diff options
| -rw-r--r-- | fs/nsfs.c | 158 | ||||
| -rw-r--r-- | include/linux/exportfs.h | 6 | ||||
| -rw-r--r-- | include/uapi/linux/nsfs.h | 9 |
3 files changed, 173 insertions, 0 deletions
diff --git a/fs/nsfs.c b/fs/nsfs.c index 80e631aeb3ce..926e2680414e 100644 --- a/fs/nsfs.c +++ b/fs/nsfs.c @@ -13,6 +13,12 @@ #include <linux/nsfs.h> #include <linux/uaccess.h> #include <linux/mnt_namespace.h> +#include <linux/ipc_namespace.h> +#include <linux/time_namespace.h> +#include <linux/utsname.h> +#include <linux/exportfs.h> +#include <linux/nstree.h> +#include <net/net_namespace.h> #include "mount.h" #include "internal.h" @@ -417,12 +423,164 @@ static const struct stashed_operations nsfs_stashed_ops = { .put_data = nsfs_put_data, }; +#define NSFS_FID_SIZE_U32_VER0 (NSFS_FILE_HANDLE_SIZE_VER0 / sizeof(u32)) +#define NSFS_FID_SIZE_U32_LATEST (NSFS_FILE_HANDLE_SIZE_LATEST / sizeof(u32)) + +static int nsfs_encode_fh(struct inode *inode, u32 *fh, int *max_len, + struct inode *parent) +{ + struct nsfs_file_handle *fid = (struct nsfs_file_handle *)fh; + struct ns_common *ns = inode->i_private; + int len = *max_len; + + if (parent) + return FILEID_INVALID; + + if (len < NSFS_FID_SIZE_U32_VER0) { + *max_len = NSFS_FID_SIZE_U32_LATEST; + return FILEID_INVALID; + } else if (len > NSFS_FID_SIZE_U32_LATEST) { + *max_len = NSFS_FID_SIZE_U32_LATEST; + } + + fid->ns_id = ns->ns_id; + fid->ns_type = ns->ops->type; + fid->ns_inum = inode->i_ino; + return FILEID_NSFS; +} + +static struct dentry *nsfs_fh_to_dentry(struct super_block *sb, struct fid *fh, + int fh_len, int fh_type) +{ + struct path path __free(path_put) = {}; + struct nsfs_file_handle *fid = (struct nsfs_file_handle *)fh; + struct user_namespace *owning_ns = NULL; + struct ns_common *ns; + int ret; + + if (fh_len < NSFS_FID_SIZE_U32_VER0) + return NULL; + + /* Check that any trailing bytes are zero. */ + if ((fh_len > NSFS_FID_SIZE_U32_LATEST) && + memchr_inv((void *)fid + NSFS_FID_SIZE_U32_LATEST, 0, + fh_len - NSFS_FID_SIZE_U32_LATEST)) + return NULL; + + switch (fh_type) { + case FILEID_NSFS: + break; + default: + return NULL; + } + + scoped_guard(rcu) { + ns = ns_tree_lookup_rcu(fid->ns_id, fid->ns_type); + if (!ns) + return NULL; + + VFS_WARN_ON_ONCE(ns->ns_id != fid->ns_id); + VFS_WARN_ON_ONCE(ns->ops->type != fid->ns_type); + VFS_WARN_ON_ONCE(ns->inum != fid->ns_inum); + + if (!refcount_inc_not_zero(&ns->count)) + return NULL; + } + + switch (ns->ops->type) { +#ifdef CONFIG_CGROUPS + case CLONE_NEWCGROUP: + if (!current_in_namespace(to_cg_ns(ns))) + owning_ns = to_cg_ns(ns)->user_ns; + break; +#endif +#ifdef CONFIG_IPC_NS + case CLONE_NEWIPC: + if (!current_in_namespace(to_ipc_ns(ns))) + owning_ns = to_ipc_ns(ns)->user_ns; + break; +#endif + case CLONE_NEWNS: + if (!current_in_namespace(to_mnt_ns(ns))) + owning_ns = to_mnt_ns(ns)->user_ns; + break; +#ifdef CONFIG_NET_NS + case CLONE_NEWNET: + if (!current_in_namespace(to_net_ns(ns))) + owning_ns = to_net_ns(ns)->user_ns; + break; +#endif +#ifdef CONFIG_PID_NS + case CLONE_NEWPID: + if (!current_in_namespace(to_pid_ns(ns))) { + owning_ns = to_pid_ns(ns)->user_ns; + } else if (!READ_ONCE(to_pid_ns(ns)->child_reaper)) { + ns->ops->put(ns); + return ERR_PTR(-EPERM); + } + break; +#endif +#ifdef CONFIG_TIME_NS + case CLONE_NEWTIME: + if (!current_in_namespace(to_time_ns(ns))) + owning_ns = to_time_ns(ns)->user_ns; + break; +#endif +#ifdef CONFIG_USER_NS + case CLONE_NEWUSER: + if (!current_in_namespace(to_user_ns(ns))) + owning_ns = to_user_ns(ns); + break; +#endif +#ifdef CONFIG_UTS_NS + case CLONE_NEWUTS: + if (!current_in_namespace(to_uts_ns(ns))) + owning_ns = to_uts_ns(ns)->user_ns; + break; +#endif + default: + return ERR_PTR(-EOPNOTSUPP); + } + + if (owning_ns && !ns_capable(owning_ns, CAP_SYS_ADMIN)) { + ns->ops->put(ns); + return ERR_PTR(-EPERM); + } + + /* path_from_stashed() unconditionally consumes the reference. */ + ret = path_from_stashed(&ns->stashed, nsfs_mnt, ns, &path); + if (ret) + return ERR_PTR(ret); + + return no_free_ptr(path.dentry); +} + +static int nsfs_export_permission(struct handle_to_path_ctx *ctx, + unsigned int oflags) +{ + /* nsfs_fh_to_dentry() performs all permission checks. */ + return 0; +} + +static struct file *nsfs_export_open(struct path *path, unsigned int oflags) +{ + return file_open_root(path, "", oflags, 0); +} + +static const struct export_operations nsfs_export_operations = { + .encode_fh = nsfs_encode_fh, + .fh_to_dentry = nsfs_fh_to_dentry, + .open = nsfs_export_open, + .permission = nsfs_export_permission, +}; + static int nsfs_init_fs_context(struct fs_context *fc) { struct pseudo_fs_context *ctx = init_pseudo(fc, NSFS_MAGIC); if (!ctx) return -ENOMEM; ctx->ops = &nsfs_ops; + ctx->eops = &nsfs_export_operations; ctx->dops = &ns_dentry_operations; fc->s_fs_info = (void *)&nsfs_stashed_ops; return 0; diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index cfb0dd1ea49c..3aac58a520c7 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -123,6 +123,12 @@ enum fid_type { FILEID_BCACHEFS_WITH_PARENT = 0xb2, /* + * + * 64 bit namespace identifier, 32 bit namespace type, 32 bit inode number. + */ + FILEID_NSFS = 0xf1, + + /* * 64 bit unique kernfs id */ FILEID_KERNFS = 0xfe, diff --git a/include/uapi/linux/nsfs.h b/include/uapi/linux/nsfs.h index 97d8d80d139f..fa86fe3c8bd3 100644 --- a/include/uapi/linux/nsfs.h +++ b/include/uapi/linux/nsfs.h @@ -53,4 +53,13 @@ enum init_ns_ino { MNT_NS_INIT_INO = 0xEFFFFFF8U, }; +struct nsfs_file_handle { + __u64 ns_id; + __u32 ns_type; + __u32 ns_inum; +}; + +#define NSFS_FILE_HANDLE_SIZE_VER0 16 /* sizeof first published struct */ +#define NSFS_FILE_HANDLE_SIZE_LATEST sizeof(struct nsfs_file_handle) /* sizeof latest published struct */ + #endif /* __LINUX_NSFS_H */ |