--- /dev/null
+/*
+ * Copyright (C) 2020 EfficiOS, Inc.
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#include "uprobe.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "common/compat/getenv.h"
+#include "common/string-utils/string-utils.h"
+#include "common/utils.h"
+#include "lttng/constant.h"
+
+#include "command.h"
+
+/*
+ * Walk the directories in the PATH environment variable to find the target
+ * binary passed as parameter.
+ *
+ * On success, the full path of the binary is copied in binary_full_path out
+ * parameter. This buffer is allocated by the caller and must be at least
+ * LTTNG_PATH_MAX bytes long.
+ * On failure, returns -1;
+ */
+static
+int walk_command_search_path(const char *binary, char *binary_full_path)
+{
+ char *tentative_binary_path = NULL;
+ char *command_search_path = NULL;
+ char *curr_search_dir_end = NULL;
+ char *curr_search_dir = NULL;
+ struct stat stat_output;
+ int ret = 0;
+
+ command_search_path = lttng_secure_getenv("PATH");
+ if (!command_search_path) {
+ ret = -1;
+ goto end;
+ }
+
+ /*
+ * Duplicate the $PATH string as the char pointer returned by getenv() should
+ * not be modified.
+ */
+ command_search_path = strdup(command_search_path);
+ if (!command_search_path) {
+ ret = -1;
+ goto end;
+ }
+
+ /*
+ * This char array is used to concatenate path to binary to look for
+ * the binary.
+ */
+ tentative_binary_path = (char *) zmalloc(LTTNG_PATH_MAX * sizeof(char));
+ if (!tentative_binary_path) {
+ ret = -1;
+ goto alloc_error;
+ }
+
+ curr_search_dir = command_search_path;
+ do {
+ /*
+ * Split on ':'. The return value of this call points to the
+ * matching character.
+ */
+ curr_search_dir_end = strchr(curr_search_dir, ':');
+ if (curr_search_dir_end != NULL) {
+ /*
+ * Add a NULL byte to the end of the first token so it
+ * can be used as a string.
+ */
+ curr_search_dir_end[0] = '\0';
+ }
+
+ /* Empty the tentative path */
+ memset(tentative_binary_path, 0, LTTNG_PATH_MAX * sizeof(char));
+
+ /*
+ * Build the tentative path to the binary using the current
+ * search directory and the name of the binary.
+ */
+ ret = snprintf(tentative_binary_path, LTTNG_PATH_MAX, "%s/%s",
+ curr_search_dir, binary);
+ if (ret < 0) {
+ goto free_binary_path;
+ }
+ if (ret < LTTNG_PATH_MAX) {
+ /*
+ * Use STAT(2) to see if the file exists.
+ */
+ ret = stat(tentative_binary_path, &stat_output);
+ if (ret == 0) {
+ /*
+ * Verify that it is a regular file or a
+ * symlink and not a special file (e.g.
+ * device).
+ */
+ if (S_ISREG(stat_output.st_mode)
+ || S_ISLNK(stat_output.st_mode)) {
+ /*
+ * Found a match, set the out parameter
+ * and return success.
+ */
+ ret = lttng_strncpy(binary_full_path,
+ tentative_binary_path,
+ LTTNG_PATH_MAX);
+ if (ret == -1) {
+ ERR("Source path does not fit "
+ "in destination buffer.");
+ }
+ goto free_binary_path;
+ }
+ }
+ }
+ /* Go to the next entry in the $PATH variable. */
+ curr_search_dir = curr_search_dir_end + 1;
+ } while (curr_search_dir_end != NULL);
+
+free_binary_path:
+ free(tentative_binary_path);
+alloc_error:
+ free(command_search_path);
+end:
+ return ret;
+}
+
+/*
+ * Check if the symbol field passed by the user is in fact an address or an
+ * offset from a symbol. Those two instrumentation types are not supported yet.
+ * It's expected to be a common mistake because of the existing --probe option
+ * that does support these formats.
+ *
+ * Here are examples of these unsupported formats for the --userspace-probe
+ * option:
+ * elf:/path/to/binary:0x400430
+ * elf:/path/to/binary:4194364
+ * elf:/path/to/binary:my_symbol+0x323
+ * elf:/path/to/binary:my_symbol+43
+ */
+static
+int warn_userspace_probe_syntax(const char *symbol)
+{
+ int ret;
+
+ /* Check if the symbol field is an hex address. */
+ ret = sscanf(symbol, "0x%*x");
+ if (ret > 0) {
+ /* If there is a match, print a warning and return an error. */
+ ERR("Userspace probe on address not supported yet.");
+ ret = CMD_UNSUPPORTED;
+ goto error;
+ }
+
+ /* Check if the symbol field is an decimal address. */
+ ret = sscanf(symbol, "%*u");
+ if (ret > 0) {
+ /* If there is a match, print a warning and return an error. */
+ ERR("Userspace probe on address not supported yet.");
+ ret = CMD_UNSUPPORTED;
+ goto error;
+ }
+
+ /* Check if the symbol field is symbol+hex_offset. */
+ ret = sscanf(symbol, "%*[^+]+0x%*x");
+ if (ret > 0) {
+ /* If there is a match, print a warning and return an error. */
+ ERR("Userspace probe on symbol+offset not supported yet.");
+ ret = CMD_UNSUPPORTED;
+ goto error;
+ }
+
+ /* Check if the symbol field is symbol+decimal_offset. */
+ ret = sscanf(symbol, "%*[^+]+%*u");
+ if (ret > 0) {
+ /* If there is a match, print a warning and return an error. */
+ ERR("Userspace probe on symbol+offset not supported yet.");
+ ret = CMD_UNSUPPORTED;
+ goto error;
+ }
+
+ ret = 0;
+
+error:
+ return ret;
+}
+
+/*
+ * Parse userspace probe options
+ * Set the userspace probe fields in the lttng_event struct and set the
+ * target_path to the path to the binary.
+ */
+int parse_userspace_probe_opts(const char *opt,
+ struct lttng_userspace_probe_location **probe_location)
+{
+ int ret = CMD_SUCCESS;
+ size_t num_token = 0;
+ char *target_path = NULL;
+ char *unescaped_target_path = NULL;
+ char *real_target_path = NULL;
+ char *symbol_name = NULL, *probe_name = NULL, *provider_name = NULL;
+ struct lttng_userspace_probe_location *probe_location_local = NULL;
+ struct lttng_userspace_probe_location_lookup_method *lookup_method = NULL;
+ struct lttng_dynamic_pointer_array tokens;
+
+ LTTNG_ASSERT(opt);
+
+ /*
+ * userspace probe fields are separated by ':'.
+ */
+ ret = strutils_split(opt, ':', true, &tokens);
+ if (ret == 0) {
+ num_token = lttng_dynamic_pointer_array_get_count(&tokens);
+ }
+
+ /*
+ * Early sanity check that the number of parameter is between 2 and 4
+ * inclusively.
+ * elf:PATH:SYMBOL
+ * std:PATH:PROVIDER_NAME:PROBE_NAME
+ * PATH:SYMBOL (same behavior as ELF)
+ */
+ if (ret < 0 || num_token < 2 || num_token > 4) {
+ ret = CMD_ERROR;
+ goto end;
+ }
+
+ /*
+ * Looking up the first parameter will tell the technique to use to
+ * interpret the userspace probe/function description.
+ */
+ switch (num_token) {
+ case 2:
+ /* When the probe type is omitted we assume ELF for now. */
+ case 3:
+ if (num_token == 3 && strcmp((const char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 0), "elf") == 0) {
+ target_path = (char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 1);
+ symbol_name = (char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 2);
+ } else if (num_token == 2) {
+ target_path = (char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 0);
+ symbol_name = (char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 1);
+ } else {
+ ret = CMD_ERROR;
+ goto end;
+ }
+ lookup_method =
+ lttng_userspace_probe_location_lookup_method_function_elf_create();
+ if (!lookup_method) {
+ WARN("Failed to create ELF lookup method");
+ ret = CMD_ERROR;
+ goto end;
+ }
+ break;
+ case 4:
+ if (strcmp((const char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 0), "sdt") == 0) {
+ target_path = (char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 1);
+ provider_name = (char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 2);
+ probe_name = (char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 3);
+ } else {
+ ret = CMD_ERROR;
+ goto end;
+ }
+ lookup_method =
+ lttng_userspace_probe_location_lookup_method_tracepoint_sdt_create();
+ if (!lookup_method) {
+ WARN("Failed to create SDT lookup method");
+ ret = CMD_ERROR;
+ goto end;
+ }
+ break;
+ default:
+ ret = CMD_ERROR;
+ goto end;
+ }
+
+ /* strutils_unescape_string allocates a new char *. */
+ unescaped_target_path = strutils_unescape_string(target_path, 0);
+ if (!unescaped_target_path) {
+ ret = CMD_ERROR;
+ goto end;
+ }
+
+ /*
+ * If there is not forward slash in the path. Walk the $PATH else
+ * expand.
+ */
+ if (strchr(unescaped_target_path, '/') == NULL) {
+ /* Walk the $PATH variable to find the targeted binary. */
+ real_target_path = (char *) zmalloc(LTTNG_PATH_MAX * sizeof(char));
+ if (!real_target_path) {
+ PERROR("Error allocating path buffer");
+ ret = CMD_ERROR;
+ goto end;
+ }
+ ret = walk_command_search_path(unescaped_target_path, real_target_path);
+ if (ret) {
+ ERR("Binary not found.");
+ ret = CMD_ERROR;
+ goto end;
+ }
+ } else {
+ /*
+ * Expand references to `/./` and `/../`. This function does not check
+ * if the file exists. This call returns an allocated buffer on
+ * success.
+ */
+ real_target_path = utils_expand_path_keep_symlink(unescaped_target_path);
+ if (!real_target_path) {
+ ERR("Error expanding the path to binary.");
+ ret = CMD_ERROR;
+ goto end;
+ }
+
+ /*
+ * Check if the file exists using access(2), If it does not,
+ * return an error.
+ */
+ ret = access(real_target_path, F_OK);
+ if (ret) {
+ ERR("Cannot find binary at path: %s.", real_target_path);
+ ret = CMD_ERROR;
+ goto end;
+ }
+ }
+
+ switch (lttng_userspace_probe_location_lookup_method_get_type(lookup_method)) {
+ case LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_FUNCTION_ELF:
+ /*
+ * Check for common mistakes in userspace probe description syntax.
+ */
+ ret = warn_userspace_probe_syntax(symbol_name);
+ if (ret) {
+ goto end;
+ }
+
+ probe_location_local = lttng_userspace_probe_location_function_create(
+ real_target_path, symbol_name, lookup_method);
+ if (!probe_location_local) {
+ WARN("Failed to create function probe location");
+ ret = CMD_ERROR;
+ goto end;
+ }
+
+ /* Ownership transferred to probe_location. */
+ lookup_method = NULL;
+ break;
+ case LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_TRACEPOINT_SDT:
+ probe_location_local = lttng_userspace_probe_location_tracepoint_create(
+ real_target_path, provider_name, probe_name, lookup_method);
+ if (!probe_location_local) {
+ WARN("Failed to create function probe location");
+ ret = CMD_ERROR;
+ goto end;
+ }
+
+ /* Ownership transferred to probe_location. */
+ lookup_method = NULL;
+ break;
+ default:
+ ret = CMD_ERROR;
+ goto end;
+ }
+
+ /*
+ * Everything went fine, transfer ownership of probe location to
+ * caller.
+ */
+ *probe_location = probe_location_local;
+ probe_location_local = NULL;
+
+end:
+ lttng_userspace_probe_location_destroy(probe_location_local);
+ lttng_userspace_probe_location_lookup_method_destroy(lookup_method);
+ lttng_dynamic_pointer_array_reset(&tokens);
+ /*
+ * Freeing both char * here makes the error handling simplier. free()
+ * performs not action if the pointer is NULL.
+ */
+ free(real_target_path);
+ free(unescaped_target_path);
+
+ return ret;
+}
projects / lttng-tools.git / blobdiff