Date: Mon, 23 Mar 2015 01:58:52 +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: <20150323005852.GB6798@dft-labs.eu> In-Reply-To: <20150322131524.GA95795@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>
next in thread | previous in thread | raw e-mail | index | archive | help
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).
> 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.
> + 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");
>
> @@ -3170,11 +3230,6 @@ corefile_open(const char *comm, uid_t uid, pid_t pid, struct thread *td,
> case 'U': /* user id */
> sbuf_printf(&sb, "%u", uid);
> break;
> - default:
> - log(LOG_ERR,
> - "Unknown format character %c in "
> - "corename `%s'\n", format[i], format);
> - break;
> }
This case should be an assertion. E.g. KASSERT(0, "unknown format in
character")
> break;
> default:
> --
> 2.1.2
>
> Best regards,
> Tiwei Bie
>
--
Mateusz Guzik <mjguzik gmail.com>
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20150323005852.GB6798>