| 1 | |
| 2 | |
| 3 | * FUSE: Filesystem in Userspace
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| 4 | * Copyright (C) 2016 Canonical Ltd. <[email protected]>
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| 5 |
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| 6 |
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| 7 | #include "fuse_i.h"
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| 8 |
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| 9 | #include <linux/posix_acl.h>
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| 10 | #include <linux/posix_acl_xattr.h>
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| 11 |
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| 12 | static struct posix_acl *__fuse_get_acl(struct fuse_conn *fc,
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| 13 | struct inode *inode, int type, bool rcu)
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| 14 | {
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| 15 | int size;
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| 16 | const char *name;
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| 17 | void *value = NULL;
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| 18 | struct posix_acl *acl;
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| 19 |
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| 20 | if (rcu)
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| 21 | return ERR_PTR(-ECHILD);
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| 22 |
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| 23 | if (fuse_is_bad(inode))
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| 24 | return ERR_PTR(-EIO);
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| 25 |
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| 26 | if (fc->no_getxattr)
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| 27 | return NULL;
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| 28 |
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| 29 | if (type == ACL_TYPE_ACCESS)
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| 30 | name = XATTR_NAME_POSIX_ACL_ACCESS;
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| 31 | else if (type == ACL_TYPE_DEFAULT)
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| 32 | name = XATTR_NAME_POSIX_ACL_DEFAULT;
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| 33 | else
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| 34 | return ERR_PTR(-EOPNOTSUPP);
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| 35 |
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| 36 | value = kmalloc(PAGE_SIZE, GFP_KERNEL);
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| 37 | if (!value)
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| 38 | return ERR_PTR(-ENOMEM);
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| 39 | size = fuse_getxattr(inode, name, value, PAGE_SIZE);
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| 40 | if (size > 0)
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| 41 | acl = posix_acl_from_xattr(fc->user_ns, value, size);
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| 42 | else if ((size == 0) || (size == -ENODATA) ||
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| 43 | (size == -EOPNOTSUPP && fc->no_getxattr))
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| 44 | acl = NULL;
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| 45 | else if (size == -ERANGE)
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| 46 | acl = ERR_PTR(-E2BIG);
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| 47 | else
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| 48 | acl = ERR_PTR(size);
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| 49 |
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| 50 | kfree(value);
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| 51 | return acl;
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| 52 | }
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| 53 |
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| 54 | static inline bool fuse_no_acl(const struct fuse_conn *fc,
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| 55 | const struct inode *inode)
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| 56 | {
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| 57 | |
| 58 | * Refuse interacting with POSIX ACLs for daemons that
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| 59 | * don't support FUSE_POSIX_ACL and are not mounted on
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| 60 | * the host to retain backwards compatibility.
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| 61 |
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| 62 | return !fc->posix_acl && (i_user_ns(inode) != &init_user_ns);
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| 63 | }
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| 64 |
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| 65 | struct posix_acl *fuse_get_acl(const struct mnt_idmap *idmap,
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| 66 | struct dentry *dentry, int type)
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| 67 | {
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| 68 | struct inode *inode = d_inode(dentry);
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| 69 | struct fuse_conn *fc = get_fuse_conn(inode);
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| 70 |
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| 71 | if (fuse_no_acl(fc, inode))
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| 72 | return ERR_PTR(-EOPNOTSUPP);
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| 73 |
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| 74 | return __fuse_get_acl(fc, inode, type, false);
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| 75 | }
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| 76 |
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| 77 | struct posix_acl *fuse_get_inode_acl(struct inode *inode, int type, bool rcu)
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| 78 | {
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| 79 | struct fuse_conn *fc = get_fuse_conn(inode);
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| 80 |
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| 81 | |
| 82 | * FUSE daemons before FUSE_POSIX_ACL was introduced could get and set
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| 83 | * POSIX ACLs without them being used for permission checking by the
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| 84 | * vfs. Retain that behavior for backwards compatibility as there are
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| 85 | * filesystems that do all permission checking for acls in the daemon
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| 86 | * and not in the kernel.
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| 87 |
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| 88 | if (!fc->posix_acl)
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| 89 | return NULL;
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| 90 | return __fuse_get_acl(fc, inode, type, rcu);
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| 91 | }
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| 92 |
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| 93 | int fuse_set_acl(const struct mnt_idmap *idmap, struct dentry *dentry,
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| 94 | struct posix_acl *acl, int type)
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| 95 | {
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| 96 | struct inode *inode = d_inode(dentry);
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| 97 | struct fuse_conn *fc = get_fuse_conn(inode);
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| 98 | const char *name;
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| 99 | int ret;
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| 100 |
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| 101 | if (fuse_is_bad(inode))
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| 102 | return -EIO;
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| 103 |
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| 104 | if (fc->no_setxattr || fuse_no_acl(fc, inode))
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| 105 | return -EOPNOTSUPP;
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| 106 |
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| 107 | if (type == ACL_TYPE_ACCESS)
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| 108 | name = XATTR_NAME_POSIX_ACL_ACCESS;
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| 109 | else if (type == ACL_TYPE_DEFAULT)
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| 110 | name = XATTR_NAME_POSIX_ACL_DEFAULT;
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| 111 | else
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| 112 | return -EINVAL;
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| 113 |
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| 114 | if (acl) {
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| 115 | unsigned int extra_flags = 0;
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| 116 | |
| 117 | * Fuse userspace is responsible for updating access
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| 118 | * permissions in the inode, if needed. fuse_setxattr
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| 119 | * invalidates the inode attributes, which will force
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| 120 | * them to be refreshed the next time they are used,
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| 121 | * and it also updates i_ctime.
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| 122 |
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| 123 | size_t size;
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| 124 | void *value;
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| 125 |
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| 126 | value = posix_acl_to_xattr(fc->user_ns, acl, &size, GFP_KERNEL);
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| 127 | if (!value)
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| 128 | return -ENOMEM;
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| 129 |
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| 130 | if (size > PAGE_SIZE) {
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| 131 | kfree(value);
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| 132 | return -E2BIG;
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| 133 | }
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| 134 |
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| 135 | |
| 136 | * Fuse daemons without FUSE_POSIX_ACL never changed the passed
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| 137 | * through POSIX ACLs. Such daemons don't expect setgid bits to
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| 138 | * be stripped.
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| 139 |
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| 140 | if (fc->posix_acl &&
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| 141 | !in_group_or_capable(idmap, inode,
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| 142 | i_gid_into_vfsgid(idmap, inode)))
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| 143 | extra_flags |= FUSE_SETXATTR_ACL_KILL_SGID;
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| 144 |
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| 145 | ret = fuse_setxattr(inode, name, value, size, 0, extra_flags);
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| 146 | kfree(value);
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| 147 | } else {
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| 148 | ret = fuse_removexattr(inode, name);
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| 149 | }
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| 150 |
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| 151 | if (fc->posix_acl) {
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| 152 | |
| 153 | * Fuse daemons without FUSE_POSIX_ACL never cached POSIX ACLs
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| 154 | * and didn't invalidate attributes. Retain that behavior.
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| 155 |
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| 156 | forget_all_cached_acls(inode);
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| 157 | fuse_invalidate_attr(inode);
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| 158 | }
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| 159 |
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| 160 | return ret;
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| 161 | }
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