Merge pull request #31230 from mrc0mmand/test-seccomp

process-util: use only the least significant byte from personality()

src/basic/process-util.c

@@ -1303,7 +1303,7 @@ int opinionated_personality(unsigned long *ret) {
         if (current < 0)
                 return current;
 
-        if (((unsigned long) current & 0xffff) == PER_LINUX32)
+        if (((unsigned long) current & OPINIONATED_PERSONALITY_MASK) == PER_LINUX32)
                 *ret = PER_LINUX32;
         else
                 *ret = PER_LINUX;

src/basic/process-util.h

@@ -101,12 +101,17 @@ bool is_main_thread(void);
 bool oom_score_adjust_is_valid(int oa);
 
 #ifndef PERSONALITY_INVALID
-/* personality(7) documents that 0xffffffffUL is used for querying the
+/* personality(2) documents that 0xFFFFFFFFUL is used for querying the
  * current personality, hence let's use that here as error
  * indicator. */
-#define PERSONALITY_INVALID 0xffffffffLU
+#define PERSONALITY_INVALID 0xFFFFFFFFUL
 #endif
 
+/* The personality() syscall returns a 32-bit value where the top three bytes are reserved for flags that
+ * emulate historical or architectural quirks, and only the least significant byte reflects the actual
+ * personality we're interested in. */
+#define OPINIONATED_PERSONALITY_MASK 0xFFUL
+
 unsigned long personality_from_string(const char *p);
 const char *personality_to_string(unsigned long);