From f14c234b4bc5184fd40d9a47830e5b32c3b36d49 Mon Sep 17 00:00:00 2001 From: Aleksa Sarai Date: Tue, 1 Oct 2019 11:10:53 +1000 Subject: clone3: switch to copy_struct_from_user() Switch clone3() syscall from it's own copying struct clone_args from userspace to the new dedicated copy_struct_from_user() helper. The change is very straightforward, and helps unify the syscall interface for struct-from-userspace syscalls. Additionally, explicitly define CLONE_ARGS_SIZE_VER0 to match the other users of the struct-extension pattern. Signed-off-by: Aleksa Sarai Reviewed-by: Kees Cook Reviewed-by: Christian Brauner [christian.brauner@ubuntu.com: improve commit message] Link: https://lore.kernel.org/r/20191001011055.19283-3-cyphar@cyphar.com Signed-off-by: Christian Brauner --- kernel/fork.c | 34 +++++++--------------------------- 1 file changed, 7 insertions(+), 27 deletions(-) (limited to 'kernel') diff --git a/kernel/fork.c b/kernel/fork.c index f9572f416126..2ef529869c64 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2525,39 +2525,19 @@ SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, #ifdef __ARCH_WANT_SYS_CLONE3 noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs, struct clone_args __user *uargs, - size_t size) + size_t usize) { + int err; struct clone_args args; - if (unlikely(size > PAGE_SIZE)) + if (unlikely(usize > PAGE_SIZE)) return -E2BIG; - - if (unlikely(size < sizeof(struct clone_args))) + if (unlikely(usize < CLONE_ARGS_SIZE_VER0)) return -EINVAL; - if (unlikely(!access_ok(uargs, size))) - return -EFAULT; - - if (size > sizeof(struct clone_args)) { - unsigned char __user *addr; - unsigned char __user *end; - unsigned char val; - - addr = (void __user *)uargs + sizeof(struct clone_args); - end = (void __user *)uargs + size; - - for (; addr < end; addr++) { - if (get_user(val, addr)) - return -EFAULT; - if (val) - return -E2BIG; - } - - size = sizeof(struct clone_args); - } - - if (copy_from_user(&args, uargs, size)) - return -EFAULT; + err = copy_struct_from_user(&args, sizeof(args), uargs, usize); + if (err) + return err; /* * Verify that higher 32bits of exit_signal are unset and that -- cgit v1.2.3-59-g8ed1b From dff3a85feceade213daf153556fd32a3b0a73c63 Mon Sep 17 00:00:00 2001 From: Aleksa Sarai Date: Tue, 1 Oct 2019 11:10:54 +1000 Subject: sched_setattr: switch to copy_struct_from_user() Switch sched_setattr() syscall from it's own copying struct sched_attr from userspace to the new dedicated copy_struct_from_user() helper. The change is very straightforward, and helps unify the syscall interface for struct-from-userspace syscalls. Ideally we could also unify sched_getattr(2)-style syscalls as well, but unfortunately the correct semantics for such syscalls are much less clear (see [1] for more detail). In future we could come up with a more sane idea for how the syscall interface should look. [1]: commit 1251201c0d34 ("sched/core: Fix uclamp ABI bug, clean up and robustify sched_read_attr() ABI logic and code") Signed-off-by: Aleksa Sarai Reviewed-by: Kees Cook Reviewed-by: Christian Brauner [christian.brauner@ubuntu.com: improve commit message] Link: https://lore.kernel.org/r/20191001011055.19283-4-cyphar@cyphar.com Signed-off-by: Christian Brauner --- kernel/sched/core.c | 43 +++++++------------------------------------ 1 file changed, 7 insertions(+), 36 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 7880f4f64d0e..dd05a378631a 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5106,9 +5106,6 @@ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *a u32 size; int ret; - if (!access_ok(uattr, SCHED_ATTR_SIZE_VER0)) - return -EFAULT; - /* Zero the full structure, so that a short copy will be nice: */ memset(attr, 0, sizeof(*attr)); @@ -5116,45 +5113,19 @@ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *a if (ret) return ret; - /* Bail out on silly large: */ - if (size > PAGE_SIZE) - goto err_size; - /* ABI compatibility quirk: */ if (!size) size = SCHED_ATTR_SIZE_VER0; - - if (size < SCHED_ATTR_SIZE_VER0) + if (size < SCHED_ATTR_SIZE_VER0 || size > PAGE_SIZE) goto err_size; - /* - * If we're handed a bigger struct than we know of, - * ensure all the unknown bits are 0 - i.e. new - * user-space does not rely on any kernel feature - * extensions we dont know about yet. - */ - if (size > sizeof(*attr)) { - unsigned char __user *addr; - unsigned char __user *end; - unsigned char val; - - addr = (void __user *)uattr + sizeof(*attr); - end = (void __user *)uattr + size; - - for (; addr < end; addr++) { - ret = get_user(val, addr); - if (ret) - return ret; - if (val) - goto err_size; - } - size = sizeof(*attr); + ret = copy_struct_from_user(attr, sizeof(*attr), uattr, size); + if (ret) { + if (ret == -E2BIG) + goto err_size; + return ret; } - ret = copy_from_user(attr, uattr, size); - if (ret) - return -EFAULT; - if ((attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) && size < SCHED_ATTR_SIZE_VER1) return -EINVAL; @@ -5354,7 +5325,7 @@ sched_attr_copy_to_user(struct sched_attr __user *uattr, * sys_sched_getattr - similar to sched_getparam, but with sched_attr * @pid: the pid in question. * @uattr: structure containing the extended parameters. - * @usize: sizeof(attr) that user-space knows about, for forwards and backwards compatibility. + * @usize: sizeof(attr) for fwd/bwd comp. * @flags: for future extension. */ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr, -- cgit v1.2.3-59-g8ed1b From c2ba8f41ad366dc12840dd87d8f1565185845126 Mon Sep 17 00:00:00 2001 From: Aleksa Sarai Date: Tue, 1 Oct 2019 11:10:55 +1000 Subject: perf_event_open: switch to copy_struct_from_user() Switch perf_event_open() syscall from it's own copying struct perf_event_attr from userspace to the new dedicated copy_struct_from_user() helper. The change is very straightforward, and helps unify the syscall interface for struct-from-userspace syscalls. Signed-off-by: Aleksa Sarai Reviewed-by: Kees Cook Reviewed-by: Christian Brauner [christian.brauner@ubuntu.com: improve commit message] Link: https://lore.kernel.org/r/20191001011055.19283-5-cyphar@cyphar.com Signed-off-by: Christian Brauner --- kernel/events/core.c | 47 +++++++++-------------------------------------- 1 file changed, 9 insertions(+), 38 deletions(-) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index 4655adbbae10..3f0cb82e4fbc 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -10586,55 +10586,26 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr, u32 size; int ret; - if (!access_ok(uattr, PERF_ATTR_SIZE_VER0)) - return -EFAULT; - - /* - * zero the full structure, so that a short copy will be nice. - */ + /* Zero the full structure, so that a short copy will be nice. */ memset(attr, 0, sizeof(*attr)); ret = get_user(size, &uattr->size); if (ret) return ret; - if (size > PAGE_SIZE) /* silly large */ - goto err_size; - - if (!size) /* abi compat */ + /* ABI compatibility quirk: */ + if (!size) size = PERF_ATTR_SIZE_VER0; - - if (size < PERF_ATTR_SIZE_VER0) + if (size < PERF_ATTR_SIZE_VER0 || size > PAGE_SIZE) goto err_size; - /* - * If we're handed a bigger struct than we know of, - * ensure all the unknown bits are 0 - i.e. new - * user-space does not rely on any kernel feature - * extensions we dont know about yet. - */ - if (size > sizeof(*attr)) { - unsigned char __user *addr; - unsigned char __user *end; - unsigned char val; - - addr = (void __user *)uattr + sizeof(*attr); - end = (void __user *)uattr + size; - - for (; addr < end; addr++) { - ret = get_user(val, addr); - if (ret) - return ret; - if (val) - goto err_size; - } - size = sizeof(*attr); + ret = copy_struct_from_user(attr, sizeof(*attr), uattr, size); + if (ret) { + if (ret == -E2BIG) + goto err_size; + return ret; } - ret = copy_from_user(attr, uattr, size); - if (ret) - return -EFAULT; - attr->size = size; if (attr->__reserved_1) -- cgit v1.2.3-59-g8ed1b