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![Junio C Hamano](/assets/img/avatar_default.png)
The fsmonitor interface read from its input without making sure there is something to read from. This bug is new in 2.31 timeframe. * jh/fsmonitor-prework: fsmonitor: avoid global-buffer-overflow READ when checking trivial response
447 lines
13 KiB
C
447 lines
13 KiB
C
#include "cache.h"
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#include "config.h"
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#include "dir.h"
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#include "ewah/ewok.h"
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#include "fsmonitor.h"
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#include "run-command.h"
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#include "strbuf.h"
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#define INDEX_EXTENSION_VERSION1 (1)
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#define INDEX_EXTENSION_VERSION2 (2)
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#define HOOK_INTERFACE_VERSION1 (1)
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#define HOOK_INTERFACE_VERSION2 (2)
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struct trace_key trace_fsmonitor = TRACE_KEY_INIT(FSMONITOR);
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static void assert_index_minimum(struct index_state *istate, size_t pos)
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{
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if (pos > istate->cache_nr)
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BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
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(uintmax_t)pos, istate->cache_nr);
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}
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static void fsmonitor_ewah_callback(size_t pos, void *is)
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{
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struct index_state *istate = (struct index_state *)is;
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struct cache_entry *ce;
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assert_index_minimum(istate, pos + 1);
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ce = istate->cache[pos];
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ce->ce_flags &= ~CE_FSMONITOR_VALID;
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}
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static int fsmonitor_hook_version(void)
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{
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int hook_version;
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if (git_config_get_int("core.fsmonitorhookversion", &hook_version))
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return -1;
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if (hook_version == HOOK_INTERFACE_VERSION1 ||
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hook_version == HOOK_INTERFACE_VERSION2)
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return hook_version;
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warning("Invalid hook version '%i' in core.fsmonitorhookversion. "
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"Must be 1 or 2.", hook_version);
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return -1;
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}
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int read_fsmonitor_extension(struct index_state *istate, const void *data,
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unsigned long sz)
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{
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const char *index = data;
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uint32_t hdr_version;
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uint32_t ewah_size;
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struct ewah_bitmap *fsmonitor_dirty;
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int ret;
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uint64_t timestamp;
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struct strbuf last_update = STRBUF_INIT;
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if (sz < sizeof(uint32_t) + 1 + sizeof(uint32_t))
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return error("corrupt fsmonitor extension (too short)");
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hdr_version = get_be32(index);
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index += sizeof(uint32_t);
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if (hdr_version == INDEX_EXTENSION_VERSION1) {
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timestamp = get_be64(index);
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strbuf_addf(&last_update, "%"PRIu64"", timestamp);
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index += sizeof(uint64_t);
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} else if (hdr_version == INDEX_EXTENSION_VERSION2) {
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strbuf_addstr(&last_update, index);
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index += last_update.len + 1;
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} else {
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return error("bad fsmonitor version %d", hdr_version);
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}
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istate->fsmonitor_last_update = strbuf_detach(&last_update, NULL);
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ewah_size = get_be32(index);
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index += sizeof(uint32_t);
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fsmonitor_dirty = ewah_new();
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ret = ewah_read_mmap(fsmonitor_dirty, index, ewah_size);
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if (ret != ewah_size) {
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ewah_free(fsmonitor_dirty);
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return error("failed to parse ewah bitmap reading fsmonitor index extension");
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}
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istate->fsmonitor_dirty = fsmonitor_dirty;
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if (!istate->split_index)
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assert_index_minimum(istate, istate->fsmonitor_dirty->bit_size);
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trace2_data_string("index", NULL, "extension/fsmn/read/token",
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istate->fsmonitor_last_update);
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trace_printf_key(&trace_fsmonitor,
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"read fsmonitor extension successful '%s'",
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istate->fsmonitor_last_update);
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return 0;
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}
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void fill_fsmonitor_bitmap(struct index_state *istate)
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{
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unsigned int i, skipped = 0;
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istate->fsmonitor_dirty = ewah_new();
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for (i = 0; i < istate->cache_nr; i++) {
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if (istate->cache[i]->ce_flags & CE_REMOVE)
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skipped++;
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else if (!(istate->cache[i]->ce_flags & CE_FSMONITOR_VALID))
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ewah_set(istate->fsmonitor_dirty, i - skipped);
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}
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}
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void write_fsmonitor_extension(struct strbuf *sb, struct index_state *istate)
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{
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uint32_t hdr_version;
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uint32_t ewah_start;
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uint32_t ewah_size = 0;
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int fixup = 0;
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if (!istate->split_index)
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assert_index_minimum(istate, istate->fsmonitor_dirty->bit_size);
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put_be32(&hdr_version, INDEX_EXTENSION_VERSION2);
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strbuf_add(sb, &hdr_version, sizeof(uint32_t));
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strbuf_addstr(sb, istate->fsmonitor_last_update);
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strbuf_addch(sb, 0); /* Want to keep a NUL */
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fixup = sb->len;
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strbuf_add(sb, &ewah_size, sizeof(uint32_t)); /* we'll fix this up later */
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ewah_start = sb->len;
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ewah_serialize_strbuf(istate->fsmonitor_dirty, sb);
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ewah_free(istate->fsmonitor_dirty);
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istate->fsmonitor_dirty = NULL;
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/* fix up size field */
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put_be32(&ewah_size, sb->len - ewah_start);
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memcpy(sb->buf + fixup, &ewah_size, sizeof(uint32_t));
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trace2_data_string("index", NULL, "extension/fsmn/write/token",
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istate->fsmonitor_last_update);
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trace_printf_key(&trace_fsmonitor,
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"write fsmonitor extension successful '%s'",
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istate->fsmonitor_last_update);
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}
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/*
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* Call the query-fsmonitor hook passing the last update token of the saved results.
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*/
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static int query_fsmonitor(int version, const char *last_update, struct strbuf *query_result)
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{
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struct child_process cp = CHILD_PROCESS_INIT;
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int result;
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if (!core_fsmonitor)
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return -1;
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strvec_push(&cp.args, core_fsmonitor);
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strvec_pushf(&cp.args, "%d", version);
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strvec_pushf(&cp.args, "%s", last_update);
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cp.use_shell = 1;
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cp.dir = get_git_work_tree();
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trace2_region_enter("fsm_hook", "query", NULL);
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result = capture_command(&cp, query_result, 1024);
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if (result)
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trace2_data_intmax("fsm_hook", NULL, "query/failed", result);
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else {
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trace2_data_intmax("fsm_hook", NULL, "query/response-length",
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query_result->len);
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if (fsmonitor_is_trivial_response(query_result))
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trace2_data_intmax("fsm_hook", NULL,
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"query/trivial-response", 1);
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}
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trace2_region_leave("fsm_hook", "query", NULL);
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return result;
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}
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int fsmonitor_is_trivial_response(const struct strbuf *query_result)
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{
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static char trivial_response[3] = { '\0', '/', '\0' };
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return query_result->len >= 3 &&
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!memcmp(trivial_response,
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&query_result->buf[query_result->len - 3], 3);
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}
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static void fsmonitor_refresh_callback(struct index_state *istate, char *name)
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{
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int i, len = strlen(name);
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if (name[len - 1] == '/') {
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/*
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* TODO We should binary search to find the first path with
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* TODO this directory prefix. Then linearly update entries
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* TODO while the prefix matches. Taking care to search without
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* TODO the trailing slash -- because '/' sorts after a few
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* TODO interesting special chars, like '.' and ' '.
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*/
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/* Mark all entries for the folder invalid */
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for (i = 0; i < istate->cache_nr; i++) {
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if (istate->cache[i]->ce_flags & CE_FSMONITOR_VALID &&
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starts_with(istate->cache[i]->name, name))
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istate->cache[i]->ce_flags &= ~CE_FSMONITOR_VALID;
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}
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/* Need to remove the / from the path for the untracked cache */
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name[len - 1] = '\0';
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} else {
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int pos = index_name_pos(istate, name, strlen(name));
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if (pos >= 0) {
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struct cache_entry *ce = istate->cache[pos];
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ce->ce_flags &= ~CE_FSMONITOR_VALID;
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}
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}
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/*
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* Mark the untracked cache dirty even if it wasn't found in the index
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* as it could be a new untracked file.
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*/
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trace_printf_key(&trace_fsmonitor, "fsmonitor_refresh_callback '%s'", name);
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untracked_cache_invalidate_path(istate, name, 0);
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}
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void refresh_fsmonitor(struct index_state *istate)
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{
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struct strbuf query_result = STRBUF_INIT;
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int query_success = 0, hook_version = -1;
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size_t bol = 0; /* beginning of line */
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uint64_t last_update;
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struct strbuf last_update_token = STRBUF_INIT;
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char *buf;
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unsigned int i;
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if (!core_fsmonitor || istate->fsmonitor_has_run_once)
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return;
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hook_version = fsmonitor_hook_version();
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istate->fsmonitor_has_run_once = 1;
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trace_printf_key(&trace_fsmonitor, "refresh fsmonitor");
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/*
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* This could be racy so save the date/time now and query_fsmonitor
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* should be inclusive to ensure we don't miss potential changes.
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*/
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last_update = getnanotime();
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if (hook_version == HOOK_INTERFACE_VERSION1)
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strbuf_addf(&last_update_token, "%"PRIu64"", last_update);
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/*
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* If we have a last update token, call query_fsmonitor for the set of
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* changes since that token, else assume everything is possibly dirty
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* and check it all.
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*/
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if (istate->fsmonitor_last_update) {
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if (hook_version == -1 || hook_version == HOOK_INTERFACE_VERSION2) {
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query_success = !query_fsmonitor(HOOK_INTERFACE_VERSION2,
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istate->fsmonitor_last_update, &query_result);
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if (query_success) {
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if (hook_version < 0)
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hook_version = HOOK_INTERFACE_VERSION2;
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/*
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* First entry will be the last update token
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* Need to use a char * variable because static
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* analysis was suggesting to use strbuf_addbuf
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* but we don't want to copy the entire strbuf
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* only the chars up to the first NUL
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*/
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buf = query_result.buf;
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strbuf_addstr(&last_update_token, buf);
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if (!last_update_token.len) {
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warning("Empty last update token.");
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query_success = 0;
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} else {
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bol = last_update_token.len + 1;
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}
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} else if (hook_version < 0) {
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hook_version = HOOK_INTERFACE_VERSION1;
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if (!last_update_token.len)
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strbuf_addf(&last_update_token, "%"PRIu64"", last_update);
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}
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}
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if (hook_version == HOOK_INTERFACE_VERSION1) {
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query_success = !query_fsmonitor(HOOK_INTERFACE_VERSION1,
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istate->fsmonitor_last_update, &query_result);
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}
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trace_performance_since(last_update, "fsmonitor process '%s'", core_fsmonitor);
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trace_printf_key(&trace_fsmonitor, "fsmonitor process '%s' returned %s",
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core_fsmonitor, query_success ? "success" : "failure");
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}
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/* a fsmonitor process can return '/' to indicate all entries are invalid */
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if (query_success && query_result.buf[bol] != '/') {
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/* Mark all entries returned by the monitor as dirty */
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buf = query_result.buf;
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for (i = bol; i < query_result.len; i++) {
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if (buf[i] != '\0')
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continue;
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fsmonitor_refresh_callback(istate, buf + bol);
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bol = i + 1;
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}
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if (bol < query_result.len)
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fsmonitor_refresh_callback(istate, buf + bol);
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/* Now mark the untracked cache for fsmonitor usage */
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if (istate->untracked)
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istate->untracked->use_fsmonitor = 1;
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} else {
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/* We only want to run the post index changed hook if we've actually changed entries, so keep track
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* if we actually changed entries or not */
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int is_cache_changed = 0;
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/* Mark all entries invalid */
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for (i = 0; i < istate->cache_nr; i++) {
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if (istate->cache[i]->ce_flags & CE_FSMONITOR_VALID) {
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is_cache_changed = 1;
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istate->cache[i]->ce_flags &= ~CE_FSMONITOR_VALID;
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}
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}
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/* If we're going to check every file, ensure we save the results */
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if (is_cache_changed)
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istate->cache_changed |= FSMONITOR_CHANGED;
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if (istate->untracked)
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istate->untracked->use_fsmonitor = 0;
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}
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strbuf_release(&query_result);
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/* Now that we've updated istate, save the last_update_token */
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FREE_AND_NULL(istate->fsmonitor_last_update);
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istate->fsmonitor_last_update = strbuf_detach(&last_update_token, NULL);
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}
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/*
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* The caller wants to turn on FSMonitor. And when the caller writes
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* the index to disk, a FSMonitor extension should be included. This
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* requires that `istate->fsmonitor_last_update` not be NULL. But we
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* have not actually talked to a FSMonitor process yet, so we don't
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* have an initial value for this field.
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*
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* For a protocol V1 FSMonitor process, this field is a formatted
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* "nanoseconds since epoch" field. However, for a protocol V2
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* FSMonitor process, this field is an opaque token.
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*
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* Historically, `add_fsmonitor()` has initialized this field to the
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* current time for protocol V1 processes. There are lots of race
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* conditions here, but that code has shipped...
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*
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* The only true solution is to use a V2 FSMonitor and get a current
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* or default token value (that it understands), but we cannot do that
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* until we have actually talked to an instance of the FSMonitor process
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* (but the protocol requires that we send a token first...).
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*
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* For simplicity, just initialize like we have a V1 process and require
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* that V2 processes adapt.
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*/
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static void initialize_fsmonitor_last_update(struct index_state *istate)
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{
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struct strbuf last_update = STRBUF_INIT;
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strbuf_addf(&last_update, "%"PRIu64"", getnanotime());
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istate->fsmonitor_last_update = strbuf_detach(&last_update, NULL);
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}
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void add_fsmonitor(struct index_state *istate)
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{
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unsigned int i;
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if (!istate->fsmonitor_last_update) {
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trace_printf_key(&trace_fsmonitor, "add fsmonitor");
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istate->cache_changed |= FSMONITOR_CHANGED;
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initialize_fsmonitor_last_update(istate);
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/* reset the fsmonitor state */
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for (i = 0; i < istate->cache_nr; i++)
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istate->cache[i]->ce_flags &= ~CE_FSMONITOR_VALID;
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/* reset the untracked cache */
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if (istate->untracked) {
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add_untracked_cache(istate);
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istate->untracked->use_fsmonitor = 1;
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}
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/* Update the fsmonitor state */
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refresh_fsmonitor(istate);
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}
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}
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void remove_fsmonitor(struct index_state *istate)
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{
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if (istate->fsmonitor_last_update) {
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trace_printf_key(&trace_fsmonitor, "remove fsmonitor");
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istate->cache_changed |= FSMONITOR_CHANGED;
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FREE_AND_NULL(istate->fsmonitor_last_update);
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}
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}
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void tweak_fsmonitor(struct index_state *istate)
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{
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unsigned int i;
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int fsmonitor_enabled = git_config_get_fsmonitor();
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if (istate->fsmonitor_dirty) {
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if (fsmonitor_enabled) {
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/* Mark all entries valid */
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for (i = 0; i < istate->cache_nr; i++) {
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istate->cache[i]->ce_flags |= CE_FSMONITOR_VALID;
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}
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/* Mark all previously saved entries as dirty */
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assert_index_minimum(istate, istate->fsmonitor_dirty->bit_size);
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ewah_each_bit(istate->fsmonitor_dirty, fsmonitor_ewah_callback, istate);
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refresh_fsmonitor(istate);
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}
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ewah_free(istate->fsmonitor_dirty);
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istate->fsmonitor_dirty = NULL;
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}
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switch (fsmonitor_enabled) {
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case -1: /* keep: do nothing */
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break;
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case 0: /* false */
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remove_fsmonitor(istate);
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break;
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case 1: /* true */
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add_fsmonitor(istate);
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break;
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default: /* unknown value: do nothing */
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break;
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}
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}
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