Commit 86f44fce authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

bpf: Disallow bpf programs call prog_run command. 



The verifier cannot perform sufficient validation of bpf_attr->test.ctx_in
pointer, therefore bpf programs should not be allowed to call BPF_PROG_RUN
command from within the program.
To fix this issue split bpf_sys_bpf() bpf helper into normal kern_sys_bpf()
kernel function that can only be used by the kernel light skeleton directly.

Reported-by: default avatarYiFei Zhu <zhuyifei@google.com>
Fixes: b1d18a75 ("bpf: Extend sys_bpf commands for bpf_syscall programs.")
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent aada4766

kernel/bpf/syscall.c

+14 −6
Original line number Diff line number Diff line
@@ -5071,9 +5071,6 @@ static bool syscall_prog_is_valid_access(int off, int size, 


BPF_CALL_3(bpf_sys_bpf, int, cmd, union bpf_attr *, attr, u32, attr_size)

{

	struct bpf_prog * __maybe_unused prog;

	struct bpf_tramp_run_ctx __maybe_unused run_ctx;



	switch (cmd) {

	case BPF_MAP_CREATE:

	case BPF_MAP_UPDATE_ELEM:
@@ -5083,6 +5080,18 @@ BPF_CALL_3(bpf_sys_bpf, int, cmd, union bpf_attr *, attr, u32, attr_size) 
	case BPF_LINK_CREATE:

	case BPF_RAW_TRACEPOINT_OPEN:

		break;

	default:

		return -EINVAL;

	}

	return __sys_bpf(cmd, KERNEL_BPFPTR(attr), attr_size);

}



int kern_sys_bpf(int cmd, union bpf_attr *attr, unsigned int size)

{

	struct bpf_prog * __maybe_unused prog;

	struct bpf_tramp_run_ctx __maybe_unused run_ctx;



	switch (cmd) {

#ifdef CONFIG_BPF_JIT /* __bpf_prog_enter_sleepable used by trampoline and JIT */

	case BPF_PROG_TEST_RUN:

		if (attr->test.data_in || attr->test.data_out ||
@@ -5113,11 +5122,10 @@ BPF_CALL_3(bpf_sys_bpf, int, cmd, union bpf_attr *, attr, u32, attr_size) 
		return 0;

#endif

	default:

		return -EINVAL;

		return ____bpf_sys_bpf(cmd, attr, size);

	}

	return __sys_bpf(cmd, KERNEL_BPFPTR(attr), attr_size);

}

EXPORT_SYMBOL(bpf_sys_bpf);

EXPORT_SYMBOL(kern_sys_bpf);



static const struct bpf_func_proto bpf_sys_bpf_proto = {

	.func		= bpf_sys_bpf,

tools/lib/bpf/skel_internal.h

+2 −2
Original line number Diff line number Diff line
@@ -66,13 +66,13 @@ struct bpf_load_and_run_opts { 
	const char *errstr;

};



long bpf_sys_bpf(__u32 cmd, void *attr, __u32 attr_size);

long kern_sys_bpf(__u32 cmd, void *attr, __u32 attr_size);



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

			  unsigned int size)

{

#ifdef __KERNEL__

	return bpf_sys_bpf(cmd, attr, size);

	return kern_sys_bpf(cmd, attr, size);

#else

	return syscall(__NR_bpf, cmd, attr, size);

#endif