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wip: friday

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This commit is contained in:
Matthew LeVan 2024-01-19 16:46:09 -05:00
parent 0d5e8b86aa
commit f7fcffc429
2 changed files with 53 additions and 43 deletions
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16
rust/ares_guard/build.rs
View File

@ -37,17 +37,17 @@ fn main() {
.flag("-g3")
.flag("-Wall")
.flag("-Wextra")
.flag("-Wgnu-pointer-arith")
.flag("-Wpointer-arith")
.flag("-Wpedantic")
.flag("-Wformat=2")
.flag("-Wno-unused-parameter")
.flag("-Wmissing-include-dirs")
.flag("-Wnested-externs")
.flag("-Wold-style-definition")
.flag("-Wpedantic")
.flag("-Wredundant-decls")
.flag("-Wshadow")
.flag("-Wwrite-strings")
.flag("-Wold-style-definition")
.flag("-Wredundant-decls")
.flag("-Wnested-externs")
.flag("-Wmissing-include-dirs")
.flag("-Wno-unused-parameter")
.flag("-Wno-pointer-arith")
.flag("-Wno-strict-prototypes")
.try_compile("guard");
if let Err(err) = res {

80
rust/ares_guard/c-src/guard.c
View File

@ -7,7 +7,8 @@
#include "guard.h"
#define GD_PAGESZ 16384
#define GD_PAGEBITS 14ULL
#define GD_PAGESIZE (1ULL << GD_PAGEBITS) /* 16K */
static void *guard_p = NULL;
static void *stack_p = NULL;
@ -19,45 +20,60 @@ typedef enum {
guard_weird = 2, // strange state
guard_spent = 3, // out of memory (bail:meme)
guard_erupt = 4, // sigint
} guard_err_t;
} guard_error;
volatile sig_atomic_t guard_err = guard_sound;
guard_err_t _focus_guard(void *si_addr) {
// Center the guard page.
guard_error _focus_guard() {
// Check for strange situations.
if (stack_p == NULL || alloc_p == NULL || si_addr == NULL) {
if (stack_p == NULL || alloc_p == NULL) {
return guard_weird;
}
// Re-center the guard page if the fault address falls within it.
if (si_addr >= guard_p && si_addr < guard_p + GD_PAGESZ) {
// Unmark the old guard page.
void *old_guard_pg = guard_p;
if (mprotect(old_guard_pg, GD_PAGESZ, PROT_READ | PROT_WRITE) == -1) {
// Unmark the old guard page.
void *old_guard_p = guard_p;
if (mprotect(old_guard_p, GD_PAGESIZE, PROT_READ | PROT_WRITE) == -1) {
return guard_armor;
}
// Place the new guard page in the center.
if (stack_p > alloc_p) {
guard_p = stack_p - ((stack_p - alloc_p) / 2);
}
else if (stack_p < alloc_p) {
guard_p = stack_p + ((alloc_p - stack_p) / 2);
}
else {
return guard_weird;
}
guard_p = (void *)((uintptr_t)guard_p & ~(GD_PAGESIZE - 1));
// Mark the new guard page.
if (guard_p != old_guard_p) {
if (mprotect(guard_p, GD_PAGESIZE, PROT_NONE) == -1) {
return guard_armor;
}
// Place the new guard page in the center.
guard_p = stack_p + ((alloc_p - stack_p) / 2);
// TODO: Ensure the guard_p is page-aligned.
// guard_p = (void *)((uintptr_t)guard_p & ~(GD_PAGESZ - 1));
if (guard_p != old_guard_pg) {
if (mprotect(guard_p, GD_PAGESZ, PROT_NONE) == -1) {
return guard_armor;
}
} else {
return guard_spent;
}
} else {
return guard_spent;
}
return guard_sound;
}
guard_error _slash_guard(void *si_addr) {
if (si_addr >= guard_p && si_addr < guard_p + GD_PAGESIZE) {
return _focus_guard();
}
return guard_weird;
}
void _signal_handler(int sig, siginfo_t *si, void *unused) {
switch (sig) {
case SIGSEGV:
guard_err = _focus_guard(si->si_addr);
guard_err = _slash_guard(si->si_addr);
break;
case SIGINT:
guard_err = guard_erupt;
@ -67,37 +83,31 @@ void _signal_handler(int sig, siginfo_t *si, void *unused) {
}
}
guard_err_t _register_handler() {
guard_err_t err = guard_sound;
guard_error _register_handler() {
struct sigaction sa;
sa.sa_flags = SA_SIGINFO;
sa.sa_sigaction = _signal_handler;
sa.sa_mask = 0;
if (sigaction(SIGSEGV, &sa, NULL)) {
err = guard_weird;
if (sigaction(SIGSEGV, &sa, NULL) || sigaction(SIGINT, &sa, NULL)) {
return guard_weird;
}
return guard_err;
return guard_sound;
}
void guard(void *(*f)(void *), void *arg, void **stack, void **alloc, void **ret) {
guard_err_t err;
stack_p = *stack;
alloc_p = *alloc;
if (_register_handler() != guard_sound) {
err = guard_weird;
guard_err = guard_weird;
goto fail;
}
if (guard_p == NULL) {
guard_p = stack_p + ((alloc_p - stack_p) / 2);
if (mprotect(guard_p, GD_PAGESZ, PROT_NONE) == -1) {
err = guard_armor;
goto fail;
}
if (guard_p == NULL && (guard_err = _focus_guard()) != guard_sound) {
goto fail;
}
*ret = f(arg);