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[Qemu-devel] [PATCH 11/29] 9pfs: local: lremovexattr: don't follow symli
From: |
Greg Kurz |
Subject: |
[Qemu-devel] [PATCH 11/29] 9pfs: local: lremovexattr: don't follow symlinks |
Date: |
Mon, 20 Feb 2017 15:40:45 +0100 |
User-agent: |
StGit/0.17.1-20-gc0b1b-dirty |
The local_lremovexattr() callback is vulnerable to symlink attacks because
it calls lremovexattr() which follows symbolic links in all path elements but
the rightmost one.
This patch converts local_lremovexattr() to rely on opendir_nofollow() and
fremovexattrat_nofollow() instead.
This partly fixes CVE-2016-9602.
Signed-off-by: Greg Kurz <address@hidden>
---
hw/9pfs/9p-posix-acl.c | 10 ++--------
hw/9pfs/9p-xattr-user.c | 8 +-------
hw/9pfs/9p-xattr.c | 8 +-------
3 files changed, 4 insertions(+), 22 deletions(-)
diff --git a/hw/9pfs/9p-posix-acl.c b/hw/9pfs/9p-posix-acl.c
index 0154e2a7605f..c20409104135 100644
--- a/hw/9pfs/9p-posix-acl.c
+++ b/hw/9pfs/9p-posix-acl.c
@@ -58,10 +58,8 @@ static int mp_pacl_removexattr(FsContext *ctx,
const char *path, const char *name)
{
int ret;
- char *buffer;
- buffer = rpath(ctx, path);
- ret = lremovexattr(buffer, MAP_ACL_ACCESS);
+ ret = local_removexattr_nofollow(ctx, MAP_ACL_ACCESS, name);
if (ret == -1 && errno == ENODATA) {
/*
* We don't get ENODATA error when trying to remove a
@@ -71,7 +69,6 @@ static int mp_pacl_removexattr(FsContext *ctx,
errno = 0;
ret = 0;
}
- g_free(buffer);
return ret;
}
@@ -111,10 +108,8 @@ static int mp_dacl_removexattr(FsContext *ctx,
const char *path, const char *name)
{
int ret;
- char *buffer;
- buffer = rpath(ctx, path);
- ret = lremovexattr(buffer, MAP_ACL_DEFAULT);
+ ret = local_removexattr_nofollow(ctx, MAP_ACL_DEFAULT, name);
if (ret == -1 && errno == ENODATA) {
/*
* We don't get ENODATA error when trying to remove a
@@ -124,7 +119,6 @@ static int mp_dacl_removexattr(FsContext *ctx,
errno = 0;
ret = 0;
}
- g_free(buffer);
return ret;
}
diff --git a/hw/9pfs/9p-xattr-user.c b/hw/9pfs/9p-xattr-user.c
index 1840a5db66f3..2c90817b75a6 100644
--- a/hw/9pfs/9p-xattr-user.c
+++ b/hw/9pfs/9p-xattr-user.c
@@ -81,9 +81,6 @@ static int mp_user_setxattr(FsContext *ctx, const char *path,
const char *name,
static int mp_user_removexattr(FsContext *ctx,
const char *path, const char *name)
{
- char *buffer;
- int ret;
-
if (strncmp(name, "user.virtfs.", 12) == 0) {
/*
* Don't allow fetch of user.virtfs namesapce
@@ -92,10 +89,7 @@ static int mp_user_removexattr(FsContext *ctx,
errno = EACCES;
return -1;
}
- buffer = rpath(ctx, path);
- ret = lremovexattr(buffer, name);
- g_free(buffer);
- return ret;
+ return local_removexattr_nofollow(ctx, path, name);
}
XattrOperations mapped_user_xattr = {
diff --git a/hw/9pfs/9p-xattr.c b/hw/9pfs/9p-xattr.c
index 72ef820f16d7..6fbfbca7e9a0 100644
--- a/hw/9pfs/9p-xattr.c
+++ b/hw/9pfs/9p-xattr.c
@@ -333,13 +333,7 @@ int pt_setxattr(FsContext *ctx, const char *path, const
char *name, void *value,
int pt_removexattr(FsContext *ctx, const char *path, const char *name)
{
- char *buffer;
- int ret;
-
- buffer = rpath(ctx, path);
- ret = lremovexattr(path, name);
- g_free(buffer);
- return ret;
+ return local_removexattr_nofollow(ctx, path, name);
}
ssize_t notsup_getxattr(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, 2017/02/20
[Qemu-devel] [PATCH 11/29] 9pfs: local: lremovexattr: don't follow symlinks,
Greg Kurz <=
[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
[Qemu-devel] [PATCH 15/29] 9pfs: local: statfs: don't follow symlinks, Greg Kurz, 2017/02/20