[PATCH 05/24] Restrict /dev/mem and /dev/kmem when the kernel is locked down
From: Matthew GarrettAllowing users to write to address space makes it possible for the kernel to be subverted, avoiding module loading restrictions. Prevent this when the kernel has been locked down. Signed-off-by: Matthew Garrett Signed-off-by: David Howells --- drivers/char/mem.c |6 ++ 1 file changed, 6 insertions(+) diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 6d9cc2d39d22..f8144049bda3 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -163,6 +163,9 @@ static ssize_t write_mem(struct file *file, const char __user *buf, if (p != *ppos) return -EFBIG; + if (kernel_is_locked_down()) + return -EPERM; + if (!valid_phys_addr_range(p, count)) return -EFAULT; @@ -513,6 +516,9 @@ static ssize_t write_kmem(struct file *file, const char __user *buf, char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ int err = 0; + if (kernel_is_locked_down()) + return -EPERM; + if (p < (unsigned long) high_memory) { unsigned long to_write = min_t(unsigned long, count, (unsigned long)high_memory - p);
[PATCH 05/24] Restrict /dev/mem and /dev/kmem when the kernel is locked down
From: Matthew Garrett Allowing users to write to address space makes it possible for the kernel to be subverted, avoiding module loading restrictions. Prevent this when the kernel has been locked down. Signed-off-by: Matthew Garrett Signed-off-by: David Howells --- drivers/char/mem.c |6 ++ 1 file changed, 6 insertions(+) diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 6d9cc2d39d22..f8144049bda3 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -163,6 +163,9 @@ static ssize_t write_mem(struct file *file, const char __user *buf, if (p != *ppos) return -EFBIG; + if (kernel_is_locked_down()) + return -EPERM; + if (!valid_phys_addr_range(p, count)) return -EFAULT; @@ -513,6 +516,9 @@ static ssize_t write_kmem(struct file *file, const char __user *buf, char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ int err = 0; + if (kernel_is_locked_down()) + return -EPERM; + if (p < (unsigned long) high_memory) { unsigned long to_write = min_t(unsigned long, count, (unsigned long)high_memory - p);
[PATCH 05/24] Restrict /dev/mem and /dev/kmem when the kernel is locked down
From: Matthew GarrettAllowing users to write to address space makes it possible for the kernel to be subverted, avoiding module loading restrictions. Prevent this when the kernel has been locked down. Signed-off-by: Matthew Garrett Signed-off-by: David Howells --- drivers/char/mem.c |6 ++ 1 file changed, 6 insertions(+) diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 6d9cc2d39d22..f8144049bda3 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -163,6 +163,9 @@ static ssize_t write_mem(struct file *file, const char __user *buf, if (p != *ppos) return -EFBIG; + if (kernel_is_locked_down()) + return -EPERM; + if (!valid_phys_addr_range(p, count)) return -EFAULT; @@ -513,6 +516,9 @@ static ssize_t write_kmem(struct file *file, const char __user *buf, char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ int err = 0; + if (kernel_is_locked_down()) + return -EPERM; + if (p < (unsigned long) high_memory) { unsigned long to_write = min_t(unsigned long, count, (unsigned long)high_memory - p);
[PATCH 05/24] Restrict /dev/mem and /dev/kmem when the kernel is locked down
From: Matthew Garrett Allowing users to write to address space makes it possible for the kernel to be subverted, avoiding module loading restrictions. Prevent this when the kernel has been locked down. Signed-off-by: Matthew Garrett Signed-off-by: David Howells --- drivers/char/mem.c |6 ++ 1 file changed, 6 insertions(+) diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 6d9cc2d39d22..f8144049bda3 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -163,6 +163,9 @@ static ssize_t write_mem(struct file *file, const char __user *buf, if (p != *ppos) return -EFBIG; + if (kernel_is_locked_down()) + return -EPERM; + if (!valid_phys_addr_range(p, count)) return -EFAULT; @@ -513,6 +516,9 @@ static ssize_t write_kmem(struct file *file, const char __user *buf, char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ int err = 0; + if (kernel_is_locked_down()) + return -EPERM; + if (p < (unsigned long) high_memory) { unsigned long to_write = min_t(unsigned long, count, (unsigned long)high_memory - p);
[PATCH 05/24] Restrict /dev/mem and /dev/kmem when the kernel is locked down
From: Matthew GarrettAllowing users to write to address space makes it possible for the kernel to be subverted, avoiding module loading restrictions. Prevent this when the kernel has been locked down. Signed-off-by: Matthew Garrett Signed-off-by: David Howells --- drivers/char/mem.c |6 ++ 1 file changed, 6 insertions(+) diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 6d9cc2d39d22..f8144049bda3 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -163,6 +163,9 @@ static ssize_t write_mem(struct file *file, const char __user *buf, if (p != *ppos) return -EFBIG; + if (kernel_is_locked_down()) + return -EPERM; + if (!valid_phys_addr_range(p, count)) return -EFAULT; @@ -513,6 +516,9 @@ static ssize_t write_kmem(struct file *file, const char __user *buf, char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ int err = 0; + if (kernel_is_locked_down()) + return -EPERM; + if (p < (unsigned long) high_memory) { unsigned long to_write = min_t(unsigned long, count, (unsigned long)high_memory - p);
[PATCH 05/24] Restrict /dev/mem and /dev/kmem when the kernel is locked down
From: Matthew Garrett Allowing users to write to address space makes it possible for the kernel to be subverted, avoiding module loading restrictions. Prevent this when the kernel has been locked down. Signed-off-by: Matthew Garrett Signed-off-by: David Howells --- drivers/char/mem.c |6 ++ 1 file changed, 6 insertions(+) diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 6d9cc2d39d22..f8144049bda3 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -163,6 +163,9 @@ static ssize_t write_mem(struct file *file, const char __user *buf, if (p != *ppos) return -EFBIG; + if (kernel_is_locked_down()) + return -EPERM; + if (!valid_phys_addr_range(p, count)) return -EFAULT; @@ -513,6 +516,9 @@ static ssize_t write_kmem(struct file *file, const char __user *buf, char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ int err = 0; + if (kernel_is_locked_down()) + return -EPERM; + if (p < (unsigned long) high_memory) { unsigned long to_write = min_t(unsigned long, count, (unsigned long)high_memory - p);