diff options
| author | Alexei Starovoitov <ast@kernel.org> | 2022-08-08 20:58:09 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2022-08-10 09:43:07 -0700 |
| commit | 86f44fcec22ce2979507742bc53db8400e454f46 (patch) | |
| tree | b583467f4aa9b030f49db5feab726942c681fb19 | |
| parent | aada476655461a9ab491d8298a415430cdd10278 (diff) | |
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 <zhuyifei@google.com>
Fixes: b1d18a7574d0 ("bpf: Extend sys_bpf commands for bpf_syscall programs.")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
| -rw-r--r-- | kernel/bpf/syscall.c | 20 | ||||
| -rw-r--r-- | tools/lib/bpf/skel_internal.h | 4 |
2 files changed, 16 insertions, 8 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 7dc3f8003631..a1cb0bdc5ad6 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -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, diff --git a/tools/lib/bpf/skel_internal.h b/tools/lib/bpf/skel_internal.h index bd6f4505e7b1..70adf7b119b9 100644 --- a/tools/lib/bpf/skel_internal.h +++ b/tools/lib/bpf/skel_internal.h @@ -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 |