diff options
Diffstat (limited to 'fs/xattr.c')
| -rw-r--r-- | fs/xattr.c | 123 |
1 files changed, 71 insertions, 52 deletions
diff --git a/fs/xattr.c b/fs/xattr.c index 402d9d43fde0..adab9a70b536 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -80,6 +80,31 @@ xattr_resolve_name(struct inode *inode, const char **name) return ERR_PTR(-EOPNOTSUPP); } +/** + * may_write_xattr - check whether inode allows writing xattr + * @mnt_userns: User namespace of the mount the inode was found from + * @inode: the inode on which to set an xattr + * + * Check whether the inode allows writing xattrs. Specifically, we can never + * set or remove an extended attribute on a read-only filesystem or on an + * immutable / append-only inode. + * + * We also need to ensure that the inode has a mapping in the mount to + * not risk writing back invalid i_{g,u}id values. + * + * Return: On success zero is returned. On error a negative errno is returned. + */ +int may_write_xattr(struct user_namespace *mnt_userns, struct inode *inode) +{ + if (IS_IMMUTABLE(inode)) + return -EPERM; + if (IS_APPEND(inode)) + return -EPERM; + if (HAS_UNMAPPED_ID(mnt_userns, inode)) + return -EPERM; + return 0; +} + /* * Check permissions for extended attribute access. This is a bit complicated * because different namespaces have very different rules. @@ -88,20 +113,12 @@ static int xattr_permission(struct user_namespace *mnt_userns, struct inode *inode, const char *name, int mask) { - /* - * We can never set or remove an extended attribute on a read-only - * filesystem or on an immutable / append-only inode. - */ if (mask & MAY_WRITE) { - if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) - return -EPERM; - /* - * Updating an xattr will likely cause i_uid and i_gid - * to be writen back improperly if their true value is - * unknown to the vfs. - */ - if (HAS_UNMAPPED_ID(mnt_userns, inode)) - return -EPERM; + int ret; + + ret = may_write_xattr(mnt_userns, inode); + if (ret) + return ret; } /* @@ -172,6 +189,9 @@ __vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry, { const struct xattr_handler *handler; + if (is_posix_acl_xattr(name)) + return -EOPNOTSUPP; + handler = xattr_resolve_name(inode, &name); if (IS_ERR(handler)) return PTR_ERR(handler); @@ -282,12 +302,6 @@ out: } EXPORT_SYMBOL_GPL(__vfs_setxattr_locked); -static inline bool is_posix_acl_xattr(const char *name) -{ - return (strcmp(name, XATTR_NAME_POSIX_ACL_ACCESS) == 0) || - (strcmp(name, XATTR_NAME_POSIX_ACL_DEFAULT) == 0); -} - int vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry, const char *name, const void *value, size_t size, int flags) @@ -354,11 +368,12 @@ out_noalloc: * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr * * Allocate memory, if not already allocated, or re-allocate correct size, - * before retrieving the extended attribute. + * before retrieving the extended attribute. The xattr value buffer should + * always be freed by the caller, even on error. * * Returns the result of alloc, if failed, or the getxattr operation. */ -ssize_t +int vfs_getxattr_alloc(struct user_namespace *mnt_userns, struct dentry *dentry, const char *name, char **xattr_value, size_t xattr_size, gfp_t flags) @@ -399,6 +414,9 @@ __vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name, { const struct xattr_handler *handler; + if (is_posix_acl_xattr(name)) + return -EOPNOTSUPP; + handler = xattr_resolve_name(inode, &name); if (IS_ERR(handler)) return PTR_ERR(handler); @@ -437,10 +455,7 @@ vfs_getxattr(struct user_namespace *mnt_userns, struct dentry *dentry, return ret; } nolsm: - error = __vfs_getxattr(dentry, inode, name, value, size); - if (error > 0 && is_posix_acl_xattr(name)) - posix_acl_getxattr_idmapped_mnt(mnt_userns, inode, value, size); - return error; + return __vfs_getxattr(dentry, inode, name, value, size); } EXPORT_SYMBOL_GPL(vfs_getxattr); @@ -471,6 +486,9 @@ __vfs_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry, struct inode *inode = d_inode(dentry); const struct xattr_handler *handler; + if (is_posix_acl_xattr(name)) + return -EOPNOTSUPP; + handler = xattr_resolve_name(inode, &name); if (IS_ERR(handler)) return PTR_ERR(handler); @@ -580,23 +598,19 @@ int setxattr_copy(const char __user *name, struct xattr_ctx *ctx) return error; } -static void setxattr_convert(struct user_namespace *mnt_userns, - struct dentry *d, struct xattr_ctx *ctx) -{ - if (ctx->size && is_posix_acl_xattr(ctx->kname->name)) - posix_acl_fix_xattr_from_user(ctx->kvalue, ctx->size); -} - -int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry, +int do_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, struct xattr_ctx *ctx) { - setxattr_convert(mnt_userns, dentry, ctx); - return vfs_setxattr(mnt_userns, dentry, ctx->kname->name, + if (is_posix_acl_xattr(ctx->kname->name)) + return do_set_acl(idmap, dentry, ctx->kname->name, + ctx->kvalue, ctx->size); + + return vfs_setxattr(mnt_idmap_owner(idmap), dentry, ctx->kname->name, ctx->kvalue, ctx->size, ctx->flags); } static long -setxattr(struct user_namespace *mnt_userns, struct dentry *d, +setxattr(struct mnt_idmap *idmap, struct dentry *d, const char __user *name, const void __user *value, size_t size, int flags) { @@ -614,7 +628,7 @@ setxattr(struct user_namespace *mnt_userns, struct dentry *d, if (error) return error; - error = do_setxattr(mnt_userns, d, &ctx); + error = do_setxattr(idmap, d, &ctx); kvfree(ctx.kvalue); return error; @@ -633,7 +647,7 @@ retry: return error; error = mnt_want_write(path.mnt); if (!error) { - error = setxattr(mnt_user_ns(path.mnt), path.dentry, name, + error = setxattr(mnt_idmap(path.mnt), path.dentry, name, value, size, flags); mnt_drop_write(path.mnt); } @@ -670,7 +684,7 @@ SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name, audit_file(f.file); error = mnt_want_write_file(f.file); if (!error) { - error = setxattr(file_mnt_user_ns(f.file), + error = setxattr(file_mnt_idmap(f.file), f.file->f_path.dentry, name, value, size, flags); mnt_drop_write_file(f.file); @@ -683,7 +697,7 @@ SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name, * Extended attribute GET operations */ ssize_t -do_getxattr(struct user_namespace *mnt_userns, struct dentry *d, +do_getxattr(struct mnt_idmap *idmap, struct dentry *d, struct xattr_ctx *ctx) { ssize_t error; @@ -697,10 +711,12 @@ do_getxattr(struct user_namespace *mnt_userns, struct dentry *d, return -ENOMEM; } - error = vfs_getxattr(mnt_userns, d, kname, ctx->kvalue, ctx->size); + if (is_posix_acl_xattr(ctx->kname->name)) + error = do_get_acl(idmap, d, kname, ctx->kvalue, ctx->size); + else + error = vfs_getxattr(mnt_idmap_owner(idmap), d, kname, + ctx->kvalue, ctx->size); if (error > 0) { - if (is_posix_acl_xattr(kname)) - posix_acl_fix_xattr_to_user(ctx->kvalue, error); if (ctx->size && copy_to_user(ctx->value, ctx->kvalue, error)) error = -EFAULT; } else if (error == -ERANGE && ctx->size >= XATTR_SIZE_MAX) { @@ -713,7 +729,7 @@ do_getxattr(struct user_namespace *mnt_userns, struct dentry *d, } static ssize_t -getxattr(struct user_namespace *mnt_userns, struct dentry *d, +getxattr(struct mnt_idmap *idmap, struct dentry *d, const char __user *name, void __user *value, size_t size) { ssize_t error; @@ -732,7 +748,7 @@ getxattr(struct user_namespace *mnt_userns, struct dentry *d, if (error < 0) return error; - error = do_getxattr(mnt_userns, d, &ctx); + error = do_getxattr(idmap, d, &ctx); kvfree(ctx.kvalue); return error; @@ -748,7 +764,7 @@ retry: error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); if (error) return error; - error = getxattr(mnt_user_ns(path.mnt), path.dentry, name, value, size); + error = getxattr(mnt_idmap(path.mnt), path.dentry, name, value, size); path_put(&path); if (retry_estale(error, lookup_flags)) { lookup_flags |= LOOKUP_REVAL; @@ -778,7 +794,7 @@ SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name, if (!f.file) return error; audit_file(f.file); - error = getxattr(file_mnt_user_ns(f.file), f.file->f_path.dentry, + error = getxattr(file_mnt_idmap(f.file), f.file->f_path.dentry, name, value, size); fdput(f); return error; @@ -863,7 +879,7 @@ SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size) * Extended attribute REMOVE operations */ static long -removexattr(struct user_namespace *mnt_userns, struct dentry *d, +removexattr(struct mnt_idmap *idmap, struct dentry *d, const char __user *name) { int error; @@ -875,7 +891,10 @@ removexattr(struct user_namespace *mnt_userns, struct dentry *d, if (error < 0) return error; - return vfs_removexattr(mnt_userns, d, kname); + if (is_posix_acl_xattr(kname)) + return vfs_remove_acl(mnt_idmap_owner(idmap), d, kname); + + return vfs_removexattr(mnt_idmap_owner(idmap), d, kname); } static int path_removexattr(const char __user *pathname, @@ -889,7 +908,7 @@ retry: return error; error = mnt_want_write(path.mnt); if (!error) { - error = removexattr(mnt_user_ns(path.mnt), path.dentry, name); + error = removexattr(mnt_idmap(path.mnt), path.dentry, name); mnt_drop_write(path.mnt); } path_put(&path); @@ -922,7 +941,7 @@ SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name) audit_file(f.file); error = mnt_want_write_file(f.file); if (!error) { - error = removexattr(file_mnt_user_ns(f.file), + error = removexattr(file_mnt_idmap(f.file), f.file->f_path.dentry, name); mnt_drop_write_file(f.file); } @@ -1262,7 +1281,7 @@ static int xattr_list_one(char **buffer, ssize_t *remaining_size, ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs, char *buffer, size_t size) { - bool trusted = capable(CAP_SYS_ADMIN); + bool trusted = ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN); struct simple_xattr *xattr; struct rb_node *rbp; ssize_t remaining_size = size; |