* Re: [PATCH] bpf: whitelist syscalls for error injection [not found] <20180313231627.1247-1-hmclauchlan@fb.com> @ 2018-03-13 23:45 ` Omar Sandoval 2018-03-13 23:49 ` Yonghong Song 0 siblings, 1 reply; 3+ messages in thread From: Omar Sandoval @ 2018-03-13 23:45 UTC (permalink / raw) To: Howard McLauchlan Cc: linux-kernel, linux-api, Al Viro, Thomas Gleixner, Yonghong Song, David S . Miller, Thomas Garnier, kernel-team, Steven Rostedt, Ingo Molnar, Josef Bacik, Alexei Starovoitov, netdev On Tue, Mar 13, 2018 at 04:16:27PM -0700, Howard McLauchlan wrote: > 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, -ENOENT); > return 0; > } > """ % pid > > b = BPF(text = prog) > while 1: > b.perf_buffer_poll() > > This patch whitelists all syscalls defined with SYSCALL_DEFINE for error > injection. > > Signed-off-by: Howard McLauchlan <hmclauchlan@fb.com> > --- > based on 4.16-rc5 > include/linux/syscalls.h | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h > index a78186d826d7..e8c6d63ace78 100644 > --- a/include/linux/syscalls.h > +++ b/include/linux/syscalls.h > @@ -191,6 +191,8 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event) > > #define SYSCALL_DEFINE0(sname) \ > SYSCALL_METADATA(_##sname, 0); \ > + asmlinkage long sys_##sname(void); \ > + ALLOW_ERROR_INJECTION(sys_##sname, ERRNO); \ > asmlinkage long sys_##sname(void) > > #define SYSCALL_DEFINE1(name, ...) SYSCALL_DEFINEx(1, _##name, __VA_ARGS__) > @@ -210,6 +212,7 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event) > #define __SYSCALL_DEFINEx(x, name, ...) \ > asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \ > __attribute__((alias(__stringify(SyS##name)))); \ > + ALLOW_ERROR_INJECTION(sys##name, ERRNO); \ > static inline long SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \ > asmlinkage long SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ > asmlinkage long SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \ > -- > 2.14.1 > Adding a few more people to Cc ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] bpf: whitelist syscalls for error injection 2018-03-13 23:45 ` [PATCH] bpf: whitelist syscalls for error injection Omar Sandoval @ 2018-03-13 23:49 ` Yonghong Song 2018-03-14 0:00 ` Howard McLauchlan 0 siblings, 1 reply; 3+ messages in thread From: Yonghong Song @ 2018-03-13 23:49 UTC (permalink / raw) To: Omar Sandoval, Howard McLauchlan Cc: linux-kernel, linux-api, Al Viro, Thomas Gleixner, David S . Miller, Thomas Garnier, kernel-team, Steven Rostedt, Ingo Molnar, Josef Bacik, Alexei Starovoitov, netdev On 3/13/18 4:45 PM, Omar Sandoval wrote: > On Tue, Mar 13, 2018 at 04:16:27PM -0700, Howard McLauchlan wrote: >> 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, -ENOENT); >> return 0; >> } >> """ % pid >> >> b = BPF(text = prog) >> while 1: >> b.perf_buffer_poll() >> >> This patch whitelists all syscalls defined with SYSCALL_DEFINE for error >> injection. >> >> Signed-off-by: Howard McLauchlan <hmclauchlan@fb.com> >> --- >> based on 4.16-rc5 >> include/linux/syscalls.h | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h >> index a78186d826d7..e8c6d63ace78 100644 >> --- a/include/linux/syscalls.h >> +++ b/include/linux/syscalls.h >> @@ -191,6 +191,8 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event) >> >> #define SYSCALL_DEFINE0(sname) \ >> SYSCALL_METADATA(_##sname, 0); \ >> + asmlinkage long sys_##sname(void); \ >> + ALLOW_ERROR_INJECTION(sys_##sname, ERRNO); \ >> asmlinkage long sys_##sname(void) duplication of asmlinkage in the above? >> >> #define SYSCALL_DEFINE1(name, ...) SYSCALL_DEFINEx(1, _##name, __VA_ARGS__) >> @@ -210,6 +212,7 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event) >> #define __SYSCALL_DEFINEx(x, name, ...) \ >> asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \ >> __attribute__((alias(__stringify(SyS##name)))); \ >> + ALLOW_ERROR_INJECTION(sys##name, ERRNO); \ >> static inline long SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \ >> asmlinkage long SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ >> asmlinkage long SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \ >> -- >> 2.14.1 >> > > Adding a few more people to Cc > ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] bpf: whitelist syscalls for error injection 2018-03-13 23:49 ` Yonghong Song @ 2018-03-14 0:00 ` Howard McLauchlan 0 siblings, 0 replies; 3+ messages in thread From: Howard McLauchlan @ 2018-03-14 0:00 UTC (permalink / raw) To: Yonghong Song, Omar Sandoval Cc: linux-kernel, linux-api, Al Viro, Thomas Gleixner, David S . Miller, Thomas Garnier, kernel-team, Steven Rostedt, Ingo Molnar, Josef Bacik, Alexei Starovoitov, netdev On 03/13/2018 04:49 PM, Yonghong Song wrote: > > > On 3/13/18 4:45 PM, Omar Sandoval wrote: >> On Tue, Mar 13, 2018 at 04:16:27PM -0700, Howard McLauchlan wrote: >>> 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, -ENOENT); >>> return 0; >>> } >>> """ % pid >>> >>> b = BPF(text = prog) >>> while 1: >>> b.perf_buffer_poll() >>> >>> This patch whitelists all syscalls defined with SYSCALL_DEFINE for error >>> injection. >>> >>> Signed-off-by: Howard McLauchlan <hmclauchlan@fb.com> >>> --- >>> based on 4.16-rc5 >>> include/linux/syscalls.h | 3 +++ >>> 1 file changed, 3 insertions(+) >>> >>> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h >>> index a78186d826d7..e8c6d63ace78 100644 >>> --- a/include/linux/syscalls.h >>> +++ b/include/linux/syscalls.h >>> @@ -191,6 +191,8 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event) >>> #define SYSCALL_DEFINE0(sname) \ >>> SYSCALL_METADATA(_##sname, 0); \ >>> + asmlinkage long sys_##sname(void); \ >>> + ALLOW_ERROR_INJECTION(sys_##sname, ERRNO); \ >>> asmlinkage long sys_##sname(void) > > duplication of asmlinkage in the above? > The pre-declaration is necessary to ensure ALLOW_ERROR_INJECTION works appropriately. There can be syscalls that are not pre-declared elsewhere which will fail compilation if not declared in this block. >>> #define SYSCALL_DEFINE1(name, ...) SYSCALL_DEFINEx(1, _##name, __VA_ARGS__) >>> @@ -210,6 +212,7 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event) >>> #define __SYSCALL_DEFINEx(x, name, ...) \ >>> asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \ >>> __attribute__((alias(__stringify(SyS##name)))); \ >>> + ALLOW_ERROR_INJECTION(sys##name, ERRNO); \ >>> static inline long SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \ >>> asmlinkage long SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ >>> asmlinkage long SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \ >>> -- >>> 2.14.1 >>> >> >> Adding a few more people to Cc >> ^ permalink raw reply [flat|nested] 3+ messages in thread
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2018-03-13 23:45 ` [PATCH] bpf: whitelist syscalls for error injection Omar Sandoval
2018-03-13 23:49 ` Yonghong Song
2018-03-14 0:00 ` Howard McLauchlan
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