From 0a6a2674fa6cbfda986b20d76f64802f0f65c2f0 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Andr=C3=A9s=20Medina?= Date: Thu, 21 Sep 2023 21:02:20 -0700 Subject: [PATCH] aya: Fix program loading on kernels with a patch > 255 --- aya/src/programs/mod.rs | 10 ++------- aya/src/util.rs | 48 +++++++++++++++++++++++++++++------------ 2 files changed, 36 insertions(+), 22 deletions(-) diff --git a/aya/src/programs/mod.rs b/aya/src/programs/mod.rs index bb9622fe..0f2ebdd6 100644 --- a/aya/src/programs/mod.rs +++ b/aya/src/programs/mod.rs @@ -617,14 +617,8 @@ fn load_program( }, ) = obj; - let target_kernel_version = kernel_version.unwrap_or_else(|| { - let KernelVersion { - major, - minor, - patch, - } = KernelVersion::current().unwrap(); - (u32::from(major) << 16) + (u32::from(minor) << 8) + u32::from(patch) - }); + let target_kernel_version = + kernel_version.unwrap_or_else(|| KernelVersion::current().unwrap().code()); let prog_name = if let Some(name) = name { let mut name = name.clone(); diff --git a/aya/src/util.rs b/aya/src/util.rs index 54c289b0..b7a80006 100644 --- a/aya/src/util.rs +++ b/aya/src/util.rs @@ -49,23 +49,43 @@ impl KernelVersion { /// Returns the kernel version of the currently running kernel. pub fn current() -> Result { - let kernel_version = Self::get_kernel_version(); + Self::get_kernel_version() + } - // The kernel version is clamped to 4.19.255 on kernels 4.19.222 and above. - // - // See https://github.com/torvalds/linux/commit/a256aac. - const CLAMPED_KERNEL_MAJOR: u8 = 4; - const CLAMPED_KERNEL_MINOR: u8 = 19; - if let Ok(Self { - major: CLAMPED_KERNEL_MAJOR, - minor: CLAMPED_KERNEL_MINOR, - patch: 222.., - }) = kernel_version - { - return Ok(Self::new(CLAMPED_KERNEL_MAJOR, CLAMPED_KERNEL_MINOR, 255)); + /// The equivalent of LINUX_VERSION_CODE. + pub(crate) fn code(self) -> u32 { + let Self { + major, + minor, + mut patch, + } = self; + + // Certain LTS kernels went above the "max" 255 patch so + // backports were done to cap the patch version + let max_patch = match (major, minor) { + // On 4.4 + 4.9, any patch 257 or above was hardcoded to 255. + // See: https://github.com/torvalds/linux/commit/a15813a + + // https://github.com/torvalds/linux/commit/42efb098 + (4, 4 | 9) => 257, + // On 4.14, any patch 252 or above was hardcoded to 255. + // See: https://github.com/torvalds/linux/commit/e131e0e + (4, 14) => 252, + // On 4.19, any patch 222 or above was hardcoded to 255. + // See: https://github.com/torvalds/linux/commit/a256aac + (4, 19) => 222, + // For other kernels (i.e., newer LTS kernels as other + // ones won't reach 255+ patches) clamp it to 255. See: + // https://github.com/torvalds/linux/commit/9b82f13e + _ => 255, + }; + + // anything greater or equal to `max_patch` is hardcoded to + // 255. + if patch >= max_patch { + patch = 255; } - kernel_version + (u32::from(major) << 16) + (u32::from(minor) << 8) + u32::from(patch) } // This is ported from https://github.com/torvalds/linux/blob/3f01e9f/tools/lib/bpf/libbpf_probes.c#L21-L101.