /* user_ns the caps and keyrings are relative to. */
struct group_info *group_info; /* supplementary groups for euid/fsgid */
/* RCU deletion */
union {
int non_rcu; /* Can we skip RCU deletion? */
struct rcu_head rcu; /* RCU deletion hook */
};
} __randomize_layout;
file
size: kmalloc-256
alloc path:
free path:
exploit path:
覆盖f_op对应的file_operations函数表
struct file {
union {
struct llist_node fu_llist;
struct rcu_head fu_rcuhead;
} f_u;
struct path f_path;
struct inode *f_inode; /* cached value */
const struct file_operations *f_op;
/*
* Protects f_ep_links, f_flags.
* Must not be taken from IRQ context.
*/
spinlock_t f_lock;
enum rw_hint f_write_hint;
atomic_long_t f_count;
unsigned int f_flags;
fmode_t f_mode;
struct mutex f_pos_lock;
loff_t f_pos;
struct fown_struct f_owner;
const struct cred *f_cred;
struct file_ra_state f_ra;
u64 f_version;
#ifdef CONFIG_SECURITY
void *f_security;
#endif
/* needed for tty driver, and maybe others */
void *private_data;
#ifdef CONFIG_EPOLL
/* Used by fs/eventpoll.c to link all the hooks to this file */
struct list_head f_ep_links;
struct list_head f_tfile_llink;
#endif /* #ifdef CONFIG_EPOLL */
struct address_space *f_mapping;
errseq_t f_wb_err;
} __randomize_layout
__attribute__((aligned(4))); /* lest something weird decides that 2 is OK */
timerfd_ctx
size: kmalloc-256
alloc path:
free path:
exploit path:
tmr拥有函数指针
struct timerfd_ctx {
union {
struct hrtimer tmr;
struct alarm alarm;
} t;
ktime_t tintv;
ktime_t moffs;
wait_queue_head_t wqh;
u64 ticks;
int clockid;
short unsigned expired;
short unsigned settime_flags; /* to show in fdinfo */
struct rcu_head rcu;
struct list_head clist;
spinlock_t cancel_lock;
bool might_cancel;
};
struct hrtimer {
struct timerqueue_node node;
ktime_t _softexpires;
enum hrtimer_restart (*function)(struct hrtimer *);
struct hrtimer_clock_base *base;
u8 state;
u8 is_rel;
u8 is_soft;
};
tty_struct
size: 0x2e0 kmalloc-1024
alloc path:
open("/dev/ptmx",O_RDWR);
free path:
exploit path:
tty_operations 大量函数指针
struct tty_struct {
int magic;
struct kref kref;
struct device *dev;
struct tty_driver *driver;
const struct tty_operations *ops;
int index;
/* Protects ldisc changes: Lock tty not pty */
struct ld_semaphore ldisc_sem;
struct tty_ldisc *ldisc;
struct mutex atomic_write_lock;
struct mutex legacy_mutex;
struct mutex throttle_mutex;
struct rw_semaphore termios_rwsem;
struct mutex winsize_mutex;
spinlock_t ctrl_lock;
spinlock_t flow_lock;
/* Termios values are protected by the termios rwsem */
struct ktermios termios, termios_locked;
struct termiox *termiox; /* May be NULL for unsupported */
char name[64];
struct pid *pgrp; /* Protected by ctrl lock */
struct pid *session;
unsigned long flags;
int count;
struct winsize winsize; /* winsize_mutex */
unsigned long stopped:1, /* flow_lock */
flow_stopped:1,
unused:BITS_PER_LONG - 2;
int hw_stopped;
unsigned long ctrl_status:8, /* ctrl_lock */
packet:1,
unused_ctrl:BITS_PER_LONG - 9;
unsigned int receive_room; /* Bytes free for queue */
int flow_change;
struct tty_struct *link;
struct fasync_struct *fasync;
wait_queue_head_t write_wait;
wait_queue_head_t read_wait;
struct work_struct hangup_work;
void *disc_data;
void *driver_data;
spinlock_t files_lock; /* protects tty_files list */
struct list_head tty_files;
#define N_TTY_BUF_SIZE 4096
int closing;
unsigned char *write_buf;
int write_cnt;
/* If the tty has a pending do_SAK, queue it here - akpm */
struct work_struct SAK_work;
struct tty_port *port;
} __randomize_layout;
packet_socket
size: kmalloc-2048
alloc path:
sock(AF_PACKET) -> packet_create -> sk_alloc
socket(AF_PACKET, SOCK_DGRAM, htons(ETH_P_ARP));
free path:
exploit path:
packet_sock->rx_ring->prb_bdqc->retire_blk_timer->func
函数指针，timeout时间后调用，携带参数
packet_socket->xmit
函数指针，接受数据时调用
struct packet_sock {
/* struct sock has to be the first member of packet_sock */
struct sock sk;
struct packet_fanout *fanout;
union tpacket_stats_u stats;
struct packet_ring_buffer rx_ring;
struct packet_ring_buffer tx_ring;
int copy_thresh;
spinlock_t bind_lock;
struct mutex pg_vec_lock;
unsigned int running:1, /* prot_hook is attached*/
auxdata:1,
origdev:1,
has_vnet_hdr:1;
int pressure;
int ifindex; /* bound device */
__be16 num;
struct packet_rollover *rollover;
struct packet_mclist *mclist;
atomic_t mapped;
enum tpacket_versions tp_version;
unsigned int tp_hdrlen;
unsigned int tp_reserve;
unsigned int tp_loss:1;
unsigned int tp_tx_has_off:1;
unsigned int tp_tstamp;
struct net_device __rcu *cached_dev;
int (*xmit)(struct sk_buff *skb);
struct packet_type prot_hook ____cacheline_aligned_in_smp;
};
参考文献
[1] https://ptr-yudai.hatenablog.com/entry/2020/03/16/165628
