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| author | Kees Cook <keescook@chromium.org> | 2016-06-01 19:29:15 -0700 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2016-06-14 10:54:41 -0700 |
| commit | ce6526e8afa4b6ad0ab134a4cc50c9c863319637 (patch) | |
| tree | c3074e4661ee9432faf518fd2eef8527c5811730 | |
| parent | 8112c4f140fa03f9ee68aad2cc79afa7df5418d3 (diff) | |
| download | linux-ce6526e8afa4b6ad0ab134a4cc50c9c863319637.tar.gz linux-ce6526e8afa4b6ad0ab134a4cc50c9c863319637.tar.bz2 linux-ce6526e8afa4b6ad0ab134a4cc50c9c863319637.zip | |
seccomp: recheck the syscall after RET_TRACE
When RET_TRACE triggers, a tracer may change a syscall into something that
should be filtered by seccomp. This re-runs seccomp after a trace event
to make sure things continue to pass.
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@kernel.org>
| -rw-r--r-- | kernel/seccomp.c | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 14a37d71b612..54d15eb2b701 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -556,7 +556,8 @@ void secure_computing_strict(int this_syscall) #else #ifdef CONFIG_SECCOMP_FILTER -static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd) +static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, + const bool recheck_after_trace) { u32 filter_ret, action; int data; @@ -588,6 +589,10 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd) goto skip; case SECCOMP_RET_TRACE: + /* We've been put in this state by the ptracer already. */ + if (recheck_after_trace) + return 0; + /* ENOSYS these calls if there is no tracer attached. */ if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) { syscall_set_return_value(current, @@ -611,6 +616,15 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd) if (this_syscall < 0) goto skip; + /* + * Recheck the syscall, since it may have changed. This + * intentionally uses a NULL struct seccomp_data to force + * a reload of all registers. This does not goto skip since + * a skip would have already been reported. + */ + if (__seccomp_filter(this_syscall, NULL, true)) + return -1; + return 0; case SECCOMP_RET_ALLOW: @@ -629,7 +643,8 @@ skip: return -1; } #else -static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd) +static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, + const bool recheck_after_trace) { BUG(); } @@ -652,7 +667,7 @@ int __secure_computing(const struct seccomp_data *sd) __secure_computing_strict(this_syscall); /* may call do_exit */ return 0; case SECCOMP_MODE_FILTER: - return __seccomp_filter(this_syscall, sd); + return __seccomp_filter(this_syscall, sd, false); default: BUG(); } |