1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
use git_sec::{permission::Resource, Access, Trust};

use crate::permission;

/// Permissions associated with various resources of a git repository
#[derive(Debug, Clone)]
pub struct Permissions {
    /// Control how a git-dir can be used.
    ///
    /// Note that a repository won't be usable at all unless read and write permissions are given.
    pub git_dir: Access<Resource, git_sec::ReadWrite>,
    /// Permissions related to the environment
    pub env: Environment,
    /// Permissions related to the handling of git configuration.
    pub config: Config,
}

/// Configure security relevant options when loading a git configuration.
#[derive(Copy, Clone, Ord, PartialOrd, PartialEq, Eq, Debug, Hash)]
pub struct Config {
    /// Whether to use the system configuration.
    /// This is defined as `$(prefix)/etc/gitconfig` on unix.
    pub system: bool,
    /// Whether to use the git application configuration.
    ///
    /// A platform defined location for where a user's git application configuration should be located.
    /// If `$XDG_CONFIG_HOME` is not set or empty, `$HOME/.config/git/config` will be used
    /// on unix.
    pub git: bool,
    /// Whether to use the user configuration.
    /// This is usually `~/.gitconfig` on unix.
    pub user: bool,
    /// Whether to use worktree configuration from `config.worktree`.
    // TODO: figure out how this really applies and provide more information here.
    // pub worktree: bool,
    /// Whether to use the configuration from environment variables.
    pub env: bool,
    /// Whether to follow include files are encountered in loaded configuration,
    /// via `include` and `includeIf` sections.
    ///
    /// Note that this needs access to `GIT_*` prefixed environment variables.
    pub includes: bool,
}

impl Config {
    /// Allow everything which usually relates to a fully trusted environment
    pub fn all() -> Self {
        Config {
            system: true,
            git: true,
            user: true,
            env: true,
            includes: true,
        }
    }
}

impl Default for Config {
    fn default() -> Self {
        Self::all()
    }
}

/// Permissions related to the usage of environment variables
#[derive(Debug, Clone)]
pub struct Environment {
    /// Control whether resources pointed to by `XDG_CONFIG_HOME` can be used when looking up common configuration values.
    ///
    /// Note that [`git_sec::Permission::Forbid`] will cause the operation to abort if a resource is set via the XDG config environment.
    pub xdg_config_home: permission::env_var::Resource,
    /// Control the way resources pointed to by the home directory (similar to `xdg_config_home`) may be used.
    pub home: permission::env_var::Resource,
    /// Control if resources pointed to by `GIT_*` prefixed environment variables can be used.
    pub git_prefix: permission::env_var::Resource,
}

impl Environment {
    /// Allow access to the entire environment.
    pub fn all() -> Self {
        Environment {
            xdg_config_home: Access::resource(git_sec::Permission::Allow),
            home: Access::resource(git_sec::Permission::Allow),
            git_prefix: Access::resource(git_sec::Permission::Allow),
        }
    }
}

impl Permissions {
    /// Return permissions similar to what git does when the repository isn't owned by the current user,
    /// thus refusing all operations in it.
    pub fn strict() -> Self {
        Permissions {
            git_dir: Access::resource(git_sec::ReadWrite::READ),
            env: Environment::all(),
            config: Config::all(),
        }
    }

    /// Return permissions that will not include configuration files not owned by the current user,
    /// but trust system and global configuration files along with those which are owned by the current user.
    ///
    /// This allows to read and write repositories even if they aren't owned by the current user, but avoid using
    /// anything else that could cause us to write into unknown locations or use programs beyond our `PATH`.
    pub fn secure() -> Self {
        Permissions {
            git_dir: Access::resource(git_sec::ReadWrite::all()),
            env: Environment::all(),
            config: Config::all(),
        }
    }

    /// Everything is allowed with this set of permissions, thus we read all configuration and do what git typically
    /// does with owned repositories.
    pub fn all() -> Self {
        Permissions {
            git_dir: Access::resource(git_sec::ReadWrite::all()),
            env: Environment::all(),
            config: Config::all(),
        }
    }
}

impl git_sec::trust::DefaultForLevel for Permissions {
    fn default_for_level(level: Trust) -> Self {
        match level {
            Trust::Full => Permissions::all(),
            Trust::Reduced => Permissions::secure(),
        }
    }
}

impl Default for Permissions {
    fn default() -> Self {
        Permissions::secure()
    }
}