| Message ID | 20190622000358.19895-23-matthewgarrett@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Lockdown as an LSM | expand |
On Fri, Jun 21, 2019 at 05:03:51PM -0700, Matthew Garrett wrote: > From: David Howells <dhowells@redhat.com> > > Disallow the creation of perf and ftrace kprobes when the kernel is > locked down in confidentiality mode by preventing their registration. > This prevents kprobes from being used to access kernel memory to steal > crypto data, but continues to allow the use of kprobes from signed > modules. > > Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> > Signed-off-by: David Howells <dhowells@redhat.com> > Signed-off-by: Matthew Garrett <mjg59@google.com> > Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com> > Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> > Cc: davem@davemloft.net > Cc: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> -Kees > --- > include/linux/security.h | 1 + > kernel/trace/trace_kprobe.c | 5 +++++ > security/lockdown/lockdown.c | 1 + > 3 files changed, 7 insertions(+) > > diff --git a/include/linux/security.h b/include/linux/security.h > index 3875f6df2ecc..e6e3e2403474 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -96,6 +96,7 @@ enum lockdown_reason { > LOCKDOWN_MMIOTRACE, > LOCKDOWN_INTEGRITY_MAX, > LOCKDOWN_KCORE, > + LOCKDOWN_KPROBES, > LOCKDOWN_CONFIDENTIALITY_MAX, > }; > > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > index 5d5129b05df7..5a76a0f79d48 100644 > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -11,6 +11,7 @@ > #include <linux/uaccess.h> > #include <linux/rculist.h> > #include <linux/error-injection.h> > +#include <linux/security.h> > > #include "trace_dynevent.h" > #include "trace_kprobe_selftest.h" > @@ -415,6 +416,10 @@ static int __register_trace_kprobe(struct trace_kprobe *tk) > { > int i, ret; > > + ret = security_locked_down(LOCKDOWN_KPROBES); > + if (ret) > + return ret; > + > if (trace_probe_is_registered(&tk->tp)) > return -EINVAL; > > diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c > index 4c9b324dfc55..5a08c17f224d 100644 > --- a/security/lockdown/lockdown.c > +++ b/security/lockdown/lockdown.c > @@ -32,6 +32,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { > [LOCKDOWN_MMIOTRACE] = "unsafe mmio", > [LOCKDOWN_INTEGRITY_MAX] = "integrity", > [LOCKDOWN_KCORE] = "/proc/kcore access", > + [LOCKDOWN_KPROBES] = "use of kprobes", > [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", > }; > > -- > 2.22.0.410.gd8fdbe21b5-goog >
On Fri, 21 Jun 2019 17:03:51 -0700 Matthew Garrett <matthewgarrett@google.com> wrote: > From: David Howells <dhowells@redhat.com> > > Disallow the creation of perf and ftrace kprobes when the kernel is > locked down in confidentiality mode by preventing their registration. > This prevents kprobes from being used to access kernel memory to steal > crypto data, but continues to allow the use of kprobes from signed > modules. Looks (and sounds) good to me. Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Thank you, > > Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> > Signed-off-by: David Howells <dhowells@redhat.com> > Signed-off-by: Matthew Garrett <mjg59@google.com> > Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com> > Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> > Cc: davem@davemloft.net > Cc: Masami Hiramatsu <mhiramat@kernel.org> > --- > include/linux/security.h | 1 + > kernel/trace/trace_kprobe.c | 5 +++++ > security/lockdown/lockdown.c | 1 + > 3 files changed, 7 insertions(+) > > diff --git a/include/linux/security.h b/include/linux/security.h > index 3875f6df2ecc..e6e3e2403474 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -96,6 +96,7 @@ enum lockdown_reason { > LOCKDOWN_MMIOTRACE, > LOCKDOWN_INTEGRITY_MAX, > LOCKDOWN_KCORE, > + LOCKDOWN_KPROBES, > LOCKDOWN_CONFIDENTIALITY_MAX, > }; > > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > index 5d5129b05df7..5a76a0f79d48 100644 > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -11,6 +11,7 @@ > #include <linux/uaccess.h> > #include <linux/rculist.h> > #include <linux/error-injection.h> > +#include <linux/security.h> > > #include "trace_dynevent.h" > #include "trace_kprobe_selftest.h" > @@ -415,6 +416,10 @@ static int __register_trace_kprobe(struct trace_kprobe *tk) > { > int i, ret; > > + ret = security_locked_down(LOCKDOWN_KPROBES); > + if (ret) > + return ret; > + > if (trace_probe_is_registered(&tk->tp)) > return -EINVAL; > > diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c > index 4c9b324dfc55..5a08c17f224d 100644 > --- a/security/lockdown/lockdown.c > +++ b/security/lockdown/lockdown.c > @@ -32,6 +32,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { > [LOCKDOWN_MMIOTRACE] = "unsafe mmio", > [LOCKDOWN_INTEGRITY_MAX] = "integrity", > [LOCKDOWN_KCORE] = "/proc/kcore access", > + [LOCKDOWN_KPROBES] = "use of kprobes", > [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", > }; > > -- > 2.22.0.410.gd8fdbe21b5-goog >
diff --git a/include/linux/security.h b/include/linux/security.h index 3875f6df2ecc..e6e3e2403474 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -96,6 +96,7 @@ enum lockdown_reason { LOCKDOWN_MMIOTRACE, LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_KCORE, + LOCKDOWN_KPROBES, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 5d5129b05df7..5a76a0f79d48 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -11,6 +11,7 @@ #include <linux/uaccess.h> #include <linux/rculist.h> #include <linux/error-injection.h> +#include <linux/security.h> #include "trace_dynevent.h" #include "trace_kprobe_selftest.h" @@ -415,6 +416,10 @@ static int __register_trace_kprobe(struct trace_kprobe *tk) { int i, ret; + ret = security_locked_down(LOCKDOWN_KPROBES); + if (ret) + return ret; + if (trace_probe_is_registered(&tk->tp)) return -EINVAL; diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index 4c9b324dfc55..5a08c17f224d 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -32,6 +32,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { [LOCKDOWN_MMIOTRACE] = "unsafe mmio", [LOCKDOWN_INTEGRITY_MAX] = "integrity", [LOCKDOWN_KCORE] = "/proc/kcore access", + [LOCKDOWN_KPROBES] = "use of kprobes", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", };