Question
Rider .NET debugger attach fails on Linux under ptrace restrictions
Nia Finch
0 reputation · 21 Aug 2021, 15:01 UTC
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0 reputation · 21 Aug 2021, 15:01 UTC
Rider attempts to attach its .NET debugger to a running process on Linux using ptrace. When kernel.yama.ptrace_scope is set to 1 or 2, the attach can fail for processes that are not children of the IDE or are owned by another user. Rider typically reports a generic attach failure instead of identifying ptrace denial as the cause.
The exact error text, diagnostic log location, and fallback behavior vary across Rider versions, JetBrains Runtime builds, and target .NET runtimes. It is unresolved whether Rider should detect ptrace denial at attach time and surface a distribution-specific remediation hint inside the IDE.
What should Rider display when ptrace blocks an attach? Should the IDE distinguish ptrace denial from other attach failures? Is a distro-specific hint appropriate, or should Rider only advise checking system ptrace settings?
Rider should distinguish ptrace denial from general attach failures and surface a specific warning when the OS returns an EPERM (Operation not permitted) error during the attach sequence. Rather than a generic failure message, the IDE should inform the user that the system's security policy is blocking the debugger from accessing the target process.
A distribution-specific hint is generally too narrow, as ptrace_scope is a kernel-level setting used across various Linux distributions (e.g., Ubuntu, Fedora). Instead, Rider should provide a general Linux-centric remediation hint that points to the kernel.yama.ptrace_scope setting.
The ideal workflow for the IDE would be:
linux
riderptrace call./proc/sys/kernel/yama/ptrace_scope.The .NET debugger on Linux relies on the ptrace system call to inject the debugging agent into the target process. The Yama security module governs this behavior via /proc/sys/kernel/yama/ptrace_scope:
| Value | Restriction Level | Impact on Rider Attach |
|---|---|---|
| 0 | Classic ptrace | Attach succeeds for any process owned by the same user. |
| 1 | Restricted ptrace | Attach fails unless the target is a direct child of Rider. |
| 2 | Admin-only ptrace | Attach fails unless the IDE is running with root privileges. |
To confirm if ptrace restrictions are causing the attach failure, use the following scoped commands:
Check current restriction level:
cat /proc/sys/kernel/yama/ptrace_scopeTemporarily relax restrictions for the current session:
sudo sysctl -w kernel.yama.ptrace_scope=0If the debugger attaches successfully after setting the value to 0, the issue is confirmed as a ptrace restriction. Note that reducing this value lowers system security by allowing any process owned by the user to attach to any other process owned by that user.
To refine the recommendation, it is necessary to know: Is the target process running inside a container (Docker/Podman) or a separate PID namespace? If so, the restriction may be enforced by the container runtime's seccomp profile rather than the host's Yama settings.
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