aya_ebpf/maps/
program_array.rs

1use core::{cell::UnsafeCell, hint::unreachable_unchecked, mem};
2
3use aya_ebpf_cty::c_long;
4
5use crate::{
6    bindings::{bpf_map_def, bpf_map_type::BPF_MAP_TYPE_PROG_ARRAY},
7    helpers::bpf_tail_call,
8    maps::PinningType,
9    EbpfContext,
10};
11
12/// A BPF map that stores an array of program indices for tail calling.
13///
14/// # Examples
15///
16/// ```no_run
17/// # #![allow(dead_code)]
18/// use aya_ebpf::{macros::map, maps::ProgramArray, cty::c_long};
19/// # use aya_ebpf::{programs::LsmContext};
20///
21/// #[map]
22/// static JUMP_TABLE: ProgramArray = ProgramArray::with_max_entries(16, 0);
23///
24/// # unsafe fn try_test(ctx: &LsmContext) -> Result<(), c_long> {
25/// let index: u32 = 13;
26///
27/// if let Err(e) = JUMP_TABLE.tail_call(ctx, index) {
28///     return Err(e);
29/// }
30///
31/// # Err(-1)
32/// }
33/// ```
34#[repr(transparent)]
35pub struct ProgramArray {
36    def: UnsafeCell<bpf_map_def>,
37}
38
39unsafe impl Sync for ProgramArray {}
40
41impl ProgramArray {
42    pub const fn with_max_entries(max_entries: u32, flags: u32) -> ProgramArray {
43        ProgramArray {
44            def: UnsafeCell::new(bpf_map_def {
45                type_: BPF_MAP_TYPE_PROG_ARRAY,
46                key_size: mem::size_of::<u32>() as u32,
47                value_size: mem::size_of::<u32>() as u32,
48                max_entries,
49                map_flags: flags,
50                id: 0,
51                pinning: PinningType::None as u32,
52            }),
53        }
54    }
55
56    pub const fn pinned(max_entries: u32, flags: u32) -> ProgramArray {
57        ProgramArray {
58            def: UnsafeCell::new(bpf_map_def {
59                type_: BPF_MAP_TYPE_PROG_ARRAY,
60                key_size: mem::size_of::<u32>() as u32,
61                value_size: mem::size_of::<u32>() as u32,
62                max_entries,
63                map_flags: flags,
64                id: 0,
65                pinning: PinningType::ByName as u32,
66            }),
67        }
68    }
69
70    /// Perform a tail call into a program indexed by this map.
71    ///
72    /// # Safety
73    ///
74    /// This function is inherently unsafe, since it causes control flow to jump into
75    /// another eBPF program. This can have side effects, such as drop methods not being
76    /// called. Note that tail calling into an eBPF program is not the same thing as
77    /// a function call -- control flow never returns to the caller.
78    ///
79    /// # Return Value
80    ///
81    /// On success, this function **does not return** into the original program.
82    /// On failure, a negative error is returned, wrapped in `Err()`.
83    #[cfg(not(unstable))]
84    pub unsafe fn tail_call<C: EbpfContext>(&self, ctx: &C, index: u32) -> Result<(), c_long> {
85        let res = bpf_tail_call(ctx.as_ptr(), self.def.get() as *mut _, index);
86        if res != 0 {
87            Err(res)
88        } else {
89            unreachable_unchecked()
90        }
91    }
92
93    /// Perform a tail call into a program indexed by this map.
94    ///
95    /// # Safety
96    ///
97    /// This function is inherently unsafe, since it causes control flow to jump into
98    /// another eBPF program. This can have side effects, such as drop methods not being
99    /// called. Note that tail calling into an eBPF program is not the same thing as
100    /// a function call -- control flow never returns to the caller.
101    ///
102    /// # Return Value
103    ///
104    /// On success, this function **does not return** into the original program.
105    /// On failure, a negative error is returned, wrapped in `Err()`.
106    #[cfg(unstable)]
107    pub unsafe fn tail_call<C: EbpfContext>(&self, ctx: &C, index: u32) -> Result<!, c_long> {
108        let res = bpf_tail_call(ctx.as_ptr(), self.def.get() as *mut _, index);
109        if res != 0 {
110            Err(res)
111        } else {
112            unreachable_unchecked()
113        }
114    }
115}
aya_ebpf/maps/program_array.rs

aya_ebpf/maps/
program_array.rs
