From: Dmitry V. Levin <ldv@altlinux.org>
Date: Sat, 8 Jul 2017 19:27:26 +0000 (+0000)
Subject: net: accept arbitrary option length for getsockopt's SO_PEERCRED
X-Git-Tag: v4.19~312
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=0c4052b9ca0b423d09d3cbd9dc29feeb3f00dd50;p=strace

net: accept arbitrary option length for getsockopt's SO_PEERCRED

* print_fields.h (PRINT_FIELD_UID): New macro.
* net.c (print_ucred): Rewrite to match the kernel behaviour.
* NEWS: Mention this.
---

diff --git a/NEWS b/NEWS
index 947d506c..50ca640a 100644
--- a/NEWS
+++ b/NEWS
@@ -3,7 +3,8 @@ Noteworthy changes in release ?.?? (????-??-??)
 
 * Improvements
   * Enhanced decoding of optlen argument of getsockopt syscall.
-  * Enhanced decoding of SO_LINGER option of getsockopt and setsockopt syscalls.
+  * Enhanced decoding of SO_LINGER and SO_PEERCRED options
+    of getsockopt and setsockopt syscalls.
   * Implemented decoding of linux socket filter programs specified
     for SO_ATTACH_FILTER and SO_ATTACH_REUSEPORT_CBPF socket options.
 
diff --git a/net.c b/net.c
index 257e0df3..01f53b68 100644
--- a/net.c
+++ b/net.c
@@ -533,19 +533,31 @@ print_get_linger(struct tcb *const tcp, const kernel_ulong_t addr,
 
 #ifdef SO_PEERCRED
 static void
-print_ucred(struct tcb *const tcp, const kernel_ulong_t addr, const int len)
+print_ucred(struct tcb *const tcp, const kernel_ulong_t addr, unsigned int len)
 {
 	struct ucred uc;
 
-	if (len != sizeof(uc) ||
-	    umove(tcp, addr, &uc) < 0) {
-		printaddr(addr);
+	if (len < sizeof(uc)) {
+		if (len != sizeof(uc.pid)
+		    && len != offsetofend(struct ucred, uid)) {
+			printstr_ex(tcp, addr, len, QUOTE_FORCE_HEX);
+			return;
+		}
 	} else {
-		tprintf("{pid=%u, uid=%u, gid=%u}",
-			(unsigned) uc.pid,
-			(unsigned) uc.uid,
-			(unsigned) uc.gid);
+		len = sizeof(uc);
+	}
+
+	if (umoven(tcp, addr, len, &uc) < 0) {
+		printaddr(addr);
+		return;
 	}
+
+	PRINT_FIELD_D("{", uc, pid);
+	if (len > sizeof(uc.pid))
+		PRINT_FIELD_UID(", ", uc, uid);
+	if (len == sizeof(uc))
+		PRINT_FIELD_UID(", ", uc, gid);
+	tprints("}");
 }
 #endif /* SO_PEERCRED */
 
diff --git a/print_fields.h b/print_fields.h
index 92b8a8a1..43a26bc7 100644
--- a/print_fields.h
+++ b/print_fields.h
@@ -65,4 +65,13 @@
 		printxval((xlat_), (where_).field_, (dflt_));		\
 	} while (0)
 
+#define PRINT_FIELD_UID(prefix_, where_, field_)					\
+	do {										\
+		if (sign_extend_unsigned_to_ll((where_).field_) == -1LL)		\
+			STRACE_PRINTF("%s%s=-1", (prefix_), #field_);			\
+		else									\
+			STRACE_PRINTF("%s%s=%llu", (prefix_), #field_,			\
+				      zero_extend_signed_to_ull((where_).field_));	\
+	} while (0)
+
 #endif /* !STRACE_PRINT_FIELDS_H */