seccomp: Invalidate seccomp mode to catch death failures
commit 495ac3069a6235bfdf516812a2a9b256671bbdf9 upstream.
If seccomp tries to kill a process, it should never see that process
again. To enforce this proactively, switch the mode to something
impossible. If encountered: WARN, reject all syscalls, and attempt to
kill the process again even harder.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will Drewry <wad@chromium.org>
Fixes: 8112c4f140
("seccomp: remove 2-phase API")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
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@ -28,6 +28,9 @@
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#include <linux/syscalls.h>
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#include <linux/syscalls.h>
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#include <linux/sysctl.h>
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#include <linux/sysctl.h>
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/* Not exposed in headers: strictly internal use only. */
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#define SECCOMP_MODE_DEAD (SECCOMP_MODE_FILTER + 1)
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#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
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#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
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#include <asm/syscall.h>
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#include <asm/syscall.h>
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#endif
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#endif
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@ -706,6 +709,7 @@ static void __secure_computing_strict(int this_syscall)
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#ifdef SECCOMP_DEBUG
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#ifdef SECCOMP_DEBUG
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dump_stack();
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dump_stack();
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#endif
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#endif
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current->seccomp.mode = SECCOMP_MODE_DEAD;
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seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
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seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
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do_exit(SIGKILL);
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do_exit(SIGKILL);
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}
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}
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@ -892,6 +896,7 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
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case SECCOMP_RET_KILL_THREAD:
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case SECCOMP_RET_KILL_THREAD:
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case SECCOMP_RET_KILL_PROCESS:
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case SECCOMP_RET_KILL_PROCESS:
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default:
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default:
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current->seccomp.mode = SECCOMP_MODE_DEAD;
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seccomp_log(this_syscall, SIGSYS, action, true);
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seccomp_log(this_syscall, SIGSYS, action, true);
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/* Dump core only if this is the last remaining thread. */
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/* Dump core only if this is the last remaining thread. */
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if (action == SECCOMP_RET_KILL_PROCESS ||
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if (action == SECCOMP_RET_KILL_PROCESS ||
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@ -944,6 +949,11 @@ int __secure_computing(const struct seccomp_data *sd)
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return 0;
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return 0;
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case SECCOMP_MODE_FILTER:
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case SECCOMP_MODE_FILTER:
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return __seccomp_filter(this_syscall, sd, false);
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return __seccomp_filter(this_syscall, sd, false);
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/* Surviving SECCOMP_RET_KILL_* must be proactively impossible. */
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case SECCOMP_MODE_DEAD:
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WARN_ON_ONCE(1);
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do_exit(SIGKILL);
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return -1;
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default:
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default:
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BUG();
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BUG();
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}
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}
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