diff options
| -rw-r--r-- | docs/tools/virtiofsd.rst | 4 | ||||
| -rw-r--r-- | tools/virtiofsd/passthrough_ll.c | 77 |
2 files changed, 80 insertions, 1 deletions
diff --git a/docs/tools/virtiofsd.rst b/docs/tools/virtiofsd.rst index 866b7db..00554c7 100644 --- a/docs/tools/virtiofsd.rst +++ b/docs/tools/virtiofsd.rst @@ -228,6 +228,10 @@ The 'map' type adds a number of separate rules to add **prepend** as a prefix to the matched **key** (or all attributes if **key** is empty). There may be at most one 'map' rule and it must be the last rule in the set. +Note: When the 'security.capability' xattr is remapped, the daemon has to do +extra work to remove it during many operations, which the host kernel normally +does itself. + xattr-mapping Examples ---------------------- diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 58d24c0..fc7e1b1 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -148,6 +148,7 @@ struct lo_data { int posix_lock; int xattr; char *xattrmap; + char *xattr_security_capability; char *source; char *modcaps; double timeout; @@ -217,6 +218,8 @@ static __thread bool cap_loaded = 0; static struct lo_inode *lo_find(struct lo_data *lo, struct stat *st, uint64_t mnt_id); +static int xattr_map_client(const struct lo_data *lo, const char *client_name, + char **out_name); static int is_dot_or_dotdot(const char *name) { @@ -356,6 +359,37 @@ out: return ret; } +/* + * The host kernel normally drops security.capability xattr's on + * any write, however if we're remapping xattr names we need to drop + * whatever the clients security.capability is actually stored as. + */ +static int drop_security_capability(const struct lo_data *lo, int fd) +{ + if (!lo->xattr_security_capability) { + /* We didn't remap the name, let the host kernel do it */ + return 0; + } + if (!fremovexattr(fd, lo->xattr_security_capability)) { + /* All good */ + return 0; + } + + switch (errno) { + case ENODATA: + /* Attribute didn't exist, that's fine */ + return 0; + + case ENOTSUP: + /* FS didn't support attribute anyway, also fine */ + return 0; + + default: + /* Hmm other error */ + return errno; + } +} + static void lo_map_init(struct lo_map *map) { map->elems = NULL; @@ -737,6 +771,11 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, uid_t uid = (valid & FUSE_SET_ATTR_UID) ? attr->st_uid : (uid_t)-1; gid_t gid = (valid & FUSE_SET_ATTR_GID) ? attr->st_gid : (gid_t)-1; + saverr = drop_security_capability(lo, ifd); + if (saverr) { + goto out_err; + } + res = fchownat(ifd, "", uid, gid, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW); if (res == -1) { saverr = errno; @@ -759,6 +798,14 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, } } + saverr = drop_security_capability(lo, truncfd); + if (saverr) { + if (!fi) { + close(truncfd); + } + goto out_err; + } + if (kill_suidgid) { res = drop_effective_cap("FSETID", &cap_fsetid_dropped); if (res != 0) { @@ -1784,6 +1831,13 @@ static int lo_do_open(struct lo_data *lo, struct lo_inode *inode, if (fd < 0) { return -fd; } + if (fi->flags & (O_TRUNC)) { + int err = drop_security_capability(lo, fd); + if (err) { + close(fd); + return err; + } + } } pthread_mutex_lock(&lo->mutex); @@ -2191,6 +2245,12 @@ static void lo_write_buf(fuse_req_t req, fuse_ino_t ino, "lo_write_buf(ino=%" PRIu64 ", size=%zd, off=%lu kill_priv=%d)\n", ino, out_buf.buf[0].size, (unsigned long)off, fi->kill_priv); + res = drop_security_capability(lo_data(req), out_buf.buf[0].fd); + if (res) { + fuse_reply_err(req, res); + return; + } + /* * If kill_priv is set, drop CAP_FSETID which should lead to kernel * clearing setuid/setgid on file. Note, for WRITE, we need to do @@ -2432,6 +2492,7 @@ static void parse_xattrmap(struct lo_data *lo) { const char *map = lo->xattrmap; const char *tmp; + int ret; lo->xattr_map_nentries = 0; while (*map) { @@ -2462,7 +2523,7 @@ static void parse_xattrmap(struct lo_data *lo) * the last entry. */ parse_xattrmap_map(lo, map, sep); - return; + break; } else { fuse_log(FUSE_LOG_ERR, "%s: Unexpected type;" @@ -2531,6 +2592,19 @@ static void parse_xattrmap(struct lo_data *lo) fuse_log(FUSE_LOG_ERR, "Empty xattr map\n"); exit(1); } + + ret = xattr_map_client(lo, "security.capability", + &lo->xattr_security_capability); + if (ret) { + fuse_log(FUSE_LOG_ERR, "Failed to map security.capability: %s\n", + strerror(ret)); + exit(1); + } + if (!strcmp(lo->xattr_security_capability, "security.capability")) { + /* 1-1 mapping, don't need to do anything */ + free(lo->xattr_security_capability); + lo->xattr_security_capability = NULL; + } } /* @@ -3588,6 +3662,7 @@ static void fuse_lo_data_cleanup(struct lo_data *lo) free(lo->xattrmap); free_xattrmap(lo); + free(lo->xattr_security_capability); free(lo->source); } |