From: Jeff Xu <[email protected]>
The new MFD_NOEXEC_SEAL and MFD_EXEC flags allows application to
set executable bit at creation time (memfd_create).
When MFD_NOEXEC_SEAL is set, memfd is created without executable bit
(mode:0666), and sealed with F_SEAL_EXEC, so it can't be chmod to
be executable (mode: 0777) after creation.
when MFD_EXEC flag is set, memfd is created with executable bit
(mode:0777), this is the same as the old behavior of memfd_create.
The new pid namespaced sysctl vm.memfd_noexec has 3 values:
0: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL acts like
MFD_EXEC was set.
1: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL acts like
MFD_NOEXEC_SEAL was set.
2: memfd_create() without MFD_NOEXEC_SEAL will be rejected.
The sysctl allows finer control of memfd_create for old-software
that doesn't set the executable bit, for example, a container with
vm.memfd_noexec=1 means the old-software will create non-executable
memfd by default. Also, the value of memfd_noexec is passed to child
namespace at creation time. For example, if the init namespace has
vm.memfd_noexec=2, all its children namespaces will be created with 2.
Signed-off-by: Jeff Xu <[email protected]>
Co-developed-by: Daniel Verkamp <[email protected]>
Signed-off-by: Daniel Verkamp <[email protected]>
Reported-by: kernel test robot <[email protected]>
---
include/linux/pid_namespace.h | 19 +++++++++++
include/uapi/linux/memfd.h | 4 +++
kernel/pid_namespace.c | 5 +++
kernel/pid_sysctl.h | 59 +++++++++++++++++++++++++++++++++++
mm/memfd.c | 48 ++++++++++++++++++++++++++--
5 files changed, 133 insertions(+), 2 deletions(-)
create mode 100644 kernel/pid_sysctl.h
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 07481bb87d4e..a4789a7b34a9 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -16,6 +16,21 @@
struct fs_pin;
+#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
+/*
+ * sysctl for vm.memfd_noexec
+ * 0: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL
+ * acts like MFD_EXEC was set.
+ * 1: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL
+ * acts like MFD_NOEXEC_SEAL was set.
+ * 2: memfd_create() without MFD_NOEXEC_SEAL will be
+ * rejected.
+ */
+#define MEMFD_NOEXEC_SCOPE_EXEC 0
+#define MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL 1
+#define MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED 2
+#endif
+
struct pid_namespace {
struct idr idr;
struct rcu_head rcu;
@@ -31,6 +46,10 @@ struct pid_namespace {
struct ucounts *ucounts;
int reboot; /* group exit code if this pidns was rebooted */
struct ns_common ns;
+#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
+ /* sysctl for vm.memfd_noexec */
+ int memfd_noexec_scope;
+#endif
} __randomize_layout;
extern struct pid_namespace init_pid_ns;
diff --git a/include/uapi/linux/memfd.h b/include/uapi/linux/memfd.h
index 7a8a26751c23..273a4e15dfcf 100644
--- a/include/uapi/linux/memfd.h
+++ b/include/uapi/linux/memfd.h
@@ -8,6 +8,10 @@
#define MFD_CLOEXEC 0x0001U
#define MFD_ALLOW_SEALING 0x0002U
#define MFD_HUGETLB 0x0004U
+/* not executable and sealed to prevent changing to executable. */
+#define MFD_NOEXEC_SEAL 0x0008U
+/* executable */
+#define MFD_EXEC 0x0010U
/*
* Huge page size encoding when MFD_HUGETLB is specified, and a huge page
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index f4f8cb0435b4..8a98b1af9376 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -23,6 +23,7 @@
#include <linux/sched/task.h>
#include <linux/sched/signal.h>
#include <linux/idr.h>
+#include "pid_sysctl.h"
static DEFINE_MUTEX(pid_caches_mutex);
static struct kmem_cache *pid_ns_cachep;
@@ -110,6 +111,8 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
ns->ucounts = ucounts;
ns->pid_allocated = PIDNS_ADDING;
+ initialize_memfd_noexec_scope(ns);
+
return ns;
out_free_idr:
@@ -455,6 +458,8 @@ static __init int pid_namespaces_init(void)
#ifdef CONFIG_CHECKPOINT_RESTORE
register_sysctl_paths(kern_path, pid_ns_ctl_table);
#endif
+
+ register_pid_ns_sysctl_table_vm();
return 0;
}
diff --git a/kernel/pid_sysctl.h b/kernel/pid_sysctl.h
new file mode 100644
index 000000000000..5986d6493b5b
--- /dev/null
+++ b/kernel/pid_sysctl.h
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef LINUX_PID_SYSCTL_H
+#define LINUX_PID_SYSCTL_H
+
+#include <linux/pid_namespace.h>
+
+#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
+static inline void initialize_memfd_noexec_scope(struct pid_namespace *ns)
+{
+ ns->memfd_noexec_scope =
+ task_active_pid_ns(current)->memfd_noexec_scope;
+}
+
+static int pid_mfd_noexec_dointvec_minmax(struct ctl_table *table,
+ int write, void *buf, size_t *lenp, loff_t *ppos)
+{
+ struct pid_namespace *ns = task_active_pid_ns(current);
+ struct ctl_table table_copy;
+
+ if (write && !capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ table_copy = *table;
+ if (ns != &init_pid_ns)
+ table_copy.data = &ns->memfd_noexec_scope;
+
+ /*
+ * set minimum to current value, the effect is only bigger
+ * value is accepted.
+ */
+ if (*(int *)table_copy.data > *(int *)table_copy.extra1)
+ table_copy.extra1 = table_copy.data;
+
+ return proc_dointvec_minmax(&table_copy, write, buf, lenp, ppos);
+}
+
+static struct ctl_table pid_ns_ctl_table_vm[] = {
+ {
+ .procname = "memfd_noexec",
+ .data = &init_pid_ns.memfd_noexec_scope,
+ .maxlen = sizeof(init_pid_ns.memfd_noexec_scope),
+ .mode = 0644,
+ .proc_handler = pid_mfd_noexec_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_TWO,
+ },
+ { }
+};
+static struct ctl_path vm_path[] = { { .procname = "vm", }, { } };
+static inline void register_pid_ns_sysctl_table_vm(void)
+{
+ register_sysctl_paths(vm_path, pid_ns_ctl_table_vm);
+}
+#else
+static inline void set_memfd_noexec_scope(struct pid_namespace *ns) {}
+static inline void register_pid_ns_ctl_table_vm(void) {}
+#endif
+
+#endif /* LINUX_PID_SYSCTL_H */
diff --git a/mm/memfd.c b/mm/memfd.c
index 4ebeab94aa74..ec70675a7069 100644
--- a/mm/memfd.c
+++ b/mm/memfd.c
@@ -18,6 +18,7 @@
#include <linux/hugetlb.h>
#include <linux/shmem_fs.h>
#include <linux/memfd.h>
+#include <linux/pid_namespace.h>
#include <uapi/linux/memfd.h>
/*
@@ -263,12 +264,14 @@ long memfd_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
#define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1)
#define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN)
-#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB)
+#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB | MFD_NOEXEC_SEAL | MFD_EXEC)
SYSCALL_DEFINE2(memfd_create,
const char __user *, uname,
unsigned int, flags)
{
+ char comm[TASK_COMM_LEN];
+ struct pid_namespace *ns;
unsigned int *file_seals;
struct file *file;
int fd, error;
@@ -285,6 +288,39 @@ SYSCALL_DEFINE2(memfd_create,
return -EINVAL;
}
+ /* Invalid if both EXEC and NOEXEC_SEAL are set.*/
+ if ((flags & MFD_EXEC) && (flags & MFD_NOEXEC_SEAL))
+ return -EINVAL;
+
+ if (!(flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) {
+#ifdef CONFIG_SYSCTL
+ int sysctl = MEMFD_NOEXEC_SCOPE_EXEC;
+
+ ns = task_active_pid_ns(current);
+ if (ns)
+ sysctl = ns->memfd_noexec_scope;
+
+ switch (sysctl) {
+ case MEMFD_NOEXEC_SCOPE_EXEC:
+ flags |= MFD_EXEC;
+ break;
+ case MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL:
+ flags |= MFD_NOEXEC_SEAL;
+ break;
+ default:
+ pr_warn_ratelimited(
+ "memfd_create(): MFD_NOEXEC_SEAL is enforced, pid=%d '%s'\n",
+ task_pid_nr(current), get_task_comm(comm, current));
+ return -EINVAL;
+ }
+#else
+ flags |= MFD_EXEC;
+#endif
+ pr_warn_ratelimited(
+ "memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n",
+ task_pid_nr(current), get_task_comm(comm, current));
+ }
+
/* length includes terminating zero */
len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1);
if (len <= 0)
@@ -328,7 +364,15 @@ SYSCALL_DEFINE2(memfd_create,
file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
file->f_flags |= O_LARGEFILE;
- if (flags & MFD_ALLOW_SEALING) {
+ if (flags & MFD_NOEXEC_SEAL) {
+ struct inode *inode = file_inode(file);
+
+ inode->i_mode &= ~0111;
+ file_seals = memfd_file_seals_ptr(file);
+ *file_seals &= ~F_SEAL_SEAL;
+ *file_seals |= F_SEAL_EXEC;
+ } else if (flags & MFD_ALLOW_SEALING) {
+ /* MFD_EXEC and MFD_ALLOW_SEALING are set */
file_seals = memfd_file_seals_ptr(file);
*file_seals &= ~F_SEAL_SEAL;
}
--
2.39.0.rc0.267.gcb52ba06e7-goog
On Wed, Dec 07, 2022 at 03:49:36PM +0000, [email protected] wrote:
> From: Jeff Xu <[email protected]>
>
> The new MFD_NOEXEC_SEAL and MFD_EXEC flags allows application to
> set executable bit at creation time (memfd_create).
>
> When MFD_NOEXEC_SEAL is set, memfd is created without executable bit
> (mode:0666), and sealed with F_SEAL_EXEC, so it can't be chmod to
> be executable (mode: 0777) after creation.
>
> when MFD_EXEC flag is set, memfd is created with executable bit
> (mode:0777), this is the same as the old behavior of memfd_create.
>
> The new pid namespaced sysctl vm.memfd_noexec has 3 values:
> 0: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL acts like
> MFD_EXEC was set.
> 1: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL acts like
> MFD_NOEXEC_SEAL was set.
> 2: memfd_create() without MFD_NOEXEC_SEAL will be rejected.
>
> The sysctl allows finer control of memfd_create for old-software
> that doesn't set the executable bit, for example, a container with
> vm.memfd_noexec=1 means the old-software will create non-executable
> memfd by default. Also, the value of memfd_noexec is passed to child
> namespace at creation time. For example, if the init namespace has
> vm.memfd_noexec=2, all its children namespaces will be created with 2.
>
> Signed-off-by: Jeff Xu <[email protected]>
> Co-developed-by: Daniel Verkamp <[email protected]>
> Signed-off-by: Daniel Verkamp <[email protected]>
> Reported-by: kernel test robot <[email protected]>
Please rearrange these tags, and add a link to the lkp report:
Reported-by: kernel test robot <[email protected]>
Link: ...url.to.lkp.lore.email...
Co-developed-by: Daniel Verkamp <[email protected]>
Signed-off-by: Daniel Verkamp <[email protected]>
Signed-off-by: Jeff Xu <[email protected]>
> ---
> include/linux/pid_namespace.h | 19 +++++++++++
> include/uapi/linux/memfd.h | 4 +++
> kernel/pid_namespace.c | 5 +++
> kernel/pid_sysctl.h | 59 +++++++++++++++++++++++++++++++++++
> mm/memfd.c | 48 ++++++++++++++++++++++++++--
> 5 files changed, 133 insertions(+), 2 deletions(-)
> create mode 100644 kernel/pid_sysctl.h
>
> diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
> index 07481bb87d4e..a4789a7b34a9 100644
> --- a/include/linux/pid_namespace.h
> +++ b/include/linux/pid_namespace.h
> @@ -16,6 +16,21 @@
>
> struct fs_pin;
>
> +#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
> +/*
> + * sysctl for vm.memfd_noexec
> + * 0: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL
> + * acts like MFD_EXEC was set.
> + * 1: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL
> + * acts like MFD_NOEXEC_SEAL was set.
> + * 2: memfd_create() without MFD_NOEXEC_SEAL will be
> + * rejected.
> + */
> +#define MEMFD_NOEXEC_SCOPE_EXEC 0
> +#define MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL 1
> +#define MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED 2
These don't align? I think a tab is missing on MEMFD_NOEXEC_SCOPE_EXEC.
> +#endif
> +
> struct pid_namespace {
> struct idr idr;
> struct rcu_head rcu;
> @@ -31,6 +46,10 @@ struct pid_namespace {
> struct ucounts *ucounts;
> int reboot; /* group exit code if this pidns was rebooted */
> struct ns_common ns;
> +#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
> + /* sysctl for vm.memfd_noexec */
> + int memfd_noexec_scope;
> +#endif
> } __randomize_layout;
>
> extern struct pid_namespace init_pid_ns;
> diff --git a/include/uapi/linux/memfd.h b/include/uapi/linux/memfd.h
> index 7a8a26751c23..273a4e15dfcf 100644
> --- a/include/uapi/linux/memfd.h
> +++ b/include/uapi/linux/memfd.h
> @@ -8,6 +8,10 @@
> #define MFD_CLOEXEC 0x0001U
> #define MFD_ALLOW_SEALING 0x0002U
> #define MFD_HUGETLB 0x0004U
> +/* not executable and sealed to prevent changing to executable. */
> +#define MFD_NOEXEC_SEAL 0x0008U
> +/* executable */
> +#define MFD_EXEC 0x0010U
>
> /*
> * Huge page size encoding when MFD_HUGETLB is specified, and a huge page
> diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
> index f4f8cb0435b4..8a98b1af9376 100644
> --- a/kernel/pid_namespace.c
> +++ b/kernel/pid_namespace.c
> @@ -23,6 +23,7 @@
> #include <linux/sched/task.h>
> #include <linux/sched/signal.h>
> #include <linux/idr.h>
> +#include "pid_sysctl.h"
>
> static DEFINE_MUTEX(pid_caches_mutex);
> static struct kmem_cache *pid_ns_cachep;
> @@ -110,6 +111,8 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
> ns->ucounts = ucounts;
> ns->pid_allocated = PIDNS_ADDING;
>
> + initialize_memfd_noexec_scope(ns);
> +
> return ns;
>
> out_free_idr:
> @@ -455,6 +458,8 @@ static __init int pid_namespaces_init(void)
> #ifdef CONFIG_CHECKPOINT_RESTORE
> register_sysctl_paths(kern_path, pid_ns_ctl_table);
> #endif
> +
> + register_pid_ns_sysctl_table_vm();
> return 0;
> }
>
> diff --git a/kernel/pid_sysctl.h b/kernel/pid_sysctl.h
> new file mode 100644
> index 000000000000..5986d6493b5b
> --- /dev/null
> +++ b/kernel/pid_sysctl.h
> @@ -0,0 +1,59 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef LINUX_PID_SYSCTL_H
> +#define LINUX_PID_SYSCTL_H
> +
> +#include <linux/pid_namespace.h>
> +
> +#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
> +static inline void initialize_memfd_noexec_scope(struct pid_namespace *ns)
> +{
> + ns->memfd_noexec_scope =
> + task_active_pid_ns(current)->memfd_noexec_scope;
> +}
> +
> +static int pid_mfd_noexec_dointvec_minmax(struct ctl_table *table,
> + int write, void *buf, size_t *lenp, loff_t *ppos)
> +{
> + struct pid_namespace *ns = task_active_pid_ns(current);
> + struct ctl_table table_copy;
> +
> + if (write && !capable(CAP_SYS_ADMIN))
> + return -EPERM;
Should this be CAP_SYS_ADMIN within the userns, rather than the global
init_task CAP_SYS_ADMIN?
> +
> + table_copy = *table;
> + if (ns != &init_pid_ns)
> + table_copy.data = &ns->memfd_noexec_scope;
> +
> + /*
> + * set minimum to current value, the effect is only bigger
> + * value is accepted.
> + */
> + if (*(int *)table_copy.data > *(int *)table_copy.extra1)
> + table_copy.extra1 = table_copy.data;
> +
> + return proc_dointvec_minmax(&table_copy, write, buf, lenp, ppos);
> +}
> +
> +static struct ctl_table pid_ns_ctl_table_vm[] = {
> + {
> + .procname = "memfd_noexec",
> + .data = &init_pid_ns.memfd_noexec_scope,
> + .maxlen = sizeof(init_pid_ns.memfd_noexec_scope),
> + .mode = 0644,
> + .proc_handler = pid_mfd_noexec_dointvec_minmax,
> + .extra1 = SYSCTL_ZERO,
> + .extra2 = SYSCTL_TWO,
> + },
> + { }
> +};
> +static struct ctl_path vm_path[] = { { .procname = "vm", }, { } };
> +static inline void register_pid_ns_sysctl_table_vm(void)
> +{
> + register_sysctl_paths(vm_path, pid_ns_ctl_table_vm);
> +}
> +#else
> +static inline void set_memfd_noexec_scope(struct pid_namespace *ns) {}
> +static inline void register_pid_ns_ctl_table_vm(void) {}
> +#endif
> +
> +#endif /* LINUX_PID_SYSCTL_H */
> diff --git a/mm/memfd.c b/mm/memfd.c
> index 4ebeab94aa74..ec70675a7069 100644
> --- a/mm/memfd.c
> +++ b/mm/memfd.c
> @@ -18,6 +18,7 @@
> #include <linux/hugetlb.h>
> #include <linux/shmem_fs.h>
> #include <linux/memfd.h>
> +#include <linux/pid_namespace.h>
> #include <uapi/linux/memfd.h>
>
> /*
> @@ -263,12 +264,14 @@ long memfd_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
> #define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1)
> #define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN)
>
> -#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB)
> +#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB | MFD_NOEXEC_SEAL | MFD_EXEC)
>
> SYSCALL_DEFINE2(memfd_create,
> const char __user *, uname,
> unsigned int, flags)
> {
> + char comm[TASK_COMM_LEN];
I'm fine with using "comm", but technically, it's not needed: task->comm
will always be %NUL terminated.
> + struct pid_namespace *ns;
> unsigned int *file_seals;
> struct file *file;
> int fd, error;
> @@ -285,6 +288,39 @@ SYSCALL_DEFINE2(memfd_create,
> return -EINVAL;
> }
>
> + /* Invalid if both EXEC and NOEXEC_SEAL are set.*/
> + if ((flags & MFD_EXEC) && (flags & MFD_NOEXEC_SEAL))
> + return -EINVAL;
> +
> + if (!(flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) {
> +#ifdef CONFIG_SYSCTL
> + int sysctl = MEMFD_NOEXEC_SCOPE_EXEC;
> +
> + ns = task_active_pid_ns(current);
> + if (ns)
> + sysctl = ns->memfd_noexec_scope;
> +
> + switch (sysctl) {
> + case MEMFD_NOEXEC_SCOPE_EXEC:
> + flags |= MFD_EXEC;
> + break;
> + case MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL:
> + flags |= MFD_NOEXEC_SEAL;
> + break;
> + default:
> + pr_warn_ratelimited(
> + "memfd_create(): MFD_NOEXEC_SEAL is enforced, pid=%d '%s'\n",
> + task_pid_nr(current), get_task_comm(comm, current));
> + return -EINVAL;
> + }
> +#else
> + flags |= MFD_EXEC;
> +#endif
> + pr_warn_ratelimited(
> + "memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n",
> + task_pid_nr(current), get_task_comm(comm, current));
> + }
> +
> /* length includes terminating zero */
> len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1);
> if (len <= 0)
> @@ -328,7 +364,15 @@ SYSCALL_DEFINE2(memfd_create,
> file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
> file->f_flags |= O_LARGEFILE;
>
> - if (flags & MFD_ALLOW_SEALING) {
> + if (flags & MFD_NOEXEC_SEAL) {
> + struct inode *inode = file_inode(file);
> +
> + inode->i_mode &= ~0111;
> + file_seals = memfd_file_seals_ptr(file);
> + *file_seals &= ~F_SEAL_SEAL;
> + *file_seals |= F_SEAL_EXEC;
> + } else if (flags & MFD_ALLOW_SEALING) {
> + /* MFD_EXEC and MFD_ALLOW_SEALING are set */
> file_seals = memfd_file_seals_ptr(file);
> *file_seals &= ~F_SEAL_SEAL;
> }
> --
> 2.39.0.rc0.267.gcb52ba06e7-goog
>
Otherwise looks good!
--
Kees Cook
On Thu, Dec 8, 2022 at 8:27 AM Kees Cook <[email protected]> wrote:
>
> On Wed, Dec 07, 2022 at 03:49:36PM +0000, [email protected] wrote:
> > From: Jeff Xu <[email protected]>
> >
> > The new MFD_NOEXEC_SEAL and MFD_EXEC flags allows application to
> > set executable bit at creation time (memfd_create).
> >
> > When MFD_NOEXEC_SEAL is set, memfd is created without executable bit
> > (mode:0666), and sealed with F_SEAL_EXEC, so it can't be chmod to
> > be executable (mode: 0777) after creation.
> >
> > when MFD_EXEC flag is set, memfd is created with executable bit
> > (mode:0777), this is the same as the old behavior of memfd_create.
> >
> > The new pid namespaced sysctl vm.memfd_noexec has 3 values:
> > 0: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL acts like
> > MFD_EXEC was set.
> > 1: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL acts like
> > MFD_NOEXEC_SEAL was set.
> > 2: memfd_create() without MFD_NOEXEC_SEAL will be rejected.
> >
> > The sysctl allows finer control of memfd_create for old-software
> > that doesn't set the executable bit, for example, a container with
> > vm.memfd_noexec=1 means the old-software will create non-executable
> > memfd by default. Also, the value of memfd_noexec is passed to child
> > namespace at creation time. For example, if the init namespace has
> > vm.memfd_noexec=2, all its children namespaces will be created with 2.
> >
> > Signed-off-by: Jeff Xu <[email protected]>
> > Co-developed-by: Daniel Verkamp <[email protected]>
> > Signed-off-by: Daniel Verkamp <[email protected]>
> > Reported-by: kernel test robot <[email protected]>
>
> Please rearrange these tags, and add a link to the lkp report:
>
> Reported-by: kernel test robot <[email protected]>
> Link: ...url.to.lkp.lore.email...
> Co-developed-by: Daniel Verkamp <[email protected]>
> Signed-off-by: Daniel Verkamp <[email protected]>
> Signed-off-by: Jeff Xu <[email protected]>
>
> > ---
> > include/linux/pid_namespace.h | 19 +++++++++++
> > include/uapi/linux/memfd.h | 4 +++
> > kernel/pid_namespace.c | 5 +++
> > kernel/pid_sysctl.h | 59 +++++++++++++++++++++++++++++++++++
> > mm/memfd.c | 48 ++++++++++++++++++++++++++--
> > 5 files changed, 133 insertions(+), 2 deletions(-)
> > create mode 100644 kernel/pid_sysctl.h
> >
> > diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
> > index 07481bb87d4e..a4789a7b34a9 100644
> > --- a/include/linux/pid_namespace.h
> > +++ b/include/linux/pid_namespace.h
> > @@ -16,6 +16,21 @@
> >
> > struct fs_pin;
> >
> > +#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
> > +/*
> > + * sysctl for vm.memfd_noexec
> > + * 0: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL
> > + * acts like MFD_EXEC was set.
> > + * 1: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL
> > + * acts like MFD_NOEXEC_SEAL was set.
> > + * 2: memfd_create() without MFD_NOEXEC_SEAL will be
> > + * rejected.
> > + */
> > +#define MEMFD_NOEXEC_SCOPE_EXEC 0
> > +#define MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL 1
> > +#define MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED 2
>
> These don't align? I think a tab is missing on MEMFD_NOEXEC_SCOPE_EXEC.
>
Done
> > +#endif
> > +
> > struct pid_namespace {
> > struct idr idr;
> > struct rcu_head rcu;
> > @@ -31,6 +46,10 @@ struct pid_namespace {
> > struct ucounts *ucounts;
> > int reboot; /* group exit code if this pidns was rebooted */
> > struct ns_common ns;
> > +#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
> > + /* sysctl for vm.memfd_noexec */
> > + int memfd_noexec_scope;
> > +#endif
> > } __randomize_layout;
> >
> > extern struct pid_namespace init_pid_ns;
> > diff --git a/include/uapi/linux/memfd.h b/include/uapi/linux/memfd.h
> > index 7a8a26751c23..273a4e15dfcf 100644
> > --- a/include/uapi/linux/memfd.h
> > +++ b/include/uapi/linux/memfd.h
> > @@ -8,6 +8,10 @@
> > #define MFD_CLOEXEC 0x0001U
> > #define MFD_ALLOW_SEALING 0x0002U
> > #define MFD_HUGETLB 0x0004U
> > +/* not executable and sealed to prevent changing to executable. */
> > +#define MFD_NOEXEC_SEAL 0x0008U
> > +/* executable */
> > +#define MFD_EXEC 0x0010U
> >
> > /*
> > * Huge page size encoding when MFD_HUGETLB is specified, and a huge page
> > diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
> > index f4f8cb0435b4..8a98b1af9376 100644
> > --- a/kernel/pid_namespace.c
> > +++ b/kernel/pid_namespace.c
> > @@ -23,6 +23,7 @@
> > #include <linux/sched/task.h>
> > #include <linux/sched/signal.h>
> > #include <linux/idr.h>
> > +#include "pid_sysctl.h"
> >
> > static DEFINE_MUTEX(pid_caches_mutex);
> > static struct kmem_cache *pid_ns_cachep;
> > @@ -110,6 +111,8 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
> > ns->ucounts = ucounts;
> > ns->pid_allocated = PIDNS_ADDING;
> >
> > + initialize_memfd_noexec_scope(ns);
> > +
> > return ns;
> >
> > out_free_idr:
> > @@ -455,6 +458,8 @@ static __init int pid_namespaces_init(void)
> > #ifdef CONFIG_CHECKPOINT_RESTORE
> > register_sysctl_paths(kern_path, pid_ns_ctl_table);
> > #endif
> > +
> > + register_pid_ns_sysctl_table_vm();
> > return 0;
> > }
> >
> > diff --git a/kernel/pid_sysctl.h b/kernel/pid_sysctl.h
> > new file mode 100644
> > index 000000000000..5986d6493b5b
> > --- /dev/null
> > +++ b/kernel/pid_sysctl.h
> > @@ -0,0 +1,59 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#ifndef LINUX_PID_SYSCTL_H
> > +#define LINUX_PID_SYSCTL_H
> > +
> > +#include <linux/pid_namespace.h>
> > +
> > +#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
> > +static inline void initialize_memfd_noexec_scope(struct pid_namespace *ns)
> > +{
> > + ns->memfd_noexec_scope =
> > + task_active_pid_ns(current)->memfd_noexec_scope;
> > +}
> > +
> > +static int pid_mfd_noexec_dointvec_minmax(struct ctl_table *table,
> > + int write, void *buf, size_t *lenp, loff_t *ppos)
> > +{
> > + struct pid_namespace *ns = task_active_pid_ns(current);
> > + struct ctl_table table_copy;
> > +
> > + if (write && !capable(CAP_SYS_ADMIN))
> > + return -EPERM;
>
> Should this be CAP_SYS_ADMIN within the userns, rather than the global
> init_task CAP_SYS_ADMIN?
>
Done.
> > +
> > + table_copy = *table;
> > + if (ns != &init_pid_ns)
> > + table_copy.data = &ns->memfd_noexec_scope;
> > +
> > + /*
> > + * set minimum to current value, the effect is only bigger
> > + * value is accepted.
> > + */
> > + if (*(int *)table_copy.data > *(int *)table_copy.extra1)
> > + table_copy.extra1 = table_copy.data;
> > +
> > + return proc_dointvec_minmax(&table_copy, write, buf, lenp, ppos);
> > +}
> > +
> > +static struct ctl_table pid_ns_ctl_table_vm[] = {
> > + {
> > + .procname = "memfd_noexec",
> > + .data = &init_pid_ns.memfd_noexec_scope,
> > + .maxlen = sizeof(init_pid_ns.memfd_noexec_scope),
> > + .mode = 0644,
> > + .proc_handler = pid_mfd_noexec_dointvec_minmax,
> > + .extra1 = SYSCTL_ZERO,
> > + .extra2 = SYSCTL_TWO,
> > + },
> > + { }
> > +};
> > +static struct ctl_path vm_path[] = { { .procname = "vm", }, { } };
> > +static inline void register_pid_ns_sysctl_table_vm(void)
> > +{
> > + register_sysctl_paths(vm_path, pid_ns_ctl_table_vm);
> > +}
> > +#else
> > +static inline void set_memfd_noexec_scope(struct pid_namespace *ns) {}
> > +static inline void register_pid_ns_ctl_table_vm(void) {}
> > +#endif
> > +
> > +#endif /* LINUX_PID_SYSCTL_H */
> > diff --git a/mm/memfd.c b/mm/memfd.c
> > index 4ebeab94aa74..ec70675a7069 100644
> > --- a/mm/memfd.c
> > +++ b/mm/memfd.c
> > @@ -18,6 +18,7 @@
> > #include <linux/hugetlb.h>
> > #include <linux/shmem_fs.h>
> > #include <linux/memfd.h>
> > +#include <linux/pid_namespace.h>
> > #include <uapi/linux/memfd.h>
> >
> > /*
> > @@ -263,12 +264,14 @@ long memfd_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
> > #define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1)
> > #define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN)
> >
> > -#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB)
> > +#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB | MFD_NOEXEC_SEAL | MFD_EXEC)
> >
> > SYSCALL_DEFINE2(memfd_create,
> > const char __user *, uname,
> > unsigned int, flags)
> > {
> > + char comm[TASK_COMM_LEN];
>
> I'm fine with using "comm", but technically, it's not needed: task->comm
> will always be %NUL terminated.
>
get_task_comm takes a lock.
Do we need to consider the case of task->comm mutation in a
multithreaded environment ?
There seems to be work related with replacing task->comm with
get_task_comm, such as:
https://lore.kernel.org/netdev/[email protected]/
> > + struct pid_namespace *ns;
> > unsigned int *file_seals;
> > struct file *file;
> > int fd, error;
> > @@ -285,6 +288,39 @@ SYSCALL_DEFINE2(memfd_create,
> > return -EINVAL;
> > }
> >
> > + /* Invalid if both EXEC and NOEXEC_SEAL are set.*/
> > + if ((flags & MFD_EXEC) && (flags & MFD_NOEXEC_SEAL))
> > + return -EINVAL;
> > +
> > + if (!(flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) {
> > +#ifdef CONFIG_SYSCTL
> > + int sysctl = MEMFD_NOEXEC_SCOPE_EXEC;
> > +
> > + ns = task_active_pid_ns(current);
> > + if (ns)
> > + sysctl = ns->memfd_noexec_scope;
> > +
> > + switch (sysctl) {
> > + case MEMFD_NOEXEC_SCOPE_EXEC:
> > + flags |= MFD_EXEC;
> > + break;
> > + case MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL:
> > + flags |= MFD_NOEXEC_SEAL;
> > + break;
> > + default:
> > + pr_warn_ratelimited(
> > + "memfd_create(): MFD_NOEXEC_SEAL is enforced, pid=%d '%s'\n",
> > + task_pid_nr(current), get_task_comm(comm, current));
> > + return -EINVAL;
> > + }
> > +#else
> > + flags |= MFD_EXEC;
> > +#endif
> > + pr_warn_ratelimited(
> > + "memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n",
> > + task_pid_nr(current), get_task_comm(comm, current));
> > + }
> > +
> > /* length includes terminating zero */
> > len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1);
> > if (len <= 0)
> > @@ -328,7 +364,15 @@ SYSCALL_DEFINE2(memfd_create,
> > file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
> > file->f_flags |= O_LARGEFILE;
> >
> > - if (flags & MFD_ALLOW_SEALING) {
> > + if (flags & MFD_NOEXEC_SEAL) {
> > + struct inode *inode = file_inode(file);
> > +
> > + inode->i_mode &= ~0111;
> > + file_seals = memfd_file_seals_ptr(file);
> > + *file_seals &= ~F_SEAL_SEAL;
> > + *file_seals |= F_SEAL_EXEC;
> > + } else if (flags & MFD_ALLOW_SEALING) {
> > + /* MFD_EXEC and MFD_ALLOW_SEALING are set */
> > file_seals = memfd_file_seals_ptr(file);
> > *file_seals &= ~F_SEAL_SEAL;
> > }
> > --
> > 2.39.0.rc0.267.gcb52ba06e7-goog
> >
>
> Otherwise looks good!
>
> --
> Kees Cook
Hi, Jeff,
On Thu, Dec 08, 2022 at 02:55:45PM -0800, Jeff Xu wrote:
> > > + if (!(flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) {
[...]
> > > + pr_warn_ratelimited(
> > > + "memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n",
> > > + task_pid_nr(current), get_task_comm(comm, current));
This will be frequently dumped right now with mm-unstable. Is that what it
wanted to achieve?
[ 10.822575] memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=491 'systemd'
[ 10.824743] memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=495 '(sd-executor)'
...
If there's already a sane default value (and also knobs for the user to
change the default) not sure whether it's saner to just keep it silent as
before?
--
Peter Xu
On Fri, Dec 16, 2022 at 7:47 AM Peter Xu <[email protected]> wrote:
>
> Hi, Jeff,
>
> On Thu, Dec 08, 2022 at 02:55:45PM -0800, Jeff Xu wrote:
> > > > + if (!(flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) {
>
> [...]
>
> > > > + pr_warn_ratelimited(
> > > > + "memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n",
> > > > + task_pid_nr(current), get_task_comm(comm, current));
>
> This will be frequently dumped right now with mm-unstable. Is that what it
> wanted to achieve?
>
> [ 10.822575] memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=491 'systemd'
> [ 10.824743] memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=495 '(sd-executor)'
> ...
>
> If there's already a sane default value (and also knobs for the user to
> change the default) not sure whether it's saner to just keep it silent as
> before?
>
Thanks for your comments.
The intention is it is a reminder to adjust API calls to explicitly
setting this bit.
The sysctl vm.memfd_noexec = 0 1 is for transaction to the final
state, and 2 depends on API call setting this bit.
The log is ratelimited, and there is a rate limit setting:
/proc/sys/kernel/printk_ratelimit
/proc/sys/kernel/printk_ratelimit_burst
Best regards,
Jeff
> --
> Peter Xu
>
On Fri, 16 Dec 2022 09:15:40 -0800 Jeff Xu <[email protected]> wrote:
> On Fri, Dec 16, 2022 at 7:47 AM Peter Xu <[email protected]> wrote:
> >
> > Hi, Jeff,
> >
> > On Thu, Dec 08, 2022 at 02:55:45PM -0800, Jeff Xu wrote:
> > > > > + if (!(flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) {
> >
> > [...]
> >
> > > > > + pr_warn_ratelimited(
> > > > > + "memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n",
> > > > > + task_pid_nr(current), get_task_comm(comm, current));
> >
> > This will be frequently dumped right now with mm-unstable. Is that what it
> > wanted to achieve?
> >
> > [ 10.822575] memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=491 'systemd'
> > [ 10.824743] memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=495 '(sd-executor)'
> > ...
> >
> > If there's already a sane default value (and also knobs for the user to
> > change the default) not sure whether it's saner to just keep it silent as
> > before?
> >
> Thanks for your comments.
>
> The intention is it is a reminder to adjust API calls to explicitly
> setting this bit.
Do we need to warn more than once per boot? If not, use pr_warn_once()?
> The sysctl vm.memfd_noexec = 0 1 is for transaction to the final
> state, and 2 depends on API call setting this bit.
>
> The log is ratelimited, and there is a rate limit setting:
> /proc/sys/kernel/printk_ratelimit
> /proc/sys/kernel/printk_ratelimit_burst
>
On Fri, Dec 16, 2022 at 9:43 AM Andrew Morton <[email protected]> wrote:
>
> On Fri, 16 Dec 2022 09:15:40 -0800 Jeff Xu <[email protected]> wrote:
>
> > On Fri, Dec 16, 2022 at 7:47 AM Peter Xu <[email protected]> wrote:
> > >
> > > Hi, Jeff,
> > >
> > > On Thu, Dec 08, 2022 at 02:55:45PM -0800, Jeff Xu wrote:
> > > > > > + if (!(flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) {
> > >
> > > [...]
> > >
> > > > > > + pr_warn_ratelimited(
> > > > > > + "memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n",
> > > > > > + task_pid_nr(current), get_task_comm(comm, current));
> > >
> > > This will be frequently dumped right now with mm-unstable. Is that what it
> > > wanted to achieve?
> > >
> > > [ 10.822575] memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=491 'systemd'
> > > [ 10.824743] memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=495 '(sd-executor)'
> > > ...
> > >
> > > If there's already a sane default value (and also knobs for the user to
> > > change the default) not sure whether it's saner to just keep it silent as
> > > before?
> > >
> > Thanks for your comments.
> >
> > The intention is it is a reminder to adjust API calls to explicitly
> > setting this bit.
>
> Do we need to warn more than once per boot? If not, use pr_warn_once()?
>
Once per boot seems too little, it would be nice if we can list all processes.
I agree ratelimited might be too much.
There is a feature gap here for logging.
Kees, what do you think ?
> > The sysctl vm.memfd_noexec = 0 1 is for transaction to the final
> > state, and 2 depends on API call setting this bit.
> >
> > The log is ratelimited, and there is a rate limit setting:
> > /proc/sys/kernel/printk_ratelimit
> > /proc/sys/kernel/printk_ratelimit_burst
> >
>
On Fri, Dec 16, 2022 at 10:11:44AM -0800, Jeff Xu wrote:
> Once per boot seems too little, it would be nice if we can list all processes.
> I agree ratelimited might be too much.
> There is a feature gap here for logging.
>
> Kees, what do you think ?
I agree once per boot is kind of frustrating "I fixed the one warning,
oh, now it's coming from a different process". But ratelimit is, in
retrospect, still too often.
Let's go with per boot -- this should be noisy "enough" to get the
changes in API into the callers without being too much of a hassle.
--
Kees Cook
On Fri, Dec 16, 2022 at 12:35 PM Kees Cook <[email protected]> wrote:
>
> On Fri, Dec 16, 2022 at 10:11:44AM -0800, Jeff Xu wrote:
> > Once per boot seems too little, it would be nice if we can list all processes.
> > I agree ratelimited might be too much.
> > There is a feature gap here for logging.
> >
> > Kees, what do you think ?
>
> I agree once per boot is kind of frustrating "I fixed the one warning,
> oh, now it's coming from a different process". But ratelimit is, in
> retrospect, still too often.
>
> Let's go with per boot -- this should be noisy "enough" to get the
> changes in API into the callers without being too much of a hassle.
>
Agreed. Let's go with per boot.
Hi Andrew, what is your preference ? I can send a patch or you
directly fix it in mm-unstable ?
Thanks
-Jeff
> --
> Kees Cook
On Fri, 16 Dec 2022 13:46:58 -0800 Jeff Xu <[email protected]> wrote:
> On Fri, Dec 16, 2022 at 12:35 PM Kees Cook <[email protected]> wrote:
> >
> > On Fri, Dec 16, 2022 at 10:11:44AM -0800, Jeff Xu wrote:
> > > Once per boot seems too little, it would be nice if we can list all processes.
> > > I agree ratelimited might be too much.
> > > There is a feature gap here for logging.
> > >
> > > Kees, what do you think ?
> >
> > I agree once per boot is kind of frustrating "I fixed the one warning,
> > oh, now it's coming from a different process". But ratelimit is, in
> > retrospect, still too often.
> >
> > Let's go with per boot -- this should be noisy "enough" to get the
> > changes in API into the callers without being too much of a hassle.
> >
> Agreed. Let's go with per boot.
>
> Hi Andrew, what is your preference ? I can send a patch or you
> directly fix it in mm-unstable ?
Like this?
--- a/mm/memfd.c~mm-memfd-add-mfd_noexec_seal-and-mfd_exec-fix-3
+++ a/mm/memfd.c
@@ -308,7 +308,7 @@ SYSCALL_DEFINE2(memfd_create,
flags |= MFD_NOEXEC_SEAL;
break;
default:
- pr_warn_ratelimited(
+ pr_warn_once(
"memfd_create(): MFD_NOEXEC_SEAL is enforced, pid=%d '%s'\n",
task_pid_nr(current), get_task_comm(comm, current));
return -EINVAL;
@@ -316,7 +316,7 @@ SYSCALL_DEFINE2(memfd_create,
#else
flags |= MFD_EXEC;
#endif
- pr_warn_ratelimited(
+ pr_warn_once(
"memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n",
task_pid_nr(current), get_task_comm(comm, current));
}
_
On Fri, Dec 16, 2022 at 2:06 PM Andrew Morton <[email protected]> wrote:
>
> On Fri, 16 Dec 2022 13:46:58 -0800 Jeff Xu <[email protected]> wrote:
>
> > On Fri, Dec 16, 2022 at 12:35 PM Kees Cook <[email protected]> wrote:
> > >
> > > On Fri, Dec 16, 2022 at 10:11:44AM -0800, Jeff Xu wrote:
> > > > Once per boot seems too little, it would be nice if we can list all processes.
> > > > I agree ratelimited might be too much.
> > > > There is a feature gap here for logging.
> > > >
> > > > Kees, what do you think ?
> > >
> > > I agree once per boot is kind of frustrating "I fixed the one warning,
> > > oh, now it's coming from a different process". But ratelimit is, in
> > > retrospect, still too often.
> > >
> > > Let's go with per boot -- this should be noisy "enough" to get the
> > > changes in API into the callers without being too much of a hassle.
> > >
> > Agreed. Let's go with per boot.
> >
> > Hi Andrew, what is your preference ? I can send a patch or you
> > directly fix it in mm-unstable ?
>
> Like this?
>
Yes. Thanks!
> --- a/mm/memfd.c~mm-memfd-add-mfd_noexec_seal-and-mfd_exec-fix-3
> +++ a/mm/memfd.c
> @@ -308,7 +308,7 @@ SYSCALL_DEFINE2(memfd_create,
> flags |= MFD_NOEXEC_SEAL;
> break;
> default:
> - pr_warn_ratelimited(
> + pr_warn_once(
> "memfd_create(): MFD_NOEXEC_SEAL is enforced, pid=%d '%s'\n",
> task_pid_nr(current), get_task_comm(comm, current));
> return -EINVAL;
> @@ -316,7 +316,7 @@ SYSCALL_DEFINE2(memfd_create,
> #else
> flags |= MFD_EXEC;
> #endif
> - pr_warn_ratelimited(
> + pr_warn_once(
> "memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n",
> task_pid_nr(current), get_task_comm(comm, current));
> }
> _
>
On 12/16/22 16:40, Jeff Xu wrote:
> On Fri, Dec 16, 2022 at 2:06 PM Andrew Morton <[email protected]> wrote:
>>
>> On Fri, 16 Dec 2022 13:46:58 -0800 Jeff Xu <[email protected]> wrote:
>>
>>> On Fri, Dec 16, 2022 at 12:35 PM Kees Cook <[email protected]> wrote:
>>>>
>>>> On Fri, Dec 16, 2022 at 10:11:44AM -0800, Jeff Xu wrote:
>>>>> Once per boot seems too little, it would be nice if we can list all processes.
>>>>> I agree ratelimited might be too much.
>>>>> There is a feature gap here for logging.
>>>>>
>>>>> Kees, what do you think ?
>>>>
>>>> I agree once per boot is kind of frustrating "I fixed the one warning,
>>>> oh, now it's coming from a different process". But ratelimit is, in
>>>> retrospect, still too often.
>>>>
>>>> Let's go with per boot -- this should be noisy "enough" to get the
>>>> changes in API into the callers without being too much of a hassle.
>>>>
>>> Agreed. Let's go with per boot.
>>>
>>> Hi Andrew, what is your preference ? I can send a patch or you
>>> directly fix it in mm-unstable ?
>>
>> Like this?
>>
> Yes. Thanks!
>
Sorry jumping into this discussion a bit late. Is it possible to provide
a way to enable full logging as a debug option to tag more processes?
thanks,
-- Shuah
On Tue, Dec 20, 2022 at 8:55 AM Shuah Khan <[email protected]> wrote:
>
> On 12/16/22 16:40, Jeff Xu wrote:
> > On Fri, Dec 16, 2022 at 2:06 PM Andrew Morton <[email protected]> wrote:
> >>
> >> On Fri, 16 Dec 2022 13:46:58 -0800 Jeff Xu <[email protected]> wrote:
> >>
> >>> On Fri, Dec 16, 2022 at 12:35 PM Kees Cook <[email protected]> wrote:
> >>>>
> >>>> On Fri, Dec 16, 2022 at 10:11:44AM -0800, Jeff Xu wrote:
> >>>>> Once per boot seems too little, it would be nice if we can list all processes.
> >>>>> I agree ratelimited might be too much.
> >>>>> There is a feature gap here for logging.
> >>>>>
> >>>>> Kees, what do you think ?
> >>>>
> >>>> I agree once per boot is kind of frustrating "I fixed the one warning,
> >>>> oh, now it's coming from a different process". But ratelimit is, in
> >>>> retrospect, still too often.
> >>>>
> >>>> Let's go with per boot -- this should be noisy "enough" to get the
> >>>> changes in API into the callers without being too much of a hassle.
> >>>>
> >>> Agreed. Let's go with per boot.
> >>>
> >>> Hi Andrew, what is your preference ? I can send a patch or you
> >>> directly fix it in mm-unstable ?
> >>
> >> Like this?
> >>
> > Yes. Thanks!
> >
>
> Sorry jumping into this discussion a bit late. Is it possible to provide
> a way to enable full logging as a debug option to tag more processes?
>
Codewise it is possible, maybe by adding a sysctl or CONFIG_, but I am not sure
the best practice to do this with the kernel?
Kees/Andrew, do you have suggestions ?
Thanks
Jeff
> thanks,
> -- Shuah
>