diff options
Diffstat (limited to 'debian/patches/libffi-pax.diff')
| -rw-r--r-- | debian/patches/libffi-pax.diff | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/debian/patches/libffi-pax.diff b/debian/patches/libffi-pax.diff new file mode 100644 index 0000000..e8666f8 --- /dev/null +++ b/debian/patches/libffi-pax.diff @@ -0,0 +1,161 @@ +From 757876336c183f5b20b6620d674cc9817fd0d280 Mon Sep 17 00:00:00 2001 +From: =?UTF-8?q?Stefan=20B=C3=BChler?= <buehler@cert.uni-stuttgart.de> +Date: Wed, 7 Sep 2016 15:50:54 +0200 +Subject: [PATCH 2/2] always check for PaX MPROTECT on linux, make EMUTRAMP + experimental + +- ffi_prep_closure_loc doesn't necessarily generate trampolines recognized by + PaX EMUTRAMP handler; there is no way to check before, and it isn't working +on x86-64 right now -> experimental +- if MPROTECT is enabled use the same workaround as is used for SELinux (double + mmap()) +--- + configure.ac | 11 +++++++--- + src/closures.c | 68 +++++++++++++++++++++++++++++++++++++++------------------- + 2 files changed, 54 insertions(+), 25 deletions(-) + +--- a/src/libffi/configure.ac ++++ b/src/libffi/configure.ac +@@ -177,12 +177,17 @@ + ;; + esac + +-# On PaX enable kernels that have MPROTECT enable we can't use PROT_EXEC. ++# On PaX enable kernels that have MPROTECT enable we can't use PROT_EXEC; ++# if EMUTRAMP is active too ffi could try mapping without PROT_EXEC, ++# but the kernel needs to recognize the trampoline generated by ffi. ++# Otherwise fallback to double mmap trick. + AC_ARG_ENABLE(pax_emutramp, +- [ --enable-pax_emutramp enable pax emulated trampolines, for we can't use PROT_EXEC], ++ [ --enable-pax_emutramp enable pax emulated trampolines (experimental)], + if test "$enable_pax_emutramp" = "yes"; then ++ AC_MSG_WARN([EMUTRAMP is experimental only. Use --enable-pax_emutramp=experimental to enforce.]) ++ elif test "$enable_pax_emutramp" = "experimental"; then + AC_DEFINE(FFI_MMAP_EXEC_EMUTRAMP_PAX, 1, +- [Define this if you want to enable pax emulated trampolines]) ++ [Define this if you want to enable pax emulated trampolines (experimental)]) + fi) + + FFI_EXEC_TRAMPOLINE_TABLE=0 +--- a/src/libffi/src/closures.c ++++ b/src/libffi/src/closures.c +@@ -53,14 +53,18 @@ + # endif + #endif + +-#if FFI_MMAP_EXEC_WRIT && !defined FFI_MMAP_EXEC_SELINUX +-# ifdef __linux__ ++#if FFI_MMAP_EXEC_WRIT && defined __linux__ ++# if !defined FFI_MMAP_EXEC_SELINUX + /* When defined to 1 check for SELinux and if SELinux is active, + don't attempt PROT_EXEC|PROT_WRITE mapping at all, as that + might cause audit messages. */ + # define FFI_MMAP_EXEC_SELINUX 1 +-# endif +-#endif ++# endif /* !defined FFI_MMAP_EXEC_SELINUX */ ++# if !defined FFI_MMAP_PAX ++/* Also check for PaX MPROTECT */ ++# define FFI_MMAP_PAX 1 ++# endif /* !defined FFI_MMAP_PAX */ ++#endif /* FFI_MMAP_EXEC_WRIT && defined __linux__ */ + + #if FFI_CLOSURES + +@@ -172,14 +176,18 @@ + + #endif /* !FFI_MMAP_EXEC_SELINUX */ + +-/* On PaX enable kernels that have MPROTECT enable we can't use PROT_EXEC. */ +-#ifdef FFI_MMAP_EXEC_EMUTRAMP_PAX ++/* On PaX enable kernels that have MPROTECT enabled we can't use PROT_EXEC. */ ++#if defined FFI_MMAP_PAX + #include <stdlib.h> + +-static int emutramp_enabled = -1; ++enum { ++ PAX_MPROTECT = (1 << 0), ++ PAX_EMUTRAMP = (1 << 1), ++}; ++static int cached_pax_flags = -1; + + static int +-emutramp_enabled_check (void) ++pax_flags_check (void) + { + char *buf = NULL; + size_t len = 0; +@@ -193,9 +201,10 @@ + while (getline (&buf, &len, f) != -1) + if (!strncmp (buf, "PaX:", 4)) + { +- char emutramp; +- if (sscanf (buf, "%*s %*c%c", &emutramp) == 1) +- ret = (emutramp == 'E'); ++ if (NULL != strchr (buf + 4, 'M')) ++ ret |= PAX_MPROTECT; ++ if (NULL != strchr (buf + 4, 'E')) ++ ret |= PAX_EMUTRAMP; + break; + } + free (buf); +@@ -203,9 +212,13 @@ + return ret; + } + +-#define is_emutramp_enabled() (emutramp_enabled >= 0 ? emutramp_enabled \ +- : (emutramp_enabled = emutramp_enabled_check ())) +-#endif /* FFI_MMAP_EXEC_EMUTRAMP_PAX */ ++#define get_pax_flags() (cached_pax_flags >= 0 ? cached_pax_flags \ ++ : (cached_pax_flags = pax_flags_check ())) ++#define has_pax_flags(flags) ((flags) == ((flags) & get_pax_flags ())) ++#define is_mprotect_enabled() (has_pax_flags (PAX_MPROTECT)) ++#define is_emutramp_enabled() (has_pax_flags (PAX_EMUTRAMP)) ++ ++#endif /* defined FFI_MMAP_PAX */ + + #elif defined (__CYGWIN__) || defined(__INTERIX) + +@@ -216,9 +229,10 @@ + + #endif /* !defined(X86_WIN32) && !defined(X86_WIN64) */ + +-#ifndef FFI_MMAP_EXEC_EMUTRAMP_PAX +-#define is_emutramp_enabled() 0 +-#endif /* FFI_MMAP_EXEC_EMUTRAMP_PAX */ ++#if !defined FFI_MMAP_PAX ++# define is_mprotect_enabled() 0 ++# define is_emutramp_enabled() 0 ++#endif /* !defined FFI_MMAP_PAX */ + + /* Declare all functions defined in dlmalloc.c as static. */ + static void *dlmalloc(size_t); +@@ -525,13 +539,23 @@ + printf ("mapping in %zi\n", length); + #endif + +- if (execfd == -1 && is_emutramp_enabled ()) ++ /* -1 != execfd hints that we already decided to use dlmmap_locked ++ last time. */ ++ if (execfd == -1 && is_mprotect_enabled ()) + { +- ptr = mmap (start, length, prot & ~PROT_EXEC, flags, fd, offset); +- return ptr; ++#ifdef FFI_MMAP_EXEC_EMUTRAMP_PAX ++ if (is_emutramp_enabled ()) ++ { ++ /* emutramp requires the kernel recognizing the trampoline pattern ++ generated by ffi_prep_closure_loc; there is no way to test ++ in advance whether this will work, so this is experimental. */ ++ ptr = mmap (start, length, prot & ~PROT_EXEC, flags, fd, offset); ++ return ptr; ++ } ++#endif ++ /* fallback to dlmmap_locked. */ + } +- +- if (execfd == -1 && !is_selinux_enabled ()) ++ else if (execfd == -1 && !is_selinux_enabled ()) + { + ptr = mmap (start, length, prot | PROT_EXEC, flags, fd, offset); + |