On 2019/02/26 7:26, Darrick J. Wong wrote:
On Mon, Feb 25, 2019 at 02:47:44PM -0800, Darrick J. Wong wrote:
On Mon, Feb 25, 2019 at 02:10:52PM -0500, jeffm@xxxxxxxx wrote:
From: Jeff Mahoney<jeffm@xxxxxxxx>
src/t_attr_corruption uses the security.evm extended attribute because
it sorts before security.posix_acl_access. The security.evm attribute
is a formatted structure and when passed an uninitialized buffer, it
will fail with EPERM.
We see test failures like:
--- tests/generic/529.out2019-02-21 13:22:47.583406922 -0500
+++ /opt/xfstests/results//generic/529.out.bad 2019-02-21 13:57:31.967406922 -0500
@@ -1,2 +1,2 @@
QA output created by 529
-list attr: Numerical result out of range
+set evm: Operation not permitted
This patch uses security.capability which also sorts where it needs to
do for the test and also accepts an unformatted buffer.
Signed-off-by: Jeff Mahoney<jeffm@xxxxxxxx>
---
src/t_attr_corruption.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/t_attr_corruption.c b/src/t_attr_corruption.c
index f26611f9..0c229dbc 100644
--- a/src/t_attr_corruption.c
+++ b/src/t_attr_corruption.c
@@ -76,7 +76,7 @@ int main(int argc, char *argv[])
if (ret)
die("set posix acl");
- ret = fsetxattr(fd, "security.evm", buf, 1, 1);
+ ret = fsetxattr(fd, "security.capability", buf, 1, 1);
This fails for me both with and without EVM configured into my kernel:
fsetxattr(3, "security.capability", "\3", 1, XATTR_CREATE) = -1 EINVAL (Invalid argument)
Judging from fs/xattr.c it looks as though security.capability also has
a defined format that's parsed by security/commoncap.c...
And now that I've figured out how to reproduce the xfs bug without a
second attribute, NAK to this and I'll send a more complete fix shortly.
--D
Hi Darrick, Jeff
It seems that fsetxattr() with an uninitialized buffer fell into the
following xattr_data->type
check at security/integrity/evm/evm_main.c in kernel:
----------------------------------------------------------------------------------------------------------------------------
int evm_inode_setxattr(struct dentry *dentry, const char *xattr_name,
const void *xattr_value, size_t xattr_value_len)
{
...
if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
if (!xattr_value_len)
return -EINVAL;
if (xattr_data->type != EVM_IMA_XATTR_DIGSIG &&
xattr_data->type != EVM_XATTR_PORTABLE_DIGSIG)
return -EPERM;
}
...
}
----------------------------------------------------------------------------------------------------------------------------
Perhaps, we can skip this check by setting security.evm attribute to
special value(e.g.
EVM_IMA_XATTR_DIGSIG or EVM_XATTR_PORTABLE_DIGSIG) . For example:
---------------------------------------------------------------------------------------------------------------------
diff --git a/src/t_attr_corruption.c b/root/t_attr_corruption.c
index 1fa5e41f..05ce5b46 100644
--- a/src/t_attr_corruption.c
+++ b/root/t_attr_corruption.c
@@ -61,6 +61,7 @@ int main(int argc, char *argv[])
ssize_t sz;
int fd;
int ret;
+ int eval = 0x03;
if (argc > 1) {
ret = chdir(argv[1]);
@@ -76,7 +77,7 @@ int main(int argc, char *argv[])
if (ret)
die("set posix acl");
- ret = fsetxattr(fd, "security.evm", buf, 1, 1);
+ ret = fsetxattr(fd, "security.evm", &eval, sizeof(eval), 1);
---------------------------------------------------------------------------------------------------------------------
Best Regards,
Xiao Yang
--D
if (ret)
die("set evm");
--
2.16.4
