Hi Βαλασιάδης Φώτιος, (did I write your name correctly? I've seen it previously in the reverse order) On 2/27/23 00:22, Fotios Valasiadis wrote: > Document the role of PTRACE_O_TRACESYSGOOD option in connection with PTRACE_GET_SYSCALL_INFO. > > Signed-off-by: Fotios Valasiadis <fvalasiad@xxxxxxxxx> > Cowritten-by: Dmitry V. Levin <ldv@xxxxxxxxx> > Complements: fc91449cb "ptrace.2: Document PTRACE_GET_SYSCALL_INFO" Patch applied. Thanks! I tweaked the commit message to include the original one, which was great. I forgot to mention this, but please keep the commit message for revisions of patches; it's always easier to discard some information later if it's unnecessary, but usually it's best to keep as much as possible in the commit message. > --- > man2/ptrace.2 | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/man2/ptrace.2 b/man2/ptrace.2 > index 55d9fd36d..9737b3825 100644 > --- a/man2/ptrace.2 > +++ b/man2/ptrace.2 > @@ -1111,6 +1111,15 @@ stop. > .B PTRACE_SYSCALL_INFO_NONE > No component of the union contains relevant information. > .RE > +.IP > +In case of system call entry or exit stops, > +the data returned by > +.B PTRACE_GET_SYSCALL_INFO > +is limited to type > +.B PTRACE_SYSCALL_INFO_NONE > +unless > +.B PTRACE_O_TRACESYSGOOD > +option is set before the corresponding system call stop has occurred. > .\" > .SS Death under ptrace > When a (possibly multithreaded) process receives a killing signal On 2/27/23 00:30, Φώτης Βαλασιάδης wrote: > Tried my best, hope I did it right! > > Thanks for the assist! > > And yes, it's Greek! :-) > Signing off with my github username most of the time. Okay. > > Thanks again, here you go! > > Βαλασιάδης Φώτιος The applied patch is below: $ git show commit f04064d73b9f60f189c490e7ef5c3b9fa5498920 (HEAD -> master) Author: Fotios Valasiadis <fvalasiad@xxxxxxxxx> Date: Mon Feb 27 01:22:01 2023 +0200 ptrace.2: Add details about usage of PTRACE_GET_SYSCALL_INFO Document the role of PTRACE_O_TRACESYSGOOD option in connection with PTRACE_GET_SYSCALL_INFO. Fixed incomplete doc. PTRACE_GET_SYSCALL_INFO's description wouldn't inform the user that they need to enable PTRACE_O_TRACESYSGOOD to get detailed information from said operation. Came upon this bug after writing a test program using PTRACE_O_TRACESYSGOOD. After failing to find what's wrong I posted a stackoverflow question which you can find right here: <https://stackoverflow.com/questions/72410182/ptrace-get-syscall-info-always-returns-info-op-as-ptrace-syscall-info-none> Nate Eldredge found out what's wrong by looking into the kernel's source code, here is a link to the relevant part <https://github.com/torvalds/linux/blob/8291eaafed36f575f23951f3ce18407f480e9ecf/kernel/ptrace.c#L1018> In the code it can be seen that the union is filled if and only if the signal matches "SIGTRAP | 0x80", a signal which is only sent if the PTRACE_O_TRACESYSGOOD option is set. You can read about that in the PTRACE_O_TRACESYSGOOD section of ptrace(2)'s manual. Complements: fc91449cb "ptrace.2: Document PTRACE_GET_SYSCALL_INFO" Cowritten-by: Dmitry V. Levin <ldv@xxxxxxxxx> Signed-off-by: Dmitry V. Levin <ldv@xxxxxxxxx> Signed-off-by: Fotios Valasiadis <fvalasiad@xxxxxxxxx> Acked-by: Nate Eldredge <nate@xxxxxxxxxxxxxxxxxxxx> Cc: Elvira Khabirova <lineprinter0@xxxxxxxxx> Signed-off-by: Alejandro Colomar <alx@xxxxxxxxxx> diff --git a/man2/ptrace.2 b/man2/ptrace.2 index 55d9fd36d..9737b3825 100644 --- a/man2/ptrace.2 +++ b/man2/ptrace.2 @@ -1111,6 +1111,15 @@ .SH DESCRIPTION .B PTRACE_SYSCALL_INFO_NONE No component of the union contains relevant information. .RE +.IP +In case of system call entry or exit stops, +the data returned by +.B PTRACE_GET_SYSCALL_INFO +is limited to type +.B PTRACE_SYSCALL_INFO_NONE +unless +.B PTRACE_O_TRACESYSGOOD +option is set before the corresponding system call stop has occurred. .\" .SS Death under ptrace When a (possibly multithreaded) process receives a killing signal Please confirm if you want me to push it like that, or if there's anything you'd like to tweak. Cheers, Alex -- <http://www.alejandro-colomar.es/> GPG key fingerprint: A9348594CE31283A826FBDD8D57633D441E25BB5
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