routing/
rights.rs

1// Copyright 2021 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use crate::error::RightsRoutingError;
6use crate::walk_state::WalkStateUnit;
7use fidl_fuchsia_io as fio;
8use moniker::ExtendedMoniker;
9#[cfg(feature = "serde")]
10use serde::{de::Deserializer, ser::Serializer, Deserialize, Serialize};
11use std::fmt;
12
13/// Performs rights validation for a routing step
14#[derive(Debug, PartialEq, Eq, Clone)]
15pub(super) struct RightsWalker {
16    rights: Rights,
17    moniker: ExtendedMoniker,
18}
19
20/// Opaque rights type to define new traits like PartialOrd on.
21#[derive(Debug, PartialEq, Eq, Clone, Copy)]
22pub struct Rights(fio::Operations);
23
24impl RightsWalker {
25    pub fn new(rights: impl Into<Rights>, moniker: impl Into<ExtendedMoniker>) -> Self {
26        Self { rights: rights.into(), moniker: moniker.into() }
27    }
28}
29
30/// Allows creating rights from fio::Operations.
31impl From<fio::Operations> for Rights {
32    fn from(rights: fio::Operations) -> Self {
33        Rights(rights)
34    }
35}
36
37impl From<Rights> for fio::Flags {
38    fn from(rights: Rights) -> Self {
39        fio::Flags::from_bits_retain(rights.0.bits())
40    }
41}
42
43impl Into<u64> for Rights {
44    fn into(self) -> u64 {
45        self.0.bits()
46    }
47}
48
49impl fmt::Display for Rights {
50    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
51        let Self(rights) = &self;
52        match *rights {
53            fio::R_STAR_DIR => write!(f, "r*"),
54            fio::W_STAR_DIR => write!(f, "w*"),
55            fio::X_STAR_DIR => write!(f, "x*"),
56            fio::RW_STAR_DIR => write!(f, "rw*"),
57            fio::RX_STAR_DIR => write!(f, "rx*"),
58            ops => write!(f, "{:?}", ops),
59        }
60    }
61}
62
63#[cfg(feature = "serde")]
64impl Serialize for Rights {
65    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
66    where
67        S: Serializer,
68    {
69        let Self(rights) = self;
70        rights.bits().serialize(serializer)
71    }
72}
73
74#[cfg(feature = "serde")]
75impl<'de> Deserialize<'de> for Rights {
76    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
77    where
78        D: Deserializer<'de>,
79    {
80        let bits: u64 = Deserialize::deserialize(deserializer)?;
81        let rights = fio::Operations::from_bits(bits)
82            .ok_or_else(|| serde::de::Error::custom("invalid value for fuchsia.io/Operations"))?;
83        Ok(Self(rights))
84    }
85}
86
87impl WalkStateUnit for RightsWalker {
88    type Error = RightsRoutingError;
89
90    /// Ensures the next walk state of rights satisfies a monotonic increasing sequence. Used to
91    /// verify the expectation that no right requested from a use, offer, or expose is missing as
92    /// capability routing walks from the capability's consumer to its provider.
93    fn validate_next(&self, next_rights: &RightsWalker) -> Result<(), Self::Error> {
94        if next_rights.rights.0.contains(self.rights.0) {
95            Ok(())
96        } else {
97            Err(RightsRoutingError::Invalid {
98                moniker: self.moniker.clone(),
99                requested: self.rights,
100                provided: next_rights.rights,
101            })
102        }
103    }
104
105    fn finalize_error(&self) -> Self::Error {
106        RightsRoutingError::MissingRightsSource { moniker: self.moniker.clone() }
107    }
108}
109
110#[cfg(test)]
111mod tests {
112    use super::*;
113    use assert_matches::assert_matches;
114
115    #[test]
116    fn validate_next() {
117        assert_matches!(
118            RightsWalker::new(fio::Operations::empty(), ExtendedMoniker::ComponentManager)
119                .validate_next(&RightsWalker::new(
120                    fio::R_STAR_DIR,
121                    ExtendedMoniker::ComponentManager
122                )),
123            Ok(())
124        );
125        assert_matches!(
126            RightsWalker::new(
127                fio::Operations::READ_BYTES | fio::Operations::GET_ATTRIBUTES,
128                ExtendedMoniker::ComponentManager
129            )
130            .validate_next(&RightsWalker::new(fio::R_STAR_DIR, ExtendedMoniker::ComponentManager)),
131            Ok(())
132        );
133        let provided = fio::Operations::READ_BYTES | fio::Operations::GET_ATTRIBUTES;
134        assert_eq!(
135            RightsWalker::new(fio::R_STAR_DIR, ExtendedMoniker::ComponentManager)
136                .validate_next(&RightsWalker::new(provided, ExtendedMoniker::ComponentManager)),
137            Err(RightsRoutingError::Invalid {
138                moniker: ExtendedMoniker::ComponentManager,
139                requested: Rights::from(fio::R_STAR_DIR),
140                provided: Rights::from(provided),
141            })
142        );
143        let provided = fio::Operations::READ_BYTES | fio::Operations::GET_ATTRIBUTES;
144        assert_eq!(
145            RightsWalker::new(fio::Operations::WRITE_BYTES, ExtendedMoniker::ComponentManager)
146                .validate_next(&RightsWalker::new(provided, ExtendedMoniker::ComponentManager)),
147            Err(RightsRoutingError::Invalid {
148                moniker: ExtendedMoniker::ComponentManager,
149                requested: Rights::from(fio::Operations::WRITE_BYTES),
150                provided: Rights::from(provided),
151            })
152        );
153    }
154}
routing/rights.rs

routing/
rights.rs
