diff options
| -rw-r--r-- | Documentation/sysctl/vm.txt | 12 | ||||
| -rw-r--r-- | fs/userfaultfd.c | 5 | ||||
| -rw-r--r-- | include/linux/userfaultfd_k.h | 2 | ||||
| -rw-r--r-- | kernel/sysctl.c | 12 |
4 files changed, 31 insertions, 0 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 3f13d8599337..749322060f10 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -61,6 +61,7 @@ Currently, these files are in /proc/sys/vm: - stat_refresh - numa_stat - swappiness +- unprivileged_userfaultfd - user_reserve_kbytes - vfs_cache_pressure - watermark_boost_factor @@ -818,6 +819,17 @@ The default value is 60. ============================================================== +unprivileged_userfaultfd + +This flag controls whether unprivileged users can use the userfaultfd +system calls. Set this to 1 to allow unprivileged users to use the +userfaultfd system calls, or set this to 0 to restrict userfaultfd to only +privileged users (with SYS_CAP_PTRACE capability). + +The default value is 1. + +============================================================== + - user_reserve_kbytes When overcommit_memory is set to 2, "never overcommit" mode, reserve diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index f5de1e726356..3b30301c90ec 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -30,6 +30,8 @@ #include <linux/security.h> #include <linux/hugetlb.h> +int sysctl_unprivileged_userfaultfd __read_mostly = 1; + static struct kmem_cache *userfaultfd_ctx_cachep __read_mostly; enum userfaultfd_state { @@ -1930,6 +1932,9 @@ SYSCALL_DEFINE1(userfaultfd, int, flags) struct userfaultfd_ctx *ctx; int fd; + if (!sysctl_unprivileged_userfaultfd && !capable(CAP_SYS_PTRACE)) + return -EPERM; + BUG_ON(!current->mm); /* Check the UFFD_* constants for consistency. */ diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index 37c9eba75c98..ac9d71e24b81 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -28,6 +28,8 @@ #define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK) #define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS) +extern int sysctl_unprivileged_userfaultfd; + extern vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason); extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 599510a3355e..ba158f61aab4 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -66,6 +66,7 @@ #include <linux/kexec.h> #include <linux/bpf.h> #include <linux/mount.h> +#include <linux/userfaultfd_k.h> #include "../lib/kstrtox.h" @@ -1720,6 +1721,17 @@ static struct ctl_table vm_table[] = { .extra2 = (void *)&mmap_rnd_compat_bits_max, }, #endif +#ifdef CONFIG_USERFAULTFD + { + .procname = "unprivileged_userfaultfd", + .data = &sysctl_unprivileged_userfaultfd, + .maxlen = sizeof(sysctl_unprivileged_userfaultfd), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero, + .extra2 = &one, + }, +#endif { } }; |