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[PATCH v7 2/7] selftests: x86: test_mremap_vdso: skip if vdso is msealed

jeffxu@chromium.org posted 7 patches 11 months, 2 weeks ago
There is a newer version of this series
[PATCH v7 2/7] selftests: x86: test_mremap_vdso: skip if vdso is msealed
Posted by jeffxu@chromium.org 11 months, 2 weeks ago 
From: Jeff Xu <jeffxu@chromium.org>

Add code to detect if the vdso is memory sealed, skip the test
if it is.

Signed-off-by: Jeff Xu <jeffxu@chromium.org>
Reviewed-by: Kees Cook <kees@kernel.org>
---
 .../testing/selftests/x86/test_mremap_vdso.c  | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/tools/testing/selftests/x86/test_mremap_vdso.c b/tools/testing/selftests/x86/test_mremap_vdso.c
index d53959e03593..94bee6e0c813 100644
--- a/tools/testing/selftests/x86/test_mremap_vdso.c
+++ b/tools/testing/selftests/x86/test_mremap_vdso.c
@@ -14,6 +14,7 @@
 #include <errno.h>
 #include <unistd.h>
 #include <string.h>
+#include <stdbool.h>
 
 #include <sys/mman.h>
 #include <sys/auxv.h>
@@ -55,13 +56,55 @@ static int try_to_remap(void *vdso_addr, unsigned long size)
 
 }
 
+#define VDSO_NAME "[vdso]"
+#define VMFLAGS "VmFlags:"
+#define MSEAL_FLAGS "sl"
+#define MAX_LINE_LEN 512
+
+bool vdso_sealed(FILE *maps)
+{
+	char line[MAX_LINE_LEN];
+	bool has_vdso = false;
+
+	while (fgets(line, sizeof(line), maps)) {
+		if (strstr(line, VDSO_NAME))
+			has_vdso = true;
+
+		if (has_vdso && !strncmp(line, VMFLAGS, strlen(VMFLAGS))) {
+			if (strstr(line, MSEAL_FLAGS))
+				return true;
+
+			return false;
+		}
+	}
+
+	return false;
+}
+
 int main(int argc, char **argv, char **envp)
 {
 	pid_t child;
+	FILE *maps;
 
 	ksft_print_header();
 	ksft_set_plan(1);
 
+	maps = fopen("/proc/self/smaps", "r");
+	if (!maps) {
+		ksft_test_result_skip(
+			"Could not open /proc/self/smaps, errno=%d\n",
+			 errno);
+
+		return 0;
+	}
+
+	if (vdso_sealed(maps)) {
+		ksft_test_result_skip("vdso is sealed\n");
+		return 0;
+	}
+
+	fclose(maps);
+
 	child = fork();
 	if (child == -1)
 		ksft_exit_fail_msg("failed to fork (%d): %m\n", errno);
-- 
2.48.1.658.g4767266eb4-goog
Re: [PATCH v7 2/7] selftests: x86: test_mremap_vdso: skip if vdso is msealed
Posted by Lorenzo Stoakes 11 months, 2 weeks ago 
On Mon, Feb 24, 2025 at 10:52:41PM +0000, jeffxu@chromium.org wrote:
> From: Jeff Xu <jeffxu@chromium.org>
>
> Add code to detect if the vdso is memory sealed, skip the test
> if it is.

I feel this is a little succinct of a commit message, but I guess it gets to the
heart of what you're doing here.

Fundamentally I mean it makes sense, but I'm concerned that x86 has a test
-expliictly checking- whether mremap() of VDSO is possible - are there cases
where x86 might want to do this internal to the kernel?

I guess not since this is essentially a userland self test and probably
asserting you can do this in the way rr, etc. do.

>
> Signed-off-by: Jeff Xu <jeffxu@chromium.org>
> Reviewed-by: Kees Cook <kees@kernel.org>

Anyway, this aside, this looks fine, aside from nit below, so:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

> ---
>  .../testing/selftests/x86/test_mremap_vdso.c  | 43 +++++++++++++++++++
>  1 file changed, 43 insertions(+)
>
> diff --git a/tools/testing/selftests/x86/test_mremap_vdso.c b/tools/testing/selftests/x86/test_mremap_vdso.c
> index d53959e03593..94bee6e0c813 100644
> --- a/tools/testing/selftests/x86/test_mremap_vdso.c
> +++ b/tools/testing/selftests/x86/test_mremap_vdso.c
> @@ -14,6 +14,7 @@
>  #include <errno.h>
>  #include <unistd.h>
>  #include <string.h>
> +#include <stdbool.h>
>
>  #include <sys/mman.h>
>  #include <sys/auxv.h>
> @@ -55,13 +56,55 @@ static int try_to_remap(void *vdso_addr, unsigned long size)
>
>  }
>
> +#define VDSO_NAME "[vdso]"
> +#define VMFLAGS "VmFlags:"
> +#define MSEAL_FLAGS "sl"
> +#define MAX_LINE_LEN 512
> +
> +bool vdso_sealed(FILE *maps)

Should be static?

> +{
> +	char line[MAX_LINE_LEN];
> +	bool has_vdso = false;
> +
> +	while (fgets(line, sizeof(line), maps)) {
> +		if (strstr(line, VDSO_NAME))
> +			has_vdso = true;
> +
> +		if (has_vdso && !strncmp(line, VMFLAGS, strlen(VMFLAGS))) {
> +			if (strstr(line, MSEAL_FLAGS))
> +				return true;
> +
> +			return false;
> +		}
> +	}
> +
> +	return false;
> +}
> +
>  int main(int argc, char **argv, char **envp)
>  {
>  	pid_t child;
> +	FILE *maps;
>
>  	ksft_print_header();
>  	ksft_set_plan(1);
>
> +	maps = fopen("/proc/self/smaps", "r");
> +	if (!maps) {
> +		ksft_test_result_skip(
> +			"Could not open /proc/self/smaps, errno=%d\n",
> +			 errno);
> +
> +		return 0;
> +	}
> +
> +	if (vdso_sealed(maps)) {
> +		ksft_test_result_skip("vdso is sealed\n");
> +		return 0;
> +	}
> +
> +	fclose(maps);
> +
>  	child = fork();
>  	if (child == -1)
>  		ksft_exit_fail_msg("failed to fork (%d): %m\n", errno);
> --
> 2.48.1.658.g4767266eb4-goog
>
Re: [PATCH v7 2/7] selftests: x86: test_mremap_vdso: skip if vdso is msealed
Posted by Jeff Xu 11 months, 2 weeks ago 
On Mon, Feb 24, 2025 at 10:15 PM Lorenzo Stoakes
<lorenzo.stoakes@oracle.com> wrote:
>
> On Mon, Feb 24, 2025 at 10:52:41PM +0000, jeffxu@chromium.org wrote:
> > From: Jeff Xu <jeffxu@chromium.org>
> >
> > Add code to detect if the vdso is memory sealed, skip the test
> > if it is.
>
> I feel this is a little succinct of a commit message, but I guess it gets to the
> heart of what you're doing here.
>
> Fundamentally I mean it makes sense, but I'm concerned that x86 has a test
> -expliictly checking- whether mremap() of VDSO is possible - are there cases
> where x86 might want to do this internal to the kernel?
>
> I guess not since this is essentially a userland self test and probably
> asserting you can do this in the way rr, etc. do.
>
> >
> > Signed-off-by: Jeff Xu <jeffxu@chromium.org>
> > Reviewed-by: Kees Cook <kees@kernel.org>
>
> Anyway, this aside, this looks fine, aside from nit below, so:
>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
>
> > ---
> >  .../testing/selftests/x86/test_mremap_vdso.c  | 43 +++++++++++++++++++
> >  1 file changed, 43 insertions(+)
> >
> > diff --git a/tools/testing/selftests/x86/test_mremap_vdso.c b/tools/testing/selftests/x86/test_mremap_vdso.c
> > index d53959e03593..94bee6e0c813 100644
> > --- a/tools/testing/selftests/x86/test_mremap_vdso.c
> > +++ b/tools/testing/selftests/x86/test_mremap_vdso.c
> > @@ -14,6 +14,7 @@
> >  #include <errno.h>
> >  #include <unistd.h>
> >  #include <string.h>
> > +#include <stdbool.h>
> >
> >  #include <sys/mman.h>
> >  #include <sys/auxv.h>
> > @@ -55,13 +56,55 @@ static int try_to_remap(void *vdso_addr, unsigned long size)
> >
> >  }
> >
> > +#define VDSO_NAME "[vdso]"
> > +#define VMFLAGS "VmFlags:"
> > +#define MSEAL_FLAGS "sl"
> > +#define MAX_LINE_LEN 512
> > +
> > +bool vdso_sealed(FILE *maps)
>
> Should be static?
>
sure.

> > +{
> > +     char line[MAX_LINE_LEN];
> > +     bool has_vdso = false;
> > +
> > +     while (fgets(line, sizeof(line), maps)) {
> > +             if (strstr(line, VDSO_NAME))
> > +                     has_vdso = true;
> > +
> > +             if (has_vdso && !strncmp(line, VMFLAGS, strlen(VMFLAGS))) {
> > +                     if (strstr(line, MSEAL_FLAGS))
> > +                             return true;
> > +
> > +                     return false;
> > +             }
> > +     }
> > +
> > +     return false;
> > +}
> > +
> >  int main(int argc, char **argv, char **envp)
> >  {
> >       pid_t child;
> > +     FILE *maps;
> >
> >       ksft_print_header();
> >       ksft_set_plan(1);
> >
> > +     maps = fopen("/proc/self/smaps", "r");
> > +     if (!maps) {
> > +             ksft_test_result_skip(
> > +                     "Could not open /proc/self/smaps, errno=%d\n",
> > +                      errno);
> > +
> > +             return 0;
> > +     }
> > +
> > +     if (vdso_sealed(maps)) {
> > +             ksft_test_result_skip("vdso is sealed\n");
> > +             return 0;
> > +     }
> > +
> > +     fclose(maps);
> > +
> >       child = fork();
> >       if (child == -1)
> >               ksft_exit_fail_msg("failed to fork (%d): %m\n", errno);
> > --
> > 2.48.1.658.g4767266eb4-goog
> >
Re: [PATCH v7 2/7] selftests: x86: test_mremap_vdso: skip if vdso is msealed
Posted by Lorenzo Stoakes 11 months, 2 weeks ago 
On Tue, Feb 25, 2025 at 02:37:46PM -0800, Jeff Xu wrote:
> On Mon, Feb 24, 2025 at 10:15 PM Lorenzo Stoakes
> <lorenzo.stoakes@oracle.com> wrote:
> >
> > On Mon, Feb 24, 2025 at 10:52:41PM +0000, jeffxu@chromium.org wrote:
> > > From: Jeff Xu <jeffxu@chromium.org>
> > >
> > > Add code to detect if the vdso is memory sealed, skip the test
> > > if it is.
> >
> > I feel this is a little succinct of a commit message, but I guess it gets to the
> > heart of what you're doing here.
> >
> > Fundamentally I mean it makes sense, but I'm concerned that x86 has a test
> > -expliictly checking- whether mremap() of VDSO is possible - are there cases
> > where x86 might want to do this internal to the kernel?
> >
> > I guess not since this is essentially a userland self test and probably
> > asserting you can do this in the way rr, etc. do.
> >
> > >
> > > Signed-off-by: Jeff Xu <jeffxu@chromium.org>
> > > Reviewed-by: Kees Cook <kees@kernel.org>
> >
> > Anyway, this aside, this looks fine, aside from nit below, so:
> >
> > Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> >
> > > ---
> > >  .../testing/selftests/x86/test_mremap_vdso.c  | 43 +++++++++++++++++++
> > >  1 file changed, 43 insertions(+)
> > >
> > > diff --git a/tools/testing/selftests/x86/test_mremap_vdso.c b/tools/testing/selftests/x86/test_mremap_vdso.c
> > > index d53959e03593..94bee6e0c813 100644
> > > --- a/tools/testing/selftests/x86/test_mremap_vdso.c
> > > +++ b/tools/testing/selftests/x86/test_mremap_vdso.c
> > > @@ -14,6 +14,7 @@
> > >  #include <errno.h>
> > >  #include <unistd.h>
> > >  #include <string.h>
> > > +#include <stdbool.h>
> > >
> > >  #include <sys/mman.h>
> > >  #include <sys/auxv.h>
> > > @@ -55,13 +56,55 @@ static int try_to_remap(void *vdso_addr, unsigned long size)
> > >
> > >  }
> > >
> > > +#define VDSO_NAME "[vdso]"
> > > +#define VMFLAGS "VmFlags:"
> > > +#define MSEAL_FLAGS "sl"
> > > +#define MAX_LINE_LEN 512
> > > +
> > > +bool vdso_sealed(FILE *maps)
> >
> > Should be static?
> >
> sure.

Thanks! :)

>
> > > +{
> > > +     char line[MAX_LINE_LEN];
> > > +     bool has_vdso = false;
> > > +
> > > +     while (fgets(line, sizeof(line), maps)) {
> > > +             if (strstr(line, VDSO_NAME))
> > > +                     has_vdso = true;
> > > +
> > > +             if (has_vdso && !strncmp(line, VMFLAGS, strlen(VMFLAGS))) {
> > > +                     if (strstr(line, MSEAL_FLAGS))
> > > +                             return true;
> > > +
> > > +                     return false;
> > > +             }
> > > +     }
> > > +
> > > +     return false;
> > > +}
> > > +
> > >  int main(int argc, char **argv, char **envp)
> > >  {
> > >       pid_t child;
> > > +     FILE *maps;
> > >
> > >       ksft_print_header();
> > >       ksft_set_plan(1);
> > >
> > > +     maps = fopen("/proc/self/smaps", "r");
> > > +     if (!maps) {
> > > +             ksft_test_result_skip(
> > > +                     "Could not open /proc/self/smaps, errno=%d\n",
> > > +                      errno);
> > > +
> > > +             return 0;
> > > +     }
> > > +
> > > +     if (vdso_sealed(maps)) {
> > > +             ksft_test_result_skip("vdso is sealed\n");
> > > +             return 0;
> > > +     }
> > > +
> > > +     fclose(maps);
> > > +
> > >       child = fork();
> > >       if (child == -1)
> > >               ksft_exit_fail_msg("failed to fork (%d): %m\n", errno);
> > > --
> > > 2.48.1.658.g4767266eb4-goog
> > >

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