Commit b9989b59 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'Typeless/weak ksym for gen_loader + misc fixups' 

Kumar Kartikeya says:

====================

Patches (1,2,3,6) add typeless and weak ksym support to gen_loader. It is follow
up for the recent kfunc from modules series.

The later patches (7,8) are misc fixes for selftests, and patch 4 for libbpf
where we try to be careful to not end up with fds == 0, as libbpf assumes in
various places that they are greater than 0. Patch 5 fixes up missing O_CLOEXEC
in libbpf.

Changelog:
----------
v4 -> v5
v4: https://lore.kernel.org/bpf/20211020191526.2306852-1-memxor@gmail.com

 * Address feedback from Andrii
   * Drop use of ensure_good_fd in unneeded call sites
   * Add sys_bpf_fd
   * Add _lskel suffix to all light skeletons and change all current selftests
   * Drop early break in close loop for sk_lookup
   * Fix other nits

v3 -> v4
v3: https://lore.kernel.org/bpf/20211014205644.1837280-1-memxor@gmail.com

 * Remove gpl_only = true from bpf_kallsyms_lookup_name (Alexei)
 * Add bpf_dump_raw_ok check to ensure kptr_restrict isn't bypassed (Alexei)

v2 -> v3
v2: https://lore.kernel.org/bpf/20211013073348.1611155-1-memxor@gmail.com

 * Address feedback from Song
   * Move ksym logging to separate helper to avoid code duplication
   * Move src_reg mask stuff to separate helper
   * Fix various other nits, add acks
     * __builtin_expect is used instead of likely to as skel_internal.h is
       included in isolation.

v1 -> v2
v1: https://lore.kernel.org/bpf/20211006002853.308945-1-memxor@gmail.com



 * Remove redundant OOM checks in emit_bpf_kallsyms_lookup_name
 * Use designated initializer for sk_lookup fd array (Jakub)
 * Do fd check for all fd returning low level APIs (Andrii, Alexei)
 * Make Fixes: tag quote commit message, use selftests/bpf prefix (Song, Andrii)
 * Split typeless and weak ksym support into separate patches, expand commit
   message (Song)
 * Fix duplication in selftests stemming from use of LSKELS_EXTRA (Song)
====================

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents 2895f48f efadf2ad

include/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -2110,6 +2110,7 @@ extern const struct bpf_func_proto bpf_for_each_map_elem_proto; 
extern const struct bpf_func_proto bpf_btf_find_by_name_kind_proto;

extern const struct bpf_func_proto bpf_sk_setsockopt_proto;

extern const struct bpf_func_proto bpf_sk_getsockopt_proto;

extern const struct bpf_func_proto bpf_kallsyms_lookup_name_proto;



const struct bpf_func_proto *tracing_prog_func_proto(

  enum bpf_func_id func_id, const struct bpf_prog *prog);

include/uapi/linux/bpf.h

+16 −0
Original line number Diff line number Diff line
@@ -4923,6 +4923,21 @@ union bpf_attr { 
 *		Dynamically cast a *sk* pointer to a *unix_sock* pointer.

 *	Return

 *		*sk* if casting is valid, or **NULL** otherwise.

 *

 * long bpf_kallsyms_lookup_name(const char *name, int name_sz, int flags, u64 *res)

 *	Description

 *		Get the address of a kernel symbol, returned in *res*. *res* is

 *		set to 0 if the symbol is not found.

 *	Return

 *		On success, zero. On error, a negative value.

 *

 *		**-EINVAL** if *flags* is not zero.

 *

 *		**-EINVAL** if string *name* is not the same size as *name_sz*.

 *

 *		**-ENOENT** if symbol is not found.

 *

 *		**-EPERM** if caller does not have permission to obtain kernel address.

 */

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\
@@ -5104,6 +5119,7 @@ union bpf_attr { 
	FN(get_branch_snapshot),	\

	FN(trace_vprintk),		\

	FN(skc_to_unix_sock),		\

	FN(kallsyms_lookup_name),	\

	/* */



/* integer value in 'imm' field of BPF_CALL instruction selects which helper

kernel/bpf/syscall.c

+27 −0
Original line number Diff line number Diff line
@@ -4781,6 +4781,31 @@ static const struct bpf_func_proto bpf_sys_close_proto = { 
	.arg1_type	= ARG_ANYTHING,

};



BPF_CALL_4(bpf_kallsyms_lookup_name, const char *, name, int, name_sz, int, flags, u64 *, res)

{

	if (flags)

		return -EINVAL;



	if (name_sz <= 1 || name[name_sz - 1])

		return -EINVAL;



	if (!bpf_dump_raw_ok(current_cred()))

		return -EPERM;



	*res = kallsyms_lookup_name(name);

	return *res ? 0 : -ENOENT;

}



const struct bpf_func_proto bpf_kallsyms_lookup_name_proto = {

	.func		= bpf_kallsyms_lookup_name,

	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_PTR_TO_MEM,

	.arg2_type	= ARG_CONST_SIZE,

	.arg3_type	= ARG_ANYTHING,

	.arg4_type	= ARG_PTR_TO_LONG,

};



static const struct bpf_func_proto *

syscall_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)

{
@@ -4791,6 +4816,8 @@ syscall_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 
		return &bpf_btf_find_by_name_kind_proto;

	case BPF_FUNC_sys_close:

		return &bpf_sys_close_proto;

	case BPF_FUNC_kallsyms_lookup_name:

		return &bpf_kallsyms_lookup_name_proto;

	default:

		return tracing_prog_func_proto(func_id, prog);

	}

tools/include/uapi/linux/bpf.h

+16 −0
Original line number Diff line number Diff line
@@ -4923,6 +4923,21 @@ union bpf_attr { 
 *		Dynamically cast a *sk* pointer to a *unix_sock* pointer.

 *	Return

 *		*sk* if casting is valid, or **NULL** otherwise.

 *

 * long bpf_kallsyms_lookup_name(const char *name, int name_sz, int flags, u64 *res)

 *	Description

 *		Get the address of a kernel symbol, returned in *res*. *res* is

 *		set to 0 if the symbol is not found.

 *	Return

 *		On success, zero. On error, a negative value.

 *

 *		**-EINVAL** if *flags* is not zero.

 *

 *		**-EINVAL** if string *name* is not the same size as *name_sz*.

 *

 *		**-ENOENT** if symbol is not found.

 *

 *		**-EPERM** if caller does not have permission to obtain kernel address.

 */

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\
@@ -5104,6 +5119,7 @@ union bpf_attr { 
	FN(get_branch_snapshot),	\

	FN(trace_vprintk),		\

	FN(skc_to_unix_sock),		\

	FN(kallsyms_lookup_name),	\

	/* */



/* integer value in 'imm' field of BPF_CALL instruction selects which helper

tools/lib/bpf/bpf.c

+22 −13
Original line number Diff line number Diff line
@@ -65,13 +65,22 @@ static inline int sys_bpf(enum bpf_cmd cmd, union bpf_attr *attr, 
	return syscall(__NR_bpf, cmd, attr, size);

}



static inline int sys_bpf_fd(enum bpf_cmd cmd, union bpf_attr *attr,

			     unsigned int size)

{

	int fd;



	fd = sys_bpf(cmd, attr, size);

	return ensure_good_fd(fd);

}



static inline int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size)

{

	int retries = 5;

	int fd;



	do {

		fd = sys_bpf(BPF_PROG_LOAD, attr, size);

		fd = sys_bpf_fd(BPF_PROG_LOAD, attr, size);

	} while (fd < 0 && errno == EAGAIN && retries-- > 0);



	return fd;
@@ -104,7 +113,7 @@ int libbpf__bpf_create_map_xattr(const struct bpf_create_map_params *create_attr 
		attr.inner_map_fd = create_attr->inner_map_fd;

	attr.map_extra = create_attr->map_extra;



	fd = sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));

	fd = sys_bpf_fd(BPF_MAP_CREATE, &attr, sizeof(attr));

	return libbpf_err_errno(fd);

}
@@ -206,7 +215,7 @@ int bpf_create_map_in_map_node(enum bpf_map_type map_type, const char *name, 
		attr.numa_node = node;

	}



	fd = sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));

	fd = sys_bpf_fd(BPF_MAP_CREATE, &attr, sizeof(attr));

	return libbpf_err_errno(fd);

}
@@ -634,7 +643,7 @@ int bpf_obj_get(const char *pathname) 
	memset(&attr, 0, sizeof(attr));

	attr.pathname = ptr_to_u64((void *)pathname);



	fd = sys_bpf(BPF_OBJ_GET, &attr, sizeof(attr));

	fd = sys_bpf_fd(BPF_OBJ_GET, &attr, sizeof(attr));

	return libbpf_err_errno(fd);

}
@@ -745,7 +754,7 @@ int bpf_link_create(int prog_fd, int target_fd, 
		break;

	}

proceed:

	fd = sys_bpf(BPF_LINK_CREATE, &attr, sizeof(attr));

	fd = sys_bpf_fd(BPF_LINK_CREATE, &attr, sizeof(attr));

	return libbpf_err_errno(fd);

}
@@ -788,7 +797,7 @@ int bpf_iter_create(int link_fd) 
	memset(&attr, 0, sizeof(attr));

	attr.iter_create.link_fd = link_fd;



	fd = sys_bpf(BPF_ITER_CREATE, &attr, sizeof(attr));

	fd = sys_bpf_fd(BPF_ITER_CREATE, &attr, sizeof(attr));

	return libbpf_err_errno(fd);

}
@@ -946,7 +955,7 @@ int bpf_prog_get_fd_by_id(__u32 id) 
	memset(&attr, 0, sizeof(attr));

	attr.prog_id = id;



	fd = sys_bpf(BPF_PROG_GET_FD_BY_ID, &attr, sizeof(attr));

	fd = sys_bpf_fd(BPF_PROG_GET_FD_BY_ID, &attr, sizeof(attr));

	return libbpf_err_errno(fd);

}
@@ -958,7 +967,7 @@ int bpf_map_get_fd_by_id(__u32 id) 
	memset(&attr, 0, sizeof(attr));

	attr.map_id = id;



	fd = sys_bpf(BPF_MAP_GET_FD_BY_ID, &attr, sizeof(attr));

	fd = sys_bpf_fd(BPF_MAP_GET_FD_BY_ID, &attr, sizeof(attr));

	return libbpf_err_errno(fd);

}
@@ -970,7 +979,7 @@ int bpf_btf_get_fd_by_id(__u32 id) 
	memset(&attr, 0, sizeof(attr));

	attr.btf_id = id;



	fd = sys_bpf(BPF_BTF_GET_FD_BY_ID, &attr, sizeof(attr));

	fd = sys_bpf_fd(BPF_BTF_GET_FD_BY_ID, &attr, sizeof(attr));

	return libbpf_err_errno(fd);

}
@@ -982,7 +991,7 @@ int bpf_link_get_fd_by_id(__u32 id) 
	memset(&attr, 0, sizeof(attr));

	attr.link_id = id;



	fd = sys_bpf(BPF_LINK_GET_FD_BY_ID, &attr, sizeof(attr));

	fd = sys_bpf_fd(BPF_LINK_GET_FD_BY_ID, &attr, sizeof(attr));

	return libbpf_err_errno(fd);

}
@@ -1013,7 +1022,7 @@ int bpf_raw_tracepoint_open(const char *name, int prog_fd) 
	attr.raw_tracepoint.name = ptr_to_u64(name);

	attr.raw_tracepoint.prog_fd = prog_fd;



	fd = sys_bpf(BPF_RAW_TRACEPOINT_OPEN, &attr, sizeof(attr));

	fd = sys_bpf_fd(BPF_RAW_TRACEPOINT_OPEN, &attr, sizeof(attr));

	return libbpf_err_errno(fd);

}
@@ -1033,7 +1042,7 @@ int bpf_load_btf(const void *btf, __u32 btf_size, char *log_buf, __u32 log_buf_s 
		attr.btf_log_buf = ptr_to_u64(log_buf);

	}



	fd = sys_bpf(BPF_BTF_LOAD, &attr, sizeof(attr));

	fd = sys_bpf_fd(BPF_BTF_LOAD, &attr, sizeof(attr));



	if (fd < 0 && !do_log && log_buf && log_buf_size) {

		do_log = true;
@@ -1075,7 +1084,7 @@ int bpf_enable_stats(enum bpf_stats_type type) 
	memset(&attr, 0, sizeof(attr));

	attr.enable_stats.type = type;



	fd = sys_bpf(BPF_ENABLE_STATS, &attr, sizeof(attr));

	fd = sys_bpf_fd(BPF_ENABLE_STATS, &attr, sizeof(attr));

	return libbpf_err_errno(fd);

}