2022-07-28 19:52:19 +00:00
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#include <Common/Exception.h>
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#include <IO/ReadHelpers.h>
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#include <fmt/format.h>
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#include <vector>
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#include <sys/types.h>
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#include <unistd.h>
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#include <pwd.h>
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#include <grp.h>
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/// "su" means "set user"
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/// In fact, this program can set Unix user and group.
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///
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/// Usage:
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/// clickhouse su user[:group] args...
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///
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/// - will set user and, optionally, group and exec the remaining args.
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/// user and group can be numeric identifiers or strings.
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///
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/// The motivation for this tool is very obscure and idiosyncratic. It is needed for Docker.
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/// People want to run programs inside Docker with dropped privileges (less than root).
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/// But the standard Linux "su" program is not suitable for usage inside Docker,
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/// because it is creating pseudoterminals to avoid hijacking input from the terminal, for security,
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/// but Docker is also doing something with the terminal and it is incompatible.
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/// For this reason, people use alternative and less "secure" versions of "su" tools like "gosu" or "su-exec".
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/// But it would be very strange to use 3rd-party software only to do two-three syscalls.
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/// That's why we provide this tool.
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///
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/// Note: ClickHouse does not need Docker at all and works better without Docker.
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/// ClickHouse has no dependencies, it is packaged and distributed in single binary.
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/// There is no reason to use Docker unless you are already running all your software in Docker.
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int BAD_ARGUMENTS;
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extern const int SYSTEM_ERROR;
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}
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void setUserAndGroup(std::string arg_uid, std::string arg_gid)
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{
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static constexpr size_t buf_size = 16384; /// Linux man page says it is enough. Nevertheless, we will check if it's not enough and throw.
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std::unique_ptr<char[]> buf(new char[buf_size]);
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/// Set the group first, because if we set user, the privileges will be already dropped and we will not be able to set the group later.
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if (!arg_gid.empty())
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{
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gid_t gid = 0;
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if (!tryParse(gid, arg_gid) || gid == 0)
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{
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group entry{};
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group * result{};
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if (0 != getgrnam_r(arg_gid.data(), &entry, buf.get(), buf_size, &result))
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2023-12-15 18:25:49 +00:00
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throw ErrnoException(ErrorCodes::SYSTEM_ERROR, "Cannot do 'getgrnam_r' to obtain gid from group name ({})", arg_gid);
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2022-07-28 19:52:19 +00:00
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if (!result)
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2024-11-08 22:07:28 +00:00
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{
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if (0 != getgrgid_r(gid, &entry, buf.get(), buf_size, &result))
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throw ErrnoException(ErrorCodes::SYSTEM_ERROR, "Cannot do 'getgrnam_r' to obtain gid from group name ({})", arg_gid);
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if (!result)
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throw Exception(ErrorCodes::BAD_ARGUMENTS, "Group {} is not found in the system", arg_gid);
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}
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2022-07-28 19:52:19 +00:00
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gid = entry.gr_gid;
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}
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if (gid == 0 && getgid() != 0)
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2023-01-23 21:13:58 +00:00
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throw Exception(ErrorCodes::BAD_ARGUMENTS, "Group has id 0, but dropping privileges to gid 0 does not make sense");
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2022-07-28 19:52:19 +00:00
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if (0 != setgid(gid))
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2023-12-15 18:25:49 +00:00
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throw ErrnoException(ErrorCodes::SYSTEM_ERROR, "Cannot do 'setgid' to user ({})", arg_gid);
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2022-07-28 19:52:19 +00:00
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}
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if (!arg_uid.empty())
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{
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/// Is it numeric id or name?
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uid_t uid = 0;
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if (!tryParse(uid, arg_uid) || uid == 0)
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{
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passwd entry{};
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passwd * result{};
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if (0 != getpwnam_r(arg_uid.data(), &entry, buf.get(), buf_size, &result))
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2023-12-15 18:25:49 +00:00
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throw ErrnoException(ErrorCodes::SYSTEM_ERROR, "Cannot do 'getpwnam_r' to obtain uid from user name ({})", arg_uid);
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2022-07-28 19:52:19 +00:00
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if (!result)
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2024-11-08 22:07:28 +00:00
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{
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if (0 != getpwuid_r(uid, &entry, buf.get(), buf_size, &result))
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throw ErrnoException(ErrorCodes::SYSTEM_ERROR, "Cannot do 'getpwuid_r' to obtain uid from user name ({})", uid);
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if (!result)
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throw Exception(ErrorCodes::BAD_ARGUMENTS, "User {} is not found in the system", arg_uid);
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}
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2022-07-28 19:52:19 +00:00
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uid = entry.pw_uid;
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}
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if (uid == 0 && getuid() != 0)
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2023-01-23 21:13:58 +00:00
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throw Exception(ErrorCodes::BAD_ARGUMENTS, "User has id 0, but dropping privileges to uid 0 does not make sense");
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2022-07-28 19:52:19 +00:00
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if (0 != setuid(uid))
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2023-12-15 18:25:49 +00:00
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throw ErrnoException(ErrorCodes::SYSTEM_ERROR, "Cannot do 'setuid' to user ({})", arg_uid);
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2022-07-28 19:52:19 +00:00
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}
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}
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}
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int mainEntryClickHouseSU(int argc, char ** argv)
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try
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{
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using namespace DB;
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if (argc < 3)
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{
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2024-02-11 19:00:37 +00:00
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std::cout << "A tool similar to 'su'" << std::endl;
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2023-04-20 22:54:34 +00:00
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std::cout << "Usage: ./clickhouse su user:group ..." << std::endl;
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2022-08-21 18:24:17 +00:00
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exit(0); // NOLINT(concurrency-mt-unsafe)
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2022-07-28 19:52:19 +00:00
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}
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std::string_view user_and_group = argv[1];
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std::string user;
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std::string group;
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auto pos = user_and_group.find(':');
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if (pos == std::string_view::npos)
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{
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user = user_and_group;
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}
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else
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{
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user = user_and_group.substr(0, pos);
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group = user_and_group.substr(pos + 1);
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}
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setUserAndGroup(std::move(user), std::move(group));
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std::vector<char *> new_argv;
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new_argv.reserve(argc - 1);
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new_argv.insert(new_argv.begin(), argv + 2, argv + argc);
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new_argv.push_back(nullptr);
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execvp(new_argv.front(), new_argv.data());
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2023-12-15 18:25:49 +00:00
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throw ErrnoException(ErrorCodes::SYSTEM_ERROR, "Cannot execvp");
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2022-07-28 19:52:19 +00:00
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}
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catch (...)
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{
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std::cerr << DB::getCurrentExceptionMessage(false) << '\n';
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return 1;
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}
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