Prevent tracees from becoming undumpable

bjia56 · Sep 5, 2019 · 3ea655b · 3ea655b
1 parent 0c2da81
commit 3ea655b
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Showing 2 changed files with 11 additions and 0 deletions.
diff --git a/src/syscall/enter.c b/src/syscall/enter.c
@@ -27,6 +27,7 @@
 #include <fcntl.h>       /* AT_FDCWD, */
 #include <limits.h>      /* PATH_MAX, */
 #include <string.h>      /* strcpy */
+#include <sys/prctl.h>   /* PR_SET_DUMPABLE */
 
 #include "syscall/syscall.h"
 #include "syscall/sysnum.h"
@@ -566,6 +567,15 @@ int translate_syscall_enter(Tracee *tracee)
 
 		status = translate_path2(tracee, newdirfd, newpath, SYSARG_3, SYMLINK);
 		break;
+
+	case PR_prctl:
+		/* Prevent tracees from setting dumpable flag.
+		 * (Otherwise it could break tracee memory access)  */
+		if (peek_reg(tracee, CURRENT, SYSARG_1) == PR_SET_DUMPABLE) {
+			set_sysnum(tracee, PR_void);
+			status = 0;
+		}
+		break;
 	}
 
 end:

diff --git a/src/syscall/seccomp.c b/src/syscall/seccomp.c
@@ -377,6 +377,7 @@ static FilteredSysnum proot_sysnums[] = {
 	{ PR_open,		0 },
 	{ PR_openat,		0 },
 	{ PR_pivot_root,	0 },
+	{ PR_prctl, 		0 },
 	{ PR_prlimit64,		FILTER_SYSEXIT },
 	{ PR_ptrace,		FILTER_SYSEXIT },
 	{ PR_readlink,		FILTER_SYSEXIT },