Date: Tue, 24 Mar 2015 13:35:17 +0100 From: Mateusz Guzik <mjguzik@gmail.com> To: Tiwei Bie <btw@mail.ustc.edu.cn> Cc: Konstantin Belousov <kostikbel@gmail.com>, freebsd-hackers@freebsd.org Subject: Re: [PATCH] Finish the task 'Validate coredump format string' Message-ID: <20150324123517.GA25678@dft-labs.eu> In-Reply-To: <20150323020314.GA30143@freebsd> References: <1426946345-67889-1-git-send-email-btw@mail.ustc.edu.cn> <20150321200500.GC14650@dft-labs.eu> <20150322091853.GA89976@freebsd> <20150322101401.GH14650@dft-labs.eu> <20150322112555.GA44277@freebsd> <20150322113822.GB2379@kib.kiev.ua> <20150322120655.GA59757@freebsd> <20150322131524.GA95795@freebsd> <20150323005852.GB6798@dft-labs.eu> <20150323020314.GA30143@freebsd>
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On Mon, Mar 23, 2015 at 10:03:14AM +0800, Tiwei Bie wrote:
> On Mon, Mar 23, 2015 at 01:58:52AM +0100, Mateusz Guzik wrote:
> > On Sun, Mar 22, 2015 at 09:15:24PM +0800, Tiwei Bie wrote:
> > > On Sun, Mar 22, 2015 at 08:06:55PM +0800, Tiwei Bie wrote:
> > > > On Sun, Mar 22, 2015 at 01:38:22PM +0200, Konstantin Belousov wrote:
> > > > > On Sun, Mar 22, 2015 at 07:25:55PM +0800, Tiwei Bie wrote:
> > > > > > On Sun, Mar 22, 2015 at 11:14:01AM +0100, Mateusz Guzik wrote:
> > > > > > > On Sun, Mar 22, 2015 at 05:19:40PM +0800, Tiwei Bie wrote:
> > > >
> > > [..]
> > > > I will submit my new patch later.
> > > >
> > >
> > > Here is my new patch:
> > >
> > > ---
> > > sys/kern/kern_sig.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++-------
> > > 1 file changed, 64 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
> > > index 8410d9d..5162ab6 100644
> > > --- a/sys/kern/kern_sig.c
> > > +++ b/sys/kern/kern_sig.c
> > > @@ -3094,21 +3094,81 @@ static int compress_user_cores = 0;
> > > */
> > > #define corefilename_lock allproc_lock
> > >
> > > -static char corefilename[MAXPATHLEN] = {"%N.core"};
> > > +static char corefilename[MAXPATHLEN] = "%N.core";
> > > +
> > > +static bool
> > > +corefilename_check(const char *format)
> > > +{
> > > + int i, counti;
> > > +
> > > + counti = 0;
> > > + for (i = 0; i < MAXPATHLEN && format[i] != '\0'; i++) {
> > > + if (format[i] == '%') {
> > > + i++;
> > > + switch (format[i]) {
> > > + case 'I':
> > > + counti++;
> > > + if (counti > 1)
> > > + return (false);
> > > + case '%':
> > > + case 'H':
> > > + case 'N':
> > > + case 'P':
> > > + case 'U':
> > > + break;
> > > + default:
> > > + return (false);
> > > + }
> > > + }
> > > + }
> > > +
> > > + if (i == MAXPATHLEN)
> > > + return (false);
> > > +
> > > + return (true);
> > > +}
> > > +
> > > +static void
> > > +corefilename_init(void *arg)
> > > +{
> > > + char *format;
> > > +
> > > + format = kern_getenv("kern.corefile");
> > > + if (format != NULL && corefilename_check(format))
> > > + strcpy(corefilename, format);
> > > +}
> > > +SYSINIT(corefilename, SI_SUB_KMEM, SI_ORDER_FIRST, corefilename_init, 0);
> > >
> >
> > The user should know that the tunable got discarded (e.g. like with
> > prinf removed below).
> >
>
> I don't know how to do this. We need to update the man-pages?
>
> And sorry again, maybe I was too tired yesterday. I just find a new bug in
> the codes above when reading your comments. Though it won't affect anything
> cause dynamic_kenv hasn't been enabled at this time, it is really a bug.
>
> `format' needs to be freed, sorry... What a terrible day. ;-(
>
core(5). yeah, would be nice to mention all this stuff.
> > > static int
> > > sysctl_kern_corefile(SYSCTL_HANDLER_ARGS)
> > > {
> > > + char *format;
> > > int error;
> > >
> > > + format = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
> > > +
> > > + sx_slock(&corefilename_lock);
> > > + strcpy(format, corefilename);
> > > + sx_sunlock(&corefilename_lock);
> > > +
> > > + error = sysctl_handle_string(oidp, format, MAXPATHLEN, req);
> > > + if (error || !req->newptr || strcmp(format, corefilename) == 0)
> > > + goto out;
> > > +
> >
> > Is this strcmp useful? Normally you don't replace the pattern with
> > identical one.
> >
>
> I wrote these codes after consulting the codes in kern/kern_clocksource.c
>
[..]
> It also needs to validate the user's inputs. And it uses a strcasecmp()
> to check whether a different timer has been specified by the user.
>
> If the user is going to replace the pattern with identical one, we won't
> need to do any update, we just `goto out'.
>
Well, I presume original author did not want to play with timers when
changing to the same timer.
Corefile is safe to change, so I suggest just dropping that strcmp.
Also see below.
> My new patch:
>
> ---
> sys/kern/kern_sig.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 70 insertions(+), 7 deletions(-)
>
> diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
> index 8410d9d..0254517 100644
> --- a/sys/kern/kern_sig.c
> +++ b/sys/kern/kern_sig.c
> @@ -3094,21 +3094,85 @@ static int compress_user_cores = 0;
> */
> #define corefilename_lock allproc_lock
>
> -static char corefilename[MAXPATHLEN] = {"%N.core"};
> +static char corefilename[MAXPATHLEN] = "%N.core";
> +
> +static bool
> +corefilename_check(const char *format)
> +{
> + int i, counti;
> +
> + counti = 0;
> + for (i = 0; i < MAXPATHLEN && format[i] != '\0'; i++) {
> + if (format[i] == '%') {
> + i++;
> + switch (format[i]) {
> + case 'I':
> + counti++;
> + if (counti > 1)
> + return (false);
countI?
> + case '%':
> + case 'H':
> + case 'N':
> + case 'P':
> + case 'U':
> + break;
> + default:
> + return (false);
> + }
> + }
> + }
> +
> + if (i == MAXPATHLEN)
> + return (false);
> +
> + return (true);
> +}
> +
> +static void
> +corefilename_init(void *arg)
> +{
> + char *format;
> +
> + format = kern_getenv("kern.corefile");
> +
> + if (format != NULL) {
> + if (corefilename_check(format))
> + strcpy(corefilename, format);
> + freeenv(format);
> + }
> +}
printf something. "invalid format specified" or the like.
Also the code may be nicer if you
if (format == NULL)
return;
instead
> +SYSINIT(corefilename, SI_SUB_KMEM, SI_ORDER_FIRST, corefilename_init, 0);
>
> static int
> sysctl_kern_corefile(SYSCTL_HANDLER_ARGS)
> {
> + char *format;
> int error;
>
> + format = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
> +
> + sx_slock(&corefilename_lock);
> + strcpy(format, corefilename);
> + sx_sunlock(&corefilename_lock);
> +
> + error = sysctl_handle_string(oidp, format, MAXPATHLEN, req);
> + if (error || !req->newptr || strcmp(format, corefilename) == 0)
> + goto out;
> +
this should be if (error != 0 || req->newptr == NULL).
strmcp was covered earlier in the mail
> + if (!corefilename_check(format)) {
> + error = EINVAL;
> + goto out;
> + }
> +
> sx_xlock(&corefilename_lock);
> - error = sysctl_handle_string(oidp, corefilename, sizeof(corefilename),
> - req);
> + strcpy(corefilename, format);
> sx_xunlock(&corefilename_lock);
>
> +out:
> + free(format, M_TEMP);
> return (error);
> }
> -SYSCTL_PROC(_kern, OID_AUTO, corefile, CTLTYPE_STRING | CTLFLAG_RWTUN |
> +SYSCTL_PROC(_kern, OID_AUTO, corefile, CTLTYPE_STRING | CTLFLAG_RW |
> CTLFLAG_MPSAFE, 0, 0, sysctl_kern_corefile, "A",
> "Process corefile name format string");
>
> @@ -3171,9 +3235,8 @@ corefile_open(const char *comm, uid_t uid, pid_t pid, struct thread *td,
> sbuf_printf(&sb, "%u", uid);
> break;
> default:
> - log(LOG_ERR,
> - "Unknown format character %c in "
> - "corename `%s'\n", format[i], format);
> + KASSERT(0, ("Unknown format character %c in "
> + "corename `%s'\n", format[i], format));
> break;
> }
> break;
> --
> 2.1.2
>
> Best regards,
> Tiwei Bie
>
--
Mateusz Guzik <mjguzik gmail.com>
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