4:11 p.m.
Hello,
The fanotify interface allows user space daemons to make access
control decisions. Under common criteria requirements, we need to
optionally record decisions based on policy. This patch adds a bit mask,
FAN_AUDIT, that a user space daemon can 'or' into the response decision
which will tell the kernel that it made a decision and record it.
It would be used something like this in user space code:
response.response = FAN_DENY | FAN_AUDIT;
write(fd, &response, sizeof(struct fanotify_response));
When the syscall ends, the audit system will record the decision as a
AUDIT_FANOTIFY auxiliary record to denote that the reason this event
occurred is the result of an access control decision from fanotify
rather than DAC or MAC policy.
A sample event looks like this:
type=PATH msg=audit(1504310584.332:290): item=0 name="./evil-ls"
inode=1319561 dev=fc:03 mode=0100755 ouid=1000 ogid=1000 rdev=00:00
obj=unconfined_u:object_r:user_home_t:s0 nametype=NORMAL
type=CWD msg=audit(1504310584.332:290): cwd="/home/sgrubb"
type=SYSCALL msg=audit(1504310584.332:290): arch=c000003e syscall=2
success=no exit=-1 a0=32cb3fca90 a1=0 a2=43 a3=8 items=1 ppid=901
pid=959 auid=1000 uid=1000 gid=1000 euid=1000 suid=1000
fsuid=1000 egid=1000 sgid=1000 fsgid=1000 tty=pts1 ses=3 comm="bash"
exe="/usr/bin/bash" subj=unconfined_u:unconfined_r:unconfined_t:
s0-s0:c0.c1023 key=(null)
type=FANOTIFY msg=audit(1504310584.332:290): resp=2
Prior to using the audit flag, the developer needs to call
fanotify_init or'ing in FAN_ENABLE_AUDIT to ensure that the kernel
supports auditing. The calling process must also have the CAP_AUDIT_WRITE
capability.
* This v6 update adds empty inline audit_fanotify function for when
CONFIG_AUDITSYSCALL is not defined.
Signed-off-by: sgrubb <sgrubb(a)redhat.com>
Reviewed-by: Amir Goldstein <amir73il(a)gmail.com>
---
fs/notify/fanotify/fanotify.c | 8 +++++++-
fs/notify/fanotify/fanotify_user.c | 16 +++++++++++++++-
fs/notify/fdinfo.c | 3 +++
include/linux/audit.h | 10 ++++++++++
include/linux/fsnotify_backend.h | 1 +
include/uapi/linux/audit.h | 1 +
include/uapi/linux/fanotify.h | 3 +++
kernel/auditsc.c | 6 ++++++
8 files changed, 46 insertions(+), 2 deletions(-)
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 2fa99ae..1968d21 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -9,6 +9,7 @@
#include <linux/sched/user.h>
#include <linux/types.h>
#include <linux/wait.h>
+#include <linux/audit.h>
#include "fanotify.h"
@@ -78,7 +79,7 @@ static int fanotify_get_response(struct fsnotify_group *group,
fsnotify_finish_user_wait(iter_info);
out:
/* userspace responded, convert to something usable */
- switch (event->response) {
+ switch (event->response & ~FAN_AUDIT) {
case FAN_ALLOW:
ret = 0;
break;
@@ -86,6 +87,11 @@ static int fanotify_get_response(struct fsnotify_group *group,
default:
ret = -EPERM;
}
+
+ /* Check if the response should be audited */
+ if (event->response & FAN_AUDIT)
+ audit_fanotify(event->response & ~FAN_AUDIT);
+
event->response = 0;
pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 907a481..ea3c458 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -179,7 +179,7 @@ static int process_access_response(struct fsnotify_group *group,
* userspace can send a valid response or we will clean it up after the
* timeout
*/
- switch (response) {
+ switch (response & ~FAN_AUDIT) {
case FAN_ALLOW:
case FAN_DENY:
break;
@@ -190,6 +190,9 @@ static int process_access_response(struct fsnotify_group *group,
if (fd < 0)
return -EINVAL;
+ if ((response & FAN_AUDIT) && !group->fanotify_data.audit_enabled)
+ return -EINVAL;
+
event = dequeue_event(group, fd);
if (!event)
return -ENOENT;
@@ -721,7 +724,11 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int,
event_f_flags)
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
+#ifdef CONFIG_AUDITSYSCALL
+ if (flags & ~(FAN_ALL_INIT_FLAGS | FAN_ENABLE_AUDIT))
+#else
if (flags & ~FAN_ALL_INIT_FLAGS)
+#endif
return -EINVAL;
if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS)
@@ -805,6 +812,13 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int,
event_f_flags)
group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS;
}
+ if (flags & FAN_ENABLE_AUDIT) {
+ fd = -EPERM;
+ if (!capable(CAP_AUDIT_WRITE))
+ goto out_destroy_group;
+ group->fanotify_data.audit_enabled = true;
+ }
+
fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
if (fd < 0)
goto out_destroy_group;
diff --git a/fs/notify/fdinfo.c b/fs/notify/fdinfo.c
index dd63aa9..ed311e3 100644
--- a/fs/notify/fdinfo.c
+++ b/fs/notify/fdinfo.c
@@ -156,6 +156,9 @@ void fanotify_show_fdinfo(struct seq_file *m, struct file *f)
if (group->fanotify_data.max_marks == UINT_MAX)
flags |= FAN_UNLIMITED_MARKS;
+ if (group->fanotify_data.audit_enabled)
+ flags |= FAN_ENABLE_AUDIT;
+
seq_printf(m, "fanotify flags:%x event-flags:%x\n",
flags, group->fanotify_data.f_flags);
diff --git a/include/linux/audit.h b/include/linux/audit.h
index 2150bdc..9095617 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -360,6 +360,7 @@ extern int __audit_log_bprm_fcaps(struct linux_binprm *bprm,
extern void __audit_log_capset(const struct cred *new, const struct cred *old);
extern void __audit_mmap_fd(int fd, int flags);
extern void __audit_log_kern_module(char *name);
+extern void __audit_fanotify(unsigned int response);
static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp)
{
@@ -456,6 +457,12 @@ static inline void audit_log_kern_module(char *name)
__audit_log_kern_module(name);
}
+static inline void audit_fanotify(unsigned int response)
+{
+ if (!audit_dummy_context())
+ __audit_fanotify(response);
+}
+
extern int audit_n_rules;
extern int audit_signals;
#else /* CONFIG_AUDITSYSCALL */
@@ -572,6 +579,9 @@ static inline void audit_log_kern_module(char *name)
{
}
+static inline void audit_fanotify(unsigned int response)
+{ }
+
static inline void audit_ptrace(struct task_struct *t)
{ }
#define audit_n_rules 0
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index c6c6931..f4131f2 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -190,6 +190,7 @@ struct fsnotify_group {
int f_flags;
unsigned int max_marks;
struct user_struct *user;
+ bool audit_enabled;
} fanotify_data;
#endif /* CONFIG_FANOTIFY */
};
diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index 0714a66..221f8b7 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -112,6 +112,7 @@
#define AUDIT_FEATURE_CHANGE 1328 /* audit log listing feature changes */
#define AUDIT_REPLACE 1329 /* Replace auditd if this packet unanswerd */
#define AUDIT_KERN_MODULE 1330 /* Kernel Module events */
+#define AUDIT_FANOTIFY 1331 /* Fanotify access decision */
#define AUDIT_AVC 1400 /* SE Linux avc denial or grant */
#define AUDIT_SELINUX_ERR 1401 /* Internal SE Linux Errors */
diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h
index 030508d..5dda19a 100644
--- a/include/uapi/linux/fanotify.h
+++ b/include/uapi/linux/fanotify.h
@@ -35,6 +35,7 @@
#define FAN_UNLIMITED_QUEUE 0x00000010
#define FAN_UNLIMITED_MARKS 0x00000020
+#define FAN_ENABLE_AUDIT 0x00000040
#define FAN_ALL_INIT_FLAGS (FAN_CLOEXEC | FAN_NONBLOCK | \
FAN_ALL_CLASS_BITS | FAN_UNLIMITED_QUEUE |\
@@ -99,6 +100,8 @@ struct fanotify_response {
/* Legit userspace responses to a _PERM event */
#define FAN_ALLOW 0x01
#define FAN_DENY 0x02
+#define FAN_AUDIT 0x10 /* Bit mask to create audit record for result */
+
/* No fd set in event */
#define FAN_NOFD -1
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 3260ba2..e046de8 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2390,6 +2390,12 @@ void __audit_log_kern_module(char *name)
context->type = AUDIT_KERN_MODULE;
}
+void __audit_fanotify(unsigned int response)
+{
+ audit_log(current->audit_context, GFP_KERNEL,
+ AUDIT_FANOTIFY, "resp=%u", response);
+}
+
static void audit_log_task(struct audit_buffer *ab)
{
kuid_t auid, uid;
--
2.9.5
2:35 p.m.
Hi Steve,
[auto build test ERROR on linus/master]
[also build test ERROR on v4.14-rc2 next-20170929]
[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/Steve-Grubb/audit-Record-fanotif...
config: i386-randconfig-x0-09300058 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All error/warnings (new ones prefixed by >>):
In file included from fs/exec.c:56:0:
> include/linux/audit.h:215:23: error: expected identifier or
'(' before numeric constant
#define audit_enabled 0
^
> include/linux/fsnotify_backend.h:193:9: note: in expansion of
macro 'audit_enabled'
bool audit_enabled;
^~~~~~~~~~~~~
In file included from include/linux/fsnotify.h:14:0,
from fs/exec.c:59:
> include/linux/fsnotify_backend.h:194:3: warning: no semicolon at
end of struct or union
} fanotify_data;
^
vim +215 include/linux/audit.h
96368701 Paul Moore 2016-01-13 168
96368701 Paul Moore 2016-01-13 169 extern u32 audit_enabled;
96368701 Paul Moore 2016-01-13 170 #else /* CONFIG_AUDIT */
96368701 Paul Moore 2016-01-13 171 static inline __printf(4, 5)
96368701 Paul Moore 2016-01-13 172 void audit_log(struct audit_context *ctx, gfp_t
gfp_mask, int type,
96368701 Paul Moore 2016-01-13 173 const char *fmt, ...)
96368701 Paul Moore 2016-01-13 174 { }
96368701 Paul Moore 2016-01-13 175 static inline struct audit_buffer
*audit_log_start(struct audit_context *ctx,
96368701 Paul Moore 2016-01-13 176 gfp_t gfp_mask, int type)
96368701 Paul Moore 2016-01-13 177 {
96368701 Paul Moore 2016-01-13 178 return NULL;
96368701 Paul Moore 2016-01-13 179 }
96368701 Paul Moore 2016-01-13 180 static inline __printf(2, 3)
96368701 Paul Moore 2016-01-13 181 void audit_log_format(struct audit_buffer *ab, const
char *fmt, ...)
96368701 Paul Moore 2016-01-13 182 { }
96368701 Paul Moore 2016-01-13 183 static inline void audit_log_end(struct audit_buffer
*ab)
96368701 Paul Moore 2016-01-13 184 { }
96368701 Paul Moore 2016-01-13 185 static inline void audit_log_n_hex(struct
audit_buffer *ab,
96368701 Paul Moore 2016-01-13 186 const unsigned char *buf, size_t len)
96368701 Paul Moore 2016-01-13 187 { }
96368701 Paul Moore 2016-01-13 188 static inline void audit_log_n_string(struct
audit_buffer *ab,
96368701 Paul Moore 2016-01-13 189 const char *buf, size_t n)
96368701 Paul Moore 2016-01-13 190 { }
96368701 Paul Moore 2016-01-13 191 static inline void
audit_log_n_untrustedstring(struct audit_buffer *ab,
96368701 Paul Moore 2016-01-13 192 const char *string, size_t n)
96368701 Paul Moore 2016-01-13 193 { }
96368701 Paul Moore 2016-01-13 194 static inline void audit_log_untrustedstring(struct
audit_buffer *ab,
96368701 Paul Moore 2016-01-13 195 const char *string)
96368701 Paul Moore 2016-01-13 196 { }
96368701 Paul Moore 2016-01-13 197 static inline void audit_log_d_path(struct
audit_buffer *ab,
96368701 Paul Moore 2016-01-13 198 const char *prefix,
96368701 Paul Moore 2016-01-13 199 const struct path *path)
96368701 Paul Moore 2016-01-13 200 { }
96368701 Paul Moore 2016-01-13 201 static inline void audit_log_key(struct audit_buffer
*ab, char *key)
96368701 Paul Moore 2016-01-13 202 { }
96368701 Paul Moore 2016-01-13 203 static inline void audit_log_link_denied(const char
*string,
96368701 Paul Moore 2016-01-13 204 const struct path *link)
96368701 Paul Moore 2016-01-13 205 { }
96368701 Paul Moore 2016-01-13 206 static inline void audit_log_secctx(struct
audit_buffer *ab, u32 secid)
96368701 Paul Moore 2016-01-13 207 { }
96368701 Paul Moore 2016-01-13 208 static inline int audit_log_task_context(struct
audit_buffer *ab)
96368701 Paul Moore 2016-01-13 209 {
96368701 Paul Moore 2016-01-13 210 return 0;
96368701 Paul Moore 2016-01-13 211 }
96368701 Paul Moore 2016-01-13 212 static inline void audit_log_task_info(struct
audit_buffer *ab,
96368701 Paul Moore 2016-01-13 213 struct task_struct *tsk)
96368701 Paul Moore 2016-01-13 214 { }
96368701 Paul Moore 2016-01-13 @215 #define audit_enabled 0
96368701 Paul Moore 2016-01-13 216 #endif /* CONFIG_AUDIT */
96368701 Paul Moore 2016-01-13 217
:::::: The code at line 215 was first introduced by commit
:::::: 96368701e1c89057bbf39222e965161c68a85b4b audit: force seccomp event logging to
honor the audit_enabled flag
:::::: TO: Paul Moore <pmoore(a)redhat.com>
:::::: CC: Paul Moore <paul(a)paul-moore.com>
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
7:09 p.m.
Hi Steve,
[auto build test ERROR on linus/master]
[also build test ERROR on v4.14-rc2 next-20170929]
[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/Steve-Grubb/audit-Record-fanotif...
config: x86_64-randconfig-b0-09300453 (attached as .config)
compiler: gcc-4.4 (Debian 4.4.7-8) 4.4.7
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64
All errors (new ones prefixed by >>):
In file included from include/linux/fsnotify.h:14,
from fs/exec.c:59:
> include/linux/fsnotify_backend.h:193: error: expected identifier
or '(' before numeric constant
include/linux/fsnotify_backend.h:194:
warning: no semicolon at end of struct or union
vim +193 include/linux/fsnotify_backend.h
122
123 /*
124 * A group is a "thing" that wants to receive notification about
filesystem
125 * events. The mask holds the subset of event types this group cares about.
126 * refcnt on a group is up to the implementor and at any moment if it goes 0
127 * everything will be cleaned up.
128 */
129 struct fsnotify_group {
130 /*
131 * How the refcnt is used is up to each group. When the refcnt hits 0
132 * fsnotify will clean up all of the resources associated with this group.
133 * As an example, the dnotify group will always have a refcnt=1 and that
134 * will never change. Inotify, on the other hand, has a group per
135 * inotify_init() and the refcnt will hit 0 only when that fd has been
136 * closed.
137 */
138 atomic_t refcnt; /* things with interest in this group */
139
140 const struct fsnotify_ops *ops; /* how this group handles things */
141
142 /* needed to send notification to userspace */
143 spinlock_t notification_lock; /* protect the notification_list */
144 struct list_head notification_list; /* list of event_holder this group needs to
send to userspace */
145 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on
this waitq */
146 unsigned int q_len; /* events on the queue */
147 unsigned int max_events; /* maximum events allowed on the list */
148 /*
149 * Valid fsnotify group priorities. Events are send in order from highest
150 * priority to lowest priority. We default to the lowest priority.
151 */
152 #define FS_PRIO_0 0 /* normal notifiers, no permissions */
153 #define FS_PRIO_1 1 /* fanotify content based access control */
154 #define FS_PRIO_2 2 /* fanotify pre-content access */
155 unsigned int priority;
156 bool shutdown; /* group is being shut down, don't queue more events */
157
158 /* stores all fastpath marks assoc with this group so they can be cleaned on
unregister */
159 struct mutex mark_mutex; /* protect marks_list */
160 atomic_t num_marks; /* 1 for each mark and 1 for not being
161 * past the point of no return when freeing
162 * a group */
163 struct list_head marks_list; /* all inode marks for this group */
164
165 struct fasync_struct *fsn_fa; /* async notification */
166
167 struct fsnotify_event *overflow_event; /* Event we queue when the
168 * notification list is too
169 * full */
170 atomic_t user_waits; /* Number of tasks waiting for user
171 * response */
172
173 /* groups can define private fields here or use the void *private */
174 union {
175 void *private;
176 #ifdef CONFIG_INOTIFY_USER
177 struct inotify_group_private_data {
178 spinlock_t idr_lock;
179 struct idr idr;
180 struct ucounts *ucounts;
181 } inotify_data;
182 #endif
183 #ifdef CONFIG_FANOTIFY
184 struct fanotify_group_private_data {
185 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
186 /* allows a group to block waiting for a userspace response */
187 struct list_head access_list;
188 wait_queue_head_t access_waitq;
189 #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
190 int f_flags;
191 unsigned int max_marks;
192 struct user_struct *user;
193 bool audit_enabled;
194 } fanotify_data;
195 #endif /* CONFIG_FANOTIFY */
196 };
197 };
198
---
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2 comments
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participants (2)
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kbuild test robot -
Steve Grubb