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authorBrenden Blanco <bblanco@plumgrid.com>2016-07-19 12:16:56 -0700
committerDavid S. Miller <davem@davemloft.net>2016-07-19 21:46:33 -0700
commit4acf6c0b84c91243c705303cd9ff16421914150d (patch)
tree1fc015113abd682af506b436bb3788d1cc28a760 /kernel
parent9ecc2d86171adf23796133c89610987a14624875 (diff)
bpf: enable direct packet data write for xdp progs
For forwarding to be effective, XDP programs should be allowed to rewrite packet data. This requires that the drivers supporting XDP must all map the packet memory as TODEVICE or BIDIRECTIONAL before invoking the program. Signed-off-by: Brenden Blanco <bblanco@plumgrid.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/verifier.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a8d67d097b0d..f72f23b8fdab 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -653,6 +653,16 @@ static int check_map_access(struct verifier_env *env, u32 regno, int off,
#define MAX_PACKET_OFF 0xffff
+static bool may_write_pkt_data(enum bpf_prog_type type)
+{
+ switch (type) {
+ case BPF_PROG_TYPE_XDP:
+ return true;
+ default:
+ return false;
+ }
+}
+
static int check_packet_access(struct verifier_env *env, u32 regno, int off,
int size)
{
@@ -806,10 +816,15 @@ static int check_mem_access(struct verifier_env *env, u32 regno, int off,
err = check_stack_read(state, off, size, value_regno);
}
} else if (state->regs[regno].type == PTR_TO_PACKET) {
- if (t == BPF_WRITE) {
+ if (t == BPF_WRITE && !may_write_pkt_data(env->prog->type)) {
verbose("cannot write into packet\n");
return -EACCES;
}
+ if (t == BPF_WRITE && value_regno >= 0 &&
+ is_pointer_value(env, value_regno)) {
+ verbose("R%d leaks addr into packet\n", value_regno);
+ return -EACCES;
+ }
err = check_packet_access(env, regno, off, size);
if (!err && t == BPF_READ && value_regno >= 0)
mark_reg_unknown_value(state->regs, value_regno);