CVE-2022-2785: git/bpf/bpf.git - BPF kernel tree

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: YiFei Zhu [email protected] Fixes: b1d18a7574d0 (“bpf: Extend sys_bpf commands for bpf_syscall programs.”) Signed-off-by: Alexei Starovoitov [email protected]

@@ -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,

@@ -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