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OpenCloudOS-Kernel/kernel/bpf/cgroup.c

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/*
* Functions to manage eBPF programs attached to cgroups
*
* Copyright (c) 2016 Daniel Mack
*
* This file is subject to the terms and conditions of version 2 of the GNU
* General Public License. See the file COPYING in the main directory of the
* Linux distribution for more details.
*/
#include <linux/kernel.h>
#include <linux/atomic.h>
#include <linux/cgroup.h>
#include <linux/filter.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
#include <linux/string.h>
#include <linux/bpf.h>
#include <linux/bpf-cgroup.h>
#include <net/sock.h>
DEFINE_STATIC_KEY_FALSE(cgroup_bpf_enabled_key);
EXPORT_SYMBOL(cgroup_bpf_enabled_key);
/**
* cgroup_bpf_put() - put references of all bpf programs
* @cgrp: the cgroup to modify
*/
void cgroup_bpf_put(struct cgroup *cgrp)
{
enum bpf_cgroup_storage_type stype;
unsigned int type;
for (type = 0; type < ARRAY_SIZE(cgrp->bpf.progs); type++) {
struct list_head *progs = &cgrp->bpf.progs[type];
struct bpf_prog_list *pl, *tmp;
list_for_each_entry_safe(pl, tmp, progs, node) {
list_del(&pl->node);
bpf_prog_put(pl->prog);
for_each_cgroup_storage_type(stype) {
bpf_cgroup_storage_unlink(pl->storage[stype]);
bpf_cgroup_storage_free(pl->storage[stype]);
}
kfree(pl);
static_branch_dec(&cgroup_bpf_enabled_key);
}
bpf_prog_array_free(cgrp->bpf.effective[type]);
}
}
/* count number of elements in the list.
* it's slow but the list cannot be long
*/
static u32 prog_list_length(struct list_head *head)
{
struct bpf_prog_list *pl;
u32 cnt = 0;
list_for_each_entry(pl, head, node) {
if (!pl->prog)
continue;
cnt++;
}
return cnt;
}
/* if parent has non-overridable prog attached,
* disallow attaching new programs to the descendent cgroup.
* if parent has overridable or multi-prog, allow attaching
*/
static bool hierarchy_allows_attach(struct cgroup *cgrp,
enum bpf_attach_type type,
u32 new_flags)
{
struct cgroup *p;
p = cgroup_parent(cgrp);
if (!p)
return true;
do {
u32 flags = p->bpf.flags[type];
u32 cnt;
if (flags & BPF_F_ALLOW_MULTI)
return true;
cnt = prog_list_length(&p->bpf.progs[type]);
WARN_ON_ONCE(cnt > 1);
if (cnt == 1)
return !!(flags & BPF_F_ALLOW_OVERRIDE);
p = cgroup_parent(p);
} while (p);
return true;
}
/* compute a chain of effective programs for a given cgroup:
* start from the list of programs in this cgroup and add
* all parent programs.
* Note that parent's F_ALLOW_OVERRIDE-type program is yielding
* to programs in this cgroup
*/
static int compute_effective_progs(struct cgroup *cgrp,
enum bpf_attach_type type,
struct bpf_prog_array __rcu **array)
{
enum bpf_cgroup_storage_type stype;
struct bpf_prog_array *progs;
struct bpf_prog_list *pl;
struct cgroup *p = cgrp;
int cnt = 0;
/* count number of effective programs by walking parents */
do {
if (cnt == 0 || (p->bpf.flags[type] & BPF_F_ALLOW_MULTI))
cnt += prog_list_length(&p->bpf.progs[type]);
p = cgroup_parent(p);
} while (p);
progs = bpf_prog_array_alloc(cnt, GFP_KERNEL);
if (!progs)
return -ENOMEM;
/* populate the array with effective progs */
cnt = 0;
p = cgrp;
do {
if (cnt > 0 && !(p->bpf.flags[type] & BPF_F_ALLOW_MULTI))
continue;
list_for_each_entry(pl, &p->bpf.progs[type], node) {
if (!pl->prog)
continue;
progs->items[cnt].prog = pl->prog;
for_each_cgroup_storage_type(stype)
progs->items[cnt].cgroup_storage[stype] =
pl->storage[stype];
cnt++;
}
} while ((p = cgroup_parent(p)));
rcu_assign_pointer(*array, progs);
return 0;
}
static void activate_effective_progs(struct cgroup *cgrp,
enum bpf_attach_type type,
struct bpf_prog_array __rcu *array)
{
struct bpf_prog_array __rcu *old_array;
old_array = xchg(&cgrp->bpf.effective[type], array);
/* free prog array after grace period, since __cgroup_bpf_run_*()
* might be still walking the array
*/
bpf_prog_array_free(old_array);
}
/**
* cgroup_bpf_inherit() - inherit effective programs from parent
* @cgrp: the cgroup to modify
*/
int cgroup_bpf_inherit(struct cgroup *cgrp)
{
/* has to use marco instead of const int, since compiler thinks
* that array below is variable length
*/
#define NR ARRAY_SIZE(cgrp->bpf.effective)
struct bpf_prog_array __rcu *arrays[NR] = {};
int i;
for (i = 0; i < NR; i++)
INIT_LIST_HEAD(&cgrp->bpf.progs[i]);
for (i = 0; i < NR; i++)
if (compute_effective_progs(cgrp, i, &arrays[i]))
goto cleanup;
for (i = 0; i < NR; i++)
activate_effective_progs(cgrp, i, arrays[i]);
return 0;
cleanup:
for (i = 0; i < NR; i++)
bpf_prog_array_free(arrays[i]);
return -ENOMEM;
}
static int update_effective_progs(struct cgroup *cgrp,
enum bpf_attach_type type)
{
struct cgroup_subsys_state *css;
int err;
/* allocate and recompute effective prog arrays */
css_for_each_descendant_pre(css, &cgrp->self) {
struct cgroup *desc = container_of(css, struct cgroup, self);
err = compute_effective_progs(desc, type, &desc->bpf.inactive);
if (err)
goto cleanup;
}
/* all allocations were successful. Activate all prog arrays */
css_for_each_descendant_pre(css, &cgrp->self) {
struct cgroup *desc = container_of(css, struct cgroup, self);
activate_effective_progs(desc, type, desc->bpf.inactive);
desc->bpf.inactive = NULL;
}
return 0;
cleanup:
/* oom while computing effective. Free all computed effective arrays
* since they were not activated
*/
css_for_each_descendant_pre(css, &cgrp->self) {
struct cgroup *desc = container_of(css, struct cgroup, self);
bpf_prog_array_free(desc->bpf.inactive);
desc->bpf.inactive = NULL;
}
return err;
}
#define BPF_CGROUP_MAX_PROGS 64
/**
* __cgroup_bpf_attach() - Attach the program to a cgroup, and
* propagate the change to descendants
* @cgrp: The cgroup which descendants to traverse
* @prog: A program to attach
* @type: Type of attach operation
* @flags: Option flags
*
* Must be called with cgroup_mutex held.
*/
int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
enum bpf_attach_type type, u32 flags)
{
struct list_head *progs = &cgrp->bpf.progs[type];
struct bpf_prog *old_prog = NULL;
struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE],
*old_storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {NULL};
enum bpf_cgroup_storage_type stype;
struct bpf_prog_list *pl;
bool pl_was_allocated;
int err;
if ((flags & BPF_F_ALLOW_OVERRIDE) && (flags & BPF_F_ALLOW_MULTI))
/* invalid combination */
return -EINVAL;
if (!hierarchy_allows_attach(cgrp, type, flags))
return -EPERM;
if (!list_empty(progs) && cgrp->bpf.flags[type] != flags)
/* Disallow attaching non-overridable on top
* of existing overridable in this cgroup.
* Disallow attaching multi-prog if overridable or none
*/
return -EPERM;
if (prog_list_length(progs) >= BPF_CGROUP_MAX_PROGS)
return -E2BIG;
for_each_cgroup_storage_type(stype) {
storage[stype] = bpf_cgroup_storage_alloc(prog, stype);
if (IS_ERR(storage[stype])) {
storage[stype] = NULL;
for_each_cgroup_storage_type(stype)
bpf_cgroup_storage_free(storage[stype]);
return -ENOMEM;
}
}
if (flags & BPF_F_ALLOW_MULTI) {
list_for_each_entry(pl, progs, node) {
if (pl->prog == prog) {
/* disallow attaching the same prog twice */
for_each_cgroup_storage_type(stype)
bpf_cgroup_storage_free(storage[stype]);
return -EINVAL;
}
}
pl = kmalloc(sizeof(*pl), GFP_KERNEL);
if (!pl) {
for_each_cgroup_storage_type(stype)
bpf_cgroup_storage_free(storage[stype]);
return -ENOMEM;
}
pl_was_allocated = true;
pl->prog = prog;
for_each_cgroup_storage_type(stype)
pl->storage[stype] = storage[stype];
list_add_tail(&pl->node, progs);
} else {
if (list_empty(progs)) {
pl = kmalloc(sizeof(*pl), GFP_KERNEL);
if (!pl) {
for_each_cgroup_storage_type(stype)
bpf_cgroup_storage_free(storage[stype]);
return -ENOMEM;
}
pl_was_allocated = true;
list_add_tail(&pl->node, progs);
} else {
pl = list_first_entry(progs, typeof(*pl), node);
old_prog = pl->prog;
for_each_cgroup_storage_type(stype) {
old_storage[stype] = pl->storage[stype];
bpf_cgroup_storage_unlink(old_storage[stype]);
}
pl_was_allocated = false;
}
pl->prog = prog;
for_each_cgroup_storage_type(stype)
pl->storage[stype] = storage[stype];
}
cgrp->bpf.flags[type] = flags;
err = update_effective_progs(cgrp, type);
if (err)
goto cleanup;
static_branch_inc(&cgroup_bpf_enabled_key);
for_each_cgroup_storage_type(stype) {
if (!old_storage[stype])
continue;
bpf_cgroup_storage_free(old_storage[stype]);
}
if (old_prog) {
bpf_prog_put(old_prog);
static_branch_dec(&cgroup_bpf_enabled_key);
}
for_each_cgroup_storage_type(stype)
bpf_cgroup_storage_link(storage[stype], cgrp, type);
return 0;
cleanup:
/* and cleanup the prog list */
pl->prog = old_prog;
for_each_cgroup_storage_type(stype) {
bpf_cgroup_storage_free(pl->storage[stype]);
pl->storage[stype] = old_storage[stype];
bpf_cgroup_storage_link(old_storage[stype], cgrp, type);
}
if (pl_was_allocated) {
list_del(&pl->node);
kfree(pl);
}
return err;
}
/**
* __cgroup_bpf_detach() - Detach the program from a cgroup, and
* propagate the change to descendants
* @cgrp: The cgroup which descendants to traverse
* @prog: A program to detach or NULL
* @type: Type of detach operation
*
* Must be called with cgroup_mutex held.
*/
int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
enum bpf_attach_type type)
{
struct list_head *progs = &cgrp->bpf.progs[type];
enum bpf_cgroup_storage_type stype;
u32 flags = cgrp->bpf.flags[type];
struct bpf_prog *old_prog = NULL;
struct bpf_prog_list *pl;
int err;
if (flags & BPF_F_ALLOW_MULTI) {
if (!prog)
/* to detach MULTI prog the user has to specify valid FD
* of the program to be detached
*/
return -EINVAL;
} else {
if (list_empty(progs))
/* report error when trying to detach and nothing is attached */
return -ENOENT;
}
if (flags & BPF_F_ALLOW_MULTI) {
/* find the prog and detach it */
list_for_each_entry(pl, progs, node) {
if (pl->prog != prog)
continue;
old_prog = prog;
/* mark it deleted, so it's ignored while
* recomputing effective
*/
pl->prog = NULL;
break;
}
if (!old_prog)
return -ENOENT;
} else {
/* to maintain backward compatibility NONE and OVERRIDE cgroups
* allow detaching with invalid FD (prog==NULL)
*/
pl = list_first_entry(progs, typeof(*pl), node);
old_prog = pl->prog;
pl->prog = NULL;
}
err = update_effective_progs(cgrp, type);
if (err)
goto cleanup;
/* now can actually delete it from this cgroup list */
list_del(&pl->node);
for_each_cgroup_storage_type(stype) {
bpf_cgroup_storage_unlink(pl->storage[stype]);
bpf_cgroup_storage_free(pl->storage[stype]);
}
kfree(pl);
if (list_empty(progs))
/* last program was detached, reset flags to zero */
cgrp->bpf.flags[type] = 0;
bpf_prog_put(old_prog);
static_branch_dec(&cgroup_bpf_enabled_key);
return 0;
cleanup:
/* and restore back old_prog */
pl->prog = old_prog;
return err;
}
/* Must be called with cgroup_mutex held to avoid races. */
int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
union bpf_attr __user *uattr)
{
__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
enum bpf_attach_type type = attr->query.attach_type;
struct list_head *progs = &cgrp->bpf.progs[type];
u32 flags = cgrp->bpf.flags[type];
int cnt, ret = 0, i;
if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE)
cnt = bpf_prog_array_length(cgrp->bpf.effective[type]);
else
cnt = prog_list_length(progs);
if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
return -EFAULT;
if (copy_to_user(&uattr->query.prog_cnt, &cnt, sizeof(cnt)))
return -EFAULT;
if (attr->query.prog_cnt == 0 || !prog_ids || !cnt)
/* return early if user requested only program count + flags */
return 0;
if (attr->query.prog_cnt < cnt) {
cnt = attr->query.prog_cnt;
ret = -ENOSPC;
}
if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE) {
return bpf_prog_array_copy_to_user(cgrp->bpf.effective[type],
prog_ids, cnt);
} else {
struct bpf_prog_list *pl;
u32 id;
i = 0;
list_for_each_entry(pl, progs, node) {
id = pl->prog->aux->id;
if (copy_to_user(prog_ids + i, &id, sizeof(id)))
return -EFAULT;
if (++i == cnt)
break;
}
}
return ret;
}
int cgroup_bpf_prog_attach(const union bpf_attr *attr,
enum bpf_prog_type ptype, struct bpf_prog *prog)
{
struct cgroup *cgrp;
int ret;
cgrp = cgroup_get_from_fd(attr->target_fd);
if (IS_ERR(cgrp))
return PTR_ERR(cgrp);
ret = cgroup_bpf_attach(cgrp, prog, attr->attach_type,
attr->attach_flags);
cgroup_put(cgrp);
return ret;
}
int cgroup_bpf_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype)
{
struct bpf_prog *prog;
struct cgroup *cgrp;
int ret;
cgrp = cgroup_get_from_fd(attr->target_fd);
if (IS_ERR(cgrp))
return PTR_ERR(cgrp);
prog = bpf_prog_get_type(attr->attach_bpf_fd, ptype);
if (IS_ERR(prog))
prog = NULL;
ret = cgroup_bpf_detach(cgrp, prog, attr->attach_type, 0);
if (prog)
bpf_prog_put(prog);
cgroup_put(cgrp);
return ret;
}
int cgroup_bpf_prog_query(const union bpf_attr *attr,
union bpf_attr __user *uattr)
{
struct cgroup *cgrp;
int ret;
cgrp = cgroup_get_from_fd(attr->query.target_fd);
if (IS_ERR(cgrp))
return PTR_ERR(cgrp);
ret = cgroup_bpf_query(cgrp, attr, uattr);
cgroup_put(cgrp);
return ret;
}
/**
* __cgroup_bpf_run_filter_skb() - Run a program for packet filtering
* @sk: The socket sending or receiving traffic
* @skb: The skb that is being sent or received
* @type: The type of program to be exectuted
*
* If no socket is passed, or the socket is not of type INET or INET6,
* this function does nothing and returns 0.
*
* The program type passed in via @type must be suitable for network
* filtering. No further check is performed to assert that.
*
* This function will return %-EPERM if any if an attached program was found
* and if it returned != 1 during execution. In all other cases, 0 is returned.
*/
int __cgroup_bpf_run_filter_skb(struct sock *sk,
struct sk_buff *skb,
enum bpf_attach_type type)
{
unsigned int offset = skb->data - skb_network_header(skb);
struct sock *save_sk;
void *saved_data_end;
struct cgroup *cgrp;
int ret;
if (!sk || !sk_fullsock(sk))
return 0;
if (sk->sk_family != AF_INET && sk->sk_family != AF_INET6)
return 0;
cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
save_sk = skb->sk;
skb->sk = sk;
__skb_push(skb, offset);
/* compute pointers for the bpf prog */
bpf_compute_and_save_data_end(skb, &saved_data_end);
ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], skb,
__bpf_prog_run_save_cb);
bpf_restore_data_end(skb, saved_data_end);
__skb_pull(skb, offset);
skb->sk = save_sk;
return ret == 1 ? 0 : -EPERM;
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_skb);
/**
* __cgroup_bpf_run_filter_sk() - Run a program on a sock
* @sk: sock structure to manipulate
* @type: The type of program to be exectuted
*
* socket is passed is expected to be of type INET or INET6.
*
* The program type passed in via @type must be suitable for sock
* filtering. No further check is performed to assert that.
*
* This function will return %-EPERM if any if an attached program was found
* and if it returned != 1 during execution. In all other cases, 0 is returned.
*/
int __cgroup_bpf_run_filter_sk(struct sock *sk,
enum bpf_attach_type type)
{
struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
int ret;
ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], sk, BPF_PROG_RUN);
return ret == 1 ? 0 : -EPERM;
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sk);
/**
* __cgroup_bpf_run_filter_sock_addr() - Run a program on a sock and
* provided by user sockaddr
* @sk: sock struct that will use sockaddr
* @uaddr: sockaddr struct provided by user
* @type: The type of program to be exectuted
* @t_ctx: Pointer to attach type specific context
*
* socket is expected to be of type INET or INET6.
*
* This function will return %-EPERM if an attached program is found and
* returned value != 1 during execution. In all other cases, 0 is returned.
*/
int __cgroup_bpf_run_filter_sock_addr(struct sock *sk,
struct sockaddr *uaddr,
enum bpf_attach_type type,
void *t_ctx)
{
struct bpf_sock_addr_kern ctx = {
.sk = sk,
.uaddr = uaddr,
.t_ctx = t_ctx,
};
struct sockaddr_storage unspec;
struct cgroup *cgrp;
int ret;
/* Check socket family since not all sockets represent network
* endpoint (e.g. AF_UNIX).
*/
if (sk->sk_family != AF_INET && sk->sk_family != AF_INET6)
return 0;
if (!ctx.uaddr) {
memset(&unspec, 0, sizeof(unspec));
ctx.uaddr = (struct sockaddr *)&unspec;
}
cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], &ctx, BPF_PROG_RUN);
return ret == 1 ? 0 : -EPERM;
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_addr);
/**
* __cgroup_bpf_run_filter_sock_ops() - Run a program on a sock
* @sk: socket to get cgroup from
* @sock_ops: bpf_sock_ops_kern struct to pass to program. Contains
* sk with connection information (IP addresses, etc.) May not contain
* cgroup info if it is a req sock.
* @type: The type of program to be exectuted
*
* socket passed is expected to be of type INET or INET6.
*
* The program type passed in via @type must be suitable for sock_ops
* filtering. No further check is performed to assert that.
*
* This function will return %-EPERM if any if an attached program was found
* and if it returned != 1 during execution. In all other cases, 0 is returned.
*/
int __cgroup_bpf_run_filter_sock_ops(struct sock *sk,
struct bpf_sock_ops_kern *sock_ops,
enum bpf_attach_type type)
{
struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
int ret;
ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], sock_ops,
BPF_PROG_RUN);
return ret == 1 ? 0 : -EPERM;
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_ops);
int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
short access, enum bpf_attach_type type)
{
struct cgroup *cgrp;
struct bpf_cgroup_dev_ctx ctx = {
.access_type = (access << 16) | dev_type,
.major = major,
.minor = minor,
};
int allow = 1;
rcu_read_lock();
cgrp = task_dfl_cgroup(current);
allow = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], &ctx,
BPF_PROG_RUN);
rcu_read_unlock();
return !allow;
}
EXPORT_SYMBOL(__cgroup_bpf_check_dev_permission);
static const struct bpf_func_proto *
cgroup_base_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
case BPF_FUNC_map_lookup_elem:
return &bpf_map_lookup_elem_proto;
case BPF_FUNC_map_update_elem:
return &bpf_map_update_elem_proto;
case BPF_FUNC_map_delete_elem:
return &bpf_map_delete_elem_proto;
case BPF_FUNC_get_current_uid_gid:
return &bpf_get_current_uid_gid_proto;
case BPF_FUNC_get_local_storage:
return &bpf_get_local_storage_proto;
case BPF_FUNC_get_current_cgroup_id:
return &bpf_get_current_cgroup_id_proto;
case BPF_FUNC_trace_printk:
if (capable(CAP_SYS_ADMIN))
return bpf_get_trace_printk_proto();
/* fall through */
default:
return NULL;
}
}
static const struct bpf_func_proto *
cgroup_dev_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
return cgroup_base_func_proto(func_id, prog);
}
static bool cgroup_dev_is_valid_access(int off, int size,
enum bpf_access_type type,
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)
{
const int size_default = sizeof(__u32);
if (type == BPF_WRITE)
return false;
if (off < 0 || off + size > sizeof(struct bpf_cgroup_dev_ctx))
return false;
/* The verifier guarantees that size > 0. */
if (off % size != 0)
return false;
switch (off) {
case bpf_ctx_range(struct bpf_cgroup_dev_ctx, access_type):
bpf_ctx_record_field_size(info, size_default);
if (!bpf_ctx_narrow_access_ok(off, size, size_default))
return false;
break;
default:
if (size != size_default)
return false;
}
return true;
}
const struct bpf_prog_ops cg_dev_prog_ops = {
};
const struct bpf_verifier_ops cg_dev_verifier_ops = {
.get_func_proto = cgroup_dev_func_proto,
.is_valid_access = cgroup_dev_is_valid_access,
};
/**
* __cgroup_bpf_run_filter_sysctl - Run a program on sysctl
*
* @head: sysctl table header
* @table: sysctl table
* @write: sysctl is being read (= 0) or written (= 1)
* @buf: pointer to buffer passed by user space
* @pcount: value-result argument: value is size of buffer pointed to by @buf,
* result is size of @new_buf if program set new value, initial value
* otherwise
* @new_buf: pointer to pointer to new buffer that will be allocated if program
* overrides new value provided by user space on sysctl write
* NOTE: it's caller responsibility to free *new_buf if it was set
* @type: type of program to be executed
*
* Program is run when sysctl is being accessed, either read or written, and
* can allow or deny such access.
*
* This function will return %-EPERM if an attached program is found and
* returned value != 1 during execution. In all other cases 0 is returned.
*/
int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
struct ctl_table *table, int write,
void __user *buf, size_t *pcount,
void **new_buf, enum bpf_attach_type type)
{
struct bpf_sysctl_kern ctx = {
.head = head,
.table = table,
.write = write,
.cur_val = NULL,
.cur_len = PAGE_SIZE,
.new_val = NULL,
.new_len = 0,
.new_updated = 0,
};
struct cgroup *cgrp;
int ret;
ctx.cur_val = kmalloc_track_caller(ctx.cur_len, GFP_KERNEL);
if (ctx.cur_val) {
mm_segment_t old_fs;
loff_t pos = 0;
old_fs = get_fs();
set_fs(KERNEL_DS);
if (table->proc_handler(table, 0, (void __user *)ctx.cur_val,
&ctx.cur_len, &pos)) {
/* Let BPF program decide how to proceed. */
ctx.cur_len = 0;
}
set_fs(old_fs);
} else {
/* Let BPF program decide how to proceed. */
ctx.cur_len = 0;
}
if (write && buf && *pcount) {
/* BPF program should be able to override new value with a
* buffer bigger than provided by user.
*/
ctx.new_val = kmalloc_track_caller(PAGE_SIZE, GFP_KERNEL);
ctx.new_len = min(PAGE_SIZE, *pcount);
if (!ctx.new_val ||
copy_from_user(ctx.new_val, buf, ctx.new_len))
/* Let BPF program decide how to proceed. */
ctx.new_len = 0;
}
rcu_read_lock();
cgrp = task_dfl_cgroup(current);
ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], &ctx, BPF_PROG_RUN);
rcu_read_unlock();
kfree(ctx.cur_val);
if (ret == 1 && ctx.new_updated) {
*new_buf = ctx.new_val;
*pcount = ctx.new_len;
} else {
kfree(ctx.new_val);
}
return ret == 1 ? 0 : -EPERM;
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sysctl);
static ssize_t sysctl_cpy_dir(const struct ctl_dir *dir, char **bufp,
size_t *lenp)
{
ssize_t tmp_ret = 0, ret;
if (dir->header.parent) {
tmp_ret = sysctl_cpy_dir(dir->header.parent, bufp, lenp);
if (tmp_ret < 0)
return tmp_ret;
}
ret = strscpy(*bufp, dir->header.ctl_table[0].procname, *lenp);
if (ret < 0)
return ret;
*bufp += ret;
*lenp -= ret;
ret += tmp_ret;
/* Avoid leading slash. */
if (!ret)
return ret;
tmp_ret = strscpy(*bufp, "/", *lenp);
if (tmp_ret < 0)
return tmp_ret;
*bufp += tmp_ret;
*lenp -= tmp_ret;
return ret + tmp_ret;
}
BPF_CALL_4(bpf_sysctl_get_name, struct bpf_sysctl_kern *, ctx, char *, buf,
size_t, buf_len, u64, flags)
{
ssize_t tmp_ret = 0, ret;
if (!buf)
return -EINVAL;
if (!(flags & BPF_F_SYSCTL_BASE_NAME)) {
if (!ctx->head)
return -EINVAL;
tmp_ret = sysctl_cpy_dir(ctx->head->parent, &buf, &buf_len);
if (tmp_ret < 0)
return tmp_ret;
}
ret = strscpy(buf, ctx->table->procname, buf_len);
return ret < 0 ? ret : tmp_ret + ret;
}
static const struct bpf_func_proto bpf_sysctl_get_name_proto = {
.func = bpf_sysctl_get_name,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_PTR_TO_MEM,
.arg3_type = ARG_CONST_SIZE,
.arg4_type = ARG_ANYTHING,
};
static int copy_sysctl_value(char *dst, size_t dst_len, char *src,
size_t src_len)
{
if (!dst)
return -EINVAL;
if (!dst_len)
return -E2BIG;
if (!src || !src_len) {
memset(dst, 0, dst_len);
return -EINVAL;
}
memcpy(dst, src, min(dst_len, src_len));
if (dst_len > src_len) {
memset(dst + src_len, '\0', dst_len - src_len);
return src_len;
}
dst[dst_len - 1] = '\0';
return -E2BIG;
}
BPF_CALL_3(bpf_sysctl_get_current_value, struct bpf_sysctl_kern *, ctx,
char *, buf, size_t, buf_len)
{
return copy_sysctl_value(buf, buf_len, ctx->cur_val, ctx->cur_len);
}
static const struct bpf_func_proto bpf_sysctl_get_current_value_proto = {
.func = bpf_sysctl_get_current_value,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_PTR_TO_UNINIT_MEM,
.arg3_type = ARG_CONST_SIZE,
};
BPF_CALL_3(bpf_sysctl_get_new_value, struct bpf_sysctl_kern *, ctx, char *, buf,
size_t, buf_len)
{
if (!ctx->write) {
if (buf && buf_len)
memset(buf, '\0', buf_len);
return -EINVAL;
}
return copy_sysctl_value(buf, buf_len, ctx->new_val, ctx->new_len);
}
static const struct bpf_func_proto bpf_sysctl_get_new_value_proto = {
.func = bpf_sysctl_get_new_value,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_PTR_TO_UNINIT_MEM,
.arg3_type = ARG_CONST_SIZE,
};
BPF_CALL_3(bpf_sysctl_set_new_value, struct bpf_sysctl_kern *, ctx,
const char *, buf, size_t, buf_len)
{
if (!ctx->write || !ctx->new_val || !ctx->new_len || !buf || !buf_len)
return -EINVAL;
if (buf_len > PAGE_SIZE - 1)
return -E2BIG;
memcpy(ctx->new_val, buf, buf_len);
ctx->new_len = buf_len;
ctx->new_updated = 1;
return 0;
}
static const struct bpf_func_proto bpf_sysctl_set_new_value_proto = {
.func = bpf_sysctl_set_new_value,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_PTR_TO_MEM,
.arg3_type = ARG_CONST_SIZE,
};
static const struct bpf_func_proto *
sysctl_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
case BPF_FUNC_sysctl_get_name:
return &bpf_sysctl_get_name_proto;
case BPF_FUNC_sysctl_get_current_value:
return &bpf_sysctl_get_current_value_proto;
case BPF_FUNC_sysctl_get_new_value:
return &bpf_sysctl_get_new_value_proto;
case BPF_FUNC_sysctl_set_new_value:
return &bpf_sysctl_set_new_value_proto;
default:
return cgroup_base_func_proto(func_id, prog);
}
}
static bool sysctl_is_valid_access(int off, int size, enum bpf_access_type type,
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)
{
const int size_default = sizeof(__u32);
if (off < 0 || off + size > sizeof(struct bpf_sysctl) ||
off % size || type != BPF_READ)
return false;
switch (off) {
case offsetof(struct bpf_sysctl, write):
bpf_ctx_record_field_size(info, size_default);
return bpf_ctx_narrow_access_ok(off, size, size_default);
default:
return false;
}
}
static u32 sysctl_convert_ctx_access(enum bpf_access_type type,
const struct bpf_insn *si,
struct bpf_insn *insn_buf,
struct bpf_prog *prog, u32 *target_size)
{
struct bpf_insn *insn = insn_buf;
switch (si->off) {
case offsetof(struct bpf_sysctl, write):
*insn++ = BPF_LDX_MEM(
BPF_SIZE(si->code), si->dst_reg, si->src_reg,
bpf_target_off(struct bpf_sysctl_kern, write,
FIELD_SIZEOF(struct bpf_sysctl_kern,
write),
target_size));
break;
}
return insn - insn_buf;
}
const struct bpf_verifier_ops cg_sysctl_verifier_ops = {
.get_func_proto = sysctl_func_proto,
.is_valid_access = sysctl_is_valid_access,
.convert_ctx_access = sysctl_convert_ctx_access,
};
const struct bpf_prog_ops cg_sysctl_prog_ops = {
};
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