Hoist out the nth filter resolving logic that ptrace uses into a new
function. We'll use this in the next patch to implement the new
PTRACE_SECCOMP_GET_FILTER_FLAGS command.
v3: * significantly revamp get_nth_filter logic (Oleg)
* rebase on 4.14-rc4, using the new __{get,put}_seccomp_filter
primitives
Signed-off-by: Tycho Andersen <[email protected]>
CC: Kees Cook <[email protected]>
CC: Andy Lutomirski <[email protected]>
CC: Oleg Nesterov <[email protected]>
---
kernel/seccomp.c | 77 +++++++++++++++++++++++++++++++++-----------------------
1 file changed, 45 insertions(+), 32 deletions(-)
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index bb3a38005b9c..2e1568261ac4 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -977,49 +977,68 @@ long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter)
}
#if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
-long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
- void __user *data)
+static struct seccomp_filter *get_nth_filter(struct task_struct *task,
+ unsigned long filter_off)
{
- struct seccomp_filter *filter;
- struct sock_fprog_kern *fprog;
- long ret;
- unsigned long count = 0;
-
- if (!capable(CAP_SYS_ADMIN) ||
- current->seccomp.mode != SECCOMP_MODE_DISABLED) {
- return -EACCES;
- }
+ struct seccomp_filter *orig, *filter;
+ unsigned long count;
+ /*
+ * Note: this is only correct because the caller should be the (ptrace)
+ * tracer of the task, otherwise lock_task_sighand is needed.
+ */
spin_lock_irq(&task->sighand->siglock);
+
if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
- ret = -EINVAL;
- goto out;
+ spin_unlock_irq(&task->sighand->siglock);
+ return ERR_PTR(-EINVAL);
}
- filter = task->seccomp.filter;
- while (filter) {
- filter = filter->prev;
+ orig = task->seccomp.filter;
+ __get_seccomp_filter(orig);
+ spin_unlock_irq(&task->sighand->siglock);
+
+ count = 0;
+ for (filter = orig; filter; filter = filter->prev)
count++;
- }
if (filter_off >= count) {
- ret = -ENOENT;
+ filter = ERR_PTR(-ENOENT);
goto out;
}
- count -= filter_off;
- filter = task->seccomp.filter;
- while (filter && count > 1) {
- filter = filter->prev;
+ count -= filter_off;
+ for (filter = orig; filter && count > 1; filter = filter->prev)
count--;
- }
if (WARN_ON(count != 1 || !filter)) {
- /* The filter tree shouldn't shrink while we're using it. */
- ret = -ENOENT;
+ filter = ERR_PTR(-ENOENT);
goto out;
}
+ __get_seccomp_filter(filter);
+
+out:
+ __put_seccomp_filter(orig);
+ return filter;
+}
+
+long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
+ void __user *data)
+{
+ struct seccomp_filter *filter;
+ struct sock_fprog_kern *fprog;
+ long ret;
+
+ if (!capable(CAP_SYS_ADMIN) ||
+ current->seccomp.mode != SECCOMP_MODE_DISABLED) {
+ return -EACCES;
+ }
+
+ filter = get_nth_filter(task, filter_off);
+ if (IS_ERR(filter))
+ return PTR_ERR(filter);
+
fprog = filter->prog->orig_prog;
if (!fprog) {
/* This must be a new non-cBPF filter, since we save
@@ -1034,17 +1053,11 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
if (!data)
goto out;
- __get_seccomp_filter(filter);
- spin_unlock_irq(&task->sighand->siglock);
-
if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
ret = -EFAULT;
- __put_seccomp_filter(filter);
- return ret;
-
out:
- spin_unlock_irq(&task->sighand->siglock);
+ __put_seccomp_filter(filter);
return ret;
}
#endif
--
2.11.0
From 1585267907961879709@xxx Tue Nov 28 00:34:48 +0000 2017
X-GM-THRID: 1584805791154205642
X-Gmail-Labels: Inbox,Category Forums,HistoricalUnread
With the new SECCOMP_FILTER_FLAG_LOG, we need to be able to extract these
flags for checkpoint restore, since they describe the state of a filter.
So, let's add PTRACE_SECCOMP_GET_METADATA, similar to ..._GET_FILTER, which
returns the metadata of the nth filter (right now, just the flags).
Hopefully this will be future proof, and new per-filter metadata can be
added to this struct.
v3: * use GET_METADATA instead of GET_FLAGS
Signed-off-by: Tycho Andersen <[email protected]>
CC: Kees Cook <[email protected]>
CC: Andy Lutomirski <[email protected]>
CC: Oleg Nesterov <[email protected]>
---
include/linux/seccomp.h | 8 ++++++++
include/uapi/linux/ptrace.h | 6 ++++++
kernel/ptrace.c | 4 ++++
kernel/seccomp.c | 34 ++++++++++++++++++++++++++++++++++
4 files changed, 52 insertions(+)
diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
index c8bef436b61d..a6dee99cd187 100644
--- a/include/linux/seccomp.h
+++ b/include/linux/seccomp.h
@@ -94,11 +94,19 @@ static inline void get_seccomp_filter(struct task_struct *tsk)
#if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
extern long seccomp_get_filter(struct task_struct *task,
unsigned long filter_off, void __user *data);
+extern long seccomp_get_metadata(struct task_struct *task,
+ unsigned long filter_off, void __user *data);
#else
static inline long seccomp_get_filter(struct task_struct *task,
unsigned long n, void __user *data)
{
return -EINVAL;
}
+static inline long seccomp_get_metadata(struct task_struct *task,
+ unsigned long filter_off,
+ void __user *data)
+{
+ return -EINVAL;
+}
#endif /* CONFIG_SECCOMP_FILTER && CONFIG_CHECKPOINT_RESTORE */
#endif /* _LINUX_SECCOMP_H */
diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h
index fb8106509000..4e9774812dba 100644
--- a/include/uapi/linux/ptrace.h
+++ b/include/uapi/linux/ptrace.h
@@ -65,6 +65,12 @@ struct ptrace_peeksiginfo_args {
#define PTRACE_SETSIGMASK 0x420b
#define PTRACE_SECCOMP_GET_FILTER 0x420c
+#define PTRACE_SECCOMP_GET_METADATA 0x420d
+
+struct seccomp_metadata {
+ unsigned long filter_off; /* Input: which filter */
+ unsigned int flags; /* Output: filter's flags */
+};
/* Read signals from a shared (process wide) queue */
#define PTRACE_PEEKSIGINFO_SHARED (1 << 0)
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 84b1367935e4..58291e9f3276 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -1092,6 +1092,10 @@ int ptrace_request(struct task_struct *child, long request,
ret = seccomp_get_filter(child, addr, datavp);
break;
+ case PTRACE_SECCOMP_GET_METADATA:
+ ret = seccomp_get_metadata(child, addr, datavp);
+ break;
+
default:
break;
}
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 2e1568261ac4..ea762af4974d 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -1060,6 +1060,40 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
__put_seccomp_filter(filter);
return ret;
}
+
+long seccomp_get_metadata(struct task_struct *task,
+ unsigned long size, void __user *data)
+{
+ long ret;
+ struct seccomp_filter *filter;
+ struct seccomp_metadata kmd = {};
+
+ if (!capable(CAP_SYS_ADMIN) ||
+ current->seccomp.mode != SECCOMP_MODE_DISABLED) {
+ return -EACCES;
+ }
+
+ size = min_t(unsigned long, size, sizeof(kmd));
+
+ if (copy_from_user(&kmd, data, size))
+ return -EFAULT;
+
+ filter = get_nth_filter(task, kmd.filter_off);
+ if (IS_ERR(filter))
+ return PTR_ERR(filter);
+
+ memset(&kmd, 0, sizeof(kmd));
+ if (filter->log)
+ kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
+
+ ret = size;
+ if (copy_to_user(data, &kmd, size))
+ ret = -EFAULT;
+
+ __put_seccomp_filter(filter);
+ return ret;
+
+}
#endif
#ifdef CONFIG_SYSCTL
--
2.11.0
From 1585313027922139764@xxx Tue Nov 28 12:31:58 +0000 2017
X-GM-THRID: 1585306359796561251
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