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/*
* Copyright (c) 2013 Luca Clementi <luca.clementi@gmail.com>
* Copyright (c) 2013-2018 The strace developers.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "defs.h"
#include <limits.h>
#include "largefile_wrappers.h"
#include "mmap_cache.h"
#include "mmap_notify.h"
#include "xstring.h"
static unsigned int mmap_cache_generation;
static void
mmap_cache_invalidate(struct tcb *tcp, void *unused)
{
#if SUPPORTED_PERSONALITIES > 1
if (tcp->currpers != DEFAULT_PERSONALITY) {
/* disable stack trace */
return;
}
#endif
mmap_cache_generation++;
debug_func_msg("tgen=%u, ggen=%u, tcp=%p, cache=%p",
tcp->mmap_cache ? tcp->mmap_cache->generation : 0,
mmap_cache_generation, tcp,
tcp->mmap_cache ? tcp->mmap_cache->entry : 0);
}
void
mmap_cache_enable(void)
{
static bool use_mmap_cache;
if (!use_mmap_cache) {
mmap_notify_register_client(mmap_cache_invalidate, NULL);
use_mmap_cache = true;
}
}
/* deleting the cache */
static void
delete_mmap_cache(struct tcb *tcp, const char *caller)
{
debug_func_msg("tgen=%u, ggen=%u, tcp=%p, cache=%p, caller=%s",
tcp->mmap_cache ? tcp->mmap_cache->generation : 0,
mmap_cache_generation, tcp,
tcp->mmap_cache ? tcp->mmap_cache->entry : 0, caller);
if (!tcp->mmap_cache)
return;
while (tcp->mmap_cache->size) {
unsigned int i = --tcp->mmap_cache->size;
free(tcp->mmap_cache->entry[i].binary_filename);
tcp->mmap_cache->entry[i].binary_filename = NULL;
}
free(tcp->mmap_cache->entry);
tcp->mmap_cache->entry = NULL;
free(tcp->mmap_cache);
tcp->mmap_cache = NULL;
}
/*
* caching of /proc/ID/maps for each process to speed up stack tracing
*
* The cache must be refreshed after syscalls that affect memory mappings,
* e.g. mmap, mprotect, munmap, execve.
*/
extern enum mmap_cache_rebuild_result
mmap_cache_rebuild_if_invalid(struct tcb *tcp, const char *caller)
{
if (tcp->mmap_cache
&& tcp->mmap_cache->generation != mmap_cache_generation)
delete_mmap_cache(tcp, caller);
if (tcp->mmap_cache)
return MMAP_CACHE_REBUILD_READY;
char filename[sizeof("/proc/4294967296/maps")];
xsprintf(filename, "/proc/%u/maps", tcp->pid);
FILE *fp = fopen_stream(filename, "r");
if (!fp) {
perror_msg("fopen: %s", filename);
return MMAP_CACHE_REBUILD_NOCACHE;
}
struct mmap_cache_t cache = {
.free_fn = delete_mmap_cache,
.generation = mmap_cache_generation
};
/* start with a small dynamically-allocated array and then expand it */
size_t allocated = 0;
char buffer[PATH_MAX + 80];
while (fgets(buffer, sizeof(buffer), fp) != NULL) {
unsigned long start_addr, end_addr, mmap_offset;
char read_bit;
char write_bit;
char exec_bit;
char shared_bit;
unsigned long major, minor;
char binary_path[sizeof(buffer)];
if (sscanf(buffer, "%lx-%lx %c%c%c%c %lx %lx:%lx %*d %[^\n]",
&start_addr, &end_addr,
&read_bit, &write_bit, &exec_bit, &shared_bit,
&mmap_offset,
&major, &minor,
binary_path) != 10)
continue;
/* skip mappings that have unknown protection */
if (!(read_bit == '-' || read_bit == 'r'))
continue;
if (!(write_bit == '-' || write_bit == 'w'))
continue;
if (!(exec_bit == '-' || exec_bit == 'x'))
continue;
if (!(shared_bit == 'p' || shared_bit == 's'))
continue;
if (end_addr < start_addr) {
error_msg("%s: unrecognized file format", filename);
break;
}
struct mmap_cache_entry_t *entry;
/*
* sanity check to make sure that we're storing
* non-overlapping regions in ascending order
*/
if (cache.size > 0) {
entry = &cache.entry[cache.size - 1];
if (entry->start_addr == start_addr &&
entry->end_addr == end_addr) {
/* duplicate entry, e.g. [vsyscall] */
continue;
}
if (start_addr <= entry->start_addr ||
start_addr < entry->end_addr) {
debug_msg("%s: overlapping memory region: "
"\"%s\" [%08lx-%08lx] overlaps with "
"\"%s\" [%08lx-%08lx]",
filename, binary_path, start_addr,
end_addr, entry->binary_filename,
entry->start_addr, entry->end_addr);
continue;
}
}
if (cache.size >= allocated)
cache.entry = xgrowarray(cache.entry, &allocated,
sizeof(*cache.entry));
entry = &cache.entry[cache.size];
entry->start_addr = start_addr;
entry->end_addr = end_addr;
entry->mmap_offset = mmap_offset;
entry->protections = (
0
| ((read_bit == 'r')? MMAP_CACHE_PROT_READABLE : 0)
| ((write_bit == 'w')? MMAP_CACHE_PROT_WRITABLE : 0)
| ((exec_bit == 'x')? MMAP_CACHE_PROT_EXECUTABLE: 0)
| ((shared_bit == 's')? MMAP_CACHE_PROT_SHARED : 0)
);
entry->major = major;
entry->minor = minor;
entry->binary_filename = xstrdup(binary_path);
cache.size++;
}
fclose(fp);
if (!cache.size)
return MMAP_CACHE_REBUILD_NOCACHE;
tcp->mmap_cache = xmalloc(sizeof(*tcp->mmap_cache));
memcpy(tcp->mmap_cache, &cache, sizeof(cache));
debug_func_msg("tgen=%u, ggen=%u, tcp=%p, cache=%p, caller=%s",
tcp->mmap_cache->generation, mmap_cache_generation,
tcp, tcp->mmap_cache->entry, caller);
return MMAP_CACHE_REBUILD_RENEWED;
}
struct mmap_cache_entry_t *
mmap_cache_search(struct tcb *tcp, unsigned long ip)
{
if (!tcp->mmap_cache)
return NULL;
int lower = 0;
int upper = (int) tcp->mmap_cache->size - 1;
while (lower <= upper) {
int mid = (upper + lower) / 2;
struct mmap_cache_entry_t *entry = &tcp->mmap_cache->entry[mid];
if (ip >= entry->start_addr &&
ip < entry->end_addr)
return entry;
else if (ip < entry->start_addr)
upper = mid - 1;
else
lower = mid + 1;
}
return NULL;
}
struct mmap_cache_entry_t *
mmap_cache_search_custom(struct tcb *tcp, mmap_cache_search_fn fn, void *data)
{
for (unsigned int i = 0; i < tcp->mmap_cache->size; i++) {
if (fn(tcp->mmap_cache->entry + i, data))
return tcp->mmap_cache->entry + i;
}
return NULL;
}
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