[linux-azure][PATCH] LP:#1864669 - [linux-azure] overlayfs regression - internal getxattr operations without sepolicy checking

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[linux-azure][PATCH] LP:#1864669 - [linux-azure] overlayfs regression - internal getxattr operations without sepolicy checking

Marcelo Henrique Cerri
BugLink: https://bugs.launchpad.net/bugs/1864669

As bug description.

This patch was submitted to upstream as part of a bigger patchset that
proposes to fix several individual issues. Since the patchset is
currently stalled with no ETA to be accepted, I decided to backport
just the necessary fix.

4.15 required bigger changes since some of the affected pieces of code
were missing or were different than upstream and I applied the
equivalent changes to the corresponding area in that kernel. Besides
that, all patches required a small change to remove XATTR_NOSECURITY
since that was added by a previous patch on the same series.

That's a fix that potentially can be included to our master
kernels. But since that was requested for linux-azure I believe we can
introduce this fix first to linux-azure and to the master kernels on
the following cycle. That way we can reduce the regression potential.

I didn't include bionic:linux-azure, which is currently based on5.0,
to this submission because that kernel should move to 5.3 on the next
cycle.

I've tested the affected scenario with the patched linux-azure kernel
and the results were positive.

---
Mark Salyzyn (1):
  UBUNTU: SAUCE: overlayfs: internal getxattr operations without
    sepolicy checking

 fs/overlayfs/namei.c     | 19 ++++++++++---------
 fs/overlayfs/overlayfs.h |  7 +++++++
 fs/overlayfs/util.c      |  8 ++++----
 3 files changed, 21 insertions(+), 13 deletions(-)

--
2.20.1


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[xenial:linux-azure][PATCH] UBUNTU: SAUCE: overlayfs: internal getxattr operations without sepolicy checking

Marcelo Henrique Cerri
From: Mark Salyzyn <[hidden email]>

BugLink: https://bugs.launchpad.net/bugs/1864669

[Based on v15: https://lore.kernel.org/patchwork/patch/1148514/]

Check impure, opaque, origin & meta xattr with no sepolicy audit
(using __vfs_getxattr) since these operations are internal to
overlayfs operations and do not disclose any data.  This became
an issue for credential override off since sys_admin would have
been required by the caller; whereas would have been inherently
present for the creator since it performed the mount.

This is a change in operations since we do not check in the new
ovl_do_vfs_getxattr function if the credential override is off or
not.  Reasoning is that the sepolicy check is unnecessary overhead,
especially since the check can be expensive.

Because for override credentials off, this affects _everyone_ that
underneath performs private xattr calls without the appropriate
sepolicy permissions and sys_admin capability.  Providing blanket
support for sys_admin would be bad for all possible callers.

For the override credentials on, this will affect only the mounter,
should it lack sepolicy permissions. Not considered a security
problem since mounting by definition has sys_admin capabilities,
but sepolicy contexts would still need to be crafted.

It should be noted that there is precedence, __vfs_getxattr is used
in other filesystems for their own internal trusted xattr management.

Signed-off-by: Mark Salyzyn <[hidden email]>
Cc: Miklos Szeredi <[hidden email]>
Cc: Jonathan Corbet <[hidden email]>
Cc: Vivek Goyal <[hidden email]>
Cc: Eric W. Biederman <[hidden email]>
Cc: Amir Goldstein <[hidden email]>
Cc: Randy Dunlap <[hidden email]>
Cc: Stephen Smalley <[hidden email]>
Cc: [hidden email]
Cc: [hidden email]
Cc: [hidden email]
Cc: [hidden email]
Cc: [hidden email]

v15 - revert to v13 as xattr_gs_args was rejected.
    - move ovl_do_wrapper from util.c to inline in overlayfs.h

v14 - rebase to use xattr_gs_args.

v13 - rebase to use __vfs_getxattr flags option

v12 - rebase

v11 - switch name to ovl_do_vfs_getxattr, fortify comment

v10 - added to patch series

[[hidden email]: Ignored missing context, adjusted
 arguments for __vfs_getxattr and ovl_do_vfs_getxattr]
Signed-off-by: Marcelo Henrique Cerri <[hidden email]>
---
 fs/overlayfs/namei.c     | 19 ++++++++++---------
 fs/overlayfs/overlayfs.h |  7 +++++++
 fs/overlayfs/util.c      |  8 ++++----
 3 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index ae683af0f5e3..53cb05ed2625 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -28,10 +28,10 @@ struct ovl_lookup_data {
 static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
       size_t prelen, const char *post)
 {
- int res;
+ ssize_t res;
  char *s, *next, *buf = NULL;
 
- res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, NULL, 0);
+ res = ovl_do_vfs_getxattr(dentry, OVL_XATTR_REDIRECT, NULL, 0);
  if (res < 0) {
  if (res == -ENODATA || res == -EOPNOTSUPP)
  return 0;
@@ -44,7 +44,7 @@ static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
  if (res == 0)
  goto invalid;
 
- res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, buf, res);
+ res = ovl_do_vfs_getxattr(dentry, OVL_XATTR_REDIRECT, buf, res);
  if (res < 0)
  goto fail;
  if (res == 0)
@@ -84,7 +84,7 @@ static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
  kfree(buf);
  return 0;
 fail:
- pr_warn_ratelimited("overlayfs: failed to get redirect (%i)\n", res);
+ pr_warn_ratelimited("overlayfs: failed to get redirect (%zi)\n", res);
  goto err_free;
 invalid:
  pr_warn_ratelimited("overlayfs: invalid redirect (%s)\n", buf);
@@ -98,10 +98,10 @@ static int ovl_acceptable(void *ctx, struct dentry *dentry)
 
 static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry)
 {
- int res;
+ ssize_t res;
  struct ovl_fh *fh = NULL;
 
- res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
+ res = ovl_do_vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
  if (res < 0) {
  if (res == -ENODATA || res == -EOPNOTSUPP)
  return NULL;
@@ -115,7 +115,7 @@ static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry)
  if (!fh)
  return ERR_PTR(-ENOMEM);
 
- res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, fh, res);
+ res = ovl_do_vfs_getxattr(dentry, OVL_XATTR_ORIGIN, fh, res);
  if (res < 0)
  goto fail;
 
@@ -141,10 +141,11 @@ static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry)
  return NULL;
 
 fail:
- pr_warn_ratelimited("overlayfs: failed to get origin (%i)\n", res);
+ pr_warn_ratelimited("overlayfs: failed to get origin (%zi)\n", res);
  goto out;
 invalid:
- pr_warn_ratelimited("overlayfs: invalid origin (%*phN)\n", res, fh);
+ pr_warn_ratelimited("overlayfs: invalid origin (%*phN)\n",
+    (int)res, fh);
  goto out;
 }
 
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 6fd160b3db8a..b3ae63f61605 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -198,6 +198,13 @@ static inline struct dentry *ovl_do_tmpfile(struct dentry *dentry, umode_t mode)
  return ret;
 }
 
+static inline ssize_t ovl_do_vfs_getxattr(struct dentry *dentry,
+  const char *name, void *buf,
+  size_t size)
+{
+ return __vfs_getxattr(dentry, d_inode(dentry), name, buf, size);
+}
+
 /* util.c */
 int ovl_want_write(struct dentry *dentry);
 void ovl_drop_write(struct dentry *dentry);
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 4b0d52cd7cf4..57d8ee84e657 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -348,9 +348,9 @@ void ovl_copy_up_end(struct dentry *dentry)
 
 bool ovl_check_origin_xattr(struct dentry *dentry)
 {
- int res;
+ ssize_t res;
 
- res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
+ res = ovl_do_vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
 
  /* Zero size value means "copied up but origin unknown" */
  if (res >= 0)
@@ -361,13 +361,13 @@ bool ovl_check_origin_xattr(struct dentry *dentry)
 
 bool ovl_check_dir_xattr(struct dentry *dentry, const char *name)
 {
- int res;
+ ssize_t res;
  char val;
 
  if (!d_is_dir(dentry))
  return false;
 
- res = vfs_getxattr(dentry, name, &val, 1);
+ res = ovl_do_vfs_getxattr(dentry, name, &val, 1);
  if (res == 1 && val == 'y')
  return true;
 
--
2.20.1


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[{eoan, focal}:linux-azure][PATCH] UBUNTU: SAUCE: overlayfs: internal getxattr operations without sepolicy checking

Marcelo Henrique Cerri
In reply to this post by Marcelo Henrique Cerri
From: Mark Salyzyn <[hidden email]>

BugLink: https://bugs.launchpad.net/bugs/1864669

[Based on v15: https://lore.kernel.org/patchwork/patch/1148514/]

Check impure, opaque, origin & meta xattr with no sepolicy audit
(using __vfs_getxattr) since these operations are internal to
overlayfs operations and do not disclose any data.  This became
an issue for credential override off since sys_admin would have
been required by the caller; whereas would have been inherently
present for the creator since it performed the mount.

This is a change in operations since we do not check in the new
ovl_do_vfs_getxattr function if the credential override is off or
not.  Reasoning is that the sepolicy check is unnecessary overhead,
especially since the check can be expensive.

Because for override credentials off, this affects _everyone_ that
underneath performs private xattr calls without the appropriate
sepolicy permissions and sys_admin capability.  Providing blanket
support for sys_admin would be bad for all possible callers.

For the override credentials on, this will affect only the mounter,
should it lack sepolicy permissions. Not considered a security
problem since mounting by definition has sys_admin capabilities,
but sepolicy contexts would still need to be crafted.

It should be noted that there is precedence, __vfs_getxattr is used
in other filesystems for their own internal trusted xattr management.

Signed-off-by: Mark Salyzyn <[hidden email]>
Cc: Miklos Szeredi <[hidden email]>
Cc: Jonathan Corbet <[hidden email]>
Cc: Vivek Goyal <[hidden email]>
Cc: Eric W. Biederman <[hidden email]>
Cc: Amir Goldstein <[hidden email]>
Cc: Randy Dunlap <[hidden email]>
Cc: Stephen Smalley <[hidden email]>
Cc: [hidden email]
Cc: [hidden email]
Cc: [hidden email]
Cc: [hidden email]
Cc: [hidden email]

v15 - revert to v13 as xattr_gs_args was rejected.
    - move ovl_do_wrapper from util.c to inline in overlayfs.h

v14 - rebase to use xattr_gs_args.

v13 - rebase to use __vfs_getxattr flags option

v12 - rebase

v11 - switch name to ovl_do_vfs_getxattr, fortify comment

v10 - added to patch series

[[hidden email]: Adjusted __vfs_getxattr() args and
 removed XATTR_NOSECURITY]
Signed-off-by: Marcelo Henrique Cerri <[hidden email]>
---
 fs/overlayfs/namei.c     | 12 +++++++-----
 fs/overlayfs/overlayfs.h |  7 +++++++
 fs/overlayfs/util.c      | 18 +++++++++---------
 3 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index f47c591402d7..126a93d6a5ab 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -106,10 +106,11 @@ int ovl_check_fh_len(struct ovl_fh *fh, int fh_len)
 
 static struct ovl_fh *ovl_get_fh(struct dentry *dentry, const char *name)
 {
- int res, err;
+ ssize_t res;
+ int err;
  struct ovl_fh *fh = NULL;
 
- res = vfs_getxattr(dentry, name, NULL, 0);
+ res = ovl_do_vfs_getxattr(dentry, name, NULL, 0);
  if (res < 0) {
  if (res == -ENODATA || res == -EOPNOTSUPP)
  return NULL;
@@ -123,7 +124,7 @@ static struct ovl_fh *ovl_get_fh(struct dentry *dentry, const char *name)
  if (!fh)
  return ERR_PTR(-ENOMEM);
 
- res = vfs_getxattr(dentry, name, fh, res);
+ res = ovl_do_vfs_getxattr(dentry, name, fh, res);
  if (res < 0)
  goto fail;
 
@@ -141,10 +142,11 @@ static struct ovl_fh *ovl_get_fh(struct dentry *dentry, const char *name)
  return NULL;
 
 fail:
- pr_warn_ratelimited("overlayfs: failed to get origin (%i)\n", res);
+ pr_warn_ratelimited("overlayfs: failed to get origin (%zi)\n", res);
  goto out;
 invalid:
- pr_warn_ratelimited("overlayfs: invalid origin (%*phN)\n", res, fh);
+ pr_warn_ratelimited("overlayfs: invalid origin (%*phN)\n",
+    (int)res, fh);
  goto out;
 }
 
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index ca10974b9f44..94f840eb7d7d 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -212,6 +212,13 @@ static inline bool ovl_open_flags_need_copy_up(int flags)
  return ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC));
 }
 
+static inline ssize_t ovl_do_vfs_getxattr(struct dentry *dentry,
+  const char *name, void *buf,
+  size_t size)
+{
+ return __vfs_getxattr(dentry, d_inode(dentry), name, buf, size);
+}
+
 /* util.c */
 int ovl_want_write(struct dentry *dentry);
 void ovl_drop_write(struct dentry *dentry);
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index e78d873acc3e..40b12d153c52 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -550,9 +550,9 @@ void ovl_copy_up_end(struct dentry *dentry)
 
 bool ovl_check_origin_xattr(struct dentry *dentry)
 {
- int res;
+ ssize_t res;
 
- res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
+ res = ovl_do_vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
 
  /* Zero size value means "copied up but origin unknown" */
  if (res >= 0)
@@ -563,13 +563,13 @@ bool ovl_check_origin_xattr(struct dentry *dentry)
 
 bool ovl_check_dir_xattr(struct dentry *dentry, const char *name)
 {
- int res;
+ ssize_t res;
  char val;
 
  if (!d_is_dir(dentry))
  return false;
 
- res = vfs_getxattr(dentry, name, &val, 1);
+ res = ovl_do_vfs_getxattr(dentry, name, &val, 1);
  if (res == 1 && val == 'y')
  return true;
 
@@ -850,13 +850,13 @@ int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir)
 /* err < 0, 0 if no metacopy xattr, 1 if metacopy xattr found */
 int ovl_check_metacopy_xattr(struct dentry *dentry)
 {
- int res;
+ ssize_t res;
 
  /* Only regular files can have metacopy xattr */
  if (!S_ISREG(d_inode(dentry)->i_mode))
  return 0;
 
- res = vfs_getxattr(dentry, OVL_XATTR_METACOPY, NULL, 0);
+ res = ovl_do_vfs_getxattr(dentry, OVL_XATTR_METACOPY, NULL, 0);
  if (res < 0) {
  if (res == -ENODATA || res == -EOPNOTSUPP)
  return 0;
@@ -865,7 +865,7 @@ int ovl_check_metacopy_xattr(struct dentry *dentry)
 
  return 1;
 out:
- pr_warn_ratelimited("overlayfs: failed to get metacopy (%i)\n", res);
+ pr_warn_ratelimited("overlayfs: failed to get metacopy (%zi)\n", res);
  return res;
 }
 
@@ -891,7 +891,7 @@ ssize_t ovl_getxattr(struct dentry *dentry, char *name, char **value,
  ssize_t res;
  char *buf = NULL;
 
- res = vfs_getxattr(dentry, name, NULL, 0);
+ res = ovl_do_vfs_getxattr(dentry, name, NULL, 0);
  if (res < 0) {
  if (res == -ENODATA || res == -EOPNOTSUPP)
  return -ENODATA;
@@ -903,7 +903,7 @@ ssize_t ovl_getxattr(struct dentry *dentry, char *name, char **value,
  if (!buf)
  return -ENOMEM;
 
- res = vfs_getxattr(dentry, name, buf, res);
+ res = ovl_do_vfs_getxattr(dentry, name, buf, res);
  if (res < 0)
  goto fail;
  }
--
2.20.1


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ACK/cmnt: [linux-azure][PATCH] LP:#1864669 - [linux-azure] overlayfs regression - internal getxattr operations without sepolicy checking

Kleber Souza
In reply to this post by Marcelo Henrique Cerri
On 26.03.20 15:51, Marcelo Henrique Cerri wrote:

> BugLink: https://bugs.launchpad.net/bugs/1864669
>
> As bug description.
>
> This patch was submitted to upstream as part of a bigger patchset that
> proposes to fix several individual issues. Since the patchset is
> currently stalled with no ETA to be accepted, I decided to backport
> just the necessary fix.
>
> 4.15 required bigger changes since some of the affected pieces of code
> were missing or were different than upstream and I applied the
> equivalent changes to the corresponding area in that kernel. Besides
> that, all patches required a small change to remove XATTR_NOSECURITY
> since that was added by a previous patch on the same series.
>
> That's a fix that potentially can be included to our master
> kernels. But since that was requested for linux-azure I believe we can
> introduce this fix first to linux-azure and to the master kernels on
> the following cycle. That way we can reduce the regression potential.
>
> I didn't include bionic:linux-azure, which is currently based on5.0,
> to this submission because that kernel should move to 5.3 on the next
> cycle.
>
> I've tested the affected scenario with the patched linux-azure kernel
> and the results were positive.
>
> ---
> Mark Salyzyn (1):
>   UBUNTU: SAUCE: overlayfs: internal getxattr operations without
>     sepolicy checking
>
>  fs/overlayfs/namei.c     | 19 ++++++++++---------
>  fs/overlayfs/overlayfs.h |  7 +++++++
>  fs/overlayfs/util.c      |  8 ++++----
>  3 files changed, 21 insertions(+), 13 deletions(-)
>

Looks good to me.

Just a minor nitpick, I would move the "[Based on v15: ...]" line to the
provenance block, as it makes it clearer that it has been added by us.

Acked-by: Kleber Sacilotto de Souza <[hidden email]>

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ACK: [linux-azure][PATCH] LP:#1864669 - [linux-azure] overlayfs regression - internal getxattr operations without sepolicy checking

Stefan Bader-2
In reply to this post by Marcelo Henrique Cerri
On 26.03.20 15:51, Marcelo Henrique Cerri wrote:

> BugLink: https://bugs.launchpad.net/bugs/1864669
>
> As bug description.
>
> This patch was submitted to upstream as part of a bigger patchset that
> proposes to fix several individual issues. Since the patchset is
> currently stalled with no ETA to be accepted, I decided to backport
> just the necessary fix.
>
> 4.15 required bigger changes since some of the affected pieces of code
> were missing or were different than upstream and I applied the
> equivalent changes to the corresponding area in that kernel. Besides
> that, all patches required a small change to remove XATTR_NOSECURITY
> since that was added by a previous patch on the same series.
>
> That's a fix that potentially can be included to our master
> kernels. But since that was requested for linux-azure I believe we can
> introduce this fix first to linux-azure and to the master kernels on
> the following cycle. That way we can reduce the regression potential.
>
> I didn't include bionic:linux-azure, which is currently based on5.0,
> to this submission because that kernel should move to 5.3 on the next
> cycle.
>
> I've tested the affected scenario with the patched linux-azure kernel
> and the results were positive.
>
> ---
> Mark Salyzyn (1):
>   UBUNTU: SAUCE: overlayfs: internal getxattr operations without
>     sepolicy checking
>
>  fs/overlayfs/namei.c     | 19 ++++++++++---------
>  fs/overlayfs/overlayfs.h |  7 +++++++
>  fs/overlayfs/util.c      |  8 ++++----
>  3 files changed, 21 insertions(+), 13 deletions(-)
>
Acked-by: Stefan Bader <[hidden email]>


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APPLIED[F]: [linux-azure][PATCH] LP:#1864669 - [linux-azure] overlayfs regression - internal getxattr operations without sepolicy checking

Seth Forshee
In reply to this post by Marcelo Henrique Cerri
On Thu, Mar 26, 2020 at 11:51:09AM -0300, Marcelo Henrique Cerri wrote:

> BugLink: https://bugs.launchpad.net/bugs/1864669
>
> As bug description.
>
> This patch was submitted to upstream as part of a bigger patchset that
> proposes to fix several individual issues. Since the patchset is
> currently stalled with no ETA to be accepted, I decided to backport
> just the necessary fix.
>
> 4.15 required bigger changes since some of the affected pieces of code
> were missing or were different than upstream and I applied the
> equivalent changes to the corresponding area in that kernel. Besides
> that, all patches required a small change to remove XATTR_NOSECURITY
> since that was added by a previous patch on the same series.
>
> That's a fix that potentially can be included to our master
> kernels. But since that was requested for linux-azure I believe we can
> introduce this fix first to linux-azure and to the master kernels on
> the following cycle. That way we can reduce the regression potential.
>
> I didn't include bionic:linux-azure, which is currently based on5.0,
> to this submission because that kernel should move to 5.3 on the next
> cycle.
>
> I've tested the affected scenario with the patched linux-azure kernel
> and the results were positive.

Applied for focal, with the "[Based on v15: ...]" comment moved to the
provenance block as suggested by Kleber. Thanks!

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APPLIED(x/azure, e/azure)/cmt: [linux-azure][PATCH] LP:#1864669 - [linux-azure] overlayfs regression - internal getxattr operations without sepolicy checking

Khaled Elmously
In reply to this post by Marcelo Henrique Cerri
Applied to xenial/azure and eoan/azure.

Does this need to be in bionic/azure-4.15 or bionic/azure ?




On 2020-03-26 11:51:09 , Marcelo Henrique Cerri wrote:

> BugLink: https://bugs.launchpad.net/bugs/1864669
>
> As bug description.
>
> This patch was submitted to upstream as part of a bigger patchset that
> proposes to fix several individual issues. Since the patchset is
> currently stalled with no ETA to be accepted, I decided to backport
> just the necessary fix.
>
> 4.15 required bigger changes since some of the affected pieces of code
> were missing or were different than upstream and I applied the
> equivalent changes to the corresponding area in that kernel. Besides
> that, all patches required a small change to remove XATTR_NOSECURITY
> since that was added by a previous patch on the same series.
>
> That's a fix that potentially can be included to our master
> kernels. But since that was requested for linux-azure I believe we can
> introduce this fix first to linux-azure and to the master kernels on
> the following cycle. That way we can reduce the regression potential.
>
> I didn't include bionic:linux-azure, which is currently based on5.0,
> to this submission because that kernel should move to 5.3 on the next
> cycle.
>
> I've tested the affected scenario with the patched linux-azure kernel
> and the results were positive.
>
> ---
> Mark Salyzyn (1):
>   UBUNTU: SAUCE: overlayfs: internal getxattr operations without
>     sepolicy checking
>
>  fs/overlayfs/namei.c     | 19 ++++++++++---------
>  fs/overlayfs/overlayfs.h |  7 +++++++
>  fs/overlayfs/util.c      |  8 ++++----
>  3 files changed, 21 insertions(+), 13 deletions(-)
>
> --
> 2.20.1
>
>
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