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[Qemu-devel] [PATCH 10/29] 9pfs: local: lsetxattr: don't follow symlinks
From: |
Greg Kurz |
Subject: |
[Qemu-devel] [PATCH 10/29] 9pfs: local: lsetxattr: don't follow symlinks |
Date: |
Mon, 20 Feb 2017 15:40:38 +0100 |
User-agent: |
StGit/0.17.1-20-gc0b1b-dirty |
The local_lsetxattr() callback is vulnerable to symlink attacks because
it calls lsetxattr() which follows symbolic links in all path elements but
the rightmost one.
This patch converts local_lsetxattr() to rely on opendir_nofollow() and
fsetxattrat_nofollow() instead.
This partly fixes CVE-2016-9602.
Signed-off-by: Greg Kurz <address@hidden>
---
hw/9pfs/9p-posix-acl.c | 18 ++++--------------
hw/9pfs/9p-xattr-user.c | 8 +-------
hw/9pfs/9p-xattr.c | 8 +-------
3 files changed, 6 insertions(+), 28 deletions(-)
diff --git a/hw/9pfs/9p-posix-acl.c b/hw/9pfs/9p-posix-acl.c
index 9435e27a368c..0154e2a7605f 100644
--- a/hw/9pfs/9p-posix-acl.c
+++ b/hw/9pfs/9p-posix-acl.c
@@ -50,13 +50,8 @@ static ssize_t mp_pacl_listxattr(FsContext *ctx, const char
*path,
static int mp_pacl_setxattr(FsContext *ctx, const char *path, const char *name,
void *value, size_t size, int flags)
{
- char *buffer;
- int ret;
-
- buffer = rpath(ctx, path);
- ret = lsetxattr(buffer, MAP_ACL_ACCESS, value, size, flags);
- g_free(buffer);
- return ret;
+ return local_setxattr_nofollow(ctx, path, MAP_ACL_ACCESS, value, size,
+ flags);
}
static int mp_pacl_removexattr(FsContext *ctx,
@@ -108,13 +103,8 @@ static ssize_t mp_dacl_listxattr(FsContext *ctx, const
char *path,
static int mp_dacl_setxattr(FsContext *ctx, const char *path, const char *name,
void *value, size_t size, int flags)
{
- char *buffer;
- int ret;
-
- buffer = rpath(ctx, path);
- ret = lsetxattr(buffer, MAP_ACL_DEFAULT, value, size, flags);
- g_free(buffer);
- return ret;
+ return local_setxattr_nofollow(ctx, path, MAP_ACL_DEFAULT, value, size,
+ flags);
}
static int mp_dacl_removexattr(FsContext *ctx,
diff --git a/hw/9pfs/9p-xattr-user.c b/hw/9pfs/9p-xattr-user.c
index 4071fbc4c086..1840a5db66f3 100644
--- a/hw/9pfs/9p-xattr-user.c
+++ b/hw/9pfs/9p-xattr-user.c
@@ -67,9 +67,6 @@ static ssize_t mp_user_listxattr(FsContext *ctx, const char
*path,
static int mp_user_setxattr(FsContext *ctx, const char *path, const char *name,
void *value, size_t size, int flags)
{
- char *buffer;
- int ret;
-
if (strncmp(name, "user.virtfs.", 12) == 0) {
/*
* Don't allow fetch of user.virtfs namesapce
@@ -78,10 +75,7 @@ static int mp_user_setxattr(FsContext *ctx, const char
*path, const char *name,
errno = EACCES;
return -1;
}
- buffer = rpath(ctx, path);
- ret = lsetxattr(buffer, name, value, size, flags);
- g_free(buffer);
- return ret;
+ return local_setxattr_nofollow(ctx, path, name, value, size, flags);
}
static int mp_user_removexattr(FsContext *ctx,
diff --git a/hw/9pfs/9p-xattr.c b/hw/9pfs/9p-xattr.c
index 803d4bbbc50b..72ef820f16d7 100644
--- a/hw/9pfs/9p-xattr.c
+++ b/hw/9pfs/9p-xattr.c
@@ -328,13 +328,7 @@ ssize_t pt_getxattr(FsContext *ctx, const char *path,
const char *name,
int pt_setxattr(FsContext *ctx, const char *path, const char *name, void
*value,
size_t size, int flags)
{
- char *buffer;
- int ret;
-
- buffer = rpath(ctx, path);
- ret = lsetxattr(buffer, name, value, size, flags);
- g_free(buffer);
- return ret;
+ return local_setxattr_nofollow(ctx, path, name, value, size, flags);
}
int pt_removexattr(FsContext *ctx, const char *path, const char *name)
- Re: [Qemu-devel] [PATCH 07/29] 9pfs: local: introduce symlink-attack safe xattr helpers, (continued)
[Qemu-devel] [PATCH 08/29] 9pfs: local: lgetxattr: don't follow symlinks, Greg Kurz, 2017/02/20
[Qemu-devel] [PATCH 09/29] 9pfs: local: llistxattr: don't follow symlinks, Greg Kurz, 2017/02/20
[Qemu-devel] [PATCH 10/29] 9pfs: local: lsetxattr: don't follow symlinks,
Greg Kurz <=
[Qemu-devel] [PATCH 11/29] 9pfs: local: lremovexattr: don't follow symlinks, Greg Kurz, 2017/02/20
[Qemu-devel] [PATCH 12/29] 9pfs: local: unlinkat: don't follow symlinks, Greg Kurz, 2017/02/20
[Qemu-devel] [PATCH 13/29] 9pfs: local: remove: don't follow symlinks, Greg Kurz, 2017/02/20
[Qemu-devel] [PATCH 14/29] 9pfs: local: utimensat: don't follow symlinks, Greg Kurz, 2017/02/20