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Message-ID: <20160820190430.GF1280@port70.net>
Date: Sat, 20 Aug 2016 21:04:31 +0200
From: Szabolcs Nagy <nsz@...t70.net>
To: musl@...ts.openwall.com
Subject: [PATCH] verify that ttyname refers to the same file as the fd
linux containers use separate mount namespace so the /proc
symlink might not point to the right device if the fd was
opened in the parent namespace, in this case return ENOENT.
---
related glibc issue (glibc also searches through /dev/pts):
https://sourceware.org/ml/libc-alpha/2016-08/msg00312.html
errno is not yet decided:
https://sourceware.org/ml/libc-alpha/2016-08/msg00337.html
src/unistd/ttyname_r.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/src/unistd/ttyname_r.c b/src/unistd/ttyname_r.c
index 8bac7b2..a38ba4f 100644
--- a/src/unistd/ttyname_r.c
+++ b/src/unistd/ttyname_r.c
@@ -1,10 +1,12 @@
#include <unistd.h>
#include <errno.h>
+#include <sys/stat.h>
void __procfdname(char *, unsigned);
int ttyname_r(int fd, char *name, size_t size)
{
+ struct stat st1, st2;
char procname[sizeof "/proc/self/fd/" + 3*sizeof(int) + 2];
ssize_t l;
@@ -15,8 +17,13 @@ int ttyname_r(int fd, char *name, size_t size)
if (l < 0) return errno;
else if (l == size) return ERANGE;
- else {
- name[l] = 0;
- return 0;
- }
+
+ name[l] = 0;
+
+ if (stat(name, &st1) || fstat(fd, &st2))
+ return errno;
+ if (st1.st_dev != st2.st_dev || st1.st_ino != st2.st_ino)
+ return ENOENT;
+
+ return 0;
}
--
2.8.1
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