to not copy untrusted data into untainted memory, as downstream taint-checks
would be avoided.
- Internally we currently use malloc for nontainted pools, and mmap for tainted
- pools. The disparity is for speed of testing the taintedness of pointers;
- because Linux appears to use distinct non-overlapping address allocations for
- mmap vs. everything else, which means only two pointer-compares suffice for the
- test. Other OS' cannot use that optimisation, and a more lengthy test against
- the limits of tainted-pool allcations has to be done.
-
Intermediate layers (eg. the string functions) can test for taint, and use this
for ensurinng that results have proper state. For example the
string_vformat_trc() routing supporting the string_sprintf() interface will
static void *next_yield[NPOOLS];
static int yield_length[NPOOLS] = { -1, -1, -1, -1, -1, -1 };
-/* The limits of the tainted pools. Tracking these on new allocations enables
-a fast is_tainted implementation. We assume the kernel only allocates mmaps using
-one side or the other of data+heap, not both. */
-
-void * tainted_base = (void *)-1;
-void * tainted_top = (void *)0;
-
/* pool_malloc holds the amount of memory used by the store pools; this goes up
and down as store is reset or released. nonpool_malloc is the total got by
malloc from other calls; this doesn't go down because it is just freed by
#endif
-static void * store_mmap(int, const char *, int);
static void * internal_store_malloc(int, const char *, int);
-static void internal_untainted_free(void *, const char *, int linenumber);
-static void internal_tainted_free(storeblock *, const char *, int linenumber);
+static void internal_store_free(void *, const char *, int linenumber);
/******************************************************************************/
msg, func, line);
}
-static void
-use_slow_taint_check(const uschar * why)
-{
-#ifndef COMPILE_UTILITY
-DEBUG(D_any)
- debug_printf("switching to slow-mode taint checking (after %s) "
- "taint bounds %p %p\n", why, tainted_base, tainted_top);
-#endif
-f.taint_check_slow = TRUE;
-}
-
-/* If the creation of a new tainted region results in any of the
-untainted regions appearing to be tainted, using the fast-mode test,
-we need to switch to safe-but-slow mode. */
-
-static void
-verify_all_untainted(void)
-{
-for (int pool = 0; pool < POOL_TAINT_BASE; pool++)
- for (storeblock * b = chainbase[pool]; b; b = b->next)
- {
- uschar * bc = US b + ALIGNED_SIZEOF_STOREBLOCK;
- if (is_tainted(bc))
- {
- use_slow_taint_check(US"mmap");
- return;
- }
- }
-}
-
/*************************************************
{
/* Give up on this block, because it's too small */
nblocks[pool]--;
- if (pool < POOL_TAINT_BASE)
- internal_untainted_free(newblock, func, linenumber);
- else
- internal_tainted_free(newblock, func, linenumber);
+ internal_store_free(newblock, func, linenumber);
newblock = NULL;
}
if (++nblocks[pool] > maxblocks[pool])
maxblocks[pool] = nblocks[pool];
- newblock = tainted
- ? store_mmap(mlength, func, linenumber)
- : internal_store_malloc(mlength, func, linenumber);
+ newblock = internal_store_malloc(mlength, func, linenumber);
newblock->next = NULL;
newblock->length = length;
nbytes[pool] -= siz;
pool_malloc -= siz;
nblocks[pool]--;
- if (pool < POOL_TAINT_BASE)
- internal_untainted_free(b, func, linenumber);
- else
- internal_tainted_free(b, func, linenumber);
+ internal_store_free(b, func, linenumber);
}
/* Cut out the debugging stuff for utilities, but stop picky compilers from
-/******************************************************************************/
-static void *
-store_alloc_tail(void * yield, int size, const char * func, int line,
- const uschar * type)
-{
-if ((nonpool_malloc += size) > max_nonpool_malloc)
- max_nonpool_malloc = nonpool_malloc;
-
-/* Cut out the debugging stuff for utilities, but stop picky compilers from
-giving warnings. */
-
-#ifdef COMPILE_UTILITY
-func = func; line = line; type = type;
-#else
-
-/* If running in test harness, spend time making sure all the new store
-is not filled with zeros so as to catch problems. */
-
-if (f.running_in_test_harness)
- memset(yield, 0xF0, (size_t)size);
-DEBUG(D_memory) debug_printf("--%6s %6p %5d bytes\t%-14s %4d\tpool %5d nonpool %5d\n",
- type, yield, size, func, line, pool_malloc, nonpool_malloc);
-#endif /* COMPILE_UTILITY */
-
-return yield;
-}
-
-/*************************************************
-* Mmap store *
-*************************************************/
-
-static void *
-store_mmap(int size, const char * func, int line)
-{
-void * yield, * top;
-
-if (size < 16) size = 16;
-
-if (!(yield = mmap(NULL, (size_t)size,
- PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)))
- log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to mmap %d bytes of memory: "
- "called from line %d of %s", size, line, func);
-
-if (yield < tainted_base) tainted_base = yield;
-if ((top = US yield + size) > tainted_top) tainted_top = top;
-if (!f.taint_check_slow) verify_all_untainted();
-
-return store_alloc_tail(yield, size, func, line, US"Mmap");
-}
-
/*************************************************
* Malloc store *
*************************************************/
Arguments:
size amount of store wanted
func function from which called
- linenumber line number in source file
+ line line number in source file
Returns: pointer to gotten store (panic on failure)
*/
static void *
-internal_store_malloc(int size, const char *func, int linenumber)
+internal_store_malloc(int size, const char *func, int line)
{
void * yield;
if (!(yield = malloc((size_t)size)))
log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to malloc %d bytes of memory: "
- "called from line %d in %s", size, linenumber, func);
+ "called from line %d in %s", size, line, func);
+
+if ((nonpool_malloc += size) > max_nonpool_malloc)
+ max_nonpool_malloc = nonpool_malloc;
+
+/* Cut out the debugging stuff for utilities, but stop picky compilers from
+giving warnings. */
-/* If malloc ever returns apparently tainted memory, which glibc
-malloc will as it uses mmap for larger requests, we must switch to
-the slower checking for tainting (checking an address against all
-the tainted pool block spans, rather than just the mmap span) */
+#ifdef COMPILE_UTILITY
+func = func; line = line;
+#else
+
+/* If running in test harness, spend time making sure all the new store
+is not filled with zeros so as to catch problems. */
-if (!f.taint_check_slow && is_tainted(yield))
- use_slow_taint_check(US"malloc");
+if (f.running_in_test_harness)
+ memset(yield, 0xF0, (size_t)size);
+DEBUG(D_memory) debug_printf("--Malloc %6p %5d bytes\t%-14s %4d\tpool %5d nonpool %5d\n",
+ yield, size, func, line, pool_malloc, nonpool_malloc);
+#endif /* COMPILE_UTILITY */
-return store_alloc_tail(yield, size, func, linenumber, US"Malloc");
+return yield;
}
void *
*/
static void
-internal_untainted_free(void * block, const char * func, int linenumber)
+internal_store_free(void * block, const char * func, int linenumber)
{
#ifdef COMPILE_UTILITY
func = func;
store_free_3(void * block, const char * func, int linenumber)
{
n_nonpool_blocks--;
-internal_untainted_free(block, func, linenumber);
-}
-
-/******************************************************************************/
-static void
-internal_tainted_free(storeblock * block, const char * func, int linenumber)
-{
-#ifdef COMPILE_UTILITY
-func = func;
-linenumber = linenumber;
-#else
-DEBUG(D_memory)
- debug_printf("---Unmap %6p %-20s %4d\n", block, func, linenumber);
-#endif
-munmap((void *)block, block->length + ALIGNED_SIZEOF_STOREBLOCK);
+internal_store_free(block, func, linenumber);
}
/******************************************************************************/
git://git.exim.org / exim.git / blobdiff