When filtering xattr list for reading, presence of trusted xattr results in a security audit log. However, if there is other content no errno will be set, and if there isn't, the errno will be -ENODATA and not -EPERM as is usually associated with a lack of capability. The check does not block the request to list the xattrs present.
Switch to has_capability_noaudit to reflect a more appropriate check.
Signed-off-by: Mark Salyzyn salyzyn@android.com Cc: linux-security-module@vger.kernel.org Cc: kernel-team@android.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: stable@vger.kernel.org # v3.18 Fixes: upstream a082c6f680da ("ovl: filter trusted xattr for non-admin") Fixes: 3.18 4bcc9b4b3a0a ("ovl: filter trusted xattr for non-admin") --- Replaced ns_capable_noaudit with 3.18.y tree specific has_capability_noaudit present in original submission to kernel.org commit 5c2e9f346b815841f9bed6029ebcb06415caf640 ("ovl: filter of trusted xattr results in audit")
fs/overlayfs/inode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index a01ec1836a72..1175efa5e956 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -265,7 +265,8 @@ static bool ovl_can_list(const char *s) return true;
/* Never list trusted.overlay, list other trusted for superuser only */ - return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN); + return !ovl_is_private_xattr(s) && + has_capability_noaudit(current, CAP_SYS_ADMIN); }
ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
On Mon, Oct 07, 2019 at 09:09:16AM -0700, Mark Salyzyn wrote:
When filtering xattr list for reading, presence of trusted xattr results in a security audit log. However, if there is other content no errno will be set, and if there isn't, the errno will be -ENODATA and not -EPERM as is usually associated with a lack of capability. The check does not block the request to list the xattrs present.
Switch to has_capability_noaudit to reflect a more appropriate check.
Signed-off-by: Mark Salyzyn salyzyn@android.com Cc: linux-security-module@vger.kernel.org Cc: kernel-team@android.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: stable@vger.kernel.org # v3.18 Fixes: upstream a082c6f680da ("ovl: filter trusted xattr for non-admin") Fixes: 3.18 4bcc9b4b3a0a ("ovl: filter trusted xattr for non-admin")
Replaced ns_capable_noaudit with 3.18.y tree specific has_capability_noaudit present in original submission to kernel.org commit 5c2e9f346b815841f9bed6029ebcb06415caf640 ("ovl: filter of trusted xattr results in audit")
fs/overlayfs/inode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index a01ec1836a72..1175efa5e956 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -265,7 +265,8 @@ static bool ovl_can_list(const char *s) return true; /* Never list trusted.overlay, list other trusted for superuser only */
- return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN);
- return !ovl_is_private_xattr(s) &&
has_capability_noaudit(current, CAP_SYS_ADMIN);} ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) -- 2.23.0.581.g78d2f28ef7-goog
Thanks for the backport, this one worked!
greg k-h
On Mon, Oct 07, 2019 at 06:16:16PM +0200, Greg Kroah-Hartman wrote:
On Mon, Oct 07, 2019 at 09:09:16AM -0700, Mark Salyzyn wrote:
When filtering xattr list for reading, presence of trusted xattr results in a security audit log. However, if there is other content no errno will be set, and if there isn't, the errno will be -ENODATA and not -EPERM as is usually associated with a lack of capability. The check does not block the request to list the xattrs present.
Switch to has_capability_noaudit to reflect a more appropriate check.
Signed-off-by: Mark Salyzyn salyzyn@android.com Cc: linux-security-module@vger.kernel.org Cc: kernel-team@android.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: stable@vger.kernel.org # v3.18 Fixes: upstream a082c6f680da ("ovl: filter trusted xattr for non-admin") Fixes: 3.18 4bcc9b4b3a0a ("ovl: filter trusted xattr for non-admin")
Replaced ns_capable_noaudit with 3.18.y tree specific has_capability_noaudit present in original submission to kernel.org commit 5c2e9f346b815841f9bed6029ebcb06415caf640 ("ovl: filter of trusted xattr results in audit")
fs/overlayfs/inode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index a01ec1836a72..1175efa5e956 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -265,7 +265,8 @@ static bool ovl_can_list(const char *s) return true; /* Never list trusted.overlay, list other trusted for superuser only */
- return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN);
- return !ovl_is_private_xattr(s) &&
has_capability_noaudit(current, CAP_SYS_ADMIN);} ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) -- 2.23.0.581.g78d2f28ef7-goog
Thanks for the backport, this one worked!
I spoke too soon:
ERROR: "has_capability_noaudit" [fs/overlayfs/overlay.ko] undefined!
That function isn't exported for modules :(
greg k-h
On Mon, Oct 07, 2019 at 06:17:25PM +0200, Greg Kroah-Hartman wrote:
On Mon, Oct 07, 2019 at 06:16:16PM +0200, Greg Kroah-Hartman wrote:
On Mon, Oct 07, 2019 at 09:09:16AM -0700, Mark Salyzyn wrote:
When filtering xattr list for reading, presence of trusted xattr results in a security audit log. However, if there is other content no errno will be set, and if there isn't, the errno will be -ENODATA and not -EPERM as is usually associated with a lack of capability. The check does not block the request to list the xattrs present.
Switch to has_capability_noaudit to reflect a more appropriate check.
Signed-off-by: Mark Salyzyn salyzyn@android.com Cc: linux-security-module@vger.kernel.org Cc: kernel-team@android.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: stable@vger.kernel.org # v3.18 Fixes: upstream a082c6f680da ("ovl: filter trusted xattr for non-admin") Fixes: 3.18 4bcc9b4b3a0a ("ovl: filter trusted xattr for non-admin")
Replaced ns_capable_noaudit with 3.18.y tree specific has_capability_noaudit present in original submission to kernel.org commit 5c2e9f346b815841f9bed6029ebcb06415caf640 ("ovl: filter of trusted xattr results in audit")
fs/overlayfs/inode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index a01ec1836a72..1175efa5e956 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -265,7 +265,8 @@ static bool ovl_can_list(const char *s) return true; /* Never list trusted.overlay, list other trusted for superuser only */
- return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN);
- return !ovl_is_private_xattr(s) &&
has_capability_noaudit(current, CAP_SYS_ADMIN);} ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) -- 2.23.0.581.g78d2f28ef7-goog
Thanks for the backport, this one worked!
I spoke too soon:
ERROR: "has_capability_noaudit" [fs/overlayfs/overlay.ko] undefined!
That function isn't exported for modules :(
But, if this really is needed, and it fixes the issue, I'll go export that symbol with EXPORT_SYMBOL_GPL() to fix the problem. Any objections?
thanks,
greg k-h
On 10/7/19 9:40 AM, Greg Kroah-Hartman wrote:
On Mon, Oct 07, 2019 at 06:17:25PM +0200, Greg Kroah-Hartman wrote:
On Mon, Oct 07, 2019 at 06:16:16PM +0200, Greg Kroah-Hartman wrote:
On Mon, Oct 07, 2019 at 09:09:16AM -0700, Mark Salyzyn wrote:
When filtering xattr list for reading, presence of trusted xattr results in a security audit log. However, if there is other content no errno will be set, and if there isn't, the errno will be -ENODATA and not -EPERM as is usually associated with a lack of capability. The check does not block the request to list the xattrs present.
Switch to has_capability_noaudit to reflect a more appropriate check.
Signed-off-by: Mark Salyzyn salyzyn@android.com Cc: linux-security-module@vger.kernel.org Cc: kernel-team@android.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: stable@vger.kernel.org # v3.18 Fixes: upstream a082c6f680da ("ovl: filter trusted xattr for non-admin") Fixes: 3.18 4bcc9b4b3a0a ("ovl: filter trusted xattr for non-admin")
Replaced ns_capable_noaudit with 3.18.y tree specific has_capability_noaudit present in original submission to kernel.org commit 5c2e9f346b815841f9bed6029ebcb06415caf640 ("ovl: filter of trusted xattr results in audit")
fs/overlayfs/inode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index a01ec1836a72..1175efa5e956 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -265,7 +265,8 @@ static bool ovl_can_list(const char *s) return true; /* Never list trusted.overlay, list other trusted for superuser only */
- return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN);
- return !ovl_is_private_xattr(s) &&
has_capability_noaudit(current, CAP_SYS_ADMIN);ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) -- 2.23.0.581.g78d2f28ef7-goog
Thanks for the backport, this one worked!
I spoke too soon:
ERROR: "has_capability_noaudit" [fs/overlayfs/overlay.ko] undefined!
That function isn't exported for modules :(
But, if this really is needed, and it fixes the issue, I'll go export that symbol with EXPORT_SYMBOL_GPL() to fix the problem. Any objections?
thanks,
greg k-h
Ok, you just answered my question in cross-emails. Yes, EXPORT_SYMBOL_GPL() (my option 2).
Thanks
-- Mark Salyzyn
On 10/7/19 9:17 AM, Greg Kroah-Hartman wrote:
On Mon, Oct 07, 2019 at 06:16:16PM +0200, Greg Kroah-Hartman wrote:
On Mon, Oct 07, 2019 at 09:09:16AM -0700, Mark Salyzyn wrote:
When filtering xattr list for reading, presence of trusted xattr results in a security audit log. However, if there is other content no errno will be set, and if there isn't, the errno will be -ENODATA and not -EPERM as is usually associated with a lack of capability. The check does not block the request to list the xattrs present.
Switch to has_capability_noaudit to reflect a more appropriate check.
Signed-off-by: Mark Salyzyn salyzyn@android.com Cc: linux-security-module@vger.kernel.org Cc: kernel-team@android.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: stable@vger.kernel.org # v3.18 Fixes: upstream a082c6f680da ("ovl: filter trusted xattr for non-admin") Fixes: 3.18 4bcc9b4b3a0a ("ovl: filter trusted xattr for non-admin")
Replaced ns_capable_noaudit with 3.18.y tree specific has_capability_noaudit present in original submission to kernel.org commit 5c2e9f346b815841f9bed6029ebcb06415caf640 ("ovl: filter of trusted xattr results in audit")
fs/overlayfs/inode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index a01ec1836a72..1175efa5e956 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -265,7 +265,8 @@ static bool ovl_can_list(const char *s) return true; /* Never list trusted.overlay, list other trusted for superuser only */
- return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN);
- return !ovl_is_private_xattr(s) &&
has_capability_noaudit(current, CAP_SYS_ADMIN);ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) -- 2.23.0.581.g78d2f28ef7-goog
Thanks for the backport, this one worked!
I spoke too soon:
ERROR: "has_capability_noaudit" [fs/overlayfs/overlay.ko] undefined!
That function isn't exported for modules :(
greg k-h
<sigh>
Now what is the playbook, we have three options in order of preference:
1) #ifdef MODULE use capable() to preserve API, add a short comment about the side effects if overlayfs is used as a module.
2) export has_capability_nodaudit (proc and oom_kill use it, and are both built-in only), but affect the 3.18 API at near EOL. AFAIK no one wants that?
3) Do nothing more. Make this a distro concern only. Leave this posted as a back-port for the record, but never merged, for those that are _interested_ and declare 3.18 stable as noisy for sepolicy and overlayfs under some usage patterns with few user space mitigation unless they explicitly take this back-port into their tree (eg: android common kernel) if used built-in. This way, in 3.18.y at least the module and built-in version behave the _same_ in stable.
Looking for feedback.
Sincerely -- Mark Salyzyn
On Mon, Oct 07, 2019 at 09:42:08AM -0700, Mark Salyzyn wrote:
<sigh>
Now what is the playbook, we have three options in order of preference:
- #ifdef MODULE use capable() to preserve API, add a short comment about
the side effects if overlayfs is used as a module.
- export has_capability_nodaudit (proc and oom_kill use it, and are both
built-in only), but affect the 3.18 API at near EOL. AFAIK no one wants that?
I'll just do this. 3.18 is EOL, this is only being done for a distro-specific tree (i.e. AOSP).
- Do nothing more. Make this a distro concern only. Leave this posted as a
back-port for the record, but never merged, for those that are _interested_ and declare 3.18 stable as noisy for sepolicy and overlayfs under some usage patterns with few user space mitigation unless they explicitly take this back-port into their tree (eg: android common kernel) if used built-in. This way, in 3.18.y at least the module and built-in version behave the _same_ in stable.
I'll just add the export to the patch and check this into AOSP, thanks!
greg k-h
linux-stable-mirror@lists.linaro.org
-
Greg Kroah-Hartman -
Mark Salyzyn