X-Git-Url: http://git.samba.org/?p=amitay%2Fsamba.git;a=blobdiff_plain;f=source3%2Flib%2Fsystem.c;h=9c1da3a78bdcdf301883cc74fcdc6bfcb00a5834;hp=a58d9037a79dc54964c4c72b1688ae95152d501c;hb=899bd0005f56dcc1e95c3988d41ab3f628bb15db;hpb=2dd301e5cd6ff97943c4bf9c7cd9b820d6193b45

diff --git a/source3/lib/system.c b/source3/lib/system.c
index a58d9037a79..9c1da3a78bd 100644
--- a/source3/lib/system.c
+++ b/source3/lib/system.c
@@ -883,6 +883,11 @@ char *sys_getwd(char *s)
 
 #if defined(HAVE_POSIX_CAPABILITIES)
 
+/* This define hasn't made it into the glibc capabilities header yet. */
+#ifndef SECURE_NO_SETUID_FIXUP
+#define SECURE_NO_SETUID_FIXUP          2
+#endif
+
 /**************************************************************************
  Try and abstract process capabilities (for systems that have them).
 ****************************************************************************/
@@ -913,6 +918,32 @@ static bool set_process_capability(enum smbd_capability capability,
 	}
 #endif
 
+#if defined(HAVE_PRCTL) && defined(PR_SET_SECUREBITS) && defined(SECURE_NO_SETUID_FIXUP)
+        /* New way of setting capabilities as "sticky". */
+
+	/*
+	 * Use PR_SET_SECUREBITS to prevent setresuid()
+	 * atomically dropping effective capabilities on
+	 * uid change. Only available in Linux kernels
+	 * 2.6.26 and above.
+	 *
+	 * See here:
+	 * http://www.kernel.org/doc/man-pages/online/pages/man7/capabilities.7.html
+	 * for details.
+	 *
+	 * Specifically the CAP_KILL capability we need
+	 * to allow Linux threads under different euids
+	 * to send signals to each other.
+	 */
+
+	if (prctl(PR_SET_SECUREBITS, 1 << SECURE_NO_SETUID_FIXUP)) {
+		DEBUG(0,("set_process_capability: "
+			"prctl PR_SET_SECUREBITS failed with error %s\n",
+			strerror(errno) ));
+		return false;
+	}
+#endif
+
 	cap = cap_get_proc();
 	if (cap == NULL) {
 		DEBUG(0,("set_process_capability: cap_get_proc failed: %s\n",
@@ -939,6 +970,11 @@ static bool set_process_capability(enum smbd_capability capability,
 		case LEASE_CAPABILITY:
 #ifdef CAP_LEASE
 			cap_vals[num_cap_vals++] = CAP_LEASE;
+#endif
+			break;
+		case KILL_CAPABILITY:
+#ifdef CAP_KILL
+			cap_vals[num_cap_vals++] = CAP_KILL;
 #endif
 			break;
 	}
@@ -950,16 +986,37 @@ static bool set_process_capability(enum smbd_capability capability,
 		return True;
 	}
 
-	cap_set_flag(cap, CAP_EFFECTIVE, num_cap_vals, cap_vals,
-		enable ? CAP_SET : CAP_CLEAR);
+	/*
+	 * Ensure the capability is effective. We assume that as a root
+	 * process it's always permitted.
+	 */
+
+	if (cap_set_flag(cap, CAP_EFFECTIVE, num_cap_vals, cap_vals,
+			enable ? CAP_SET : CAP_CLEAR) == -1) {
+		DEBUG(0, ("set_process_capability: cap_set_flag effective "
+			"failed (%d): %s\n",
+			(int)capability,
+			strerror(errno)));
+		cap_free(cap);
+		return false;
+	}
 
 	/* We never want to pass capabilities down to our children, so make
 	 * sure they are not inherited.
 	 */
-	cap_set_flag(cap, CAP_INHERITABLE, num_cap_vals, cap_vals, CAP_CLEAR);
+	if (cap_set_flag(cap, CAP_INHERITABLE, num_cap_vals,
+			cap_vals, CAP_CLEAR) == -1) {
+		DEBUG(0, ("set_process_capability: cap_set_flag inheritable "
+			"failed (%d): %s\n",
+			(int)capability,
+			strerror(errno)));
+		cap_free(cap);
+		return false;
+	}
 
 	if (cap_set_proc(cap) == -1) {
-		DEBUG(0, ("set_process_capability: cap_set_proc failed: %s\n",
+		DEBUG(0, ("set_process_capability: cap_set_flag (%d) failed: %s\n",
+			(int)capability,
 			strerror(errno)));
 		cap_free(cap);
 		return False;