* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*/
-#include <stdio.h>
-#include <sys/socket.h>
-#include <string.h>
-#include <sys/un.h>
-#include <limits.h>
-#include <signal.h>
-#include <errno.h>
-#include <stdlib.h>
+
+#include "qemu/osdep.h"
#include <sys/resource.h>
-#include <sys/stat.h>
#include <getopt.h>
-#include <unistd.h>
#include <syslog.h>
#include <sys/capability.h>
#include <sys/fsuid.h>
-#include <stdarg.h>
-#include <stdbool.h>
#include <sys/vfs.h>
-#include <sys/stat.h>
+#include <sys/ioctl.h>
+#include <linux/fs.h>
+#ifdef CONFIG_LINUX_MAGIC_H
+#include <linux/magic.h>
+#endif
#include "qemu-common.h"
-#include "virtio-9p-marshal.h"
-#include "hw/9pfs/virtio-9p-proxy.h"
-#include "fsdev/virtio-9p-marshal.h"
+#include "qemu/sockets.h"
+#include "qemu/xattr.h"
+#include "9p-iov-marshal.h"
+#include "hw/9pfs/9p-proxy.h"
+#include "fsdev/9p-iov-marshal.h"
#define PROGNAME "virtfs-proxy-helper"
+#ifndef XFS_SUPER_MAGIC
+#define XFS_SUPER_MAGIC 0x58465342
+#endif
+#ifndef EXT2_SUPER_MAGIC
+#define EXT2_SUPER_MAGIC 0xEF53
+#endif
+#ifndef REISERFS_SUPER_MAGIC
+#define REISERFS_SUPER_MAGIC 0x52654973
+#endif
+#ifndef BTRFS_SUPER_MAGIC
+#define BTRFS_SUPER_MAGIC 0x9123683E
+#endif
+
static struct option helper_opts[] = {
{"fd", required_argument, NULL, 'f'},
{"path", required_argument, NULL, 'p'},
{"nodaemon", no_argument, NULL, 'n'},
+ {"socket", required_argument, NULL, 's'},
+ {"uid", required_argument, NULL, 'u'},
+ {"gid", required_argument, NULL, 'g'},
+ {},
};
static bool is_daemon;
+static bool get_version; /* IOC getversion IOCTL supported */
-static void do_log(int loglevel, const char *format, ...)
+static void GCC_FMT_ATTR(2, 3) do_log(int loglevel, const char *format, ...)
{
va_list ap;
static int init_capabilities(void)
{
- /* helper needs following capbabilities only */
+ /* helper needs following capabilities only */
cap_value_t cap_list[] = {
CAP_CHOWN,
CAP_DAC_OVERRIDE,
static int send_status(int sockfd, struct iovec *iovec, int status)
{
ProxyHeader header;
- int retval, msg_size;;
+ int retval, msg_size;
if (status < 0) {
header.type = T_ERROR;
*/
msg_size = proxy_marshal(iovec, 0, "ddd", header.type,
header.size, status);
+ if (msg_size < 0) {
+ return msg_size;
+ }
retval = socket_write(sockfd, iovec->iov_base, msg_size);
if (retval < 0) {
return retval;
/*
* from man 7 capabilities, section
* Effect of User ID Changes on Capabilities:
- * 4. If the file system user ID is changed from 0 to nonzero (see setfsuid(2))
- * then the following capabilities are cleared from the effective set:
- * CAP_CHOWN, CAP_DAC_OVERRIDE, CAP_DAC_READ_SEARCH, CAP_FOWNER, CAP_FSETID,
- * CAP_LINUX_IMMUTABLE (since Linux 2.2.30), CAP_MAC_OVERRIDE, and CAP_MKNOD
- * (since Linux 2.2.30). If the file system UID is changed from nonzero to 0,
- * then any of these capabilities that are enabled in the permitted set
- * are enabled in the effective set.
+ * If the effective user ID is changed from nonzero to 0, then the permitted
+ * set is copied to the effective set. If the effective user ID is changed
+ * from 0 to nonzero, then all capabilities are are cleared from the effective
+ * set.
+ *
+ * The setfsuid/setfsgid man pages warn that changing the effective user ID may
+ * expose the program to unwanted signals, but this is not true anymore: for an
+ * unprivileged (without CAP_KILL) program to send a signal, the real or
+ * effective user ID of the sending process must equal the real or saved user
+ * ID of the target process. Even when dropping privileges, it is enough to
+ * keep the saved UID to a "privileged" value and virtfs-proxy-helper won't
+ * be exposed to signals. So just use setresuid/setresgid.
*/
-static int setfsugid(int uid, int gid)
+static int setugid(int uid, int gid, int *suid, int *sgid)
{
+ int retval;
+
/*
- * We still need DAC_OVERRIDE because we don't change
+ * We still need DAC_OVERRIDE because we don't change
* supplementary group ids, and hence may be subjected DAC rules
*/
cap_value_t cap_list[] = {
CAP_DAC_OVERRIDE,
};
- setfsgid(gid);
- setfsuid(uid);
+ *suid = geteuid();
+ *sgid = getegid();
+
+ if (setresgid(-1, gid, *sgid) == -1) {
+ retval = -errno;
+ goto err_out;
+ }
+
+ if (setresuid(-1, uid, *suid) == -1) {
+ retval = -errno;
+ goto err_sgid;
+ }
if (uid != 0 || gid != 0) {
- return do_cap_set(cap_list, ARRAY_SIZE(cap_list), 0);
+ if (do_cap_set(cap_list, ARRAY_SIZE(cap_list), 0) < 0) {
+ retval = -errno;
+ goto err_suid;
+ }
}
return 0;
+
+err_suid:
+ if (setresuid(-1, *suid, *suid) == -1) {
+ abort();
+ }
+err_sgid:
+ if (setresgid(-1, *sgid, *sgid) == -1) {
+ abort();
+ }
+err_out:
+ return retval;
+}
+
+/*
+ * This is used to reset the ugid back with the saved values
+ * There is nothing much we can do checking error values here.
+ */
+static void resetugid(int suid, int sgid)
+{
+ if (setresgid(-1, sgid, sgid) == -1) {
+ abort();
+ }
+ if (setresuid(-1, suid, suid) == -1) {
+ abort();
+ }
}
/*
proxy_marshal(iovec, 0, "dd", header.type, header.size);
retval = socket_write(sock, iovec->iov_base, header.size + PROXY_HDR_SZ);
if (retval < 0) {
- return retval;;
+ return retval;
}
return 0;
}
+/*
+ * gets generation number
+ * returns -errno on failure and sizeof(generation number) on success
+ */
+static int do_getversion(struct iovec *iovec, struct iovec *out_iovec)
+{
+ uint64_t version;
+ int retval = -ENOTTY;
+#ifdef FS_IOC_GETVERSION
+ int fd;
+ V9fsString path;
+#endif
+
+
+ /* no need to issue ioctl */
+ if (!get_version) {
+ version = 0;
+ retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, "q", version);
+ return retval;
+ }
+#ifdef FS_IOC_GETVERSION
+ retval = proxy_unmarshal(iovec, PROXY_HDR_SZ, "s", &path);
+ if (retval < 0) {
+ return retval;
+ }
+
+ fd = open(path.data, O_RDONLY);
+ if (fd < 0) {
+ retval = -errno;
+ goto err_out;
+ }
+ if (ioctl(fd, FS_IOC_GETVERSION, &version) < 0) {
+ retval = -errno;
+ } else {
+ retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, "q", version);
+ }
+ close(fd);
+err_out:
+ v9fs_string_free(&path);
+#endif
+ return retval;
+}
+
+static int do_getxattr(int type, struct iovec *iovec, struct iovec *out_iovec)
+{
+ int size = 0, offset, retval;
+ V9fsString path, name, xattr;
+
+ v9fs_string_init(&xattr);
+ v9fs_string_init(&path);
+ retval = proxy_unmarshal(iovec, PROXY_HDR_SZ, "ds", &size, &path);
+ if (retval < 0) {
+ return retval;
+ }
+ offset = PROXY_HDR_SZ + retval;
+
+ if (size) {
+ xattr.data = g_malloc(size);
+ xattr.size = size;
+ }
+ switch (type) {
+ case T_LGETXATTR:
+ v9fs_string_init(&name);
+ retval = proxy_unmarshal(iovec, offset, "s", &name);
+ if (retval > 0) {
+ retval = lgetxattr(path.data, name.data, xattr.data, size);
+ if (retval < 0) {
+ retval = -errno;
+ } else {
+ xattr.size = retval;
+ }
+ }
+ v9fs_string_free(&name);
+ break;
+ case T_LLISTXATTR:
+ retval = llistxattr(path.data, xattr.data, size);
+ if (retval < 0) {
+ retval = -errno;
+ } else {
+ xattr.size = retval;
+ }
+ break;
+ }
+ if (retval < 0) {
+ goto err_out;
+ }
+
+ if (!size) {
+ proxy_marshal(out_iovec, PROXY_HDR_SZ, "d", retval);
+ retval = sizeof(retval);
+ } else {
+ retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, "s", &xattr);
+ }
+err_out:
+ v9fs_string_free(&xattr);
+ v9fs_string_free(&path);
+ return retval;
+}
+
static void stat_to_prstat(ProxyStat *pr_stat, struct stat *stat)
{
memset(pr_stat, 0, sizeof(*pr_stat));
}
buffer = g_malloc(size);
v9fs_string_init(&target);
- retval = readlink(path.data, buffer, size);
+ retval = readlink(path.data, buffer, size - 1);
if (retval > 0) {
buffer[retval] = '\0';
v9fs_string_sprintf(&target, "%s", buffer);
v9fs_string_init(&path);
v9fs_string_init(&oldpath);
- cur_uid = geteuid();
- cur_gid = getegid();
retval = proxy_unmarshal(iovec, offset, "dd", &uid, &gid);
if (retval < 0) {
return retval;
}
offset += retval;
- retval = setfsugid(uid, gid);
+ retval = setugid(uid, gid, &cur_uid, &cur_gid);
if (retval < 0) {
- retval = -errno;
- goto err_out;
+ goto unmarshal_err_out;
}
switch (type) {
case T_MKNOD:
}
err_out:
+ resetugid(cur_uid, cur_gid);
+unmarshal_err_out:
v9fs_string_free(&path);
v9fs_string_free(&oldpath);
- setfsugid(cur_uid, cur_gid);
return retval;
}
if (ret < 0) {
goto unmarshal_err_out;
}
- cur_uid = geteuid();
- cur_gid = getegid();
- ret = setfsugid(uid, gid);
+ ret = setugid(uid, gid, &cur_uid, &cur_gid);
if (ret < 0) {
- /*
- * On failure reset back to the
- * old uid/gid
- */
- ret = -errno;
- goto err_out;
+ goto unmarshal_err_out;
}
ret = open(path.data, flags, mode);
if (ret < 0) {
ret = -errno;
}
-err_out:
- setfsugid(cur_uid, cur_gid);
+ resetugid(cur_uid, cur_gid);
unmarshal_err_out:
v9fs_string_free(&path);
return ret;
return ret;
}
+/* create unix domain socket and return the descriptor */
+static int proxy_socket(const char *path, uid_t uid, gid_t gid)
+{
+ int sock, client;
+ struct sockaddr_un proxy, qemu;
+ socklen_t size;
+
+ /* requested socket already exists, refuse to start */
+ if (!access(path, F_OK)) {
+ do_log(LOG_CRIT, "socket already exists\n");
+ return -1;
+ }
+
+ if (strlen(path) >= sizeof(proxy.sun_path)) {
+ do_log(LOG_CRIT, "UNIX domain socket path exceeds %zu characters\n",
+ sizeof(proxy.sun_path));
+ return -1;
+ }
+
+ sock = socket(AF_UNIX, SOCK_STREAM, 0);
+ if (sock < 0) {
+ do_perror("socket");
+ return -1;
+ }
+
+ /* mask other part of mode bits */
+ umask(7);
+
+ proxy.sun_family = AF_UNIX;
+ strcpy(proxy.sun_path, path);
+ if (bind(sock, (struct sockaddr *)&proxy,
+ sizeof(struct sockaddr_un)) < 0) {
+ do_perror("bind");
+ goto error;
+ }
+ if (chown(proxy.sun_path, uid, gid) < 0) {
+ do_perror("chown");
+ goto error;
+ }
+ if (listen(sock, 1) < 0) {
+ do_perror("listen");
+ goto error;
+ }
+
+ size = sizeof(qemu);
+ client = accept(sock, (struct sockaddr *)&qemu, &size);
+ if (client < 0) {
+ do_perror("accept");
+ goto error;
+ }
+ close(sock);
+ return client;
+
+error:
+ close(sock);
+ return -1;
+}
+
static void usage(char *prog)
{
fprintf(stderr, "usage: %s\n"
" -p|--path <path> 9p path to export\n"
" {-f|--fd <socket-descriptor>} socket file descriptor to be used\n"
+ " {-s|--socket <socketname> socket file used for communication\n"
+ " \t-u|--uid <uid> -g|--gid <gid>} - uid:gid combination to give "
+ " access to this socket\n"
+ " \tNote: -s & -f can not be used together\n"
" [-n|--nodaemon] Run as a normal program\n",
basename(prog));
}
case T_MKDIR:
case T_SYMLINK:
case T_LINK:
+ case T_CHMOD:
+ case T_CHOWN:
+ case T_TRUNCATE:
+ case T_UTIME:
+ case T_RENAME:
+ case T_REMOVE:
+ case T_LSETXATTR:
+ case T_LREMOVEXATTR:
if (send_status(sock, out_iovec, retval) < 0) {
return -1;
}
case T_LSTAT:
case T_STATFS:
case T_READLINK:
+ case T_LGETXATTR:
+ case T_LLISTXATTR:
+ case T_GETVERSION:
if (send_response(sock, out_iovec, retval) < 0) {
return -1;
}
static int process_requests(int sock)
{
+ int flags;
+ int size = 0;
int retval = 0;
+ uint64_t offset;
ProxyHeader header;
+ int mode, uid, gid;
+ V9fsString name, value;
+ struct timespec spec[2];
V9fsString oldpath, path;
struct iovec in_iovec, out_iovec;
case T_READLINK:
retval = do_readlink(&in_iovec, &out_iovec);
break;
+ case T_CHMOD:
+ v9fs_string_init(&path);
+ retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ,
+ "sd", &path, &mode);
+ if (retval > 0) {
+ retval = chmod(path.data, mode);
+ if (retval < 0) {
+ retval = -errno;
+ }
+ }
+ v9fs_string_free(&path);
+ break;
+ case T_CHOWN:
+ v9fs_string_init(&path);
+ retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sdd", &path,
+ &uid, &gid);
+ if (retval > 0) {
+ retval = lchown(path.data, uid, gid);
+ if (retval < 0) {
+ retval = -errno;
+ }
+ }
+ v9fs_string_free(&path);
+ break;
+ case T_TRUNCATE:
+ v9fs_string_init(&path);
+ retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sq",
+ &path, &offset);
+ if (retval > 0) {
+ retval = truncate(path.data, offset);
+ if (retval < 0) {
+ retval = -errno;
+ }
+ }
+ v9fs_string_free(&path);
+ break;
+ case T_UTIME:
+ v9fs_string_init(&path);
+ retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sqqqq", &path,
+ &spec[0].tv_sec, &spec[0].tv_nsec,
+ &spec[1].tv_sec, &spec[1].tv_nsec);
+ if (retval > 0) {
+ retval = qemu_utimens(path.data, spec);
+ if (retval < 0) {
+ retval = -errno;
+ }
+ }
+ v9fs_string_free(&path);
+ break;
+ case T_RENAME:
+ v9fs_string_init(&path);
+ v9fs_string_init(&oldpath);
+ retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ,
+ "ss", &oldpath, &path);
+ if (retval > 0) {
+ retval = rename(oldpath.data, path.data);
+ if (retval < 0) {
+ retval = -errno;
+ }
+ }
+ v9fs_string_free(&oldpath);
+ v9fs_string_free(&path);
+ break;
+ case T_REMOVE:
+ v9fs_string_init(&path);
+ retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "s", &path);
+ if (retval > 0) {
+ retval = remove(path.data);
+ if (retval < 0) {
+ retval = -errno;
+ }
+ }
+ v9fs_string_free(&path);
+ break;
+ case T_LGETXATTR:
+ case T_LLISTXATTR:
+ retval = do_getxattr(header.type, &in_iovec, &out_iovec);
+ break;
+ case T_LSETXATTR:
+ v9fs_string_init(&path);
+ v9fs_string_init(&name);
+ v9fs_string_init(&value);
+ retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sssdd", &path,
+ &name, &value, &size, &flags);
+ if (retval > 0) {
+ retval = lsetxattr(path.data,
+ name.data, value.data, size, flags);
+ if (retval < 0) {
+ retval = -errno;
+ }
+ }
+ v9fs_string_free(&path);
+ v9fs_string_free(&name);
+ v9fs_string_free(&value);
+ break;
+ case T_LREMOVEXATTR:
+ v9fs_string_init(&path);
+ v9fs_string_init(&name);
+ retval = proxy_unmarshal(&in_iovec,
+ PROXY_HDR_SZ, "ss", &path, &name);
+ if (retval > 0) {
+ retval = lremovexattr(path.data, name.data);
+ if (retval < 0) {
+ retval = -errno;
+ }
+ }
+ v9fs_string_free(&path);
+ v9fs_string_free(&name);
+ break;
+ case T_GETVERSION:
+ retval = do_getversion(&in_iovec, &out_iovec);
+ break;
default:
goto err_out;
break;
int main(int argc, char **argv)
{
int sock;
+ uid_t own_u;
+ gid_t own_g;
char *rpath = NULL;
+ char *sock_name = NULL;
struct stat stbuf;
int c, option_index;
+#ifdef FS_IOC_GETVERSION
+ int retval;
+ struct statfs st_fs;
+#endif
is_daemon = true;
sock = -1;
+ own_u = own_g = -1;
while (1) {
option_index = 0;
- c = getopt_long(argc, argv, "p:nh?f:", helper_opts,
+ c = getopt_long(argc, argv, "p:nh?f:s:u:g:", helper_opts,
&option_index);
if (c == -1) {
break;
}
switch (c) {
case 'p':
- rpath = strdup(optarg);
+ rpath = g_strdup(optarg);
break;
case 'n':
is_daemon = false;
case 'f':
sock = atoi(optarg);
break;
+ case 's':
+ sock_name = g_strdup(optarg);
+ break;
+ case 'u':
+ own_u = atoi(optarg);
+ break;
+ case 'g':
+ own_g = atoi(optarg);
+ break;
case '?':
case 'h':
default:
}
/* Parameter validation */
- if (sock == -1 || rpath == NULL) {
- fprintf(stderr, "socket descriptor or path not specified\n");
+ if ((sock_name == NULL && sock == -1) || rpath == NULL) {
+ fprintf(stderr, "socket, socket descriptor or path not specified\n");
+ usage(argv[0]);
+ return -1;
+ }
+
+ if (sock_name && sock != -1) {
+ fprintf(stderr, "both named socket and socket descriptor specified\n");
+ usage(argv[0]);
+ exit(EXIT_FAILURE);
+ }
+
+ if (sock_name && (own_u == -1 || own_g == -1)) {
+ fprintf(stderr, "owner uid:gid not specified, ");
+ fprintf(stderr,
+ "owner uid:gid specifies who can access the socket file\n");
usage(argv[0]);
exit(EXIT_FAILURE);
}
}
do_log(LOG_INFO, "Started\n");
+ if (sock_name) {
+ sock = proxy_socket(sock_name, own_u, own_g);
+ if (sock < 0) {
+ goto error;
+ }
+ }
if (chdir("/") < 0) {
do_perror("chdir");
do_perror("chroot");
goto error;
}
- umask(0);
+ get_version = false;
+#ifdef FS_IOC_GETVERSION
+ /* check whether underlying FS support IOC_GETVERSION */
+ retval = statfs("/", &st_fs);
+ if (!retval) {
+ switch (st_fs.f_type) {
+ case EXT2_SUPER_MAGIC:
+ case BTRFS_SUPER_MAGIC:
+ case REISERFS_SUPER_MAGIC:
+ case XFS_SUPER_MAGIC:
+ get_version = true;
+ break;
+ }
+ }
+#endif
+
+ umask(0);
if (init_capabilities() < 0) {
goto error;
}
projects / mirror_qemu.git / blobdiff