core.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Linux Socket Filter - Kernel level socket filtering
 *
 * Based on the design of the Berkeley Packet Filter. The new
 * internal format has been designed by PLUMgrid:
 *
 *	Copyright (c) 2011 - 2014 PLUMgrid, http://plumgrid.com
 *
 * Authors:
 *
 *	Jay Schulist <jschlst@samba.org>
 *	Alexei Starovoitov <ast@plumgrid.com>
 *	Daniel Borkmann <dborkman@redhat.com>
 *
 * Andi Kleen - Fix a few bad bugs and races.
 * Kris Katterjohn - Added many additional checks in bpf_check_classic()
 */

#include <uapi/linux/btf.h>
#include <linux/filter.h>
#include <linux/skbuff.h>
#include <linux/static_call.h>
#include <linux/vmalloc.h>
#include <linux/prandom.h>
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/hex.h>
#include <linux/objtool.h>
#include <linux/overflow.h>
#include <linux/rbtree_latch.h>
#include <linux/kallsyms.h>
#include <linux/rcupdate.h>
#include <linux/perf_event.h>
#include <linux/extable.h>
#include <linux/log2.h>
#include <linux/bpf_verifier.h>
#include <linux/nodemask.h>
#include <linux/nospec.h>
#include <linux/bpf_mem_alloc.h>
#include <linux/memcontrol.h>
#include <linux/execmem.h>
#include <crypto/sha2.h>

#include <asm/barrier.h>
#include <linux/unaligned.h>

/* Registers */
#define BPF_R0	regs[BPF_REG_0]
#define BPF_R1	regs[BPF_REG_1]
#define BPF_R2	regs[BPF_REG_2]
#define BPF_R3	regs[BPF_REG_3]
#define BPF_R4	regs[BPF_REG_4]
#define BPF_R5	regs[BPF_REG_5]
#define BPF_R6	regs[BPF_REG_6]
#define BPF_R7	regs[BPF_REG_7]
#define BPF_R8	regs[BPF_REG_8]
#define BPF_R9	regs[BPF_REG_9]
#define BPF_R10	regs[BPF_REG_10]

/* Named registers */
#define DST	regs[insn->dst_reg]
#define SRC	regs[insn->src_reg]
#define FP	regs[BPF_REG_FP]
#define AX	regs[BPF_REG_AX]
#define ARG1	regs[BPF_REG_ARG1]
#define CTX	regs[BPF_REG_CTX]
#define OFF	insn->off
#define IMM	insn->imm

struct bpf_mem_alloc bpf_global_ma;
bool bpf_global_ma_set;

/* No hurry in this branch
 *
 * Exported for the bpf jit load helper.
 */
void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, unsigned int size)
{
	u8 *ptr = NULL;

	if (k >= SKF_NET_OFF) {
		ptr = skb_network_header(skb) + k - SKF_NET_OFF;
	} else if (k >= SKF_LL_OFF) {
		if (unlikely(!skb_mac_header_was_set(skb)))
			return NULL;
		ptr = skb_mac_header(skb) + k - SKF_LL_OFF;
	}
	if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb))
		return ptr;

	return NULL;
}

/* tell bpf programs that include vmlinux.h kernel's PAGE_SIZE */
enum page_size_enum {
	__PAGE_SIZE = PAGE_SIZE
};

struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flags)
{
	gfp_t gfp_flags = bpf_memcg_flags(GFP_KERNEL | __GFP_ZERO | gfp_extra_flags);
	struct bpf_prog_aux *aux;
	struct bpf_prog *fp;

	size = round_up(size, __PAGE_SIZE);
	fp = __vmalloc(size, gfp_flags);
	if (fp == NULL)
		return NULL;

	aux = kzalloc_obj(*aux, bpf_memcg_flags(GFP_KERNEL | gfp_extra_flags));
	if (aux == NULL) {
		vfree(fp);
		return NULL;
	}
	fp->active = __alloc_percpu_gfp(sizeof(u8[BPF_NR_CONTEXTS]), 4,
					bpf_memcg_flags(GFP_KERNEL | gfp_extra_flags));
	if (!fp->active) {
		vfree(fp);
		kfree(aux);
		return NULL;
	}

	fp->pages = size / PAGE_SIZE;
	fp->aux = aux;
	fp->aux->main_prog_aux = aux;
	fp->aux->prog = fp;
	fp->jit_requested = ebpf_jit_enabled();
	fp->jit_required = IS_ENABLED(CONFIG_BPF_JIT_ALWAYS_ON);
	fp->blinding_requested = bpf_jit_blinding_enabled(fp);
#ifdef CONFIG_CGROUP_BPF
	aux->cgroup_atype = CGROUP_BPF_ATTACH_TYPE_INVALID;
#endif

	INIT_LIST_HEAD_RCU(&fp->aux->ksym.lnode);
#ifdef CONFIG_FINEIBT
	INIT_LIST_HEAD_RCU(&fp->aux->ksym_prefix.lnode);
#endif
	mutex_init(&fp->aux->used_maps_mutex);
	mutex_init(&fp->aux->ext_mutex);
	mutex_init(&fp->aux->dst_mutex);
	mutex_init(&fp->aux->st_ops_assoc_mutex);

#ifdef CONFIG_BPF_SYSCALL
	bpf_prog_stream_init(fp);
#endif

	return fp;
}

struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags)
{
	gfp_t gfp_flags = bpf_memcg_flags(GFP_KERNEL | __GFP_ZERO | gfp_extra_flags);
	struct bpf_prog *prog;
	int cpu;

	prog = bpf_prog_alloc_no_stats(size, gfp_extra_flags);
	if (!prog)
		return NULL;

	prog->stats = alloc_percpu_gfp(struct bpf_prog_stats, gfp_flags);
	if (!prog->stats) {
		free_percpu(prog->active);
		kfree(prog->aux);
		vfree(prog);
		return NULL;
	}

	for_each_possible_cpu(cpu) {
		struct bpf_prog_stats *pstats;

		pstats = per_cpu_ptr(prog->stats, cpu);
		u64_stats_init(&pstats->syncp);
	}
	return prog;
}
EXPORT_SYMBOL_GPL(bpf_prog_alloc);

int bpf_prog_alloc_jited_linfo(struct bpf_prog *prog)
{
	if (!prog->aux->nr_linfo || !prog->jit_requested)
		return 0;

	prog->aux->jited_linfo = kvzalloc_objs(*prog->aux->jited_linfo,
					       prog->aux->nr_linfo,
					       bpf_memcg_flags(GFP_KERNEL | __GFP_NOWARN));
	if (!prog->aux->jited_linfo)
		return -ENOMEM;

	return 0;
}

void bpf_prog_jit_attempt_done(struct bpf_prog *prog)
{
	if (prog->aux->jited_linfo &&
	    (!prog->jited || !prog->aux->jited_linfo[0])) {
		kvfree(prog->aux->jited_linfo);
		prog->aux->jited_linfo = NULL;
	}

	kfree(prog->aux->kfunc_tab);
	prog->aux->kfunc_tab = NULL;
}

/* The jit engine is responsible to provide an array
 * for insn_off to the jited_off mapping (insn_to_jit_off).
 *
 * The idx to this array is the insn_off.  Hence, the insn_off
 * here is relative to the prog itself instead of the main prog.
 * This array has one entry for each xlated bpf insn.
 *
 * jited_off is the byte off to the end of the jited insn.
 *
 * Hence, with
 * insn_start:
 *      The first bpf insn off of the prog.  The insn off
 *      here is relative to the main prog.
 *      e.g. if prog is a subprog, insn_start > 0
 * linfo_idx:
 *      The prog's idx to prog->aux->linfo and jited_linfo
 *
 * jited_linfo[linfo_idx] = prog->bpf_func
 *
 * For i > linfo_idx,
 *
 * jited_linfo[i] = prog->bpf_func +
 *	insn_to_jit_off[linfo[i].insn_off - insn_start - 1]
 */
void bpf_prog_fill_jited_linfo(struct bpf_prog *prog,
			       const u32 *insn_to_jit_off)
{
	u32 linfo_idx, insn_start, insn_end, nr_linfo, i;
	const struct bpf_line_info *linfo;
	void **jited_linfo;

	if (!prog->aux->jited_linfo || prog->aux->func_idx > prog->aux->func_cnt)
		/* Userspace did not provide linfo */
		return;

	linfo_idx = prog->aux->linfo_idx;
	linfo = &prog->aux->linfo[linfo_idx];
	insn_start = linfo[0].insn_off;
	insn_end = insn_start + prog->len;

	jited_linfo = &prog->aux->jited_linfo[linfo_idx];
	jited_linfo[0] = prog->bpf_func;

	nr_linfo = prog->aux->nr_linfo - linfo_idx;

	for (i = 1; i < nr_linfo && linfo[i].insn_off < insn_end; i++)
		/* The verifier ensures that linfo[i].insn_off is
		 * strictly increasing
		 */
		jited_linfo[i] = prog->bpf_func +
			insn_to_jit_off[linfo[i].insn_off - insn_start - 1];
}

struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size,
				  gfp_t gfp_extra_flags)
{
	gfp_t gfp_flags = bpf_memcg_flags(GFP_KERNEL | __GFP_ZERO | gfp_extra_flags);
	struct bpf_prog *fp;
	u32 pages;

	size = round_up(size, PAGE_SIZE);
	pages = size / PAGE_SIZE;
	if (pages <= fp_old->pages)
		return fp_old;

	fp = __vmalloc(size, gfp_flags);
	if (fp) {
		memcpy(fp, fp_old, fp_old->pages * PAGE_SIZE);
		fp->pages = pages;
		fp->aux->prog = fp;

		/* We keep fp->aux from fp_old around in the new
		 * reallocated structure.
		 */
		fp_old->aux = NULL;
		fp_old->stats = NULL;
		fp_old->active = NULL;
		__bpf_prog_free(fp_old);
	}

	return fp;
}

void __bpf_prog_free(struct bpf_prog *fp)
{
	if (fp->aux) {
		mutex_destroy(&fp->aux->used_maps_mutex);
		mutex_destroy(&fp->aux->dst_mutex);
		mutex_destroy(&fp->aux->st_ops_assoc_mutex);
		kfree(fp->aux->poke_tab);
		kfree(fp->aux);
	}
	free_percpu(fp->stats);
	free_percpu(fp->active);
	vfree(fp);
}

int bpf_prog_calc_tag(struct bpf_prog *fp)
{
	size_t size = bpf_prog_insn_size(fp);
	struct bpf_insn *dst;
	bool was_ld_map;
	u32 i;

	dst = __vmalloc(size, GFP_KERNEL_ACCOUNT);
	if (!dst)
		return -ENOMEM;

	/* We need to take out the map fd for the digest calculation
	 * since they are unstable from user space side.
	 */
	for (i = 0, was_ld_map = false; i < fp->len; i++) {
		dst[i] = fp->insnsi[i];
		if (!was_ld_map &&
		    dst[i].code == (BPF_LD | BPF_IMM | BPF_DW) &&
		    (dst[i].src_reg == BPF_PSEUDO_MAP_FD ||
		     dst[i].src_reg == BPF_PSEUDO_MAP_VALUE)) {
			was_ld_map = true;
			dst[i].imm = 0;
		} else if (was_ld_map &&
			   dst[i].code == 0 &&
			   dst[i].dst_reg == 0 &&
			   dst[i].src_reg == 0 &&
			   dst[i].off == 0) {
			was_ld_map = false;
			dst[i].imm = 0;
		} else {
			was_ld_map = false;
		}
	}
	sha256((u8 *)dst, size, fp->digest);
	vfree(dst);
	return 0;
}

static int bpf_adj_delta_to_imm(struct bpf_insn *insn, u32 pos, s32 end_old,
				s32 end_new, s32 curr, const bool probe_pass)
{
	const s64 imm_min = S32_MIN, imm_max = S32_MAX;
	s32 delta = end_new - end_old;
	s64 imm = insn->imm;

	if (curr < pos && curr + imm + 1 >= end_old)
		imm += delta;
	else if (curr >= end_new && curr + imm + 1 < end_new)
		imm -= delta;
	if (imm < imm_min || imm > imm_max)
		return -ERANGE;
	if (!probe_pass)
		insn->imm = imm;
	return 0;
}

static int bpf_adj_delta_to_off(struct bpf_insn *insn, u32 pos, s32 end_old,
				s32 end_new, s32 curr, const bool probe_pass)
{
	s64 off_min, off_max, off;
	s32 delta = end_new - end_old;

	if (insn->code == (BPF_JMP32 | BPF_JA)) {
		off = insn->imm;
		off_min = S32_MIN;
		off_max = S32_MAX;
	} else {
		off = insn->off;
		off_min = S16_MIN;
		off_max = S16_MAX;
	}

	if (curr < pos && curr + off + 1 >= end_old)
		off += delta;
	else if (curr >= end_new && curr + off + 1 < end_new)
		off -= delta;
	if (off < off_min || off > off_max)
		return -ERANGE;
	if (!probe_pass) {
		if (insn->code == (BPF_JMP32 | BPF_JA))
			insn->imm = off;
		else
			insn->off = off;
	}
	return 0;
}

static int bpf_adj_branches(struct bpf_prog *prog, u32 pos, s32 end_old,
			    s32 end_new, const bool probe_pass)
{
	u32 i, insn_cnt = prog->len + (probe_pass ? end_new - end_old : 0);
	struct bpf_insn *insn = prog->insnsi;
	int ret = 0;

	for (i = 0; i < insn_cnt; i++, insn++) {
		u8 code;

		/* In the probing pass we still operate on the original,
		 * unpatched image in order to check overflows before we
		 * do any other adjustments. Therefore skip the patchlet.
		 */
		if (probe_pass && i == pos) {
			i = end_new;
			insn = prog->insnsi + end_old;
		}
		if (bpf_pseudo_func(insn)) {
			ret = bpf_adj_delta_to_imm(insn, pos, end_old,
						   end_new, i, probe_pass);
			if (ret)
				return ret;
			continue;
		}
		code = insn->code;
		if ((BPF_CLASS(code) != BPF_JMP &&
		     BPF_CLASS(code) != BPF_JMP32) ||
		    BPF_OP(code) == BPF_EXIT)
			continue;
		/* Adjust offset of jmps if we cross patch boundaries. */
		if (BPF_OP(code) == BPF_CALL) {
			if (insn->src_reg != BPF_PSEUDO_CALL)
				continue;
			ret = bpf_adj_delta_to_imm(insn, pos, end_old,
						   end_new, i, probe_pass);
		} else {
			ret = bpf_adj_delta_to_off(insn, pos, end_old,
						   end_new, i, probe_pass);
		}
		if (ret)
			break;
	}

	return ret;
}

static void bpf_adj_linfo(struct bpf_prog *prog, u32 off, u32 delta)
{
	struct bpf_line_info *linfo;
	u32 i, nr_linfo;

	nr_linfo = prog->aux->nr_linfo;
	if (!nr_linfo || !delta)
		return;

	linfo = prog->aux->linfo;

	for (i = 0; i < nr_linfo; i++)
		if (off < linfo[i].insn_off)
			break;

	/* Push all off < linfo[i].insn_off by delta */
	for (; i < nr_linfo; i++)
		linfo[i].insn_off += delta;
}

struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
				       const struct bpf_insn *patch, u32 len)
{
	u32 insn_adj_cnt, insn_rest, insn_delta = len - 1;
	const u32 cnt_max = S16_MAX;
	struct bpf_prog *prog_adj;
	int err;

	/* Since our patchlet doesn't expand the image, we're done. */
	if (insn_delta == 0) {
		memcpy(prog->insnsi + off, patch, sizeof(*patch));
		return prog;
	}

	insn_adj_cnt = prog->len + insn_delta;

	/* Reject anything that would potentially let the insn->off
	 * target overflow when we have excessive program expansions.
	 * We need to probe here before we do any reallocation where
	 * we afterwards may not fail anymore.
	 */
	if (insn_adj_cnt > cnt_max &&
	    (err = bpf_adj_branches(prog, off, off + 1, off + len, true)))
		return ERR_PTR(err);

	/* Several new instructions need to be inserted. Make room
	 * for them. Likely, there's no need for a new allocation as
	 * last page could have large enough tailroom.
	 */
	prog_adj = bpf_prog_realloc(prog, bpf_prog_size(insn_adj_cnt),
				    GFP_USER);
	if (!prog_adj)
		return ERR_PTR(-ENOMEM);

	prog_adj->len = insn_adj_cnt;

	/* Patching happens in 3 steps:
	 *
	 * 1) Move over tail of insnsi from next instruction onwards,
	 *    so we can patch the single target insn with one or more
	 *    new ones (patching is always from 1 to n insns, n > 0).
	 * 2) Inject new instructions at the target location.
	 * 3) Adjust branch offsets if necessary.
	 */
	insn_rest = insn_adj_cnt - off - len;

	memmove(prog_adj->insnsi + off + len, prog_adj->insnsi + off + 1,
		sizeof(*patch) * insn_rest);
	memcpy(prog_adj->insnsi + off, patch, sizeof(*patch) * len);

	/* We are guaranteed to not fail at this point, otherwise
	 * the ship has sailed to reverse to the original state. An
	 * overflow cannot happen at this point.
	 */
	BUG_ON(bpf_adj_branches(prog_adj, off, off + 1, off + len, false));

	bpf_adj_linfo(prog_adj, off, insn_delta);

	return prog_adj;
}

int bpf_remove_insns(struct bpf_prog *prog, u32 off, u32 cnt)
{
	int err;

	/* Branch offsets can't overflow when program is shrinking, no need
	 * to call bpf_adj_branches(..., true) here
	 */
	memmove(prog->insnsi + off, prog->insnsi + off + cnt,
		sizeof(struct bpf_insn) * (prog->len - off - cnt));
	prog->len -= cnt;

	err = bpf_adj_branches(prog, off, off + cnt, off, false);
	WARN_ON_ONCE(err);
	return err;
}

static void bpf_prog_kallsyms_del_subprogs(struct bpf_prog *fp)
{
	int i;

	for (i = 0; i < fp->aux->real_func_cnt; i++)
		bpf_prog_kallsyms_del(fp->aux->func[i]);
}

void bpf_prog_kallsyms_del_all(struct bpf_prog *fp)
{
	bpf_prog_kallsyms_del_subprogs(fp);
	bpf_prog_kallsyms_del(fp);
}

#ifdef CONFIG_BPF_JIT
/* All BPF JIT sysctl knobs here. */
int bpf_jit_enable   __read_mostly = IS_BUILTIN(CONFIG_BPF_JIT_DEFAULT_ON);
int bpf_jit_kallsyms __read_mostly = IS_BUILTIN(CONFIG_BPF_JIT_DEFAULT_ON);
int bpf_jit_harden   __read_mostly;
long bpf_jit_limit   __read_mostly;
long bpf_jit_limit_max __read_mostly;

static void
bpf_prog_ksym_set_addr(struct bpf_prog *prog)
{
	WARN_ON_ONCE(!bpf_prog_ebpf_jited(prog));

	prog->aux->ksym.start = (unsigned long) prog->bpf_func;
	prog->aux->ksym.end   = prog->aux->ksym.start + prog->jited_len;
}

static void
bpf_prog_ksym_set_name(struct bpf_prog *prog)
{
	char *sym = prog->aux->ksym.name;
	const char *end = sym + KSYM_NAME_LEN;
	const struct btf_type *type;
	const char *func_name;

	BUILD_BUG_ON(sizeof("bpf_prog_") +
		     sizeof(prog->tag) * 2 +
		     /* name has been null terminated.
		      * We should need +1 for the '_' preceding
		      * the name.  However, the null character
		      * is double counted between the name and the
		      * sizeof("bpf_prog_") above, so we omit
		      * the +1 here.
		      */
		     sizeof(prog->aux->name) > KSYM_NAME_LEN);

	sym += snprintf(sym, KSYM_NAME_LEN, "bpf_prog_");
	sym  = bin2hex(sym, prog->tag, sizeof(prog->tag));

	/* prog->aux->name will be ignored if full btf name is available */
	if (prog->aux->func_info_cnt && prog->aux->func_idx < prog->aux->func_info_cnt) {
		type = btf_type_by_id(prog->aux->btf,
				      prog->aux->func_info[prog->aux->func_idx].type_id);
		func_name = btf_name_by_offset(prog->aux->btf, type->name_off);
		snprintf(sym, (size_t)(end - sym), "_%s", func_name);
		return;
	}

	if (prog->aux->name[0])
		snprintf(sym, (size_t)(end - sym), "_%s", prog->aux->name);
	else
		*sym = 0;
}

static unsigned long bpf_get_ksym_start(struct latch_tree_node *n)
{
	return container_of(n, struct bpf_ksym, tnode)->start;
}

static __always_inline bool bpf_tree_less(struct latch_tree_node *a,
					  struct latch_tree_node *b)
{
	return bpf_get_ksym_start(a) < bpf_get_ksym_start(b);
}

static __always_inline int bpf_tree_comp(void *key, struct latch_tree_node *n)
{
	unsigned long val = (unsigned long)key;
	const struct bpf_ksym *ksym;

	ksym = container_of(n, struct bpf_ksym, tnode);

	if (val < ksym->start)
		return -1;
	/* Ensure that we detect return addresses as part of the program, when
	 * the final instruction is a call for a program part of the stack
	 * trace. Therefore, do val > ksym->end instead of val >= ksym->end.
	 */
	if (val > ksym->end)
		return  1;

	return 0;
}

static const struct latch_tree_ops bpf_tree_ops = {
	.less	= bpf_tree_less,
	.comp	= bpf_tree_comp,
};

static DEFINE_SPINLOCK(bpf_lock);
static LIST_HEAD(bpf_kallsyms);
static struct latch_tree_root bpf_tree __cacheline_aligned;

void bpf_ksym_add(struct bpf_ksym *ksym)
{
	spin_lock_bh(&bpf_lock);
	WARN_ON_ONCE(!list_empty(&ksym->lnode));
	list_add_tail_rcu(&ksym->lnode, &bpf_kallsyms);
	latch_tree_insert(&ksym->tnode, &bpf_tree, &bpf_tree_ops);
	spin_unlock_bh(&bpf_lock);
}

static void __bpf_ksym_del(struct bpf_ksym *ksym)
{
	if (list_empty(&ksym->lnode))
		return;

	latch_tree_erase(&ksym->tnode, &bpf_tree, &bpf_tree_ops);
	list_del_rcu(&ksym->lnode);
}

void bpf_ksym_del(struct bpf_ksym *ksym)
{
	spin_lock_bh(&bpf_lock);
	__bpf_ksym_del(ksym);
	spin_unlock_bh(&bpf_lock);
}

static bool bpf_prog_kallsyms_candidate(const struct bpf_prog *fp)
{
	return fp->jited && !bpf_prog_was_classic(fp);
}

void bpf_prog_kallsyms_add(struct bpf_prog *fp)
{
	if (!bpf_prog_kallsyms_candidate(fp) ||
	    !bpf_token_capable(fp->aux->token, CAP_BPF))
		return;

	bpf_prog_ksym_set_addr(fp);
	bpf_prog_ksym_set_name(fp);
	fp->aux->ksym.prog = true;

	bpf_ksym_add(&fp->aux->ksym);

#ifdef CONFIG_FINEIBT
	/*
	 * When FineIBT, code in the __cfi_foo() symbols can get executed
	 * and hence unwinder needs help.
	 */
	if (cfi_mode != CFI_FINEIBT)
		return;

	snprintf(fp->aux->ksym_prefix.name, KSYM_NAME_LEN,
		 "__cfi_%s", fp->aux->ksym.name);

	fp->aux->ksym_prefix.start = (unsigned long) fp->bpf_func - 16;
	fp->aux->ksym_prefix.end   = (unsigned long) fp->bpf_func;

	bpf_ksym_add(&fp->aux->ksym_prefix);
#endif
}

void bpf_prog_kallsyms_del(struct bpf_prog *fp)
{
	if (!bpf_prog_kallsyms_candidate(fp))
		return;

	bpf_ksym_del(&fp->aux->ksym);
#ifdef CONFIG_FINEIBT
	if (cfi_mode != CFI_FINEIBT)
		return;
	bpf_ksym_del(&fp->aux->ksym_prefix);
#endif
}

static struct bpf_ksym *bpf_ksym_find(unsigned long addr)
{
	struct latch_tree_node *n;

	n = latch_tree_find((void *)addr, &bpf_tree, &bpf_tree_ops);
	return n ? container_of(n, struct bpf_ksym, tnode) : NULL;
}

int bpf_address_lookup(unsigned long addr, unsigned long *size,
		       unsigned long *off, char *sym)
{
	struct bpf_ksym *ksym;
	int ret = 0;

	rcu_read_lock();
	ksym = bpf_ksym_find(addr);
	if (ksym) {
		unsigned long symbol_start = ksym->start;
		unsigned long symbol_end = ksym->end;

		ret = strscpy(sym, ksym->name, KSYM_NAME_LEN);

		if (size)
			*size = symbol_end - symbol_start;
		if (off)
			*off  = addr - symbol_start;
	}
	rcu_read_unlock();

	return ret;
}

bool is_bpf_text_address(unsigned long addr)
{
	bool ret;

	rcu_read_lock();
	ret = bpf_ksym_find(addr) != NULL;
	rcu_read_unlock();

	return ret;
}

struct bpf_prog *bpf_prog_ksym_find(unsigned long addr)
{
	struct bpf_ksym *ksym;

	WARN_ON_ONCE(!rcu_read_lock_held());
	ksym = bpf_ksym_find(addr);

	return ksym && ksym->prog ?
	       container_of(ksym, struct bpf_prog_aux, ksym)->prog :
	       NULL;
}

bool bpf_has_frame_pointer(unsigned long ip)
{
	struct bpf_ksym *ksym;
	unsigned long offset;

	guard(rcu)();

	ksym = bpf_ksym_find(ip);
	if (!ksym || !ksym->fp_start || !ksym->fp_end)
		return false;

	offset = ip - ksym->start;

	return offset >= ksym->fp_start && offset < ksym->fp_end;
}

const struct exception_table_entry *search_bpf_extables(unsigned long addr)
{
	const struct exception_table_entry *e = NULL;
	struct bpf_prog *prog;

	rcu_read_lock();
	prog = bpf_prog_ksym_find(addr);
	if (!prog)
		goto out;
	if (!prog->aux->num_exentries)
		goto out;

	e = search_extable(prog->aux->extable, prog->aux->num_exentries, addr);
out:
	rcu_read_unlock();
	return e;
}

int bpf_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
		    char *sym)
{
	struct bpf_ksym *ksym;
	unsigned int it = 0;
	int ret = -ERANGE;

	if (!bpf_jit_kallsyms_enabled())
		return ret;

	rcu_read_lock();
	list_for_each_entry_rcu(ksym, &bpf_kallsyms, lnode) {
		if (it++ != symnum)
			continue;

		strscpy(sym, ksym->name, KSYM_NAME_LEN);

		*value = ksym->start;
		*type  = BPF_SYM_ELF_TYPE;

		ret = 0;
		break;
	}
	rcu_read_unlock();

	return ret;
}

int bpf_jit_add_poke_descriptor(struct bpf_prog *prog,
				struct bpf_jit_poke_descriptor *poke)
{
	struct bpf_jit_poke_descriptor *tab = prog->aux->poke_tab;
	static const u32 poke_tab_max = 1024;
	u32 slot = prog->aux->size_poke_tab;
	u32 size = slot + 1;

	if (size > poke_tab_max)
		return -ENOSPC;
	if (poke->tailcall_target || poke->tailcall_target_stable ||
	    poke->tailcall_bypass || poke->adj_off || poke->bypass_addr)
		return -EINVAL;

	switch (poke->reason) {
	case BPF_POKE_REASON_TAIL_CALL:
		if (!poke->tail_call.map)
			return -EINVAL;
		break;
	default:
		return -EINVAL;
	}

	tab = krealloc_array(tab, size, sizeof(*poke), GFP_KERNEL);
	if (!tab)
		return -ENOMEM;

	memcpy(&tab[slot], poke, sizeof(*poke));
	prog->aux->size_poke_tab = size;
	prog->aux->poke_tab = tab;

	return slot;
}

/*
 * BPF program pack allocator.
 *
 * Most BPF programs are pretty small. Allocating a hole page for each
 * program is sometime a waste. Many small bpf program also adds pressure
 * to instruction TLB. To solve this issue, we introduce a BPF program pack
 * allocator. The prog_pack allocator uses HPAGE_PMD_SIZE page (2MB on x86)
 * to host BPF programs.
 */
#define BPF_PROG_CHUNK_SHIFT	6
#define BPF_PROG_CHUNK_SIZE	(1 << BPF_PROG_CHUNK_SHIFT)
#define BPF_PROG_CHUNK_MASK	(~(BPF_PROG_CHUNK_SIZE - 1))

struct bpf_prog_pack {
	struct list_head list;
	void *ptr;
	bool arch_flush_needed;
	unsigned long bitmap[];
};

void bpf_jit_fill_hole_with_zero(void *area, unsigned int size)
{
	memset(area, 0, size);
}

DEFINE_STATIC_CALL_NULL(bpf_arch_pred_flush, bpf_arch_pred_flush);

/*
 * Enabled once bpf_arch_pred_flush points at a real flush routine. Lets the
 * pack allocator test "is a predictor flush wired up at all" with a cheap
 * static branch instead of repeatedly querying the static call target.
 */
DEFINE_STATIC_KEY_FALSE(bpf_pred_flush_enabled);

#define BPF_PROG_SIZE_TO_NBITS(size)	(round_up(size, BPF_PROG_CHUNK_SIZE) / BPF_PROG_CHUNK_SIZE)

static DEFINE_MUTEX(pack_mutex);
static LIST_HEAD(pack_list);

/* PMD_SIZE is not available in some special config, e.g. ARCH=arm with
 * CONFIG_MMU=n. Use PAGE_SIZE in these cases.
 */
#ifdef PMD_SIZE
/* PMD_SIZE is really big for some archs. It doesn't make sense to
 * reserve too much memory in one allocation. Hardcode BPF_PROG_PACK_SIZE to
 * 2MiB * num_possible_nodes(). On most architectures PMD_SIZE will be
 * greater than or equal to 2MB.
 */
#define BPF_PROG_PACK_SIZE (SZ_2M * num_possible_nodes())
#else
#define BPF_PROG_PACK_SIZE PAGE_SIZE
#endif

#define BPF_PROG_CHUNK_COUNT (BPF_PROG_PACK_SIZE / BPF_PROG_CHUNK_SIZE)

static bool bpf_jit_mem_is_rox(void)
{
	return execmem_is_rox(EXECMEM_BPF);
}

static struct bpf_prog_pack *alloc_new_pack(bpf_jit_fill_hole_t bpf_fill_ill_insns)
{
	struct bpf_prog_pack *pack;
	int err;

	pack = kzalloc_flex(*pack, bitmap, BITS_TO_LONGS(BPF_PROG_CHUNK_COUNT));
	if (!pack)
		return NULL;
	pack->ptr = bpf_jit_alloc_exec(BPF_PROG_PACK_SIZE);
	if (!pack->ptr)
		goto out;
	bitmap_zero(pack->bitmap, BPF_PROG_PACK_SIZE / BPF_PROG_CHUNK_SIZE);

	if (static_branch_unlikely(&bpf_pred_flush_enabled))
		pack->arch_flush_needed = true;
	if (!bpf_jit_mem_is_rox()) {
		bpf_fill_ill_insns(pack->ptr, BPF_PROG_PACK_SIZE);
		set_vm_flush_reset_perms(pack->ptr);
		err = set_memory_rox((unsigned long)pack->ptr,
				     BPF_PROG_PACK_SIZE / PAGE_SIZE);
		if (err)
			goto out;
	}
	list_add_tail(&pack->list, &pack_list);
	return pack;

out:
	bpf_jit_free_exec(pack->ptr);
	kfree(pack);
	return NULL;
}

void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns, bool was_classic)
{
	unsigned int nbits = BPF_PROG_SIZE_TO_NBITS(size);
	struct bpf_prog_pack *pack, *fallback_pack = NULL;
	unsigned long pos, fallback_pos = 0;
	void *ptr = NULL;

	mutex_lock(&pack_mutex);
	if (size > BPF_PROG_PACK_SIZE) {
		/*
		 * Allocations larger than a pack get their own pages, and
		 * predictors are not flushed for such allocation. This is only
		 * safe because cBPF programs (the unprivileged attack surface)
		 * are bounded well below a pack size.
		 */
		if (was_classic && static_branch_unlikely(&bpf_pred_flush_enabled))
			pr_warn_once("BPF: Predictors not flushed for allocations greater than BPF_PROG_PACK_SIZE\n");
		size = round_up(size, PAGE_SIZE);
		ptr = bpf_jit_alloc_exec(size);
		if (ptr && !bpf_jit_mem_is_rox()) {
			int err;

			bpf_fill_ill_insns(ptr, size);
			set_vm_flush_reset_perms(ptr);
			err = set_memory_rox((unsigned long)ptr,
					     size / PAGE_SIZE);
			if (err) {
				bpf_jit_free_exec(ptr);
				ptr = NULL;
			}
		}
		goto out;
	}
	list_for_each_entry(pack, &pack_list, list) {
		pos = bitmap_find_next_zero_area(pack->bitmap, BPF_PROG_CHUNK_COUNT, 0,
						 nbits, 0);
		if (pos >= BPF_PROG_CHUNK_COUNT)
			continue;
		/* Flush not enabled, use any pack */
		if (!static_branch_unlikely(&bpf_pred_flush_enabled))
			goto found_free_area;
		/*
		 * cBPF reuse of a dirty pack triggers a flush, so prefer a
		 * clean pack for cBPF. eBPF never flushes, so steer it to a
		 * dirty pack and keep clean packs free for cBPF.