Date: Wed, 25 Mar 2015 14:00:12 +0800 From: Tiwei Bie <btw@mail.ustc.edu.cn> To: Mateusz Guzik <mjguzik@gmail.com> Cc: Konstantin Belousov <kostikbel@gmail.com>, freebsd-hackers@freebsd.org Subject: Re: [PATCH] Finish the task 'Validate coredump format string' Message-ID: <20150325060012.GA75674@freebsd> In-Reply-To: <20150324143709.GA54065@freebsd> References: <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> <20150324123517.GA25678@dft-labs.eu> <20150324143709.GA54065@freebsd>
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On Tue, Mar 24, 2015 at 10:37:09PM +0800, Tiwei Bie wrote:
> On Tue, Mar 24, 2015 at 01:35:17PM +0100, Mateusz Guzik wrote:
> > 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:
> > >
[..]
> +static void
> +corefilename_init(void *arg)
> +{
> + char *format;
> +
> + format = kern_getenv("kern.corefile");
> + if (format == NULL)
> + return;
> +
> + if (corefilename_check(format))
> + strcpy(corefilename, format);
> + else
> + printf("Invalid format character specified in "
> + "corename `%s'\n", format);
> +
The message printed in corefilename_init() is not proper, it doesn't
cover the case that the length is too long, nor the case that %I is
specified more than once. I extended the corefilename_check() to be
able to return the reason (error code) if it fails. But I'm not sure
whether it is worthwhile, cause it seems currently there is no way to
specified a string longer than MAXPATHLEN via sysctl or kenv.
I also removed the '\n' character from KASSERT() in corefile_open(),
as what the other codes do.
Here is my new patch:
---
share/man/man5/core.5 | 7 ++++
sys/kern/kern_sig.c | 93 +++++++++++++++++++++++++++++++++++++++++++++++----
2 files changed, 93 insertions(+), 7 deletions(-)
diff --git a/share/man/man5/core.5 b/share/man/man5/core.5
index 3f54f89..3047e0a 100644
--- a/share/man/man5/core.5
+++ b/share/man/man5/core.5
@@ -78,6 +78,7 @@ An index starting at zero until the sysctl
is reached.
This can be useful for limiting the number of corefiles
generated by a particular process.
+This specifier can only be specified at most once.
.It Em \&%N
process name.
.It Em \&%P
@@ -91,6 +92,12 @@ The name defaults to
yielding the traditional
.Fx
behaviour.
+When changing the name via the
+.Va kern.corefile
+sysctl, it will fail if the new name contains
+unknown format specifiers, or
+.Em \&%I
+is specified more than once, or its length is too long.
.Pp
By default, a process that changes user or group credentials whether
real or effective will not create a corefile.
diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index 154c250..7fdb079 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -3094,21 +3094,101 @@ static int compress_user_cores = 0;
*/
#define corefilename_lock allproc_lock
-static char corefilename[MAXPATHLEN] = {"%N.core"};
+static char corefilename[MAXPATHLEN] = "%N.core";
+
+static int
+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 (EINVAL);
+ case '%':
+ case 'H':
+ case 'N':
+ case 'P':
+ case 'U':
+ break;
+ default:
+ return (EINVAL);
+ }
+ }
+ }
+
+ if (i == MAXPATHLEN)
+ return (ENAMETOOLONG);
+
+ return (0);
+}
+
+static void
+corefilename_init(void *arg)
+{
+ char *format;
+ int error;
+
+ format = kern_getenv("kern.corefile");
+ if (format == NULL)
+ return;
+
+ error = corefilename_check(format);
+
+ switch (error) {
+ case 0:
+ strcpy(corefilename, format);
+ break;
+ case EINVAL:
+ printf("Invalid format specified for corename `%s'\n", format);
+ break;
+ case ENAMETOOLONG:
+ printf("The format specified for corename is too long\n");
+ break;
+ default:
+ KASSERT(0, ("%s: unknown return value %d from "
+ "corefilename_check", __func__, error));
+ break;
+ }
+
+ freeenv(format);
+}
+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 != 0 || req->newptr == NULL)
+ goto out;
+
+ error = corefilename_check(format);
+ if (error != 0)
+ 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 +3251,8 @@ 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'", format[i], format));
break;
}
break;
--
2.1.2
Best regards,
Tiwei Bie
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