Audit link denied events were being unexpectedly produced in a disjoint
way when audit was disabled, and when they were expected, there were
duplicate PATH records. This patchset addresses both issues for
symlinks and hardlinks.
This was introduced with
commit b24a30a7305418ff138ff51776fc555ec57c011a
("audit: fix event coverage of AUDIT_ANOM_LINK")
commit a51d9eaa41866ab6b4b6ecad7b621f8b66ece0dc
("fs: add link restriction audit reporting")
Here are the resulting events:
symlink:
type=PROCTITLE msg=audit(03/12/2018 02:21:49.578:310) : proctitle=ls ./my-passwd
type=PATH msg=audit(03/12/2018 02:21:49.578:310) : item=1 name=/tmp/ inode=13529 dev=00:27 mode=dir,sticky,777 ouid=root ogid=root rdev=00:00 obj=system_u:object_r:tmp_t:s0 nametype=PARENT cap_fp=none cap_fi=none cap_fe=0 cap_fver=0
type=PATH msg=audit(03/12/2018 02:21:49.578:310) : item=0 name=./my-passwd inode=17090 dev=00:27 mode=link,777 ouid=rgb ogid=rgb rdev=00:00 obj=unconfined_u:object_r:user_tmp_t:s0 nametype=NORMAL cap_fp=none cap_fi=none cap_fe=0 cap_fver=0
type=CWD msg=audit(03/12/2018 02:21:49.578:310) : cwd=/tmp
type=SYSCALL msg=audit(03/12/2018 02:21:49.578:310) : arch=x86_64 syscall=stat success=no exit=EACCES(Permission denied) a0=0x7ffd79950dda a1=0x563f658a03c8 a2=0x563f658a03c8 a3=0x79950d00 items=2 ppid=552 pid=629 auid=root uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=ttyS0 ses=1 comm=ls exe=/usr/bin/ls subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null)
type=ANOM_LINK msg=audit(03/12/2018 02:21:49.578:310) : op=follow_link ppid=552 pid=629 auid=root uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=ttyS0 ses=1 comm=ls exe=/usr/bin/ls subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 res=no
----
hardlink:
type=PROCTITLE msg=audit(03/12/2018 02:24:39.813:314) : proctitle=ln test test-ln
type=PATH msg=audit(03/12/2018 02:24:39.813:314) : item=1 name=/tmp inode=13529 dev=00:27 mode=dir,sticky,777 ouid=root ogid=root rdev=00:00 obj=system_u:object_r:tmp_t:s0 nametype=PARENT cap_fp=none cap_fi=none cap_fe=0 cap_fver=0
type=PATH msg=audit(03/12/2018 02:24:39.813:314) : item=0 name=test inode=18112 dev=00:27 mode=file,700 ouid=root ogid=root rdev=00:00 obj=unconfined_u:object_r:user_tmp_t:s0 nametype=NORMAL cap_fp=none cap_fi=none cap_fe=0 cap_fver=0
type=CWD msg=audit(03/12/2018 02:24:39.813:314) : cwd=/tmp
type=SYSCALL msg=audit(03/12/2018 02:24:39.813:314) : arch=x86_64 syscall=linkat success=no exit=EPERM(Operation not permitted) a0=0xffffff9c a1=0x7ffccba77629 a2=0xffffff9c a3=0x7ffccba7762e items=2 ppid=605 pid=638 auid=rgb uid=rgb gid=rgb euid=rgb suid=rgb fsuid=rgb egid=rgb sgid=rgb fsgid=rgb tty=pts0 ses=4 comm=ln exe=/usr/bin/ln subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null)
type=ANOM_LINK msg=audit(03/12/2018 02:24:39.813:314) : op=linkat ppid=605 pid=638 auid=rgb uid=rgb gid=rgb euid=rgb suid=rgb fsuid=rgb egid=rgb sgid=rgb fsgid=rgb tty=pts0 ses=4 comm=ln exe=/usr/bin/ln subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 res=no
See: https://github.com/linux-audit/audit-kernel/issues/21
See also: https://github.com/linux-audit/audit-kernel/issues/51
Richard Guy Briggs (4):
audit: make ANOM_LINK obey audit_enabled and audit_dummy_context
audit: link denied should not directly generate PATH record
audit: add refused symlink to audit_names
audit: add parent of refused symlink to audit_names
fs/namei.c | 5 +++--
include/linux/audit.h | 9 +++++----
kernel/audit.c | 43 ++++++++++++++++++++++++++++++++-----------
3 files changed, 40 insertions(+), 17 deletions(-)
--
1.8.3.1
Audit link denied events for symlinks had duplicate PATH records rather
than just updating the existing PATH record. Update the symlink's PATH
record with the current dentry and inode information.
See: https://github.com/linux-audit/audit-kernel/issues/21
Signed-off-by: Richard Guy Briggs <[email protected]>
---
fs/namei.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/namei.c b/fs/namei.c
index 50d2533..00f5041 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -945,6 +945,7 @@ static inline int may_follow_link(struct nameidata *nd)
if (nd->flags & LOOKUP_RCU)
return -ECHILD;
+ audit_inode(nd->name, nd->stack[0].link.dentry, 0);
audit_log_link_denied("follow_link", &nd->stack[0].link);
return -EACCES;
}
--
1.8.3.1
Audit link denied events for symlinks were missing the parent PATH
record. Add it. Since the full pathname may not be available,
reconstruct it from the path in the nameidata supplied.
See: https://github.com/linux-audit/audit-kernel/issues/21
Signed-off-by: Richard Guy Briggs <[email protected]>
---
fs/namei.c | 2 +-
include/linux/audit.h | 3 +++
kernel/audit.c | 31 +++++++++++++++++++++++++++++++
3 files changed, 35 insertions(+), 1 deletion(-)
diff --git a/fs/namei.c b/fs/namei.c
index 00f5041..2f39617 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -946,7 +946,7 @@ static inline int may_follow_link(struct nameidata *nd)
return -ECHILD;
audit_inode(nd->name, nd->stack[0].link.dentry, 0);
- audit_log_link_denied("follow_link", &nd->stack[0].link);
+ audit_log_symlink_denied(&nd->stack[0].link);
return -EACCES;
}
diff --git a/include/linux/audit.h b/include/linux/audit.h
index 75d5b03..b5808e9 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -147,6 +147,7 @@ extern void audit_log_d_path(struct audit_buffer *ab,
extern void audit_log_key(struct audit_buffer *ab,
char *key);
extern void audit_log_link_denied(const char *operation);
+extern void audit_log_symlink_denied(const struct path *link);
extern void audit_log_lost(const char *message);
extern int audit_log_task_context(struct audit_buffer *ab);
@@ -195,6 +196,8 @@ static inline void audit_log_key(struct audit_buffer *ab, char *key)
{ }
static inline void audit_log_link_denied(const char *string)
{ }
+static inline void audit_log_symlink_denied(const struct path *link)
+{ }
static inline int audit_log_task_context(struct audit_buffer *ab)
{
return 0;
diff --git a/kernel/audit.c b/kernel/audit.c
index e54deaf..4acf374 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -73,6 +73,7 @@
#include <linux/freezer.h>
#include <linux/pid_namespace.h>
#include <net/netns/generic.h>
+#include <linux/namei.h> /* for LOOKUP_PARENT */
#include "audit.h"
@@ -2320,6 +2321,36 @@ void audit_log_link_denied(const char *operation)
audit_log_end(ab);
}
+/*
+ * audit_log_symlink_denied - report a symlink restriction denial
+ * @link: the path that triggered the restriction
+ */
+void audit_log_symlink_denied(const struct path *link)
+{
+ char *pathname;
+ struct filename *filename;
+
+ if (audit_dummy_context())
+ return;
+
+ pathname = kmalloc(PATH_MAX + 1, GFP_KERNEL);
+ if (!pathname) {
+ audit_panic("memory allocation error while reporting symlink denied");
+ return;
+ }
+ filename = getname_kernel(d_absolute_path(link, pathname, PATH_MAX + 1));
+ if (IS_ERR(filename)) {
+ audit_panic("error getting pathname while reporting symlink denied");
+ goto out;
+ }
+ audit_inode(filename, link->dentry->d_parent, LOOKUP_PARENT);
+ audit_log_link_denied("follow_link");
+ putname(filename);
+out:
+ kfree(pathname);
+ return;
+}
+
/**
* audit_log_end - end one audit record
* @ab: the audit_buffer
--
1.8.3.1
Audit link denied events generate duplicate PATH records which disagree
in different ways from symlink and hardlink denials.
audit_log_link_denied() should not directly generate PATH records.
While we're at it, remove the now useless struct path argument.
See: https://github.com/linux-audit/audit-kernel/issues/21
Signed-off-by: Richard Guy Briggs <[email protected]>
---
fs/namei.c | 2 +-
include/linux/audit.h | 6 ++----
kernel/audit.c | 17 ++---------------
3 files changed, 5 insertions(+), 20 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 9cc91fb..50d2533 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1011,7 +1011,7 @@ static int may_linkat(struct path *link)
if (safe_hardlink_source(inode) || inode_owner_or_capable(inode))
return 0;
- audit_log_link_denied("linkat", link);
+ audit_log_link_denied("linkat");
return -EPERM;
}
diff --git a/include/linux/audit.h b/include/linux/audit.h
index af410d9..75d5b03 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -146,8 +146,7 @@ extern void audit_log_d_path(struct audit_buffer *ab,
const struct path *path);
extern void audit_log_key(struct audit_buffer *ab,
char *key);
-extern void audit_log_link_denied(const char *operation,
- const struct path *link);
+extern void audit_log_link_denied(const char *operation);
extern void audit_log_lost(const char *message);
extern int audit_log_task_context(struct audit_buffer *ab);
@@ -194,8 +193,7 @@ static inline void audit_log_d_path(struct audit_buffer *ab,
{ }
static inline void audit_log_key(struct audit_buffer *ab, char *key)
{ }
-static inline void audit_log_link_denied(const char *string,
- const struct path *link)
+static inline void audit_log_link_denied(const char *string)
{ }
static inline int audit_log_task_context(struct audit_buffer *ab)
{
diff --git a/kernel/audit.c b/kernel/audit.c
index 7026d69..e54deaf 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -2301,36 +2301,23 @@ void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
/**
* audit_log_link_denied - report a link restriction denial
* @operation: specific link operation
- * @link: the path that triggered the restriction
*/
-void audit_log_link_denied(const char *operation, const struct path *link)
+void audit_log_link_denied(const char *operation)
{
struct audit_buffer *ab;
- struct audit_names *name;
if (!audit_enabled || audit_dummy_context())
return;
- name = kzalloc(sizeof(*name), GFP_NOFS);
- if (!name)
- return;
-
/* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */
ab = audit_log_start(current->audit_context, GFP_KERNEL,
AUDIT_ANOM_LINK);
if (!ab)
- goto out;
+ return;
audit_log_format(ab, "op=%s", operation);
audit_log_task_info(ab, current);
audit_log_format(ab, " res=0");
audit_log_end(ab);
-
- /* Generate AUDIT_PATH record with object. */
- name->type = AUDIT_TYPE_NORMAL;
- audit_copy_inode(name, link->dentry, d_backing_inode(link->dentry));
- audit_log_name(current->audit_context, name, link, 0, NULL);
-out:
- kfree(name);
}
/**
--
1.8.3.1
Audit link denied events emit disjointed records when audit is disabled.
No records should be emitted when audit is disabled.
See: https://github.com/linux-audit/audit-kernel/issues/21
Signed-off-by: Richard Guy Briggs <[email protected]>
---
kernel/audit.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/audit.c b/kernel/audit.c
index 1a3e75d..7026d69 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -2308,6 +2308,9 @@ void audit_log_link_denied(const char *operation, const struct path *link)
struct audit_buffer *ab;
struct audit_names *name;
+ if (!audit_enabled || audit_dummy_context())
+ return;
+
name = kzalloc(sizeof(*name), GFP_NOFS);
if (!name)
return;
--
1.8.3.1
On 2018-03-12 02:31, Richard Guy Briggs wrote:
> Audit link denied events were being unexpectedly produced in a disjoint
> way when audit was disabled, and when they were expected, there were
> duplicate PATH records. This patchset addresses both issues for
> symlinks and hardlinks.
>
> This was introduced with
> commit b24a30a7305418ff138ff51776fc555ec57c011a
> ("audit: fix event coverage of AUDIT_ANOM_LINK")
> commit a51d9eaa41866ab6b4b6ecad7b621f8b66ece0dc
> ("fs: add link restriction audit reporting")
>
> Here are the resulting events:
>
> symlink:
> type=PROCTITLE msg=audit(03/12/2018 02:21:49.578:310) : proctitle=ls ./my-passwd
> type=PATH msg=audit(03/12/2018 02:21:49.578:310) : item=1 name=/tmp/ inode=13529 dev=00:27 mode=dir,sticky,777 ouid=root ogid=root rdev=00:00 obj=system_u:object_r:tmp_t:s0 nametype=PARENT cap_fp=none cap_fi=none cap_fe=0 cap_fver=0
> type=PATH msg=audit(03/12/2018 02:21:49.578:310) : item=0 name=./my-passwd inode=17090 dev=00:27 mode=link,777 ouid=rgb ogid=rgb rdev=00:00 obj=unconfined_u:object_r:user_tmp_t:s0 nametype=NORMAL cap_fp=none cap_fi=none cap_fe=0 cap_fver=0
> type=CWD msg=audit(03/12/2018 02:21:49.578:310) : cwd=/tmp
> type=SYSCALL msg=audit(03/12/2018 02:21:49.578:310) : arch=x86_64 syscall=stat success=no exit=EACCES(Permission denied) a0=0x7ffd79950dda a1=0x563f658a03c8 a2=0x563f658a03c8 a3=0x79950d00 items=2 ppid=552 pid=629 auid=root uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=ttyS0 ses=1 comm=ls exe=/usr/bin/ls subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null)
> type=ANOM_LINK msg=audit(03/12/2018 02:21:49.578:310) : op=follow_link ppid=552 pid=629 auid=root uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=ttyS0 ses=1 comm=ls exe=/usr/bin/ls subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 res=no
> ----
> hardlink:
> type=PROCTITLE msg=audit(03/12/2018 02:24:39.813:314) : proctitle=ln test test-ln
> type=PATH msg=audit(03/12/2018 02:24:39.813:314) : item=1 name=/tmp inode=13529 dev=00:27 mode=dir,sticky,777 ouid=root ogid=root rdev=00:00 obj=system_u:object_r:tmp_t:s0 nametype=PARENT cap_fp=none cap_fi=none cap_fe=0 cap_fver=0
> type=PATH msg=audit(03/12/2018 02:24:39.813:314) : item=0 name=test inode=18112 dev=00:27 mode=file,700 ouid=root ogid=root rdev=00:00 obj=unconfined_u:object_r:user_tmp_t:s0 nametype=NORMAL cap_fp=none cap_fi=none cap_fe=0 cap_fver=0
> type=CWD msg=audit(03/12/2018 02:24:39.813:314) : cwd=/tmp
> type=SYSCALL msg=audit(03/12/2018 02:24:39.813:314) : arch=x86_64 syscall=linkat success=no exit=EPERM(Operation not permitted) a0=0xffffff9c a1=0x7ffccba77629 a2=0xffffff9c a3=0x7ffccba7762e items=2 ppid=605 pid=638 auid=rgb uid=rgb gid=rgb euid=rgb suid=rgb fsuid=rgb egid=rgb sgid=rgb fsgid=rgb tty=pts0 ses=4 comm=ln exe=/usr/bin/ln subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null)
> type=ANOM_LINK msg=audit(03/12/2018 02:24:39.813:314) : op=linkat ppid=605 pid=638 auid=rgb uid=rgb gid=rgb euid=rgb suid=rgb fsuid=rgb egid=rgb sgid=rgb fsgid=rgb tty=pts0 ses=4 comm=ln exe=/usr/bin/ln subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 res=no
>
> See: https://github.com/linux-audit/audit-kernel/issues/21
> See also: https://github.com/linux-audit/audit-kernel/issues/51
>
> Richard Guy Briggs (4):
> audit: make ANOM_LINK obey audit_enabled and audit_dummy_context
> audit: link denied should not directly generate PATH record
> audit: add refused symlink to audit_names
> audit: add parent of refused symlink to audit_names
>
> fs/namei.c | 5 +++--
> include/linux/audit.h | 9 +++++----
> kernel/audit.c | 43 ++++++++++++++++++++++++++++++++-----------
> 3 files changed, 40 insertions(+), 17 deletions(-)
>
> --
Changelog:
v2:
- remove now supperfluous struct path * parameter from audit_log_link_denied()
- refactor audit_log_symlink_denied() to properly free memory (pathname, filename)
> 1.8.3.1
>
- RGB
--
Richard Guy Briggs <[email protected]>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635
On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs <[email protected]> wrote:
> Audit link denied events emit disjointed records when audit is disabled.
> No records should be emitted when audit is disabled.
>
> See: https://github.com/linux-audit/audit-kernel/issues/21
> Signed-off-by: Richard Guy Briggs <[email protected]>
> ---
> kernel/audit.c | 3 +++
> 1 file changed, 3 insertions(+)
As stated previously, this has already been merged. Ignoring.
> diff --git a/kernel/audit.c b/kernel/audit.c
> index 1a3e75d..7026d69 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -2308,6 +2308,9 @@ void audit_log_link_denied(const char *operation, const struct path *link)
> struct audit_buffer *ab;
> struct audit_names *name;
>
> + if (!audit_enabled || audit_dummy_context())
> + return;
> +
> name = kzalloc(sizeof(*name), GFP_NOFS);
> if (!name)
> return;
> --
> 1.8.3.1
--
paul moore
http://www.paul-moore.com
On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs <[email protected]> wrote:
> Audit link denied events generate duplicate PATH records which disagree
> in different ways from symlink and hardlink denials.
> audit_log_link_denied() should not directly generate PATH records.
> While we're at it, remove the now useless struct path argument.
>
> See: https://github.com/linux-audit/audit-kernel/issues/21
> Signed-off-by: Richard Guy Briggs <[email protected]>
> ---
> fs/namei.c | 2 +-
> include/linux/audit.h | 6 ++----
> kernel/audit.c | 17 ++---------------
> 3 files changed, 5 insertions(+), 20 deletions(-)
I have no objection to the v2 change of removing the link parameter,
but this patch can not be merged as-is because the v1 patch has
already been merged into audit/next (as stated on the mailing list).
You need to respin this patch against audit/next and redo the
subject/description to indicate that you are just removing the unused
link parameter in this updated patch.
> diff --git a/fs/namei.c b/fs/namei.c
> index 9cc91fb..50d2533 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -1011,7 +1011,7 @@ static int may_linkat(struct path *link)
> if (safe_hardlink_source(inode) || inode_owner_or_capable(inode))
> return 0;
>
> - audit_log_link_denied("linkat", link);
> + audit_log_link_denied("linkat");
> return -EPERM;
> }
>
> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index af410d9..75d5b03 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -146,8 +146,7 @@ extern void audit_log_d_path(struct audit_buffer *ab,
> const struct path *path);
> extern void audit_log_key(struct audit_buffer *ab,
> char *key);
> -extern void audit_log_link_denied(const char *operation,
> - const struct path *link);
> +extern void audit_log_link_denied(const char *operation);
> extern void audit_log_lost(const char *message);
>
> extern int audit_log_task_context(struct audit_buffer *ab);
> @@ -194,8 +193,7 @@ static inline void audit_log_d_path(struct audit_buffer *ab,
> { }
> static inline void audit_log_key(struct audit_buffer *ab, char *key)
> { }
> -static inline void audit_log_link_denied(const char *string,
> - const struct path *link)
> +static inline void audit_log_link_denied(const char *string)
> { }
> static inline int audit_log_task_context(struct audit_buffer *ab)
> {
> diff --git a/kernel/audit.c b/kernel/audit.c
> index 7026d69..e54deaf 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -2301,36 +2301,23 @@ void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
> /**
> * audit_log_link_denied - report a link restriction denial
> * @operation: specific link operation
> - * @link: the path that triggered the restriction
> */
> -void audit_log_link_denied(const char *operation, const struct path *link)
> +void audit_log_link_denied(const char *operation)
> {
> struct audit_buffer *ab;
> - struct audit_names *name;
>
> if (!audit_enabled || audit_dummy_context())
> return;
>
> - name = kzalloc(sizeof(*name), GFP_NOFS);
> - if (!name)
> - return;
> -
> /* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */
> ab = audit_log_start(current->audit_context, GFP_KERNEL,
> AUDIT_ANOM_LINK);
> if (!ab)
> - goto out;
> + return;
> audit_log_format(ab, "op=%s", operation);
> audit_log_task_info(ab, current);
> audit_log_format(ab, " res=0");
> audit_log_end(ab);
> -
> - /* Generate AUDIT_PATH record with object. */
> - name->type = AUDIT_TYPE_NORMAL;
> - audit_copy_inode(name, link->dentry, d_backing_inode(link->dentry));
> - audit_log_name(current->audit_context, name, link, 0, NULL);
> -out:
> - kfree(name);
> }
>
> /**
> --
> 1.8.3.1
>
--
paul moore
http://www.paul-moore.com
On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs <[email protected]> wrote:
> Audit link denied events for symlinks had duplicate PATH records rather
> than just updating the existing PATH record. Update the symlink's PATH
> record with the current dentry and inode information.
>
> See: https://github.com/linux-audit/audit-kernel/issues/21
> Signed-off-by: Richard Guy Briggs <[email protected]>
> ---
> fs/namei.c | 1 +
> 1 file changed, 1 insertion(+)
Why didn't you include this in patch 4/4 like I asked during the
previous review?
> diff --git a/fs/namei.c b/fs/namei.c
> index 50d2533..00f5041 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -945,6 +945,7 @@ static inline int may_follow_link(struct nameidata *nd)
> if (nd->flags & LOOKUP_RCU)
> return -ECHILD;
>
> + audit_inode(nd->name, nd->stack[0].link.dentry, 0);
> audit_log_link_denied("follow_link", &nd->stack[0].link);
> return -EACCES;
> }
> --
> 1.8.3.1
--
paul moore
http://www.paul-moore.com
On Mon, 12 Mar 2018 02:31:16 -0400
Richard Guy Briggs <[email protected]> wrote:
> Audit link denied events were being unexpectedly produced in a
> disjoint way when audit was disabled, and when they were expected,
> there were duplicate PATH records. This patchset addresses both
> issues for symlinks and hardlinks.
>
> This was introduced with
> commit b24a30a7305418ff138ff51776fc555ec57c011a
> ("audit: fix event coverage of AUDIT_ANOM_LINK")
> commit a51d9eaa41866ab6b4b6ecad7b621f8b66ece0dc
> ("fs: add link restriction audit reporting")
>
> Here are the resulting events:
>
> symlink:
> type=PROCTITLE msg=audit(03/12/2018 02:21:49.578:310) :
> proctitle=ls ./my-passwd type=PATH msg=audit(03/12/2018
> 02:21:49.578:310) : item=1 name=/tmp/ inode=13529 dev=00:27
> mode=dir,sticky,777 ouid=root ogid=root rdev=00:00
> obj=system_u:object_r:tmp_t:s0 nametype=PARENT cap_fp=none
> cap_fi=none cap_fe=0 cap_fver=0 type=PATH msg=audit(03/12/2018
> 02:21:49.578:310) : item=0 name=./my-passwd inode=17090 dev=00:27
> mode=link,777 ouid=rgb ogid=rgb rdev=00:00
> obj=unconfined_u:object_r:user_tmp_t:s0 nametype=NORMAL cap_fp=none
> cap_fi=none cap_fe=0 cap_fver=0 type=CWD msg=audit(03/12/2018
> 02:21:49.578:310) : cwd=/tmp type=SYSCALL msg=audit(03/12/2018
> 02:21:49.578:310) : arch=x86_64 syscall=stat success=no
> exit=EACCES(Permission denied) a0=0x7ffd79950dda a1=0x563f658a03c8
> a2=0x563f658a03c8 a3=0x79950d00 items=2 ppid=552 pid=629 auid=root
> uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root
> fsgid=root tty=ttyS0 ses=1 comm=ls exe=/usr/bin/ls
> subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null)
> type=ANOM_LINK msg=audit(03/12/2018 02:21:49.578:310) :
> op=follow_link ppid=552 pid=629 auid=root uid=root gid=root euid=root
> suid=root fsuid=root egid=root sgid=root fsgid=root tty=ttyS0 ses=1
> comm=ls exe=/usr/bin/ls
So, if we now only emit the ANOM_LINK event when audit is enabled, we
should get rid of all the duplicate information in that record. The
SYSCALL record has all that information.
-Steve
> subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 res=no
> ---- hardlink: type=PROCTITLE msg=audit(03/12/2018
> 02:24:39.813:314) : proctitle=ln test test-ln type=PATH
> msg=audit(03/12/2018 02:24:39.813:314) : item=1 name=/tmp inode=13529
> dev=00:27 mode=dir,sticky,777 ouid=root ogid=root rdev=00:00
> obj=system_u:object_r:tmp_t:s0 nametype=PARENT cap_fp=none
> cap_fi=none cap_fe=0 cap_fver=0 type=PATH msg=audit(03/12/2018
> 02:24:39.813:314) : item=0 name=test inode=18112 dev=00:27
> mode=file,700 ouid=root ogid=root rdev=00:00
> obj=unconfined_u:object_r:user_tmp_t:s0 nametype=NORMAL cap_fp=none
> cap_fi=none cap_fe=0 cap_fver=0 type=CWD msg=audit(03/12/2018
> 02:24:39.813:314) : cwd=/tmp type=SYSCALL msg=audit(03/12/2018
> 02:24:39.813:314) : arch=x86_64 syscall=linkat success=no
> exit=EPERM(Operation not permitted) a0=0xffffff9c a1=0x7ffccba77629
> a2=0xffffff9c a3=0x7ffccba7762e items=2 ppid=605 pid=638 auid=rgb
> uid=rgb gid=rgb euid=rgb suid=rgb fsuid=rgb egid=rgb sgid=rgb
> fsgid=rgb tty=pts0 ses=4 comm=ln exe=/usr/bin/ln
> subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null)
> type=ANOM_LINK msg=audit(03/12/2018 02:24:39.813:314) : op=linkat
> ppid=605 pid=638 auid=rgb uid=rgb gid=rgb euid=rgb suid=rgb fsuid=rgb
> egid=rgb sgid=rgb fsgid=rgb tty=pts0 ses=4 comm=ln exe=/usr/bin/ln
> subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 res=no
>
> See: https://github.com/linux-audit/audit-kernel/issues/21
> See also: https://github.com/linux-audit/audit-kernel/issues/51
>
> Richard Guy Briggs (4):
> audit: make ANOM_LINK obey audit_enabled and audit_dummy_context
> audit: link denied should not directly generate PATH record
> audit: add refused symlink to audit_names
> audit: add parent of refused symlink to audit_names
>
> fs/namei.c | 5 +++--
> include/linux/audit.h | 9 +++++----
> kernel/audit.c | 43
> ++++++++++++++++++++++++++++++++----------- 3 files changed, 40
> insertions(+), 17 deletions(-)
>
On 2018-03-12 11:12, Paul Moore wrote:
> On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs <[email protected]> wrote:
> > Audit link denied events for symlinks had duplicate PATH records rather
> > than just updating the existing PATH record. Update the symlink's PATH
> > record with the current dentry and inode information.
> >
> > See: https://github.com/linux-audit/audit-kernel/issues/21
> > Signed-off-by: Richard Guy Briggs <[email protected]>
> > ---
> > fs/namei.c | 1 +
> > 1 file changed, 1 insertion(+)
>
> Why didn't you include this in patch 4/4 like I asked during the
> previous review?
Please see the last comment of:
https://www.redhat.com/archives/linux-audit/2018-March/msg00070.html
> > diff --git a/fs/namei.c b/fs/namei.c
> > index 50d2533..00f5041 100644
> > --- a/fs/namei.c
> > +++ b/fs/namei.c
> > @@ -945,6 +945,7 @@ static inline int may_follow_link(struct nameidata *nd)
> > if (nd->flags & LOOKUP_RCU)
> > return -ECHILD;
> >
> > + audit_inode(nd->name, nd->stack[0].link.dentry, 0);
> > audit_log_link_denied("follow_link", &nd->stack[0].link);
> > return -EACCES;
> > }
>
> paul moore
- RGB
--
Richard Guy Briggs <[email protected]>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635
On 2018-03-12 11:05, Paul Moore wrote:
> On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs <[email protected]> wrote:
> > Audit link denied events generate duplicate PATH records which disagree
> > in different ways from symlink and hardlink denials.
> > audit_log_link_denied() should not directly generate PATH records.
> > While we're at it, remove the now useless struct path argument.
> >
> > See: https://github.com/linux-audit/audit-kernel/issues/21
> > Signed-off-by: Richard Guy Briggs <[email protected]>
> > ---
> > fs/namei.c | 2 +-
> > include/linux/audit.h | 6 ++----
> > kernel/audit.c | 17 ++---------------
> > 3 files changed, 5 insertions(+), 20 deletions(-)
>
> I have no objection to the v2 change of removing the link parameter,
> but this patch can not be merged as-is because the v1 patch has
> already been merged into audit/next (as stated on the mailing list).
Yes, I self-NACKed that patch.
https://www.redhat.com/archives/linux-audit/2018-March/msg00070.html
Is it not possible to drop it, or would you have to do a revert to avoid
a rebase?
> You need to respin this patch against audit/next and redo the
> subject/description to indicate that you are just removing the unused
> link parameter in this updated patch.
So the way I had it in my devel tree rather than squashing it...
> > diff --git a/fs/namei.c b/fs/namei.c
> > index 9cc91fb..50d2533 100644
> > --- a/fs/namei.c
> > +++ b/fs/namei.c
> > @@ -1011,7 +1011,7 @@ static int may_linkat(struct path *link)
> > if (safe_hardlink_source(inode) || inode_owner_or_capable(inode))
> > return 0;
> >
> > - audit_log_link_denied("linkat", link);
> > + audit_log_link_denied("linkat");
> > return -EPERM;
> > }
> >
> > diff --git a/include/linux/audit.h b/include/linux/audit.h
> > index af410d9..75d5b03 100644
> > --- a/include/linux/audit.h
> > +++ b/include/linux/audit.h
> > @@ -146,8 +146,7 @@ extern void audit_log_d_path(struct audit_buffer *ab,
> > const struct path *path);
> > extern void audit_log_key(struct audit_buffer *ab,
> > char *key);
> > -extern void audit_log_link_denied(const char *operation,
> > - const struct path *link);
> > +extern void audit_log_link_denied(const char *operation);
> > extern void audit_log_lost(const char *message);
> >
> > extern int audit_log_task_context(struct audit_buffer *ab);
> > @@ -194,8 +193,7 @@ static inline void audit_log_d_path(struct audit_buffer *ab,
> > { }
> > static inline void audit_log_key(struct audit_buffer *ab, char *key)
> > { }
> > -static inline void audit_log_link_denied(const char *string,
> > - const struct path *link)
> > +static inline void audit_log_link_denied(const char *string)
> > { }
> > static inline int audit_log_task_context(struct audit_buffer *ab)
> > {
> > diff --git a/kernel/audit.c b/kernel/audit.c
> > index 7026d69..e54deaf 100644
> > --- a/kernel/audit.c
> > +++ b/kernel/audit.c
> > @@ -2301,36 +2301,23 @@ void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
> > /**
> > * audit_log_link_denied - report a link restriction denial
> > * @operation: specific link operation
> > - * @link: the path that triggered the restriction
> > */
> > -void audit_log_link_denied(const char *operation, const struct path *link)
> > +void audit_log_link_denied(const char *operation)
> > {
> > struct audit_buffer *ab;
> > - struct audit_names *name;
> >
> > if (!audit_enabled || audit_dummy_context())
> > return;
> >
> > - name = kzalloc(sizeof(*name), GFP_NOFS);
> > - if (!name)
> > - return;
> > -
> > /* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */
> > ab = audit_log_start(current->audit_context, GFP_KERNEL,
> > AUDIT_ANOM_LINK);
> > if (!ab)
> > - goto out;
> > + return;
> > audit_log_format(ab, "op=%s", operation);
> > audit_log_task_info(ab, current);
> > audit_log_format(ab, " res=0");
> > audit_log_end(ab);
> > -
> > - /* Generate AUDIT_PATH record with object. */
> > - name->type = AUDIT_TYPE_NORMAL;
> > - audit_copy_inode(name, link->dentry, d_backing_inode(link->dentry));
> > - audit_log_name(current->audit_context, name, link, 0, NULL);
> > -out:
> > - kfree(name);
> > }
> >
> > /**
> > --
> > 1.8.3.1
> >
>
>
>
> --
> paul moore
> http://www.paul-moore.com
>
> --
> Linux-audit mailing list
> [email protected]
> https://www.redhat.com/mailman/listinfo/linux-audit
- RGB
--
Richard Guy Briggs <[email protected]>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635
On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs <[email protected]> wrote:
> Audit link denied events for symlinks were missing the parent PATH
> record. Add it. Since the full pathname may not be available,
> reconstruct it from the path in the nameidata supplied.
>
> See: https://github.com/linux-audit/audit-kernel/issues/21
> Signed-off-by: Richard Guy Briggs <[email protected]>
> ---
> fs/namei.c | 2 +-
> include/linux/audit.h | 3 +++
> kernel/audit.c | 31 +++++++++++++++++++++++++++++++
> 3 files changed, 35 insertions(+), 1 deletion(-)
See my comment in patch 3/4; it should really be folded into this
patch. Additional comment inline below ...
> diff --git a/kernel/audit.c b/kernel/audit.c
> index e54deaf..4acf374 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -73,6 +73,7 @@
> #include <linux/freezer.h>
> #include <linux/pid_namespace.h>
> #include <net/netns/generic.h>
> +#include <linux/namei.h> /* for LOOKUP_PARENT */
>
> #include "audit.h"
>
> @@ -2320,6 +2321,36 @@ void audit_log_link_denied(const char *operation)
> audit_log_end(ab);
> }
>
> +/*
> + * audit_log_symlink_denied - report a symlink restriction denial
> + * @link: the path that triggered the restriction
> + */
> +void audit_log_symlink_denied(const struct path *link)
> +{
> + char *pathname;
> + struct filename *filename;
> +
> + if (audit_dummy_context())
> + return;
> +
> + pathname = kmalloc(PATH_MAX + 1, GFP_KERNEL);
> + if (!pathname) {
> + audit_panic("memory allocation error while reporting symlink denied");
> + return;
> + }
> + filename = getname_kernel(d_absolute_path(link, pathname, PATH_MAX + 1));
> + if (IS_ERR(filename)) {
> + audit_panic("error getting pathname while reporting symlink denied");
> + goto out;
> + }
> + audit_inode(filename, link->dentry->d_parent, LOOKUP_PARENT);
Since we are already checking audit_dummy_context() above we don't
need to check it again in audit_inode(), you should just call
__audit_inode() directly. As a reminder, make sure you convert
LOOKUP_PARENT to AUDIT_INODE_PARENT.
> + audit_log_link_denied("follow_link");
> + putname(filename);
> +out:
> + kfree(pathname);
> + return;
> +}
--
paul moore
http://www.paul-moore.com
On Mon, Mar 12, 2018 at 11:17 AM, Steve Grubb <[email protected]> wrote:
> On Mon, 12 Mar 2018 02:31:16 -0400
> Richard Guy Briggs <[email protected]> wrote:
>
>> Audit link denied events were being unexpectedly produced in a
>> disjoint way when audit was disabled, and when they were expected,
>> there were duplicate PATH records. This patchset addresses both
>> issues for symlinks and hardlinks.
>>
>> This was introduced with
>> commit b24a30a7305418ff138ff51776fc555ec57c011a
>> ("audit: fix event coverage of AUDIT_ANOM_LINK")
>> commit a51d9eaa41866ab6b4b6ecad7b621f8b66ece0dc
>> ("fs: add link restriction audit reporting")
>>
>> Here are the resulting events:
>>
>> symlink:
>> type=PROCTITLE msg=audit(03/12/2018 02:21:49.578:310) :
>> proctitle=ls ./my-passwd type=PATH msg=audit(03/12/2018
>> 02:21:49.578:310) : item=1 name=/tmp/ inode=13529 dev=00:27
>> mode=dir,sticky,777 ouid=root ogid=root rdev=00:00
>> obj=system_u:object_r:tmp_t:s0 nametype=PARENT cap_fp=none
>> cap_fi=none cap_fe=0 cap_fver=0 type=PATH msg=audit(03/12/2018
>> 02:21:49.578:310) : item=0 name=./my-passwd inode=17090 dev=00:27
>> mode=link,777 ouid=rgb ogid=rgb rdev=00:00
>> obj=unconfined_u:object_r:user_tmp_t:s0 nametype=NORMAL cap_fp=none
>> cap_fi=none cap_fe=0 cap_fver=0 type=CWD msg=audit(03/12/2018
>> 02:21:49.578:310) : cwd=/tmp type=SYSCALL msg=audit(03/12/2018
>> 02:21:49.578:310) : arch=x86_64 syscall=stat success=no
>> exit=EACCES(Permission denied) a0=0x7ffd79950dda a1=0x563f658a03c8
>> a2=0x563f658a03c8 a3=0x79950d00 items=2 ppid=552 pid=629 auid=root
>> uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root
>> fsgid=root tty=ttyS0 ses=1 comm=ls exe=/usr/bin/ls
>> subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null)
>> type=ANOM_LINK msg=audit(03/12/2018 02:21:49.578:310) :
>> op=follow_link ppid=552 pid=629 auid=root uid=root gid=root euid=root
>> suid=root fsuid=root egid=root sgid=root fsgid=root tty=ttyS0 ses=1
>> comm=ls exe=/usr/bin/ls
>
> So, if we now only emit the ANOM_LINK event when audit is enabled, we
> should get rid of all the duplicate information in that record. The
> SYSCALL record has all that information.
As discussed previously, I'm not going to merge any patches which
remove fields from existing records.
--
paul moore
http://www.paul-moore.com
On Mon, Mar 12, 2018 at 11:26 AM, Richard Guy Briggs <[email protected]> wrote:
> On 2018-03-12 11:12, Paul Moore wrote:
>> On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs <[email protected]> wrote:
>> > Audit link denied events for symlinks had duplicate PATH records rather
>> > than just updating the existing PATH record. Update the symlink's PATH
>> > record with the current dentry and inode information.
>> >
>> > See: https://github.com/linux-audit/audit-kernel/issues/21
>> > Signed-off-by: Richard Guy Briggs <[email protected]>
>> > ---
>> > fs/namei.c | 1 +
>> > 1 file changed, 1 insertion(+)
>>
>> Why didn't you include this in patch 4/4 like I asked during the
>> previous review?
>
> Please see the last comment of:
> https://www.redhat.com/archives/linux-audit/2018-March/msg00070.html
Yes, I just saw that ... I hadn't seen your replies on the v1 patches
until I had finished reviewing v2. I just replied to that mail in the
v1 thread, but basically you need to figure out what is necessary here
and let us know. If I have to figure it out it likely isn't going to
get done with enough soak time prior to the upcoming merge window.
>> > diff --git a/fs/namei.c b/fs/namei.c
>> > index 50d2533..00f5041 100644
>> > --- a/fs/namei.c
>> > +++ b/fs/namei.c
>> > @@ -945,6 +945,7 @@ static inline int may_follow_link(struct nameidata *nd)
>> > if (nd->flags & LOOKUP_RCU)
>> > return -ECHILD;
>> >
>> > + audit_inode(nd->name, nd->stack[0].link.dentry, 0);
>> > audit_log_link_denied("follow_link", &nd->stack[0].link);
>> > return -EACCES;
>> > }
>>
>> paul moore
>
> - RGB
>
> --
> Richard Guy Briggs <[email protected]>
> Sr. S/W Engineer, Kernel Security, Base Operating Systems
> Remote, Ottawa, Red Hat Canada
> IRC: rgb, SunRaycer
> Voice: +1.647.777.2635, Internal: (81) 32635
--
paul moore
http://www.paul-moore.com
On Mon, Mar 12, 2018 at 11:30 AM, Richard Guy Briggs <[email protected]> wrote:
> On 2018-03-12 11:05, Paul Moore wrote:
>> On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs <[email protected]> wrote:
>> > Audit link denied events generate duplicate PATH records which disagree
>> > in different ways from symlink and hardlink denials.
>> > audit_log_link_denied() should not directly generate PATH records.
>> > While we're at it, remove the now useless struct path argument.
>> >
>> > See: https://github.com/linux-audit/audit-kernel/issues/21
>> > Signed-off-by: Richard Guy Briggs <[email protected]>
>> > ---
>> > fs/namei.c | 2 +-
>> > include/linux/audit.h | 6 ++----
>> > kernel/audit.c | 17 ++---------------
>> > 3 files changed, 5 insertions(+), 20 deletions(-)
>>
>> I have no objection to the v2 change of removing the link parameter,
>> but this patch can not be merged as-is because the v1 patch has
>> already been merged into audit/next (as stated on the mailing list).
>
> Yes, I self-NACKed that patch.
>
> https://www.redhat.com/archives/linux-audit/2018-March/msg00070.html
>
> Is it not possible to drop it, or would you have to do a revert to avoid
> a rebase?
Yes, it is possible to drop a patch from the audit/next patch stack,
but dropping patches is considered *very* bad form and not something I
want to do without a Very Good Reason. While the v2 patch is the
"right" patch, the v1 patch is not dangerous, so I would rather you
just build on top of what is currently in audit/next.
--
paul moore
http://www.paul-moore.com
On 2018-03-12 11:53, Paul Moore wrote:
> On Mon, Mar 12, 2018 at 11:26 AM, Richard Guy Briggs <[email protected]> wrote:
> > On 2018-03-12 11:12, Paul Moore wrote:
> >> On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs <[email protected]> wrote:
> >> > Audit link denied events for symlinks had duplicate PATH records rather
> >> > than just updating the existing PATH record. Update the symlink's PATH
> >> > record with the current dentry and inode information.
> >> >
> >> > See: https://github.com/linux-audit/audit-kernel/issues/21
> >> > Signed-off-by: Richard Guy Briggs <[email protected]>
> >> > ---
> >> > fs/namei.c | 1 +
> >> > 1 file changed, 1 insertion(+)
> >>
> >> Why didn't you include this in patch 4/4 like I asked during the
> >> previous review?
> >
> > Please see the last comment of:
> > https://www.redhat.com/archives/linux-audit/2018-March/msg00070.html
>
> Yes, I just saw that ... I hadn't seen your replies on the v1 patches
> until I had finished reviewing v2. I just replied to that mail in the
> v1 thread, but basically you need to figure out what is necessary here
> and let us know. If I have to figure it out it likely isn't going to
> get done with enough soak time prior to the upcoming merge window.
Steve? I was hoping you could chime in here.
I'd just include it for completeness unless Steve thinks it will stand
on its own and doesn't want the overhead.
> >> > diff --git a/fs/namei.c b/fs/namei.c
> >> > index 50d2533..00f5041 100644
> >> > --- a/fs/namei.c
> >> > +++ b/fs/namei.c
> >> > @@ -945,6 +945,7 @@ static inline int may_follow_link(struct nameidata *nd)
> >> > if (nd->flags & LOOKUP_RCU)
> >> > return -ECHILD;
> >> >
> >> > + audit_inode(nd->name, nd->stack[0].link.dentry, 0);
> >> > audit_log_link_denied("follow_link", &nd->stack[0].link);
> >> > return -EACCES;
> >> > }
> >>
> >> paul moore
> >
> > - RGB
>
> paul moore
- RGB
--
Richard Guy Briggs <[email protected]>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635
On Mon, Mar 12, 2018 at 11:52 AM, Richard Guy Briggs <[email protected]> wrote:
> On 2018-03-12 11:53, Paul Moore wrote:
>> On Mon, Mar 12, 2018 at 11:26 AM, Richard Guy Briggs <[email protected]> wrote:
>> > On 2018-03-12 11:12, Paul Moore wrote:
>> >> On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs <[email protected]> wrote:
>> >> > Audit link denied events for symlinks had duplicate PATH records rather
>> >> > than just updating the existing PATH record. Update the symlink's PATH
>> >> > record with the current dentry and inode information.
>> >> >
>> >> > See: https://github.com/linux-audit/audit-kernel/issues/21
>> >> > Signed-off-by: Richard Guy Briggs <[email protected]>
>> >> > ---
>> >> > fs/namei.c | 1 +
>> >> > 1 file changed, 1 insertion(+)
>> >>
>> >> Why didn't you include this in patch 4/4 like I asked during the
>> >> previous review?
>> >
>> > Please see the last comment of:
>> > https://www.redhat.com/archives/linux-audit/2018-March/msg00070.html
>>
>> Yes, I just saw that ... I hadn't seen your replies on the v1 patches
>> until I had finished reviewing v2. I just replied to that mail in the
>> v1 thread, but basically you need to figure out what is necessary here
>> and let us know. If I have to figure it out it likely isn't going to
>> get done with enough soak time prior to the upcoming merge window.
>
> Steve? I was hoping you could chime in here.
>
> I'd just include it for completeness unless Steve thinks it will stand
> on its own and doesn't want the overhead.
If that's the argument, I'd rather just include it. We've been burned
by not including stuff in the past and fixing those omissions has
proven to be a major source of contention.
--
paul moore
http://www.paul-moore.com
Hi Richard,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on linus/master]
[also build test ERROR on v4.16-rc5 next-20180309]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Richard-Guy-Briggs/audit-address-ANOM_LINK-excess-records/20180313-015527
config: i386-tinyconfig (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
Note: the linux-review/Richard-Guy-Briggs/audit-address-ANOM_LINK-excess-records/20180313-015527 HEAD 12e8c56bcd359f7d20d4ae011674d37bc832bc4c builds fine.
It only hurts bisectibility.
All errors (new ones prefixed by >>):
fs/namei.c: In function 'may_follow_link':
>> fs/namei.c:929:2: error: too many arguments to function 'audit_log_link_denied'
audit_log_link_denied("follow_link", &nd->stack[0].link);
^~~~~~~~~~~~~~~~~~~~~
In file included from include/linux/fsnotify.h:16:0,
from fs/namei.c:25:
include/linux/audit.h:196:20: note: declared here
static inline void audit_log_link_denied(const char *string)
^~~~~~~~~~~~~~~~~~~~~
vim +/audit_log_link_denied +929 fs/namei.c
800179c9b Kees Cook 2012-07-25 886
800179c9b Kees Cook 2012-07-25 887 /**
800179c9b Kees Cook 2012-07-25 888 * may_follow_link - Check symlink following for unsafe situations
55852635a Randy Dunlap 2012-08-18 889 * @nd: nameidata pathwalk data
800179c9b Kees Cook 2012-07-25 890 *
800179c9b Kees Cook 2012-07-25 891 * In the case of the sysctl_protected_symlinks sysctl being enabled,
800179c9b Kees Cook 2012-07-25 892 * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
800179c9b Kees Cook 2012-07-25 893 * in a sticky world-writable directory. This is to protect privileged
800179c9b Kees Cook 2012-07-25 894 * processes from failing races against path names that may change out
800179c9b Kees Cook 2012-07-25 895 * from under them by way of other users creating malicious symlinks.
800179c9b Kees Cook 2012-07-25 896 * It will permit symlinks to be followed only when outside a sticky
800179c9b Kees Cook 2012-07-25 897 * world-writable directory, or when the uid of the symlink and follower
800179c9b Kees Cook 2012-07-25 898 * match, or when the directory owner matches the symlink's owner.
800179c9b Kees Cook 2012-07-25 899 *
800179c9b Kees Cook 2012-07-25 900 * Returns 0 if following the symlink is allowed, -ve on error.
800179c9b Kees Cook 2012-07-25 901 */
fec2fa24e Al Viro 2015-05-06 902 static inline int may_follow_link(struct nameidata *nd)
800179c9b Kees Cook 2012-07-25 903 {
800179c9b Kees Cook 2012-07-25 904 const struct inode *inode;
800179c9b Kees Cook 2012-07-25 905 const struct inode *parent;
2d7f9e2ad Seth Forshee 2016-04-26 906 kuid_t puid;
800179c9b Kees Cook 2012-07-25 907
800179c9b Kees Cook 2012-07-25 908 if (!sysctl_protected_symlinks)
800179c9b Kees Cook 2012-07-25 909 return 0;
800179c9b Kees Cook 2012-07-25 910
800179c9b Kees Cook 2012-07-25 911 /* Allowed if owner and follower match. */
fceef393a Al Viro 2015-12-29 912 inode = nd->link_inode;
81abe27b1 Eric W. Biederman 2012-08-03 913 if (uid_eq(current_cred()->fsuid, inode->i_uid))
800179c9b Kees Cook 2012-07-25 914 return 0;
800179c9b Kees Cook 2012-07-25 915
800179c9b Kees Cook 2012-07-25 916 /* Allowed if parent directory not sticky and world-writable. */
aa65fa35b Al Viro 2015-08-04 917 parent = nd->inode;
800179c9b Kees Cook 2012-07-25 918 if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH))
800179c9b Kees Cook 2012-07-25 919 return 0;
800179c9b Kees Cook 2012-07-25 920
800179c9b Kees Cook 2012-07-25 921 /* Allowed if parent directory and link owner match. */
2d7f9e2ad Seth Forshee 2016-04-26 922 puid = parent->i_uid;
2d7f9e2ad Seth Forshee 2016-04-26 923 if (uid_valid(puid) && uid_eq(puid, inode->i_uid))
800179c9b Kees Cook 2012-07-25 924 return 0;
800179c9b Kees Cook 2012-07-25 925
31956502d Al Viro 2015-05-07 926 if (nd->flags & LOOKUP_RCU)
31956502d Al Viro 2015-05-07 927 return -ECHILD;
31956502d Al Viro 2015-05-07 928
1cf2665b5 Al Viro 2015-05-06 @929 audit_log_link_denied("follow_link", &nd->stack[0].link);
800179c9b Kees Cook 2012-07-25 930 return -EACCES;
800179c9b Kees Cook 2012-07-25 931 }
800179c9b Kees Cook 2012-07-25 932
:::::: The code at line 929 was first introduced by commit
:::::: 1cf2665b5bdfc63185fb4a416bff54b14ad30c79 namei: kill nd->link
:::::: TO: Al Viro <[email protected]>
:::::: CC: Al Viro <[email protected]>
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
On 2018-03-13 02:22, kbuild test robot wrote:
> Hi Richard,
>
> Thank you for the patch! Yet something to improve:
>
> [auto build test ERROR on linus/master]
> [also build test ERROR on v4.16-rc5 next-20180309]
> [if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
My fault. It was applied to a stale tree:
git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit.git
A self-NACKed patch wasn't removed from the upstream tree as hoped. A
new patch is already in the works.
> url: https://github.com/0day-ci/linux/commits/Richard-Guy-Briggs/audit-address-ANOM_LINK-excess-records/20180313-015527
> Note: the linux-review/Richard-Guy-Briggs/audit-address-ANOM_LINK-excess-records/20180313-015527 HEAD 12e8c56bcd359f7d20d4ae011674d37bc832bc4c builds fine.
> It only hurts bisectibility.
- RGB
--
Richard Guy Briggs <[email protected]>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635
On Mon, 12 Mar 2018 11:52:56 -0400
Richard Guy Briggs <[email protected]> wrote:
> On 2018-03-12 11:53, Paul Moore wrote:
> > On Mon, Mar 12, 2018 at 11:26 AM, Richard Guy Briggs
> > <[email protected]> wrote:
> > > On 2018-03-12 11:12, Paul Moore wrote:
> > >> On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs
> > >> <[email protected]> wrote:
> > >> > Audit link denied events for symlinks had duplicate PATH
> > >> > records rather than just updating the existing PATH record.
> > >> > Update the symlink's PATH record with the current dentry and
> > >> > inode information.
> > >> >
> > >> > See: https://github.com/linux-audit/audit-kernel/issues/21
> > >> > Signed-off-by: Richard Guy Briggs <[email protected]>
> > >> > ---
> > >> > fs/namei.c | 1 +
> > >> > 1 file changed, 1 insertion(+)
> > >>
> > >> Why didn't you include this in patch 4/4 like I asked during the
> > >> previous review?
> > >
> > > Please see the last comment of:
> > > https://www.redhat.com/archives/linux-audit/2018-March/msg00070.html
> >
> > Yes, I just saw that ... I hadn't seen your replies on the v1
> > patches until I had finished reviewing v2. I just replied to that
> > mail in the v1 thread, but basically you need to figure out what is
> > necessary here and let us know. If I have to figure it out it
> > likely isn't going to get done with enough soak time prior to the
> > upcoming merge window.
>
> Steve? I was hoping you could chime in here.
If the CWD record will always be the same as the PARENT record, then we
do not need the parent record. Duplicate information is bad. Like all
the duplicate SYSCALL information.
-Steve
> I'd just include it for completeness unless Steve thinks it will stand
> on its own and doesn't want the overhead.
>
> > >> > diff --git a/fs/namei.c b/fs/namei.c
> > >> > index 50d2533..00f5041 100644
> > >> > --- a/fs/namei.c
> > >> > +++ b/fs/namei.c
> > >> > @@ -945,6 +945,7 @@ static inline int may_follow_link(struct
> > >> > nameidata *nd) if (nd->flags & LOOKUP_RCU)
> > >> > return -ECHILD;
> > >> >
> > >> > + audit_inode(nd->name, nd->stack[0].link.dentry, 0);
> > >> > audit_log_link_denied("follow_link",
> > >> > &nd->stack[0].link); return -EACCES;
> > >> > }
> > >>
> > >> paul moore
> > >
> > > - RGB
> >
> > paul moore
>
> - RGB
>
> --
> Richard Guy Briggs <[email protected]>
> Sr. S/W Engineer, Kernel Security, Base Operating Systems
> Remote, Ottawa, Red Hat Canada
> IRC: rgb, SunRaycer
> Voice: +1.647.777.2635, Internal: (81) 32635
>
> --
> Linux-audit mailing list
> [email protected]
> https://www.redhat.com/mailman/listinfo/linux-audit
On 2018-03-13 09:35, Steve Grubb wrote:
> On Mon, 12 Mar 2018 11:52:56 -0400
> Richard Guy Briggs <[email protected]> wrote:
>
> > On 2018-03-12 11:53, Paul Moore wrote:
> > > On Mon, Mar 12, 2018 at 11:26 AM, Richard Guy Briggs
> > > <[email protected]> wrote:
> > > > On 2018-03-12 11:12, Paul Moore wrote:
> > > >> On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs
> > > >> <[email protected]> wrote:
> > > >> > Audit link denied events for symlinks had duplicate PATH
> > > >> > records rather than just updating the existing PATH record.
> > > >> > Update the symlink's PATH record with the current dentry and
> > > >> > inode information.
> > > >> >
> > > >> > See: https://github.com/linux-audit/audit-kernel/issues/21
> > > >> > Signed-off-by: Richard Guy Briggs <[email protected]>
> > > >> > ---
> > > >> > fs/namei.c | 1 +
> > > >> > 1 file changed, 1 insertion(+)
> > > >>
> > > >> Why didn't you include this in patch 4/4 like I asked during the
> > > >> previous review?
> > > >
> > > > Please see the last comment of:
> > > > https://www.redhat.com/archives/linux-audit/2018-March/msg00070.html
> > >
> > > Yes, I just saw that ... I hadn't seen your replies on the v1
> > > patches until I had finished reviewing v2. I just replied to that
> > > mail in the v1 thread, but basically you need to figure out what is
> > > necessary here and let us know. If I have to figure it out it
> > > likely isn't going to get done with enough soak time prior to the
> > > upcoming merge window.
> >
> > Steve? I was hoping you could chime in here.
>
> If the CWD record will always be the same as the PARENT record, then we
> do not need the parent record. Duplicate information is bad. Like all
> the duplicate SYSCALL information.
The CWD record could be different from the PARENT record, since I could
have SYMLINK=/tmp/test/symlink, CWD=/tmp, PARENT=/tmp/test. Does the
parent record even matter since it might not be a directory operation
like creat, unlink or rename?
> -Steve
>
> > I'd just include it for completeness unless Steve thinks it will stand
> > on its own and doesn't want the overhead.
> >
> > > >> > diff --git a/fs/namei.c b/fs/namei.c
> > > >> > index 50d2533..00f5041 100644
> > > >> > --- a/fs/namei.c
> > > >> > +++ b/fs/namei.c
> > > >> > @@ -945,6 +945,7 @@ static inline int may_follow_link(struct
> > > >> > nameidata *nd) if (nd->flags & LOOKUP_RCU)
> > > >> > return -ECHILD;
> > > >> >
> > > >> > + audit_inode(nd->name, nd->stack[0].link.dentry, 0);
> > > >> > audit_log_link_denied("follow_link",
> > > >> > &nd->stack[0].link); return -EACCES;
> > > >> > }
> > > >>
> > > >> paul moore
> > > >
> > > > - RGB
> > >
> > > paul moore
> >
> > - RGB
- RGB
--
Richard Guy Briggs <[email protected]>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635
On Tue, 13 Mar 2018 06:11:08 -0400
Richard Guy Briggs <[email protected]> wrote:
> On 2018-03-13 09:35, Steve Grubb wrote:
> > On Mon, 12 Mar 2018 11:52:56 -0400
> > Richard Guy Briggs <[email protected]> wrote:
> >
> > > On 2018-03-12 11:53, Paul Moore wrote:
> > > > On Mon, Mar 12, 2018 at 11:26 AM, Richard Guy Briggs
> > > > <[email protected]> wrote:
> > > > > On 2018-03-12 11:12, Paul Moore wrote:
> > > > >> On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs
> > > > >> <[email protected]> wrote:
> > > > >> > Audit link denied events for symlinks had duplicate PATH
> > > > >> > records rather than just updating the existing PATH record.
> > > > >> > Update the symlink's PATH record with the current dentry
> > > > >> > and inode information.
> > > > >> >
> > > > >> > See: https://github.com/linux-audit/audit-kernel/issues/21
> > > > >> > Signed-off-by: Richard Guy Briggs <[email protected]>
> > > > >> > ---
> > > > >> > fs/namei.c | 1 +
> > > > >> > 1 file changed, 1 insertion(+)
> > > > >>
> > > > >> Why didn't you include this in patch 4/4 like I asked during
> > > > >> the previous review?
> > > > >
> > > > > Please see the last comment of:
> > > > > https://www.redhat.com/archives/linux-audit/2018-March/msg00070.html
> > > >
> > > > Yes, I just saw that ... I hadn't seen your replies on the v1
> > > > patches until I had finished reviewing v2. I just replied to
> > > > that mail in the v1 thread, but basically you need to figure
> > > > out what is necessary here and let us know. If I have to
> > > > figure it out it likely isn't going to get done with enough
> > > > soak time prior to the upcoming merge window.
> > >
> > > Steve? I was hoping you could chime in here.
> >
> > If the CWD record will always be the same as the PARENT record,
> > then we do not need the parent record. Duplicate information is
> > bad. Like all the duplicate SYSCALL information.
>
> The CWD record could be different from the PARENT record, since I
> could have SYMLINK=/tmp/test/symlink, CWD=/tmp, PARENT=/tmp/test.
> Does the parent record even matter since it might not be a directory
> operation like creat, unlink or rename?
There's 2 issues. One is creating the path if what we have is relative.
In this situation CWD should be enough. But if the question is whether
the PARENT directory should be included...what if the PARENT
permissions do not allow the successful name resolution? In that case
we might only get a PARENT record no? In that case we would need it.
-Steve
> > > I'd just include it for completeness unless Steve thinks it will
> > > stand on its own and doesn't want the overhead.
> > >
> > > > >> > diff --git a/fs/namei.c b/fs/namei.c
> > > > >> > index 50d2533..00f5041 100644
> > > > >> > --- a/fs/namei.c
> > > > >> > +++ b/fs/namei.c
> > > > >> > @@ -945,6 +945,7 @@ static inline int
> > > > >> > may_follow_link(struct nameidata *nd) if (nd->flags &
> > > > >> > LOOKUP_RCU) return -ECHILD;
> > > > >> >
> > > > >> > + audit_inode(nd->name, nd->stack[0].link.dentry, 0);
> > > > >> > audit_log_link_denied("follow_link",
> > > > >> > &nd->stack[0].link); return -EACCES;
> > > > >> > }
> > > > >>
> > > > >> paul moore
> > > > >
> > > > > - RGB
> > > >
> > > > paul moore
> > >
> > > - RGB
>
> - RGB
>
> --
> Richard Guy Briggs <[email protected]>
> Sr. S/W Engineer, Kernel Security, Base Operating Systems
> Remote, Ottawa, Red Hat Canada
> IRC: rgb, SunRaycer
> Voice: +1.647.777.2635, Internal: (81) 32635
On 2018-03-13 11:38, Steve Grubb wrote:
> On Tue, 13 Mar 2018 06:11:08 -0400
> Richard Guy Briggs <[email protected]> wrote:
>
> > On 2018-03-13 09:35, Steve Grubb wrote:
> > > On Mon, 12 Mar 2018 11:52:56 -0400
> > > Richard Guy Briggs <[email protected]> wrote:
> > >
> > > > On 2018-03-12 11:53, Paul Moore wrote:
> > > > > On Mon, Mar 12, 2018 at 11:26 AM, Richard Guy Briggs
> > > > > <[email protected]> wrote:
> > > > > > On 2018-03-12 11:12, Paul Moore wrote:
> > > > > >> On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs
> > > > > >> <[email protected]> wrote:
> > > > > >> > Audit link denied events for symlinks had duplicate PATH
> > > > > >> > records rather than just updating the existing PATH record.
> > > > > >> > Update the symlink's PATH record with the current dentry
> > > > > >> > and inode information.
> > > > > >> >
> > > > > >> > See: https://github.com/linux-audit/audit-kernel/issues/21
> > > > > >> > Signed-off-by: Richard Guy Briggs <[email protected]>
> > > > > >> > ---
> > > > > >> > fs/namei.c | 1 +
> > > > > >> > 1 file changed, 1 insertion(+)
> > > > > >>
> > > > > >> Why didn't you include this in patch 4/4 like I asked during
> > > > > >> the previous review?
> > > > > >
> > > > > > Please see the last comment of:
> > > > > > https://www.redhat.com/archives/linux-audit/2018-March/msg00070.html
> > > > >
> > > > > Yes, I just saw that ... I hadn't seen your replies on the v1
> > > > > patches until I had finished reviewing v2. I just replied to
> > > > > that mail in the v1 thread, but basically you need to figure
> > > > > out what is necessary here and let us know. If I have to
> > > > > figure it out it likely isn't going to get done with enough
> > > > > soak time prior to the upcoming merge window.
> > > >
> > > > Steve? I was hoping you could chime in here.
> > >
> > > If the CWD record will always be the same as the PARENT record,
> > > then we do not need the parent record. Duplicate information is
> > > bad. Like all the duplicate SYSCALL information.
> >
> > The CWD record could be different from the PARENT record, since I
> > could have SYMLINK=/tmp/test/symlink, CWD=/tmp, PARENT=/tmp/test.
> > Does the parent record even matter since it might not be a directory
> > operation like creat, unlink or rename?
>
> There's 2 issues. One is creating the path if what we have is relative.
> In this situation CWD should be enough. But if the question is whether
> the PARENT directory should be included...what if the PARENT
> permissions do not allow the successful name resolution? In that case
> we might only get a PARENT record no? In that case we would need it.
I think in the case of symlink creation, normal file create code path
would be in effect, and would properly log parent and symlink source
file paths (if a rule to log it was in effect) which is not something
that would trigger a symlink link denied error. Symlink link denied
happens only when trying to actually follow the link before
resolving the target path of a read/write/exec of the symlink target.
If the parent permissions of the link's target don't allow successful
name resolution then the symlink link denied condition isn't met, but
rather any other rule that applies to the target path.
> -Steve
>
> > > > I'd just include it for completeness unless Steve thinks it will
> > > > stand on its own and doesn't want the overhead.
> > > >
> > > > > >> > diff --git a/fs/namei.c b/fs/namei.c
> > > > > >> > index 50d2533..00f5041 100644
> > > > > >> > --- a/fs/namei.c
> > > > > >> > +++ b/fs/namei.c
> > > > > >> > @@ -945,6 +945,7 @@ static inline int
> > > > > >> > may_follow_link(struct nameidata *nd) if (nd->flags &
> > > > > >> > LOOKUP_RCU) return -ECHILD;
> > > > > >> >
> > > > > >> > + audit_inode(nd->name, nd->stack[0].link.dentry, 0);
> > > > > >> > audit_log_link_denied("follow_link",
> > > > > >> > &nd->stack[0].link); return -EACCES;
> > > > > >> > }
> > > > > >>
> > > > > >> paul moore
> > > > > >
> > > > > > - RGB
> > > > >
> > > > > paul moore
> > > >
> > > > - RGB
> >
> > - RGB
> >
> > --
> > Richard Guy Briggs <[email protected]>
> > Sr. S/W Engineer, Kernel Security, Base Operating Systems
> > Remote, Ottawa, Red Hat Canada
> > IRC: rgb, SunRaycer
> > Voice: +1.647.777.2635, Internal: (81) 32635
>
- RGB
--
Richard Guy Briggs <[email protected]>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635
On Tue, 13 Mar 2018 06:52:51 -0400
Richard Guy Briggs <[email protected]> wrote:
> On 2018-03-13 11:38, Steve Grubb wrote:
> > On Tue, 13 Mar 2018 06:11:08 -0400
> > Richard Guy Briggs <[email protected]> wrote:
> >
> > > On 2018-03-13 09:35, Steve Grubb wrote:
> > > > On Mon, 12 Mar 2018 11:52:56 -0400
> > > > Richard Guy Briggs <[email protected]> wrote:
> > > >
> > > > > On 2018-03-12 11:53, Paul Moore wrote:
> > > > > > On Mon, Mar 12, 2018 at 11:26 AM, Richard Guy Briggs
> > > > > > <[email protected]> wrote:
> > > > > > > On 2018-03-12 11:12, Paul Moore wrote:
> > > > > > >> On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs
> > > > > > >> <[email protected]> wrote:
> > > > > > >> > Audit link denied events for symlinks had duplicate
> > > > > > >> > PATH records rather than just updating the existing
> > > > > > >> > PATH record. Update the symlink's PATH record with the
> > > > > > >> > current dentry and inode information.
> > > > > > >> >
> > > > > > >> > See:
> > > > > > >> > https://github.com/linux-audit/audit-kernel/issues/21
> > > > > > >> > Signed-off-by: Richard Guy Briggs <[email protected]> ---
> > > > > > >> > fs/namei.c | 1 +
> > > > > > >> > 1 file changed, 1 insertion(+)
> > > > > > >>
> > > > > > >> Why didn't you include this in patch 4/4 like I asked
> > > > > > >> during the previous review?
> > > > > > >
> > > > > > > Please see the last comment of:
> > > > > > > https://www.redhat.com/archives/linux-audit/2018-March/msg00070.html
> > > > > >
> > > > > > Yes, I just saw that ... I hadn't seen your replies on the
> > > > > > v1 patches until I had finished reviewing v2. I just
> > > > > > replied to that mail in the v1 thread, but basically you
> > > > > > need to figure out what is necessary here and let us know.
> > > > > > If I have to figure it out it likely isn't going to get
> > > > > > done with enough soak time prior to the upcoming merge
> > > > > > window.
> > > > >
> > > > > Steve? I was hoping you could chime in here.
> > > >
> > > > If the CWD record will always be the same as the PARENT record,
> > > > then we do not need the parent record. Duplicate information is
> > > > bad. Like all the duplicate SYSCALL information.
> > >
> > > The CWD record could be different from the PARENT record, since I
> > > could have SYMLINK=/tmp/test/symlink, CWD=/tmp, PARENT=/tmp/test.
> > > Does the parent record even matter since it might not be a
> > > directory operation like creat, unlink or rename?
> >
> > There's 2 issues. One is creating the path if what we have is
> > relative. In this situation CWD should be enough. But if the
> > question is whether the PARENT directory should be included...what
> > if the PARENT permissions do not allow the successful name
> > resolution? In that case we might only get a PARENT record no? In
> > that case we would need it.
>
> I think in the case of symlink creation, normal file create code path
> would be in effect, and would properly log parent and symlink source
> file paths (if a rule to log it was in effect) which is not something
> that would trigger a symlink link denied error. Symlink link denied
> happens only when trying to actually follow the link before
> resolving the target path of a read/write/exec of the symlink target.
>
> If the parent permissions of the link's target don't allow successful
> name resolution then the symlink link denied condition isn't met, but
> rather any other rule that applies to the target path.
Then I guess the PARENT record is not needed.
-Steve
> > > > > I'd just include it for completeness unless Steve thinks it
> > > > > will stand on its own and doesn't want the overhead.
> > > > >
> > > > > > >> > diff --git a/fs/namei.c b/fs/namei.c
> > > > > > >> > index 50d2533..00f5041 100644
> > > > > > >> > --- a/fs/namei.c
> > > > > > >> > +++ b/fs/namei.c
> > > > > > >> > @@ -945,6 +945,7 @@ static inline int
> > > > > > >> > may_follow_link(struct nameidata *nd) if (nd->flags &
> > > > > > >> > LOOKUP_RCU) return -ECHILD;
> > > > > > >> >
> > > > > > >> > + audit_inode(nd->name,
> > > > > > >> > nd->stack[0].link.dentry, 0);
> > > > > > >> > audit_log_link_denied("follow_link",
> > > > > > >> > &nd->stack[0].link); return -EACCES; }
> > > > > > >>
> > > > > > >> paul moore
> > > > > > >
> > > > > > > - RGB
> > > > > >
> > > > > > paul moore
> > > > >
> > > > > - RGB
> > >
> > > - RGB
> > >
> > > --
> > > Richard Guy Briggs <[email protected]>
> > > Sr. S/W Engineer, Kernel Security, Base Operating Systems
> > > Remote, Ottawa, Red Hat Canada
> > > IRC: rgb, SunRaycer
> > > Voice: +1.647.777.2635, Internal: (81) 32635
> >
>
> - RGB
>
> --
> Richard Guy Briggs <[email protected]>
> Sr. S/W Engineer, Kernel Security, Base Operating Systems
> Remote, Ottawa, Red Hat Canada
> IRC: rgb, SunRaycer
> Voice: +1.647.777.2635, Internal: (81) 32635
On Tue, Mar 13, 2018 at 6:52 AM, Richard Guy Briggs <[email protected]> wrote:
> On 2018-03-13 11:38, Steve Grubb wrote:
>> On Tue, 13 Mar 2018 06:11:08 -0400
>> Richard Guy Briggs <[email protected]> wrote:
>>
>> > On 2018-03-13 09:35, Steve Grubb wrote:
>> > > On Mon, 12 Mar 2018 11:52:56 -0400
>> > > Richard Guy Briggs <[email protected]> wrote:
>> > >
>> > > > On 2018-03-12 11:53, Paul Moore wrote:
>> > > > > On Mon, Mar 12, 2018 at 11:26 AM, Richard Guy Briggs
>> > > > > <[email protected]> wrote:
>> > > > > > On 2018-03-12 11:12, Paul Moore wrote:
>> > > > > >> On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs
>> > > > > >> <[email protected]> wrote:
>> > > > > >> > Audit link denied events for symlinks had duplicate PATH
>> > > > > >> > records rather than just updating the existing PATH record.
>> > > > > >> > Update the symlink's PATH record with the current dentry
>> > > > > >> > and inode information.
>> > > > > >> >
>> > > > > >> > See: https://github.com/linux-audit/audit-kernel/issues/21
>> > > > > >> > Signed-off-by: Richard Guy Briggs <[email protected]>
>> > > > > >> > ---
>> > > > > >> > fs/namei.c | 1 +
>> > > > > >> > 1 file changed, 1 insertion(+)
>> > > > > >>
>> > > > > >> Why didn't you include this in patch 4/4 like I asked during
>> > > > > >> the previous review?
>> > > > > >
>> > > > > > Please see the last comment of:
>> > > > > > https://www.redhat.com/archives/linux-audit/2018-March/msg00070.html
>> > > > >
>> > > > > Yes, I just saw that ... I hadn't seen your replies on the v1
>> > > > > patches until I had finished reviewing v2. I just replied to
>> > > > > that mail in the v1 thread, but basically you need to figure
>> > > > > out what is necessary here and let us know. If I have to
>> > > > > figure it out it likely isn't going to get done with enough
>> > > > > soak time prior to the upcoming merge window.
>> > > >
>> > > > Steve? I was hoping you could chime in here.
>> > >
>> > > If the CWD record will always be the same as the PARENT record,
>> > > then we do not need the parent record. Duplicate information is
>> > > bad. Like all the duplicate SYSCALL information.
>> >
>> > The CWD record could be different from the PARENT record, since I
>> > could have SYMLINK=/tmp/test/symlink, CWD=/tmp, PARENT=/tmp/test.
>> > Does the parent record even matter since it might not be a directory
>> > operation like creat, unlink or rename?
>>
>> There's 2 issues. One is creating the path if what we have is relative.
>> In this situation CWD should be enough. But if the question is whether
>> the PARENT directory should be included...what if the PARENT
>> permissions do not allow the successful name resolution? In that case
>> we might only get a PARENT record no? In that case we would need it.
>
> I think in the case of symlink creation, normal file create code path
> would be in effect, and would properly log parent and symlink source
> file paths (if a rule to log it was in effect) which is not something
> that would trigger a symlink link denied error. Symlink link denied
> happens only when trying to actually follow the link before
> resolving the target path of a read/write/exec of the symlink target.
>
> If the parent permissions of the link's target don't allow successful
> name resolution then the symlink link denied condition isn't met, but
> rather any other rule that applies to the target path.
I'm guessing you are in the process of tracking all this down, but if
not, lets get to a point where we can answer this definitively and not
guess :)
--
paul moore
http://www.paul-moore.com
On 2018-03-13 16:24, Paul Moore wrote:
> On Tue, Mar 13, 2018 at 6:52 AM, Richard Guy Briggs <[email protected]> wrote:
> > On 2018-03-13 11:38, Steve Grubb wrote:
> >> On Tue, 13 Mar 2018 06:11:08 -0400
> >> Richard Guy Briggs <[email protected]> wrote:
> >>
> >> > On 2018-03-13 09:35, Steve Grubb wrote:
> >> > > On Mon, 12 Mar 2018 11:52:56 -0400
> >> > > Richard Guy Briggs <[email protected]> wrote:
> >> > >
> >> > > > On 2018-03-12 11:53, Paul Moore wrote:
> >> > > > > On Mon, Mar 12, 2018 at 11:26 AM, Richard Guy Briggs
> >> > > > > <[email protected]> wrote:
> >> > > > > > On 2018-03-12 11:12, Paul Moore wrote:
> >> > > > > >> On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs
> >> > > > > >> <[email protected]> wrote:
> >> > > > > >> > Audit link denied events for symlinks had duplicate PATH
> >> > > > > >> > records rather than just updating the existing PATH record.
> >> > > > > >> > Update the symlink's PATH record with the current dentry
> >> > > > > >> > and inode information.
> >> > > > > >> >
> >> > > > > >> > See: https://github.com/linux-audit/audit-kernel/issues/21
> >> > > > > >> > Signed-off-by: Richard Guy Briggs <[email protected]>
> >> > > > > >> > ---
> >> > > > > >> > fs/namei.c | 1 +
> >> > > > > >> > 1 file changed, 1 insertion(+)
> >> > > > > >>
> >> > > > > >> Why didn't you include this in patch 4/4 like I asked during
> >> > > > > >> the previous review?
> >> > > > > >
> >> > > > > > Please see the last comment of:
> >> > > > > > https://www.redhat.com/archives/linux-audit/2018-March/msg00070.html
> >> > > > >
> >> > > > > Yes, I just saw that ... I hadn't seen your replies on the v1
> >> > > > > patches until I had finished reviewing v2. I just replied to
> >> > > > > that mail in the v1 thread, but basically you need to figure
> >> > > > > out what is necessary here and let us know. If I have to
> >> > > > > figure it out it likely isn't going to get done with enough
> >> > > > > soak time prior to the upcoming merge window.
> >> > > >
> >> > > > Steve? I was hoping you could chime in here.
> >> > >
> >> > > If the CWD record will always be the same as the PARENT record,
> >> > > then we do not need the parent record. Duplicate information is
> >> > > bad. Like all the duplicate SYSCALL information.
> >> >
> >> > The CWD record could be different from the PARENT record, since I
> >> > could have SYMLINK=/tmp/test/symlink, CWD=/tmp, PARENT=/tmp/test.
> >> > Does the parent record even matter since it might not be a directory
> >> > operation like creat, unlink or rename?
> >>
> >> There's 2 issues. One is creating the path if what we have is relative.
> >> In this situation CWD should be enough. But if the question is whether
> >> the PARENT directory should be included...what if the PARENT
> >> permissions do not allow the successful name resolution? In that case
> >> we might only get a PARENT record no? In that case we would need it.
> >
> > I think in the case of symlink creation, normal file create code path
> > would be in effect, and would properly log parent and symlink source
> > file paths (if a rule to log it was in effect) which is not something
> > that would trigger a symlink link denied error. Symlink link denied
> > happens only when trying to actually follow the link before
> > resolving the target path of a read/write/exec of the symlink target.
> >
> > If the parent permissions of the link's target don't allow successful
> > name resolution then the symlink link denied condition isn't met, but
> > rather any other rule that applies to the target path.
>
> I'm guessing you are in the process of tracking all this down, but if
> not, lets get to a point where we can answer this definitively and not
> guess :)
I was fairly certain but being polite, expecting confirmation or
possibly correction if I've overlooked something.
Additionally, this denial message only happens in certain parts of the
permission check for symlinks:
/proc/sys/fs/protected_symlinks == 1
and follower and link owner don't match
and parent sticky and world-writable
and link parent and link owner don't match
If you want other symlink denials logged, you need to set a rule for the
target filtering on operation failure such as unix file permissions.
The similar situation exists for hardlinks.
> paul moore
- RGB
--
Richard Guy Briggs <[email protected]>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635