[lttng-tools.git] / src / common / runas.c

/*
 * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
 * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 * Copyright (C) 2019 Jérémie Galarneau <jeremie.galarneau@efficios.com>
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 */

#define _LGPL_SOURCE
#include <assert.h>
#include <fcntl.h>
#include <grp.h>
#include <limits.h>
#include <pwd.h>
#include <sched.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#include <common/bytecode/bytecode.h>
#include <common/lttng-kernel.h>
#include <common/common.h>
#include <common/utils.h>
#include <common/compat/errno.h>
#include <common/compat/getenv.h>
#include <common/compat/string.h>
#include <common/unix.h>
#include <common/defaults.h>
#include <common/lttng-elf.h>
#include <common/thread.h>

#include <lttng/constant.h>

#include <common/sessiond-comm/sessiond-comm.h>
#include <common/filter/filter-ast.h>

#include "runas.h"

#define GETPW_BUFFER_FALLBACK_SIZE 4096

struct run_as_data;
struct run_as_ret;
typedef int (*run_as_fct)(struct run_as_data *data, struct run_as_ret *ret_value);

enum run_as_cmd {
        RUN_AS_MKDIR,
        RUN_AS_MKDIRAT,
        RUN_AS_MKDIR_RECURSIVE,
        RUN_AS_MKDIRAT_RECURSIVE,
        RUN_AS_OPEN,
        RUN_AS_OPENAT,
        RUN_AS_UNLINK,
        RUN_AS_UNLINKAT,
        RUN_AS_RMDIR,
        RUN_AS_RMDIRAT,
        RUN_AS_RMDIR_RECURSIVE,
        RUN_AS_RMDIRAT_RECURSIVE,
        RUN_AS_RENAME,
        RUN_AS_RENAMEAT,
        RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET,
        RUN_AS_EXTRACT_SDT_PROBE_OFFSETS,
        RUN_AS_GENERATE_FILTER_BYTECODE,
};

struct run_as_mkdir_data {
        int dirfd;
        char path[LTTNG_PATH_MAX];
        mode_t mode;
} LTTNG_PACKED;

struct run_as_open_data {
        int dirfd;
        char path[LTTNG_PATH_MAX];
        int flags;
        mode_t mode;
} LTTNG_PACKED;

struct run_as_unlink_data {
        int dirfd;
        char path[LTTNG_PATH_MAX];
} LTTNG_PACKED;

struct run_as_rmdir_data {
        int dirfd;
        char path[LTTNG_PATH_MAX];
        int flags; /* enum lttng_directory_handle_rmdir_recursive_flags. */
} LTTNG_PACKED;

struct run_as_extract_elf_symbol_offset_data {
        int fd;
        char function[LTTNG_SYMBOL_NAME_LEN];
} LTTNG_PACKED;

struct run_as_extract_sdt_probe_offsets_data {
        int fd;
        char probe_name[LTTNG_SYMBOL_NAME_LEN];
        char provider_name[LTTNG_SYMBOL_NAME_LEN];
} LTTNG_PACKED;

struct run_as_generate_filter_bytecode_data {
        char filter_expression[LTTNG_FILTER_MAX_LEN];
} LTTNG_PACKED;

struct run_as_rename_data {
        /*
         * [0] = old_dirfd
         * [1] = new_dirfd
         */
        int dirfds[2];
        char old_path[LTTNG_PATH_MAX];
        char new_path[LTTNG_PATH_MAX];
} LTTNG_PACKED;

struct run_as_open_ret {
        int fd;
} LTTNG_PACKED;

struct run_as_extract_elf_symbol_offset_ret {
        uint64_t offset;
} LTTNG_PACKED;

struct run_as_extract_sdt_probe_offsets_ret {
        uint32_t num_offset;
        uint64_t offsets[LTTNG_KERNEL_ABI_MAX_UPROBE_NUM];
} LTTNG_PACKED;

struct run_as_generate_filter_bytecode_ret {
        /* A lttng_bytecode_filter struct with 'dynamic' payload. */
        char bytecode[LTTNG_FILTER_MAX_LEN];
} LTTNG_PACKED;

struct run_as_data {
        enum run_as_cmd cmd;
        union {
                struct run_as_mkdir_data mkdir;
                struct run_as_open_data open;
                struct run_as_unlink_data unlink;
                struct run_as_rmdir_data rmdir;
                struct run_as_rename_data rename;
                struct run_as_extract_elf_symbol_offset_data extract_elf_symbol_offset;
                struct run_as_extract_sdt_probe_offsets_data extract_sdt_probe_offsets;
                struct run_as_generate_filter_bytecode_data generate_filter_bytecode;
        } u;
        uid_t uid;
        gid_t gid;
} LTTNG_PACKED;

/*
 * The run_as_ret structure holds the returned value and status of the command.
 *
 * The `u` union field holds the return value of the command; in most cases it
 * represents the success or the failure of the command. In more complex
 * commands, it holds a computed value.
 *
 * The _errno field is the errno recorded after the execution of the command.
 *
 * The _error fields is used the signify that return status of the command. For
 * simple commands returning `int` the _error field will be the same as the
 * ret_int field. In complex commands, it signify the success or failure of the
 * command.
 *
 */
struct run_as_ret {
        union {
                int ret;
                struct run_as_open_ret open;
                struct run_as_extract_elf_symbol_offset_ret extract_elf_symbol_offset;
                struct run_as_extract_sdt_probe_offsets_ret extract_sdt_probe_offsets;
                struct run_as_generate_filter_bytecode_ret generate_filter_bytecode;
        } u;
        int _errno;
        bool _error;
} LTTNG_PACKED;

#define COMMAND_IN_FDS(data_ptr) ({                                     \
        int *fds = NULL;                                                \
        if (command_properties[data_ptr->cmd].in_fds_offset != -1) {    \
                fds = (int *) ((char *) data_ptr + command_properties[data_ptr->cmd].in_fds_offset); \
        }                                                               \
        fds;                                                            \
})

#define COMMAND_OUT_FDS(cmd, ret_ptr) ({                                \
        int *fds = NULL;                                                \
        if (command_properties[cmd].out_fds_offset != -1) {             \
                fds = (int *) ((char *) ret_ptr + command_properties[cmd].out_fds_offset); \
        }                                                               \
        fds;                                                            \
})

#define COMMAND_IN_FD_COUNT(data_ptr) ({                \
        command_properties[data_ptr->cmd].in_fd_count;  \
})

#define COMMAND_OUT_FD_COUNT(cmd) ({            \
        command_properties[cmd].out_fd_count;   \
})

#define COMMAND_USE_CWD_FD(data_ptr) command_properties[data_ptr->cmd].use_cwd_fd

struct run_as_command_properties {
        /* Set to -1 when not applicable. */
        ptrdiff_t in_fds_offset, out_fds_offset;
        unsigned int in_fd_count, out_fd_count;
        bool use_cwd_fd;
};

static const struct run_as_command_properties command_properties[] = {
        [RUN_AS_MKDIR] = {
                .in_fds_offset = offsetof(struct run_as_data, u.mkdir.dirfd),
                .in_fd_count = 1,
                .out_fds_offset = -1,
                .out_fd_count = 0,
                .use_cwd_fd = true,
        },
        [RUN_AS_MKDIRAT] = {
                .in_fds_offset = offsetof(struct run_as_data, u.mkdir.dirfd),
                .in_fd_count = 1,
                .out_fds_offset = -1,
                .out_fd_count = 0,
                .use_cwd_fd = false,
        },
        [RUN_AS_MKDIR_RECURSIVE] = {
                .in_fds_offset = offsetof(struct run_as_data, u.mkdir.dirfd),
                .in_fd_count = 1,
                .out_fds_offset = -1,
                .out_fd_count = 0,
                .use_cwd_fd = true,
        },
        [RUN_AS_MKDIRAT_RECURSIVE] = {
                .in_fds_offset = offsetof(struct run_as_data, u.mkdir.dirfd),
                .in_fd_count = 1,
                .out_fds_offset = -1,
                .out_fd_count = 0,
                .use_cwd_fd = false,
        },
        [RUN_AS_OPEN] = {
                .in_fds_offset = offsetof(struct run_as_data, u.open.dirfd),
                .in_fd_count = 1,
                .out_fds_offset = offsetof(struct run_as_ret, u.open.fd),
                .out_fd_count = 1,
                .use_cwd_fd = true,
        },
        [RUN_AS_OPENAT] = {
                .in_fds_offset = offsetof(struct run_as_data, u.open.dirfd),
                .in_fd_count = 1,
                .out_fds_offset = offsetof(struct run_as_ret, u.open.fd),
                .out_fd_count = 1,
                .use_cwd_fd = false,
        },
        [RUN_AS_UNLINK] = {
                .in_fds_offset = offsetof(struct run_as_data, u.unlink.dirfd),
                .in_fd_count = 1,
                .out_fds_offset = -1,
                .out_fd_count = 0,
                .use_cwd_fd = true,
        },
        [RUN_AS_UNLINKAT] = {
                .in_fds_offset = offsetof(struct run_as_data, u.unlink.dirfd),
                .in_fd_count = 1,
                .out_fds_offset = -1,
                .out_fd_count = 0,
                .use_cwd_fd = false,
        },
        [RUN_AS_RMDIR_RECURSIVE] = {
                .in_fds_offset = offsetof(struct run_as_data, u.rmdir.dirfd),
                .in_fd_count = 1,
                .out_fds_offset = -1,
                .out_fd_count = 0,
                .use_cwd_fd = true,
        },
        [RUN_AS_RMDIRAT_RECURSIVE] = {
                .in_fds_offset = offsetof(struct run_as_data, u.rmdir.dirfd),
                .in_fd_count = 1,
                .out_fds_offset = -1,
                .out_fd_count = 0,
                .use_cwd_fd = false,
        },
        [RUN_AS_RMDIR] = {
                .in_fds_offset = offsetof(struct run_as_data, u.rmdir.dirfd),
                .in_fd_count = 1,
                .out_fds_offset = -1,
                .out_fd_count = 0,
                .use_cwd_fd = true,
        },
        [RUN_AS_RMDIRAT] = {
                .in_fds_offset = offsetof(struct run_as_data, u.rmdir.dirfd),
                .in_fd_count = 1,
                .out_fds_offset = -1,
                .out_fd_count = 0,
                .use_cwd_fd = false,
        },
        [RUN_AS_RENAME] = {
                .in_fds_offset = offsetof(struct run_as_data, u.rename.dirfds),
                .in_fd_count = 2,
                .out_fds_offset = -1,
                .out_fd_count = 0,
                .use_cwd_fd = true,
        },
        [RUN_AS_RENAMEAT] = {
                .in_fds_offset = offsetof(struct run_as_data, u.rename.dirfds),
                .in_fd_count = 2,
                .out_fds_offset = -1,
                .out_fd_count = 0,
                .use_cwd_fd = false,
        },
        [RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET] = {
                .in_fds_offset = offsetof(struct run_as_data,
                                u.extract_elf_symbol_offset.fd),
                .in_fd_count = 1,
                .out_fds_offset = -1,
                .out_fd_count = 0,
                .use_cwd_fd = false,
        },
        [RUN_AS_EXTRACT_SDT_PROBE_OFFSETS] = {
                .in_fds_offset = offsetof(struct run_as_data,
                                u.extract_sdt_probe_offsets.fd),
                .in_fd_count = 1,
                .out_fds_offset = -1,
                .out_fd_count = 0,
                .use_cwd_fd = false,
        },
        [RUN_AS_GENERATE_FILTER_BYTECODE] = {
                .in_fds_offset = -1,
                .in_fd_count = 0,
                .out_fds_offset = -1,
                .out_fd_count = 0,
                .use_cwd_fd = false,
        },
};

struct run_as_worker {
        pid_t pid;      /* Worker PID. */
        int sockpair[2];
        char *procname;
};

/* Single global worker per process (for now). */
static struct run_as_worker *global_worker;
/* Lock protecting the worker. */
static pthread_mutex_t worker_lock = PTHREAD_MUTEX_INITIALIZER;

#ifdef VALGRIND
static
int use_clone(void)
{
        return 0;
}
#else
static
int use_clone(void)
{
        return !lttng_secure_getenv("LTTNG_DEBUG_NOCLONE");
}
#endif

/*
 * Create recursively directory using the FULL path.
 */
static
int _mkdirat_recursive(struct run_as_data *data, struct run_as_ret *ret_value)
{
        const char *path;
        mode_t mode;
        struct lttng_directory_handle *handle;

        path = data->u.mkdir.path;
        mode = data->u.mkdir.mode;

        handle = lttng_directory_handle_create_from_dirfd(data->u.mkdir.dirfd);
        if (!handle) {
                ret_value->_errno = errno;
                ret_value->_error = true;
                ret_value->u.ret = -1;
                goto end;
        }
        /* Ownership of dirfd is transferred to the handle. */
        data->u.mkdir.dirfd = -1;
        /* Safe to call as we have transitioned to the requested uid/gid. */
        ret_value->u.ret = lttng_directory_handle_create_subdirectory_recursive(
                        handle, path, mode);
        ret_value->_errno = errno;
        ret_value->_error = (ret_value->u.ret) ? true : false;
        lttng_directory_handle_put(handle);
end:
        return ret_value->u.ret;
}

static
int _mkdirat(struct run_as_data *data, struct run_as_ret *ret_value)
{
        const char *path;
        mode_t mode;
        struct lttng_directory_handle *handle;

        path = data->u.mkdir.path;
        mode = data->u.mkdir.mode;

        handle = lttng_directory_handle_create_from_dirfd(data->u.mkdir.dirfd);
        if (!handle) {
                ret_value->u.ret = -1;
                ret_value->_errno = errno;
                ret_value->_error = true;
                goto end;
        }
        /* Ownership of dirfd is transferred to the handle. */
        data->u.mkdir.dirfd = -1;
        /* Safe to call as we have transitioned to the requested uid/gid. */
        ret_value->u.ret = lttng_directory_handle_create_subdirectory(
                        handle, path, mode);
        ret_value->_errno = errno;
        ret_value->_error = (ret_value->u.ret) ? true : false;
        lttng_directory_handle_put(handle);
end:
        return ret_value->u.ret;
}

static
int _open(struct run_as_data *data, struct run_as_ret *ret_value)
{
        int fd;
        struct lttng_directory_handle *handle;

        handle = lttng_directory_handle_create_from_dirfd(data->u.open.dirfd);
        if (!handle) {
                ret_value->_errno = errno;
                ret_value->_error = true;
                ret_value->u.ret = -1;
                goto end;
        }
        /* Ownership of dirfd is transferred to the handle. */
        data->u.open.dirfd = -1;

        fd = lttng_directory_handle_open_file(handle,
                        data->u.open.path, data->u.open.flags,
                        data->u.open.mode);
        if (fd < 0) {
                ret_value->u.ret = -1;
                ret_value->u.open.fd = -1;
        } else {
                ret_value->u.ret = 0;
                ret_value->u.open.fd = fd;
        }

        ret_value->_errno = errno;
        ret_value->_error = fd < 0;
        lttng_directory_handle_put(handle);
end:
        return ret_value->u.ret;
}

static
int _unlink(struct run_as_data *data, struct run_as_ret *ret_value)
{
        struct lttng_directory_handle *handle;

        handle = lttng_directory_handle_create_from_dirfd(data->u.unlink.dirfd);
        if (!handle) {
                ret_value->u.ret = -1;
                ret_value->_errno = errno;
                ret_value->_error = true;
                goto end;
        }

        /* Ownership of dirfd is transferred to the handle. */
        data->u.unlink.dirfd = -1;

        ret_value->u.ret = lttng_directory_handle_unlink_file(handle,
                        data->u.unlink.path);
        ret_value->_errno = errno;
        ret_value->_error = (ret_value->u.ret) ? true : false;
        lttng_directory_handle_put(handle);
end:
        return ret_value->u.ret;
}

static
int _rmdir(struct run_as_data *data, struct run_as_ret *ret_value)
{
        struct lttng_directory_handle *handle;

        handle = lttng_directory_handle_create_from_dirfd(data->u.rmdir.dirfd);
        if (!handle) {
                ret_value->u.ret = -1;
                ret_value->_errno = errno;
                ret_value->_error = true;
                goto end;
        }

        /* Ownership of dirfd is transferred to the handle. */
        data->u.rmdir.dirfd = -1;

        ret_value->u.ret = lttng_directory_handle_remove_subdirectory(
                        handle, data->u.rmdir.path);
        ret_value->_errno = errno;
        ret_value->_error = (ret_value->u.ret) ? true : false;
        lttng_directory_handle_put(handle);
end:
        return ret_value->u.ret;
}

static
int _rmdir_recursive(struct run_as_data *data, struct run_as_ret *ret_value)
{
        struct lttng_directory_handle *handle;

        handle = lttng_directory_handle_create_from_dirfd(data->u.rmdir.dirfd);
        if (!handle) {
                ret_value->u.ret = -1;
                ret_value->_errno = errno;
                ret_value->_error = true;
                goto end;
        }

        /* Ownership of dirfd is transferred to the handle. */
        data->u.rmdir.dirfd = -1;

        ret_value->u.ret = lttng_directory_handle_remove_subdirectory_recursive(
                        handle, data->u.rmdir.path, data->u.rmdir.flags);
        ret_value->_errno = errno;
        ret_value->_error = (ret_value->u.ret) ? true : false;
        lttng_directory_handle_put(handle);
end:
        return ret_value->u.ret;
}

static
int _rename(struct run_as_data *data, struct run_as_ret *ret_value)
{
        const char *old_path, *new_path;
        struct lttng_directory_handle *old_handle = NULL, *new_handle = NULL;

        old_path = data->u.rename.old_path;
        new_path = data->u.rename.new_path;

        old_handle = lttng_directory_handle_create_from_dirfd(
                        data->u.rename.dirfds[0]);
        if (!old_handle) {
                ret_value->u.ret = -1;
                goto end;
        }
        new_handle = lttng_directory_handle_create_from_dirfd(
                        data->u.rename.dirfds[1]);
        if (!new_handle) {
                ret_value->u.ret = -1;
                goto end;
        }

        /* Ownership of dirfds are transferred to the handles. */
        data->u.rename.dirfds[0] = data->u.rename.dirfds[1] = -1;

        /* Safe to call as we have transitioned to the requested uid/gid. */
        ret_value->u.ret = lttng_directory_handle_rename(
                        old_handle, old_path, new_handle, new_path);
end:
        lttng_directory_handle_put(old_handle);
        lttng_directory_handle_put(new_handle);
        ret_value->_errno = errno;
        ret_value->_error = (ret_value->u.ret) ? true : false;
        return ret_value->u.ret;
}

#ifdef HAVE_ELF_H
static
int _extract_elf_symbol_offset(struct run_as_data *data,
                struct run_as_ret *ret_value)
{
        int ret = 0;
        uint64_t offset;

        ret_value->_error = false;
        ret = lttng_elf_get_symbol_offset(data->u.extract_elf_symbol_offset.fd,
                         data->u.extract_elf_symbol_offset.function,
                         &offset);
        if (ret) {
                DBG("Failed to extract ELF function offset");
                ret_value->_error = true;
        }
        ret_value->u.extract_elf_symbol_offset.offset = offset;

        return ret;
}

static
int _extract_sdt_probe_offsets(struct run_as_data *data,
                struct run_as_ret *ret_value)
{
        int ret = 0;
        uint64_t *offsets = NULL;
        uint32_t num_offset;

        ret_value->_error = false;

        /* On success, this call allocates the offsets paramater. */
        ret = lttng_elf_get_sdt_probe_offsets(
                        data->u.extract_sdt_probe_offsets.fd,
                        data->u.extract_sdt_probe_offsets.provider_name,
                        data->u.extract_sdt_probe_offsets.probe_name,
                        &offsets, &num_offset);

        if (ret) {
                DBG("Failed to extract SDT probe offsets");
                ret_value->_error = true;
                goto end;
        }

        if (num_offset <= 0 || num_offset > LTTNG_KERNEL_ABI_MAX_UPROBE_NUM) {
                DBG("Wrong number of probes.");
                ret = -1;
                ret_value->_error = true;
                goto free_offset;
        }

        /* Copy the content of the offsets array to the ret struct. */
        memcpy(ret_value->u.extract_sdt_probe_offsets.offsets,
                        offsets, num_offset * sizeof(uint64_t));

        ret_value->u.extract_sdt_probe_offsets.num_offset = num_offset;

free_offset:
        free(offsets);
end:
        return ret;
}
#else
static
int _extract_elf_symbol_offset(struct run_as_data *data,
                struct run_as_ret *ret_value)
{
        ERR("Unimplemented runas command RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET");
        return -1;
}

static
int _extract_sdt_probe_offsets(struct run_as_data *data,
                struct run_as_ret *ret_value)
{
        ERR("Unimplemented runas command RUN_AS_EXTRACT_SDT_PROBE_OFFSETS");
        return -1;
}
#endif

static
int _generate_filter_bytecode(struct run_as_data *data,
                struct run_as_ret *ret_value) {
        int ret = 0;
        const char *filter_expression = NULL;
        struct filter_parser_ctx *ctx = NULL;

        ret_value->_error = false;

        filter_expression = data->u.generate_filter_bytecode.filter_expression;

        if (lttng_strnlen(filter_expression, LTTNG_FILTER_MAX_LEN - 1) == LTTNG_FILTER_MAX_LEN - 1) {
                ret_value->_error = true;
                ret = -1;
                goto end;
        }

        ret = filter_parser_ctx_create_from_filter_expression(filter_expression, &ctx);
        if (ret < 0) {
                ret_value->_error = true;
                ret = -1;
                goto end;
        }

        DBG("Size of bytecode generated: %u bytes.",
                        bytecode_get_len(&ctx->bytecode->b));

        /* Copy the lttng_bytecode_filter object to the return structure. */
        memcpy(ret_value->u.generate_filter_bytecode.bytecode,
                        &ctx->bytecode->b,
                        sizeof(ctx->bytecode->b) +
                                        bytecode_get_len(&ctx->bytecode->b));

end:
        if (ctx) {
                filter_bytecode_free(ctx);
                filter_ir_free(ctx);
                filter_parser_ctx_free(ctx);
        }

        return ret;
}
static
run_as_fct run_as_enum_to_fct(enum run_as_cmd cmd)
{
        switch (cmd) {
        case RUN_AS_MKDIR:
        case RUN_AS_MKDIRAT:
                return _mkdirat;
        case RUN_AS_MKDIR_RECURSIVE:
        case RUN_AS_MKDIRAT_RECURSIVE:
                return _mkdirat_recursive;
        case RUN_AS_OPEN:
        case RUN_AS_OPENAT:
                return _open;
        case RUN_AS_UNLINK:
        case RUN_AS_UNLINKAT:
                return _unlink;
        case RUN_AS_RMDIR:
        case RUN_AS_RMDIRAT:
                return _rmdir;
        case RUN_AS_RMDIR_RECURSIVE:
        case RUN_AS_RMDIRAT_RECURSIVE:
                return _rmdir_recursive;
        case RUN_AS_RENAME:
        case RUN_AS_RENAMEAT:
                return _rename;
        case RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET:
                return _extract_elf_symbol_offset;
        case RUN_AS_EXTRACT_SDT_PROBE_OFFSETS:
                return _extract_sdt_probe_offsets;
        case RUN_AS_GENERATE_FILTER_BYTECODE:
                return _generate_filter_bytecode;
        default:
                ERR("Unknown command %d", (int) cmd);
                return NULL;
        }
}

static
int do_send_fds(int sock, const int *fds, unsigned int fd_count)
{
        ssize_t len;
        unsigned int i;

        for (i = 0; i < fd_count; i++) {
                if (fds[i] < 0) {
                        DBG("Attempt to send invalid file descriptor (fd = %i)",
                                        fds[i]);
                        /* Return 0 as this is not a fatal error. */
                        return 0;
                }
        }

        len = lttcomm_send_fds_unix_sock(sock, fds, fd_count);
        return len < 0 ? -1 : 0;
}

static
int do_recv_fds(int sock, int *fds, unsigned int fd_count)
{
        int ret = 0;
        unsigned int i;
        ssize_t len;

        len = lttcomm_recv_fds_unix_sock(sock, fds, fd_count);
        if (len == 0) {
                ret = -1;
                goto end;
        } else if (len < 0) {
                PERROR("Failed to receive file descriptors from socket");
                ret = -1;
                goto end;
        }

        for (i = 0; i < fd_count; i++) {
                if (fds[i] < 0) {
                        ERR("Invalid file descriptor received from worker (fd = %i)", fds[i]);
                        /* Return 0 as this is not a fatal error. */
                }
        }
end:
        return ret;
}

static
int send_fds_to_worker(const struct run_as_worker *worker,
                const struct run_as_data *data)
{
        int ret = 0;
        unsigned int i;

        if (COMMAND_USE_CWD_FD(data) || COMMAND_IN_FD_COUNT(data) == 0) {
                goto end;
        }

        for (i = 0; i < COMMAND_IN_FD_COUNT(data); i++) {
                if (COMMAND_IN_FDS(data)[i] < 0) {
                        ERR("Refusing to send invalid fd to worker (fd = %i)",
                                        COMMAND_IN_FDS(data)[i]);
                        ret = -1;
                        goto end;
                }
        }

        ret = do_send_fds(worker->sockpair[0], COMMAND_IN_FDS(data),
                        COMMAND_IN_FD_COUNT(data));
        if (ret < 0) {
                PERROR("Failed to send file descriptor to run-as worker");
                ret = -1;
                goto end;
        }
end:
        return ret;
}

static
int send_fds_to_master(struct run_as_worker *worker, enum run_as_cmd cmd,
                struct run_as_ret *run_as_ret)
{
        int ret = 0;
        unsigned int i;

        if (COMMAND_OUT_FD_COUNT(cmd) == 0) {
                goto end;
        }

        ret = do_send_fds(worker->sockpair[1], COMMAND_OUT_FDS(cmd, run_as_ret),
                        COMMAND_OUT_FD_COUNT(cmd));
        if (ret < 0) {
                PERROR("Failed to send file descriptor to master process");
                goto end;
        }

        for (i = 0; i < COMMAND_OUT_FD_COUNT(cmd); i++) {
                int fd = COMMAND_OUT_FDS(cmd, run_as_ret)[i];
                if (fd >= 0) {
                        int ret_close = close(fd);

                        if (ret_close < 0) {
                                PERROR("Failed to close result file descriptor (fd = %i)",
                                                fd);
                        }
                }
        }
end:
        return ret;
}

static
int recv_fds_from_worker(const struct run_as_worker *worker, enum run_as_cmd cmd,
                struct run_as_ret *run_as_ret)
{
        int ret = 0;

        if (COMMAND_OUT_FD_COUNT(cmd) == 0) {
                goto end;
        }

        ret = do_recv_fds(worker->sockpair[0], COMMAND_OUT_FDS(cmd, run_as_ret),
                        COMMAND_OUT_FD_COUNT(cmd));
        if (ret < 0) {
                PERROR("Failed to receive file descriptor from run-as worker");
                ret = -1;
        }
end:
        return ret;
}

static
int recv_fds_from_master(struct run_as_worker *worker, struct run_as_data *data)
{
        int ret = 0;

        if (COMMAND_USE_CWD_FD(data)) {
                unsigned int i;

                for (i = 0; i < COMMAND_IN_FD_COUNT(data); i++) {
                        COMMAND_IN_FDS(data)[i] = AT_FDCWD;
                }
                goto end;
        }

        if (COMMAND_IN_FD_COUNT(data) == 0) {
                goto end;
        }

        ret = do_recv_fds(worker->sockpair[1], COMMAND_IN_FDS(data),
                        COMMAND_IN_FD_COUNT(data));
        if (ret < 0) {
                PERROR("Failed to receive file descriptors from master process");
                ret = -1;
        }
end:
        return ret;
}

static
int cleanup_received_fds(struct run_as_data *data)
{
        int ret = 0, i;

        for (i = 0; i < COMMAND_IN_FD_COUNT(data); i++) {
                if (COMMAND_IN_FDS(data)[i] == -1) {
                        continue;
                }
                ret = close(COMMAND_IN_FDS(data)[i]);
                if (ret) {
                        PERROR("Failed to close file descriptor received fd in run-as worker");
                        goto end;
                }
        }
end:
        return ret;
}

static int get_user_infos_from_uid(
                uid_t uid, char **username, gid_t *primary_gid)
{
        int ret;
        char *buf = NULL;
        size_t buf_size;
        struct passwd pwd;
        struct passwd *result = NULL;

        /* Fetch the max size for the temporary buffer. */
        errno = 0;
        buf_size = sysconf(_SC_GETPW_R_SIZE_MAX);
        if (buf_size < 0) {
                if (errno != 0) {
                        PERROR("Failed to query _SC_GETPW_R_SIZE_MAX");
                        goto error;
                }

                /* Limit is indeterminate. */
                WARN("Failed to query _SC_GETPW_R_SIZE_MAX as it is "
                        "indeterminate; falling back to default buffer size");
                buf_size = GETPW_BUFFER_FALLBACK_SIZE;
        }

        buf = zmalloc(buf_size);
        if (buf == NULL) {
                PERROR("Failed to allocate buffer to get password file entries");
                goto error;
        }

        ret = getpwuid_r(uid, &pwd, buf, buf_size, &result);
        if (ret < 0) {
                PERROR("Failed to get user information for user:  uid = %d",
                                (int) uid);
                goto error;
        }

        if (result == NULL) {
                ERR("Failed to find user information in password entries: uid = %d",
                                (int) uid);
                ret = -1;
                goto error;
        }

        *username = strdup(result->pw_name);
        if (*username == NULL) {
                PERROR("Failed to copy user name");
                goto error;
        }

        *primary_gid = result->pw_gid;

end:
        free(buf);
        return ret;
error:
        *username = NULL;
        *primary_gid = -1;
        ret = -1;
        goto end;
}

static int demote_creds(
                uid_t prev_uid, gid_t prev_gid, uid_t new_uid, gid_t new_gid)
{
        int ret = 0;
        gid_t primary_gid;
        char *username = NULL;

        /* Change the group id. */
        if (prev_gid != new_gid) {
                ret = setegid(new_gid);
                if (ret < 0) {
                        PERROR("Failed to set effective group id: new_gid = %d",
                                        (int) new_gid);
                        goto end;
                }
        }

        /* Change the user id. */
        if (prev_uid != new_uid) {
                ret = get_user_infos_from_uid(new_uid, &username, &primary_gid);
                if (ret < 0) {
                        goto end;
                }

                /*
                 * Initialize the supplementary group access list.
                 *
                 * This is needed to handle cases where the supplementary groups
                 * of the user the process is demoting-to would give it access
                 * to a given file/folder, but not it's primary group.
                 *
                 * e.g
                 *   username: User1
                 *   Primary Group: User1
                 *   Secondary group: Disk, Network
                 *
                 *   mkdir inside the following directory must work since User1
                 *   is part of the Network group.
                 *
                 *   drwxrwx--- 2 root Network 4096 Jul 23 17:17 /tmp/my_folder/
                 *
                 *
                 * The order of the following initgroups and seteuid calls is
                 * important here;
                 * Only a root process or one with CAP_SETGID capability can
                 * call the the initgroups() function. We must initialize the
                 * supplementary groups before we change the effective
                 * UID to a less-privileged user.
                 */
                ret = initgroups(username, primary_gid);
                if (ret < 0) {
                        PERROR("Failed to init the supplementary group access list: "
                                        "username = `%s`, primary gid = %d", username,
                                        (int) primary_gid);
                        goto end;
                }

                ret = seteuid(new_uid);
                if (ret < 0) {
                        PERROR("Failed to set effective user id: new_uid = %d",
                                        (int) new_uid);
                        goto end;
                }
        }
end:
        free(username);
        return ret;
}

static int promote_creds(
                uid_t prev_uid, gid_t prev_gid, uid_t new_uid, gid_t new_gid)
{
        int ret = 0;
        gid_t primary_gid;
        char *username = NULL;

        /* Change the group id. */
        if (prev_gid != new_gid) {
                ret = setegid(new_gid);
                if (ret < 0) {
                        PERROR("Failed to set effective group id: new_gid = %d",
                                        (int) new_gid);
                        goto end;
                }
        }

        /* Change the user id. */
        if (prev_uid != new_uid) {
                ret = get_user_infos_from_uid(new_uid, &username, &primary_gid);
                if (ret < 0) {
                        goto end;
                }

                /*
                 * seteuid call must be done before the initgroups call because
                 * we need to be privileged (CAP_SETGID) to call initgroups().
                 */
                ret = seteuid(new_uid);
                if (ret < 0) {
                        PERROR("Failed to set effective user id: new_uid = %d",
                                        (int) new_uid);
                        goto end;
                }

                /*
                 * Initialize the supplementary group access list.
                 *
                 * There is a possibility the groups we set in the following
                 * initgroups() call are not exactly the same as the ones we
                 * had when we originally demoted. This can happen if the
                 * /etc/group file is modified after the runas process is
                 * forked. This is very unlikely.
                 */
                ret = initgroups(username, primary_gid);
                if (ret < 0) {
                        PERROR("Failed to init the supplementary group access "
                                        "list: username = `%s`, primary gid = %d",
                                        username, (int) primary_gid)
                        goto end;
                }
        }
end:
        free(username);
        return ret;
}

/*
 * Return < 0 on error, 0 if OK, 1 on hangup.
 */
static
int handle_one_cmd(struct run_as_worker *worker)
{
        int ret = 0, promote_ret;
        struct run_as_data data = {};
        ssize_t readlen, writelen;
        struct run_as_ret sendret = {};
        run_as_fct cmd;
        const uid_t prev_ruid = getuid();
        const gid_t prev_rgid = getgid();

        /*
         * Stage 1: Receive run_as_data struct from the master.
         * The structure contains the command type and all the parameters needed for
         * its execution
         */
        readlen = lttcomm_recv_unix_sock(worker->sockpair[1], &data,
                        sizeof(data));
        if (readlen == 0) {
                /* hang up */
                ret = 1;
                goto end;
        }
        if (readlen < sizeof(data)) {
                PERROR("lttcomm_recv_unix_sock error");
                ret = -1;
                goto end;
        }

        cmd = run_as_enum_to_fct(data.cmd);
        if (!cmd) {
                ret = -1;
                goto end;
        }

        /*
         * Stage 2: Receive file descriptor from master.
         * Some commands need a file descriptor as input so if it's needed we
         * receive the fd using the Unix socket.
         */
        ret = recv_fds_from_master(worker, &data);
        if (ret < 0) {
                PERROR("recv_fd_from_master error");
                ret = -1;
                goto end;
        }

        ret = demote_creds(prev_ruid, prev_rgid, data.uid, data.gid);
        if (ret < 0) {
                goto write_return;
        }

        /*
         * Also set umask to 0 for mkdir executable bit.
         */
        umask(0);

        /*
         * Stage 3: Execute the command
         */
        ret = (*cmd)(&data, &sendret);
        if (ret < 0) {
                DBG("Execution of command returned an error");
        }

write_return:
        ret = cleanup_received_fds(&data);
        if (ret < 0) {
                ERR("Error cleaning up FD");
                goto promote_back;
        }

        /*
         * Stage 4: Send run_as_ret structure to the master.
         * This structure contain the return value of the command and the errno.
         */
        writelen = lttcomm_send_unix_sock(worker->sockpair[1], &sendret,
                        sizeof(sendret));
        if (writelen < sizeof(sendret)) {
                PERROR("lttcomm_send_unix_sock error");
                ret = -1;
                goto promote_back;
        }

        /*
         * Stage 5: Send resulting file descriptors to the master.
         */
        ret = send_fds_to_master(worker, data.cmd, &sendret);
        if (ret < 0) {
                DBG("Sending FD to master returned an error");
        }

        ret = 0;

promote_back:
        /* Return to previous uid/gid. */
        promote_ret = promote_creds(data.uid, data.gid, prev_ruid, prev_rgid);
        if (promote_ret < 0) {
                ERR("Failed to promote back to the initial credentials");
        }

end:
        return ret;
}

static
int run_as_worker(struct run_as_worker *worker)
{
        int ret;
        ssize_t writelen;
        struct run_as_ret sendret;
        size_t proc_orig_len;

        /*
         * Initialize worker. Set a different process cmdline.
         */
        proc_orig_len = strlen(worker->procname);
        memset(worker->procname, 0, proc_orig_len);
        strncpy(worker->procname, DEFAULT_RUN_AS_WORKER_NAME, proc_orig_len);

        ret = lttng_thread_setname(DEFAULT_RUN_AS_WORKER_NAME);
        if (ret && ret != -ENOSYS) {
                /* Don't fail as this is not essential. */
                DBG("Failed to set pthread name attribute");
        }

        memset(&sendret, 0, sizeof(sendret));

        writelen = lttcomm_send_unix_sock(worker->sockpair[1], &sendret,
                        sizeof(sendret));
        if (writelen < sizeof(sendret)) {
                PERROR("lttcomm_send_unix_sock error");
                ret = EXIT_FAILURE;
                goto end;
        }

        for (;;) {
                ret = handle_one_cmd(worker);
                if (ret < 0) {
                        ret = EXIT_FAILURE;
                        goto end;
                } else if (ret > 0) {
                        break;
                } else {
                        continue;       /* Next command. */
                }
        }
        ret = EXIT_SUCCESS;
end:
        return ret;
}

static
int run_as_cmd(struct run_as_worker *worker,
                enum run_as_cmd cmd,
                struct run_as_data *data,
                struct run_as_ret *ret_value,
                uid_t uid, gid_t gid)
{
        int ret = 0;
        ssize_t readlen, writelen;

        /*
         * If we are non-root, we can only deal with our own uid.
         */
        if (geteuid() != 0) {
                if (uid != geteuid()) {
                        ret = -1;
                        ret_value->_errno = EPERM;
                        ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)",
                                (int) uid, (int) geteuid());
                        goto end;
                }
        }

        data->cmd = cmd;
        data->uid = uid;
        data->gid = gid;

        /*
         * Stage 1: Send the run_as_data struct to the worker process
         */
        writelen = lttcomm_send_unix_sock(worker->sockpair[0], data,
                        sizeof(*data));
        if (writelen < sizeof(*data)) {
                PERROR("Error writing message to run_as");
                ret = -1;
                ret_value->_errno = EIO;
                goto end;
        }

        /*
         * Stage 2: Send file descriptor to the worker process if needed
         */
        ret = send_fds_to_worker(worker, data);
        if (ret) {
                PERROR("do_send_fd error");
                ret = -1;
                ret_value->_errno = EIO;
                goto end;
        }

        /*
         * Stage 3: Wait for the execution of the command
         */

        /*
         * Stage 4: Receive the run_as_ret struct containing the return value and
         * errno
         */
        readlen = lttcomm_recv_unix_sock(worker->sockpair[0], ret_value,
                        sizeof(*ret_value));
        if (!readlen) {
                ERR("Run-as worker has hung-up during run_as_cmd");
                ret = -1;
                ret_value->_errno = EIO;
                goto end;
        } else if (readlen < sizeof(*ret_value)) {
                PERROR("Error reading response from run_as");
                ret = -1;
                ret_value->_errno = errno;
                goto end;
        }

        if (ret_value->_error) {
                /* Skip stage 5 on error as there will be no fd to receive. */
                goto end;
        }

        /*
         * Stage 5: Receive file descriptor if needed
         */
        ret = recv_fds_from_worker(worker, cmd, ret_value);
        if (ret < 0) {
                ERR("Error receiving fd");
                ret = -1;
                ret_value->_errno = EIO;
        }

end:
        return ret;
}

/*
 * This is for debugging ONLY and should not be considered secure.
 */
static
int run_as_noworker(enum run_as_cmd cmd,
                struct run_as_data *data, struct run_as_ret *ret_value,
                uid_t uid, gid_t gid)
{
        int ret, saved_errno;
        mode_t old_mask;
        run_as_fct fct;

        fct = run_as_enum_to_fct(cmd);
        if (!fct) {
                errno = -ENOSYS;
                ret = -1;
                goto end;
        }
        old_mask = umask(0);
        ret = fct(data, ret_value);
        saved_errno = ret_value->_errno;
        umask(old_mask);
        errno = saved_errno;
end:
        return ret;
}

static
int reset_sighandler(void)
{
        int sig;

        DBG("Resetting run_as worker signal handlers to default");
        for (sig = 1; sig <= 31; sig++) {
                (void) signal(sig, SIG_DFL);
        }
        return 0;
}

static
void worker_sighandler(int sig)
{
        const char *signame;

        /*
         * The worker will inherit its parent's signals since they are part of
         * the same process group. However, in the case of SIGINT and SIGTERM,
         * we want to give the worker a chance to teardown gracefully when its
         * parent closes the command socket.
         */
        switch (sig) {
        case SIGINT:
                signame = "SIGINT";
                break;
        case SIGTERM:
                signame = "SIGTERM";
                break;
        default:
                signame = NULL;
        }

        if (signame) {
                DBG("run_as worker received signal %s", signame);
        } else {
                DBG("run_as_worker received signal %d", sig);
        }
}

static
int set_worker_sighandlers(void)
{
        int ret = 0;
        sigset_t sigset;
        struct sigaction sa;

        if ((ret = sigemptyset(&sigset)) < 0) {
                PERROR("sigemptyset");
                goto end;
        }

        sa.sa_handler = worker_sighandler;
        sa.sa_mask = sigset;
        sa.sa_flags = 0;
        if ((ret = sigaction(SIGINT, &sa, NULL)) < 0) {
                PERROR("sigaction SIGINT");
                goto end;
        }

        if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
                PERROR("sigaction SIGTERM");
                goto end;
        }

        DBG("run_as signal handler set for SIGTERM and SIGINT");
end:
        return ret;
}

static
int run_as_create_worker_no_lock(const char *procname,
                post_fork_cleanup_cb clean_up_func,
                void *clean_up_user_data)
{
        pid_t pid;
        int i, ret = 0;
        ssize_t readlen;
        struct run_as_ret recvret;
        struct run_as_worker *worker;

        assert(!global_worker);
        if (!use_clone()) {
                /*
                 * Don't initialize a worker, all run_as tasks will be performed
                 * in the current process.
                 */
                ret = 0;
                goto end;
        }
        worker = zmalloc(sizeof(*worker));
        if (!worker) {
                ret = -ENOMEM;
                goto end;
        }
        worker->procname = strdup(procname);
        if (!worker->procname) {
                ret = -ENOMEM;
                goto error_procname_alloc;
        }
        /* Create unix socket. */
        if (lttcomm_create_anon_unix_socketpair(worker->sockpair) < 0) {
                ret = -1;
                goto error_sock;
        }

        /* Fork worker. */
        pid = fork();
        if (pid < 0) {
                PERROR("fork");
                ret = -1;
                goto error_fork;
        } else if (pid == 0) {
                /* Child */

                reset_sighandler();

                set_worker_sighandlers();

                logger_set_thread_name("Run-as worker", true);

                if (clean_up_func) {
                        if (clean_up_func(clean_up_user_data) < 0) {
                                ERR("Run-as post-fork clean-up failed, exiting.");
                                exit(EXIT_FAILURE);
                        }
                }

                /* Just close, no shutdown. */
                if (close(worker->sockpair[0])) {
                        PERROR("close");
                        exit(EXIT_FAILURE);
                }

                /*
                 * Close all FDs aside from STDIN, STDOUT, STDERR and sockpair[1]
                 * Sockpair[1] is used as a control channel with the master
                 */
                for (i = 3; i < sysconf(_SC_OPEN_MAX); i++) {
                        if (i != worker->sockpair[1]) {
                                (void) close(i);
                        }
                }

                worker->sockpair[0] = -1;
                ret = run_as_worker(worker);
                if (lttcomm_close_unix_sock(worker->sockpair[1])) {
                        PERROR("close");
                        ret = -1;
                }
                worker->sockpair[1] = -1;
                free(worker->procname);
                free(worker);
                LOG(ret ? PRINT_ERR : PRINT_DBG, "run_as worker exiting (ret = %d)", ret);
                exit(ret ? EXIT_FAILURE : EXIT_SUCCESS);
        } else {
                /* Parent */

                /* Just close, no shutdown. */
                if (close(worker->sockpair[1])) {
                        PERROR("close");
                        ret = -1;
                        goto error_fork;
                }
                worker->sockpair[1] = -1;
                worker->pid = pid;
                /* Wait for worker to become ready. */
                readlen = lttcomm_recv_unix_sock(worker->sockpair[0],
                                &recvret, sizeof(recvret));
                if (readlen < sizeof(recvret)) {
                        ERR("readlen: %zd", readlen);
                        PERROR("Error reading response from run_as at creation");
                        ret = -1;
                        goto error_fork;
                }
                global_worker = worker;
        }
end:
        return ret;

        /* Error handling. */
error_fork:
        for (i = 0; i < 2; i++) {
                if (worker->sockpair[i] < 0) {
                        continue;
                }
                if (lttcomm_close_unix_sock(worker->sockpair[i])) {
                        PERROR("close");
                }
                worker->sockpair[i] = -1;
        }
error_sock:
        free(worker->procname);
error_procname_alloc:
        free(worker);
        return ret;
}

static
void run_as_destroy_worker_no_lock(void)
{
        struct run_as_worker *worker = global_worker;

        DBG("Destroying run_as worker");
        if (!worker) {
                return;
        }
        /* Close unix socket */
        DBG("Closing run_as worker socket");
        if (lttcomm_close_unix_sock(worker->sockpair[0])) {
                PERROR("close");
        }
        worker->sockpair[0] = -1;
        /* Wait for worker. */
        for (;;) {
                int status;
                pid_t wait_ret;

                wait_ret = waitpid(worker->pid, &status, 0);
                if (wait_ret < 0) {
                        if (errno == EINTR) {
                                continue;
                        }
                        PERROR("waitpid");
                        break;
                }

                if (WIFEXITED(status)) {
                        LOG(WEXITSTATUS(status) == 0 ? PRINT_DBG : PRINT_ERR,
                                        DEFAULT_RUN_AS_WORKER_NAME " terminated with status code %d",
                                        WEXITSTATUS(status));
                        break;
                } else if (WIFSIGNALED(status)) {
                        ERR(DEFAULT_RUN_AS_WORKER_NAME " was killed by signal %d",
                                        WTERMSIG(status));
                        break;
                }
        }
        free(worker->procname);
        free(worker);
        global_worker = NULL;
}

static
int run_as_restart_worker(struct run_as_worker *worker)
{
        int ret = 0;
        char *procname = NULL;

        procname = worker->procname;

        /* Close socket to run_as worker process and clean up the zombie process */
        run_as_destroy_worker_no_lock();

        /* Create a new run_as worker process*/
        ret = run_as_create_worker_no_lock(procname, NULL, NULL);
        if (ret < 0 ) {
                ERR("Restarting the worker process failed");
                ret = -1;
                goto err;
        }
err:
        return ret;
}

static
int run_as(enum run_as_cmd cmd, struct run_as_data *data,
                   struct run_as_ret *ret_value, uid_t uid, gid_t gid)
{
        int ret, saved_errno;

        pthread_mutex_lock(&worker_lock);
        if (use_clone()) {
                DBG("Using run_as worker");

                assert(global_worker);

                ret = run_as_cmd(global_worker, cmd, data, ret_value, uid, gid);
                saved_errno = ret_value->_errno;

                /*
                 * If the worker thread crashed the errno is set to EIO. we log
                 * the error and  start a new worker process.
                 */
                if (ret == -1 && saved_errno == EIO) {
                        DBG("Socket closed unexpectedly... "
                                        "Restarting the worker process");
                        ret = run_as_restart_worker(global_worker);
                        if (ret == -1) {
                                ERR("Failed to restart worker process.");
                                goto err;
                        }
                }
        } else {
                DBG("Using run_as without worker");
                ret = run_as_noworker(cmd, data, ret_value, uid, gid);
        }
err:
        pthread_mutex_unlock(&worker_lock);
        return ret;
}

LTTNG_HIDDEN
int run_as_mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid)
{
        return run_as_mkdirat_recursive(AT_FDCWD, path, mode, uid, gid);
}

LTTNG_HIDDEN
int run_as_mkdirat_recursive(int dirfd, const char *path, mode_t mode,
                uid_t uid, gid_t gid)
{
        int ret;
        struct run_as_data data = {};
        struct run_as_ret run_as_ret = {};

        DBG3("mkdirat() recursive fd = %d%s, path = %s, mode = %d, uid = %d, gid = %d",
                        dirfd, dirfd == AT_FDCWD ? " (AT_FDCWD)" : "",
                        path, (int) mode, (int) uid, (int) gid);
        ret = lttng_strncpy(data.u.mkdir.path, path,
                        sizeof(data.u.mkdir.path));
        if (ret) {
                ERR("Failed to copy path argument of mkdirat recursive command");
                goto error;
        }
        data.u.mkdir.path[sizeof(data.u.mkdir.path) - 1] = '\0';
        data.u.mkdir.mode = mode;
        data.u.mkdir.dirfd = dirfd;
        run_as(dirfd == AT_FDCWD ? RUN_AS_MKDIR_RECURSIVE : RUN_AS_MKDIRAT_RECURSIVE,
                        &data, &run_as_ret, uid, gid);
        errno = run_as_ret._errno;
        ret = run_as_ret.u.ret;
error:
        return ret;
}

LTTNG_HIDDEN
int run_as_mkdir(const char *path, mode_t mode, uid_t uid, gid_t gid)
{
        return run_as_mkdirat(AT_FDCWD, path, mode, uid, gid);
}

LTTNG_HIDDEN
int run_as_mkdirat(int dirfd, const char *path, mode_t mode,
                uid_t uid, gid_t gid)
{
        int ret;
        struct run_as_data data = {};
        struct run_as_ret run_as_ret = {};

        DBG3("mkdirat() recursive fd = %d%s, path = %s, mode = %d, uid = %d, gid = %d",
                        dirfd, dirfd == AT_FDCWD ? " (AT_FDCWD)" : "",
                        path, (int) mode, (int) uid, (int) gid);
        ret = lttng_strncpy(data.u.mkdir.path, path,
                        sizeof(data.u.mkdir.path));
        if (ret) {
                ERR("Failed to copy path argument of mkdirat command");
                goto error;
        }
        data.u.mkdir.path[sizeof(data.u.mkdir.path) - 1] = '\0';
        data.u.mkdir.mode = mode;
        data.u.mkdir.dirfd = dirfd;
        run_as(dirfd == AT_FDCWD ? RUN_AS_MKDIR : RUN_AS_MKDIRAT,
                        &data, &run_as_ret, uid, gid);
        errno = run_as_ret._errno;
        ret = run_as_ret.u.ret;
error:
        return ret;
}

LTTNG_HIDDEN
int run_as_open(const char *path, int flags, mode_t mode, uid_t uid,
                gid_t gid)
{
        return run_as_openat(AT_FDCWD, path, flags, mode, uid, gid);
}

LTTNG_HIDDEN
int run_as_openat(int dirfd, const char *path, int flags, mode_t mode,
                uid_t uid, gid_t gid)
{
        int ret;
        struct run_as_data data = {};
        struct run_as_ret run_as_ret = {};

        DBG3("openat() fd = %d%s, path = %s, flags = %X, mode = %d, uid %d, gid %d",
                        dirfd, dirfd == AT_FDCWD ? " (AT_FDCWD)" : "",
                        path, flags, (int) mode, (int) uid, (int) gid);
        ret = lttng_strncpy(data.u.open.path, path, sizeof(data.u.open.path));
        if (ret) {
                ERR("Failed to copy path argument of open command");
                goto error;
        }
        data.u.open.flags = flags;
        data.u.open.mode = mode;
        data.u.open.dirfd = dirfd;
        run_as(dirfd == AT_FDCWD ? RUN_AS_OPEN : RUN_AS_OPENAT,
                        &data, &run_as_ret, uid, gid);
        errno = run_as_ret._errno;
        ret = run_as_ret.u.ret < 0 ? run_as_ret.u.ret :
                        run_as_ret.u.open.fd;
error:
        return ret;
}

LTTNG_HIDDEN
int run_as_unlink(const char *path, uid_t uid, gid_t gid)
{
        return run_as_unlinkat(AT_FDCWD, path, uid, gid);
}

LTTNG_HIDDEN
int run_as_unlinkat(int dirfd, const char *path, uid_t uid, gid_t gid)
{
        int ret;
        struct run_as_data data = {};
        struct run_as_ret run_as_ret = {};

        DBG3("unlinkat() fd = %d%s, path = %s, uid = %d, gid = %d",
                        dirfd, dirfd == AT_FDCWD ? " (AT_FDCWD)" : "",
                        path, (int) uid, (int) gid);
        ret = lttng_strncpy(data.u.unlink.path, path,
                        sizeof(data.u.unlink.path));
        if (ret) {
                goto error;
        }
        data.u.unlink.dirfd = dirfd;
        run_as(dirfd == AT_FDCWD ? RUN_AS_UNLINK : RUN_AS_UNLINKAT, &data,
                        &run_as_ret, uid, gid);
        errno = run_as_ret._errno;
        ret = run_as_ret.u.ret;
error:
        return ret;
}

LTTNG_HIDDEN
int run_as_rmdir(const char *path, uid_t uid, gid_t gid)
{
        return run_as_rmdirat(AT_FDCWD, path, uid, gid);
}

LTTNG_HIDDEN
int run_as_rmdirat(int dirfd, const char *path, uid_t uid, gid_t gid)
{
        int ret;
        struct run_as_data data = {};
        struct run_as_ret run_as_ret = {};

        DBG3("rmdirat() fd = %d%s, path = %s, uid = %d, gid = %d",
                        dirfd, dirfd == AT_FDCWD ? " (AT_FDCWD)" : "",
                        path, (int) uid, (int) gid);
        ret = lttng_strncpy(data.u.rmdir.path, path,
                        sizeof(data.u.rmdir.path));
        if (ret) {
                goto error;
        }
        data.u.rmdir.dirfd = dirfd;
        run_as(dirfd == AT_FDCWD ? RUN_AS_RMDIR : RUN_AS_RMDIRAT, &data,
                        &run_as_ret, uid, gid);
        errno = run_as_ret._errno;
        ret = run_as_ret.u.ret;
error:
        return ret;
}

LTTNG_HIDDEN
int run_as_rmdir_recursive(const char *path, uid_t uid, gid_t gid, int flags)
{
        return run_as_rmdirat_recursive(AT_FDCWD, path, uid, gid, flags);
}

LTTNG_HIDDEN
int run_as_rmdirat_recursive(int dirfd, const char *path, uid_t uid, gid_t gid, int flags)
{
        int ret;
        struct run_as_data data = {};
        struct run_as_ret run_as_ret = {};

        DBG3("rmdirat() recursive fd = %d%s, path = %s, uid = %d, gid = %d",
                        dirfd, dirfd == AT_FDCWD ? " (AT_FDCWD)" : "",
                        path, (int) uid, (int) gid);
        ret = lttng_strncpy(data.u.rmdir.path, path,
                        sizeof(data.u.rmdir.path));
        if (ret) {
                goto error;
        }
        data.u.rmdir.dirfd = dirfd;
        data.u.rmdir.flags = flags;
        run_as(dirfd == AT_FDCWD ? RUN_AS_RMDIR_RECURSIVE : RUN_AS_RMDIRAT_RECURSIVE,
                        &data, &run_as_ret, uid, gid);
        errno = run_as_ret._errno;
        ret = run_as_ret.u.ret;
error:
        return ret;
}

LTTNG_HIDDEN
int run_as_rename(const char *old, const char *new, uid_t uid, gid_t gid)
{
        return run_as_renameat(AT_FDCWD, old, AT_FDCWD, new, uid, gid);
}

LTTNG_HIDDEN
int run_as_renameat(int old_dirfd, const char *old_name,
                int new_dirfd, const char *new_name, uid_t uid, gid_t gid)
{
        int ret;
        struct run_as_data data = {};
        struct run_as_ret run_as_ret = {};

        DBG3("renameat() old_dirfd = %d%s, old_name = %s, new_dirfd = %d%s, new_name = %s, uid = %d, gid = %d",
                        old_dirfd, old_dirfd == AT_FDCWD ? " (AT_FDCWD)" : "",
                        old_name,
                        new_dirfd, new_dirfd == AT_FDCWD ? " (AT_FDCWD)" : "",
                        new_name, (int) uid, (int) gid);
        ret = lttng_strncpy(data.u.rename.old_path, old_name,
                        sizeof(data.u.rename.old_path));
        if (ret) {
                goto error;
        }
        ret = lttng_strncpy(data.u.rename.new_path, new_name,
                        sizeof(data.u.rename.new_path));
        if (ret) {
                goto error;
        }

        data.u.rename.dirfds[0] = old_dirfd;
        data.u.rename.dirfds[1] = new_dirfd;
        run_as(old_dirfd == AT_FDCWD && new_dirfd == AT_FDCWD ?
                        RUN_AS_RENAME : RUN_AS_RENAMEAT,
                        &data, &run_as_ret, uid, gid);
        errno = run_as_ret._errno;
        ret = run_as_ret.u.ret;
error:
        return ret;
}

LTTNG_HIDDEN
int run_as_extract_elf_symbol_offset(int fd, const char* function,
                uid_t uid, gid_t gid, uint64_t *offset)
{
        int ret;
        struct run_as_data data = {};
        struct run_as_ret run_as_ret = {};

        DBG3("extract_elf_symbol_offset() on fd=%d and function=%s "
                        "with for uid %d and gid %d", fd, function,
                        (int) uid, (int) gid);

        data.u.extract_elf_symbol_offset.fd = fd;

        strncpy(data.u.extract_elf_symbol_offset.function, function, LTTNG_SYMBOL_NAME_LEN - 1);
        data.u.extract_elf_symbol_offset.function[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
        ret = lttng_strncpy(data.u.extract_elf_symbol_offset.function,
                        function,
                        sizeof(data.u.extract_elf_symbol_offset.function));
        if (ret) {
                goto error;
        }

        run_as(RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET, &data, &run_as_ret, uid, gid);
        errno = run_as_ret._errno;
        if (run_as_ret._error) {
                ret = -1;
                goto error;
        }

        *offset = run_as_ret.u.extract_elf_symbol_offset.offset;
error:
        return ret;
}

LTTNG_HIDDEN
int run_as_extract_sdt_probe_offsets(int fd, const char* provider_name,
                const char* probe_name, uid_t uid, gid_t gid,
                uint64_t **offsets, uint32_t *num_offset)
{
        int ret;
        struct run_as_data data = {};
        struct run_as_ret run_as_ret = {};

        DBG3("extract_sdt_probe_offsets() on fd=%d, probe_name=%s and "
                        "provider_name=%s with for uid %d and gid %d", fd,
                        probe_name, provider_name, (int) uid, (int) gid);

        data.u.extract_sdt_probe_offsets.fd = fd;

        ret = lttng_strncpy(data.u.extract_sdt_probe_offsets.probe_name, probe_name,
                        sizeof(data.u.extract_sdt_probe_offsets.probe_name));
        if (ret) {
                goto error;
        }
        ret = lttng_strncpy(data.u.extract_sdt_probe_offsets.provider_name,
                        provider_name,
                        sizeof(data.u.extract_sdt_probe_offsets.provider_name));
        if (ret) {
                goto error;
        }

        run_as(RUN_AS_EXTRACT_SDT_PROBE_OFFSETS, &data, &run_as_ret, uid, gid);
        errno = run_as_ret._errno;
        if (run_as_ret._error) {
                ret = -1;
                goto error;
        }

        *num_offset = run_as_ret.u.extract_sdt_probe_offsets.num_offset;
        *offsets = zmalloc(*num_offset * sizeof(uint64_t));
        if (!*offsets) {
                ret = -ENOMEM;
                goto error;
        }

        memcpy(*offsets, run_as_ret.u.extract_sdt_probe_offsets.offsets,
                        *num_offset * sizeof(uint64_t));
error:
        return ret;
}

LTTNG_HIDDEN
int run_as_generate_filter_bytecode(const char *filter_expression,
                const struct lttng_credentials *creds,
                struct lttng_bytecode **bytecode)
{
        int ret;
        struct run_as_data data = {};
        struct run_as_ret run_as_ret = {};
        const struct lttng_bytecode *view_bytecode = NULL;
        struct lttng_bytecode *local_bytecode = NULL;
        const uid_t uid = lttng_credentials_get_uid(creds);
        const gid_t gid = lttng_credentials_get_gid(creds);

        DBG3("generate_filter_bytecode() from expression=\"%s\" for uid %d and gid %d",
                        filter_expression, (int) uid, (int) gid);

        ret = lttng_strncpy(data.u.generate_filter_bytecode.filter_expression, filter_expression,
                        sizeof(data.u.generate_filter_bytecode.filter_expression));
        if (ret) {
                goto error;
        }

        run_as(RUN_AS_GENERATE_FILTER_BYTECODE, &data, &run_as_ret, uid, gid);
        errno = run_as_ret._errno;
        if (run_as_ret._error) {
                ret = -1;
                goto error;
        }

        view_bytecode = (const struct lttng_bytecode *) run_as_ret.u.generate_filter_bytecode.bytecode;

        local_bytecode = zmalloc(sizeof(*local_bytecode) + view_bytecode->len);
        if (!local_bytecode) {
                ret = -ENOMEM;
                goto error;
        }

        memcpy(local_bytecode, run_as_ret.u.generate_filter_bytecode.bytecode,
                        sizeof(*local_bytecode) + view_bytecode->len);
        *bytecode = local_bytecode;
error:
        return ret;
}

LTTNG_HIDDEN
int run_as_create_worker(const char *procname,
                post_fork_cleanup_cb clean_up_func,
                void *clean_up_user_data)
{
        int ret;

        pthread_mutex_lock(&worker_lock);
        ret = run_as_create_worker_no_lock(procname, clean_up_func,
                        clean_up_user_data);
        pthread_mutex_unlock(&worker_lock);
        return ret;
}

LTTNG_HIDDEN
void run_as_destroy_worker(void)
{
        pthread_mutex_lock(&worker_lock);
        run_as_destroy_worker_no_lock();
        pthread_mutex_unlock(&worker_lock);
}