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authorHoward McLauchlan <hmclauchlan@fb.com>2018-03-21 18:59:08 -0700
committerDominik Brodowski <linux@dominikbrodowski.net>2018-04-02 20:16:21 +0200
commitc9a211951c7c79cfb5de888d7d9550872868b086 (patch)
tree278cec14b206aa6dcaad30b9da6f19b7b4df1fc6 /fs/namei.c
parent67a7acd3773a94df2e671601a288685485463cf9 (diff)
downloadlinux-stericsson-c9a211951c7c79cfb5de888d7d9550872868b086.tar.gz
bpf: whitelist all syscalls for error injection
Error injection is a useful mechanism to fail arbitrary kernel functions. However, it is often hard to guarantee an error propagates appropriately to user space programs. By injecting into syscalls, we can return arbitrary values to user space directly; this increases flexibility and robustness in testing, allowing us to test user space error paths effectively. The following script, for example, fails calls to sys_open() from a given pid: from bcc import BPF from sys import argv pid = argv[1] prog = r""" int kprobe__SyS_open(struct pt_regs *ctx, const char *pathname, int flags) { u32 pid = bpf_get_current_pid_tgid(); if (pid == %s) bpf_override_return(ctx, -ENOMEM); return 0; } """ % pid b = BPF(text=prog) while 1: b.perf_buffer_poll() This patch whitelists all syscalls defined with SYSCALL_DEFINE and COMPAT_SYSCALL_DEFINE for error injection. These changes are not intended to be considered stable, and would normally be configured off. Signed-off-by: Howard McLauchlan <hmclauchlan@fb.com> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
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