On 25-Mär 18:49, Andrii Nakryiko wrote: > On Wed, Mar 25, 2020 at 8:27 AM KP Singh <kpsingh@xxxxxxxxxxxx> wrote: > > > > From: KP Singh <kpsingh@xxxxxxxxxx> > > > > JITed BPF programs are dynamically attached to the LSM hooks > > using BPF trampolines. The trampoline prologue generates code to handle > > conversion of the signature of the hook to the appropriate BPF context. > > > > The allocated trampoline programs are attached to the nop functions > > initialized as LSM hooks. > > > > BPF_PROG_TYPE_LSM programs must have a GPL compatible license and > > and need CAP_SYS_ADMIN (required for loading eBPF programs). > > > > Upon attachment: > > > > * A BPF fexit trampoline is used for LSM hooks with a void return type. > > * A BPF fmod_ret trampoline is used for LSM hooks which return an > > int. The attached programs can override the return value of the > > bpf LSM hook to indicate a MAC Policy decision. > > > > Signed-off-by: KP Singh <kpsingh@xxxxxxxxxx> > > Reviewed-by: Brendan Jackman <jackmanb@xxxxxxxxxx> > > Reviewed-by: Florent Revest <revest@xxxxxxxxxx> > > --- > > include/linux/bpf_lsm.h | 11 ++++++++ > > kernel/bpf/bpf_lsm.c | 28 +++++++++++++++++++++ > > kernel/bpf/btf.c | 9 ++++++- > > kernel/bpf/syscall.c | 56 ++++++++++++++++++++++++++++------------- > > kernel/bpf/trampoline.c | 17 ++++++++++--- > > kernel/bpf/verifier.c | 19 +++++++++++--- > > 6 files changed, 113 insertions(+), 27 deletions(-) > > > > [...] > > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > > index 85567a6ea5f9..3ba30fd6101e 100644 > > --- a/kernel/bpf/syscall.c > > +++ b/kernel/bpf/syscall.c > > @@ -25,6 +25,7 @@ > > #include <linux/nospec.h> > > #include <linux/audit.h> > > #include <uapi/linux/btf.h> > > +#include <linux/bpf_lsm.h> [...] > > - if (prog->expected_attach_type == BPF_TRACE_RAW_TP) > > + if (prog->expected_attach_type == BPF_TRACE_RAW_TP) { > > this should probably also ensure prog->type == BPF_PROG_TYPE_TRACING ? > Otherwise you can trick kernel with BPF_PROG_TYPE_LSM and > expected_attach_type == BPF_TRACE_RAW_TP, no? Indeed, fixed. Thanks! - KP > > > tp_name = prog->aux->attach_func_name; > > - else > > - return bpf_tracing_prog_attach(prog); > > - } else { > > + break; > > + } > > + return bpf_tracing_prog_attach(prog); > > + case BPF_PROG_TYPE_RAW_TRACEPOINT: > > + case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE: > > if (strncpy_from_user(buf, > > u64_to_user_ptr(attr->raw_tracepoint.name), > > sizeof(buf) - 1) < 0) { > > @@ -2479,6 +2495,10 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr) > > } > > [...]