Messages in this thread Patch in this message | | | Subject | [PATCH 2/2] | From | Denys Vlasenko <> | Date | Mon, 05 Sep 2011 19:01:12 +0200 |
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On Mon, 2011-09-05 at 18:51 +0200, Denys Vlasenko wrote: > > A crude patch is below. It rolls points 1-4 from above into a single > > new option, PTRACE_O_TRACESTOP. > > For easier review, split it into two parts. Part 1 follows. > (It is still not even compile-tested).
Part 2. -- vda
Add new PTRACE_O_TRACESTOP option, make it control new ptrace behavior.
Introduce new ptrace option, PTRACE_O_TRACESTOP. This makes API more symmetric: every PTRACE_EVENT_event has corresponding PTRACE_O_TRACEevent now, as it used to have before PTRACE_SEIZE was introduced.
PTRACE_SEIZE does not assume PTRACE_O_TRACESTOP, but with this patch it allows any PTRACE_O_opts to be set at attach time (they are passed in data param) - including PTRACE_O_TRACESTOP, of course. Without any options, PTRACE_SEIZE is equivalent to PTRACE_ATTACH. With only PTRACE_O_TRACESTOP option, PTRACE_SEIZE behavior will be the same as PTRACE_SEIZE behavior before this patch.
This opens up two new possibilities: ptrace options can be set on attach (can be used to close a few corner cases in strace); PTRACE_LISTEN, PTRACE_INTERRUPT commands and PTRACE_EVENT_STOP event can be enabled with PTRACE_SETOPTIONS with PTRACE_O_TRACESTOP (not a big deal, but IMO this makes API more symmetric).
All formerly PTRACE_SEIZE-enabled behavior is now enabled by PTRACE_O_TRACESTOP instead (by PT_TRACE_STOP bit). PT_SEIZED bit is removed.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index 800f113..e2ba2dd 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -62,8 +62,9 @@ #define PTRACE_O_TRACEEXEC 0x00000010 #define PTRACE_O_TRACEVFORKDONE 0x00000020 #define PTRACE_O_TRACEEXIT 0x00000040 +#define PTRACE_O_TRACESTOP 0x00000080 -#define PTRACE_O_MASK 0x0000007f +#define PTRACE_O_MASK 0x000000ff /* Wait extended result codes for the above trace options. */ #define PTRACE_EVENT_FORK 1 @@ -85,24 +86,21 @@ * flags. When the a task is stopped the ptracer owns task->ptrace. */ -#define PT_SEIZED 0x00010000 /* SEIZE used, enable new behavior */ #define PT_PTRACED 0x00000001 #define PT_DTRACE 0x00000002 /* delayed trace (used on m68k, i386) */ -#define PT_TRACESYSGOOD 0x00000004 -#define PT_PTRACE_CAP 0x00000008 /* ptracer can follow suid-exec */ +#define PT_PTRACE_CAP 0x00000004 /* ptracer can follow suid-exec */ +#define PT_OPT_FLAG_SHIFT 3 +#define PT_TRACESYSGOOD 0x00000008 /* must be directly before PT_TRACE_event bits! */ /* PT_TRACE_* event enable flags */ -#define PT_EVENT_FLAG_SHIFT 4 -#define PT_EVENT_FLAG(event) (1 << (PT_EVENT_FLAG_SHIFT + (event) - 1)) - +#define PT_EVENT_FLAG(event) (1 << (PT_OPT_FLAG_SHIFT + (event))) #define PT_TRACE_FORK PT_EVENT_FLAG(PTRACE_EVENT_FORK) #define PT_TRACE_VFORK PT_EVENT_FLAG(PTRACE_EVENT_VFORK) #define PT_TRACE_CLONE PT_EVENT_FLAG(PTRACE_EVENT_CLONE) #define PT_TRACE_EXEC PT_EVENT_FLAG(PTRACE_EVENT_EXEC) #define PT_TRACE_VFORK_DONE PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE) #define PT_TRACE_EXIT PT_EVENT_FLAG(PTRACE_EVENT_EXIT) - -#define PT_TRACE_MASK 0x000003f4 +#define PT_TRACE_STOP PT_EVENT_FLAG(PTRACE_EVENT_STOP) /* single stepping state bits (used on ARM and PA-RISC) */ #define PT_SINGLESTEP_BIT 31 @@ -228,7 +226,7 @@ static inline void ptrace_init_task(struct task_struct *child, bool ptrace) child->ptrace = current->ptrace; __ptrace_link(child, current->parent); - if (child->ptrace & PT_SEIZED) + if (child->ptrace & PTRACE_EVENT_STOP) task_set_jobctl_pending(child, JOBCTL_TRAP_STOP); else sigaddset(&child->pending.signal, SIGSTOP); diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 9de3ecf..0bf3d74 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -219,19 +219,23 @@ static int ptrace_attach(struct task_struct *task, long request, /* * SEIZE will enable new ptrace behaviors which will be implemented - * gradually. SEIZE_DEVEL is used to prevent applications + * gradually. SEIZE_DEVEL bit is used to prevent applications * expecting full SEIZE behaviors trapping on kernel commits which * are still in the process of implementing them. * * Only test programs for new ptrace behaviors being implemented * should set SEIZE_DEVEL. If unset, SEIZE will fail with -EIO. * - * Once SEIZE behaviors are completely implemented, this flag and - * the following test will be removed. + * Once SEIZE behaviors are completely implemented, this flag + * will be removed. */ retval = -EIO; - if (seize && !(flags & PTRACE_SEIZE_DEVEL)) - goto out; + if (seize) { + if ((flags & ~(long)PTRACE_O_MASK) != PTRACE_SEIZE_DEVEL) + goto out; + flags &= ~PTRACE_SEIZE_DEVEL; + } else + flags = 0; audit_ptrace(task); @@ -243,7 +247,7 @@ static int ptrace_attach(struct task_struct *task, long request, /* * Protect exec's credential calculations against our interference; - * interference; SUID, SGID and LSM creds get determined differently + * SUID, SGID and LSM creds get determined differently * under ptrace. */ retval = -ERESTARTNOINTR; @@ -263,9 +267,7 @@ static int ptrace_attach(struct task_struct *task, long request, if (task->ptrace) goto unlock_tasklist; - task->ptrace = PT_PTRACED; - if (seize) - task->ptrace |= PT_SEIZED; + task->ptrace = PT_PTRACED | (flags << PT_OPT_FLAG_SHIFT); if (task_ns_capable(task, CAP_SYS_PTRACE)) task->ptrace |= PT_PTRACE_CAP; @@ -509,30 +511,13 @@ int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long ds static int ptrace_setoptions(struct task_struct *child, unsigned long data) { - child->ptrace &= ~PT_TRACE_MASK; - - if (data & PTRACE_O_TRACESYSGOOD) - child->ptrace |= PT_TRACESYSGOOD; - - if (data & PTRACE_O_TRACEFORK) - child->ptrace |= PT_TRACE_FORK; - - if (data & PTRACE_O_TRACEVFORK) - child->ptrace |= PT_TRACE_VFORK; - - if (data & PTRACE_O_TRACECLONE) - child->ptrace |= PT_TRACE_CLONE; - - if (data & PTRACE_O_TRACEEXEC) - child->ptrace |= PT_TRACE_EXEC; - - if (data & PTRACE_O_TRACEVFORKDONE) - child->ptrace |= PT_TRACE_VFORK_DONE; + if (data & ~(long)PTRACE_O_MASK) + return -EINVAL; - if (data & PTRACE_O_TRACEEXIT) - child->ptrace |= PT_TRACE_EXIT; + child->ptrace &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT); + child->ptrace |= (data << PT_OPT_FLAG_SHIFT); - return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; + return 0; } static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info) @@ -666,7 +651,7 @@ static int ptrace_regset(struct task_struct *task, int req, unsigned int type, int ptrace_request(struct task_struct *child, long request, unsigned long addr, unsigned long data) { - bool seized = child->ptrace & PT_SEIZED; + bool stop_events_enabled = child->ptrace & PT_TRACE_STOP; int ret = -EIO; siginfo_t siginfo, *si; void __user *datavp = (void __user *) data; @@ -715,7 +700,7 @@ int ptrace_request(struct task_struct *child, long request, * The actual trap might not be PTRACE_EVENT_STOP trap but * the pending condition is cleared regardless. */ - if (unlikely(!seized || !lock_task_sighand(child, &flags))) + if (unlikely(!stop_events_enabled || !lock_task_sighand(child, &flags))) break; /* @@ -740,7 +725,7 @@ int ptrace_request(struct task_struct *child, long request, * again. Alternatively, ptracer can issue INTERRUPT to * finish listening and re-trap tracee into STOP. */ - if (unlikely(!seized || !lock_task_sighand(child, &flags))) + if (unlikely(!stop_events_enabled || !lock_task_sighand(child, &flags))) break; si = child->last_siginfo; diff --git a/kernel/signal.c b/kernel/signal.c index 291c970..9248600 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -823,8 +823,8 @@ static int check_kill_permission(int sig, struct siginfo *info, * @t: tracee wanting to notify tracer * * This function schedules sticky ptrace trap which is cleared on the next - * TRAP_STOP to notify ptracer of an event. @t must have been seized by - * ptracer. + * TRAP_STOP to notify ptracer of an event. @t must have PTRACE_O_TRACESTOP + * option active. * * If @t is running, STOP trap will be taken. If trapped for STOP and * ptracer is listening for events, tracee is woken up so that it can @@ -837,7 +837,7 @@ static int check_kill_permission(int sig, struct siginfo *info, */ static void ptrace_trap_notify(struct task_struct *t) { - WARN_ON_ONCE(!(t->ptrace & PT_SEIZED)); + WARN_ON_ONCE(!(t->ptrace & PT_TRACE_STOP)); assert_spin_locked(&t->sighand->siglock); task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY); @@ -882,7 +882,7 @@ static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns) do { task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING); rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending); - if (likely(!(t->ptrace & PT_SEIZED))) + if (likely(!(t->ptrace & PT_TRACE_STOP))) wake_up_state(t, __TASK_STOPPED); else ptrace_trap_notify(t); @@ -2004,7 +2004,7 @@ static bool do_signal_stop(int signr) if (!task_is_stopped(t) && task_set_jobctl_pending(t, signr | gstop)) { sig->group_stop_count++; - if (likely(!(t->ptrace & PT_SEIZED))) + if (likely(!(t->ptrace & PT_TRACE_STOP))) signal_wake_up(t, 0); else ptrace_trap_notify(t); @@ -2057,13 +2057,13 @@ static bool do_signal_stop(int signr) /** * do_jobctl_trap - take care of ptrace jobctl traps * - * When PT_SEIZED, it's used for both group stop and explicit - * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with + * When PT_TRACE_STOP is on, it's used for both group stop and explicit + * INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with * accompanying siginfo. If stopped, lower eight bits of exit_code contain * the stop signal; otherwise, %SIGTRAP. * - * When !PT_SEIZED, it's used only for group stop trap with stop signal - * number as exit_code and no siginfo. + * When PT_TRACE_STOP is off, it's used only for group stop trap + * with stop signal number as exit_code and no siginfo. * * CONTEXT: * Must be called with @current->sighand->siglock held, which may be @@ -2074,7 +2074,7 @@ static void do_jobctl_trap(void) struct signal_struct *signal = current->signal; int signr = current->jobctl & JOBCTL_STOP_SIGMASK; - if (current->ptrace & PT_SEIZED) { + if (current->ptrace & PT_TRACE_STOP) { if (!signal->group_stop_count && !(signal->flags & SIGNAL_STOP_STOPPED)) signr = SIGTRAP;
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