bpf: Introduce bpf_sysctl_get_name helper (808649fb) · Commits · 戴 / test

include/uapi/linux/bpf.h

+21 −1

Original line number	Diff line number	Diff line
		@@ -2506,6 +2506,22 @@ union bpf_attr {
		* Return
		* 0 if iph and th are a valid SYN cookie ACK, or a negative error
		* otherwise.
		*
		* int bpf_sysctl_get_name(struct bpf_sysctl ctx, char buf, size_t buf_len, u64 flags)
		* Description
		* Get name of sysctl in /proc/sys/ and copy it into provided by
		* program buffer buf of size buf_len.
		*
		* The buffer is always NUL terminated, unless it's zero-sized.
		*
		* If flags is zero, full name (e.g. "net/ipv4/tcp_mem") is
		* copied. Use BPF_F_SYSCTL_BASE_NAME flag to copy base name
		* only (e.g. "tcp_mem").
		* Return
		* Number of character copied (not including the trailing NUL).
		*
		* -E2BIG if the buffer wasn't big enough (buf will contain
		* truncated name in this case).
		*/
		#define __BPF_FUNC_MAPPER(FN) \
		FN(unspec), \
		@@ -2608,7 +2624,8 @@ union bpf_attr {
		FN(skb_ecn_set_ce), \
		FN(get_listener_sock), \
		FN(skc_lookup_tcp), \
		FN(tcp_check_syncookie),
		FN(tcp_check_syncookie), \
		FN(sysctl_get_name),

		/* integer value in 'imm' field of BPF_CALL instruction selects which helper
		* function eBPF program intends to call
		@@ -2681,6 +2698,9 @@ enum bpf_func_id {
		BPF_ADJ_ROOM_ENCAP_L2_MASK) \
		<< BPF_ADJ_ROOM_ENCAP_L2_SHIFT)

		/* BPF_FUNC_sysctl_get_name flags. */
		#define BPF_F_SYSCTL_BASE_NAME (1ULL << 0)

		/* Mode for BPF_FUNC_skb_adjust_room helper. */
		enum bpf_adj_room_mode {
		BPF_ADJ_ROOM_NET,

kernel/bpf/cgroup.c

+69 −1

Original line number	Diff line number	Diff line
		@@ -14,6 +14,7 @@
		#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>
		@@ -806,11 +807,78 @@ int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
		}
		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 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;
		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,

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