selftests: x86: test_mremap_vdso: skip if vdso is msealed

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

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Jeff Xu <[e-mail]>
Reviewed-by: Kees Cook <[e-mail]>
Reviewed-by: Lorenzo Stoakes <[e-mail]>
Reviewed-by: Liam R. Howlett <[e-mail]>
Cc: Adhemerval Zanella <[e-mail]>
Cc: Alexander Mikhalitsyn <[e-mail]>
Cc: Alexey Dobriyan <[e-mail]>
Cc: Andrei Vagin <[e-mail]>
Cc: Anna-Maria Behnsen <[e-mail]>
Cc: Ard Biesheuvel <[e-mail]>
Cc: Benjamin Berg <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Dave Hansen <[e-mail]>
Cc: David Rientjes <[e-mail]>
Cc: David S. Miller <[e-mail]>
Cc: Elliot Hughes <[e-mail]>
Cc: Florian Faineli <[e-mail]>
Cc: Greg Ungerer <[e-mail]>
Cc: Guenter Roeck <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: Helge Deller <[e-mail]>
Cc: Hyeonggon Yoo <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jann Horn <[e-mail]>
Cc: Jason A. Donenfeld <[e-mail]>
Cc: Johannes Berg <[e-mail]>
Cc: Jorge Lucangeli Obes <[e-mail]>
Cc: Linus Waleij <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Matthew Wilcow (Oracle) <[e-mail]>
Cc: Michael Ellerman <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Miguel Ojeda <[e-mail]>
Cc: Mike Rapoport <[e-mail]>
Cc: Oleg Nesterov <[e-mail]>
Cc: Pedro Falcato <[e-mail]>
Cc: Peter Xu <[e-mail]>
Cc: Randy Dunlap <[e-mail]>
Cc: Stephen Röttger <[e-mail]>
Cc: Thomas Weißschuh <[e-mail]>
Cc: Vlastimil Babka <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

tools/testing/selftests/x86/test_mremap_vdso.c

···
 #include <errno.h>
 #include <unistd.h>
 #include <string.h>
+#include <stdbool.h>
 
 #include <sys/mman.h>
 #include <sys/auxv.h>
···
 
 }
 
+#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)