From: David Howells <[email protected]> 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 <[email protected]> Signed-off-by: David Howells <[email protected]> Signed-off-by: Matthew Garrett <[email protected]> Acked-by: Masami Hiramatsu <[email protected]> Reviewed-by: Kees Cook <[email protected]> Cc: Naveen N. Rao <[email protected]> Cc: Anil S Keshavamurthy <[email protected]> Cc: [email protected] Cc: Masami Hiramatsu <[email protected]> --- 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 f0cffd0977d3..987d8427f091 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -117,6 +117,7 @@ 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 7d736248a070..fcb28b0702b2 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 9c097240a3a6..ccb3e9a2a47c 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", }; -- 2.22.0.510.g264f2c817a-goog
