diff options
| -rw-r--r-- | tools/virtiofsd/passthrough_ll.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 7873692..e49650b 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -2719,6 +2719,43 @@ static void setup_mounts(const char *source) } /* + * Only keep whitelisted capabilities that are needed for file system operation + */ +static void setup_capabilities(void) +{ + pthread_mutex_lock(&cap.mutex); + capng_restore_state(&cap.saved); + + /* + * Whitelist file system-related capabilities that are needed for a file + * server to act like root. Drop everything else like networking and + * sysadmin capabilities. + * + * Exclusions: + * 1. CAP_LINUX_IMMUTABLE is not included because it's only used via ioctl + * and we don't support that. + * 2. CAP_MAC_OVERRIDE is not included because it only seems to be + * used by the Smack LSM. Omit it until there is demand for it. + */ + capng_setpid(syscall(SYS_gettid)); + capng_clear(CAPNG_SELECT_BOTH); + capng_updatev(CAPNG_ADD, CAPNG_PERMITTED | CAPNG_EFFECTIVE, + CAP_CHOWN, + CAP_DAC_OVERRIDE, + CAP_DAC_READ_SEARCH, + CAP_FOWNER, + CAP_FSETID, + CAP_SETGID, + CAP_SETUID, + CAP_MKNOD, + CAP_SETFCAP); + capng_apply(CAPNG_SELECT_BOTH); + + cap.saved = capng_save_state(); + pthread_mutex_unlock(&cap.mutex); +} + +/* * Lock down this process to prevent access to other processes or files outside * source directory. This reduces the impact of arbitrary code execution bugs. */ @@ -2728,6 +2765,7 @@ static void setup_sandbox(struct lo_data *lo, struct fuse_session *se, setup_namespaces(lo, se); setup_mounts(lo->source); setup_seccomp(enable_syslog); + setup_capabilities(); } /* Set the maximum number of open file descriptors */ |