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authorLinus Torvalds <torvalds@linux-foundation.org>2018-04-02 21:22:12 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-02 21:22:12 -0700
commit642e7fd23353e22290e3d51719fcb658dc252342 (patch)
tree93688d5ff15836d8e5b0e097748f7fabb13a303a /mm/mempolicy.c
parent21035965f60b0502fc6537b232839389bb4ce664 (diff)
parentc9a211951c7c79cfb5de888d7d9550872868b086 (diff)
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Merge branch 'syscalls-next' of git://git.kernel.org/pub/scm/linux/kernel/git/brodo/linux
Pull removal of in-kernel calls to syscalls from Dominik Brodowski: "System calls are interaction points between userspace and the kernel. Therefore, system call functions such as sys_xyzzy() or compat_sys_xyzzy() should only be called from userspace via the syscall table, but not from elsewhere in the kernel. At least on 64-bit x86, it will likely be a hard requirement from v4.17 onwards to not call system call functions in the kernel: It is better to use use a different calling convention for system calls there, where struct pt_regs is decoded on-the-fly in a syscall wrapper which then hands processing over to the actual syscall function. This means that only those parameters which are actually needed for a specific syscall are passed on during syscall entry, instead of filling in six CPU registers with random user space content all the time (which may cause serious trouble down the call chain). Those x86-specific patches will be pushed through the x86 tree in the near future. Moreover, rules on how data may be accessed may differ between kernel data and user data. This is another reason why calling sys_xyzzy() is generally a bad idea, and -- at most -- acceptable in arch-specific code. This patchset removes all in-kernel calls to syscall functions in the kernel with the exception of arch/. On top of this, it cleans up the three places where many syscalls are referenced or prototyped, namely kernel/sys_ni.c, include/linux/syscalls.h and include/linux/compat.h" * 'syscalls-next' of git://git.kernel.org/pub/scm/linux/kernel/git/brodo/linux: (109 commits) bpf: whitelist all syscalls for error injection kernel/sys_ni: remove {sys_,sys_compat} from cond_syscall definitions kernel/sys_ni: sort cond_syscall() entries syscalls/x86: auto-create compat_sys_*() prototypes syscalls: sort syscall prototypes in include/linux/compat.h net: remove compat_sys_*() prototypes from net/compat.h syscalls: sort syscall prototypes in include/linux/syscalls.h kexec: move sys_kexec_load() prototype to syscalls.h x86/sigreturn: use SYSCALL_DEFINE0 x86: fix sys_sigreturn() return type to be long, not unsigned long x86/ioport: add ksys_ioperm() helper; remove in-kernel calls to sys_ioperm() mm: add ksys_readahead() helper; remove in-kernel calls to sys_readahead() mm: add ksys_mmap_pgoff() helper; remove in-kernel calls to sys_mmap_pgoff() mm: add ksys_fadvise64_64() helper; remove in-kernel call to sys_fadvise64_64() fs: add ksys_fallocate() wrapper; remove in-kernel calls to sys_fallocate() fs: add ksys_p{read,write}64() helpers; remove in-kernel calls to syscalls fs: add ksys_truncate() wrapper; remove in-kernel calls to sys_truncate() fs: add ksys_sync_file_range helper(); remove in-kernel calls to syscall kernel: add ksys_setsid() helper; remove in-kernel call to sys_setsid() kernel: add ksys_unshare() helper; remove in-kernel calls to sys_unshare() ...
Diffstat (limited to 'mm/mempolicy.c')
-rw-r--r--mm/mempolicy.c92
1 files changed, 77 insertions, 15 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 32cba0332787..01cbb7078d6c 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1336,9 +1336,9 @@ static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode,
return copy_to_user(mask, nodes_addr(*nodes), copy) ? -EFAULT : 0;
}
-SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
- unsigned long, mode, const unsigned long __user *, nmask,
- unsigned long, maxnode, unsigned, flags)
+static long kernel_mbind(unsigned long start, unsigned long len,
+ unsigned long mode, const unsigned long __user *nmask,
+ unsigned long maxnode, unsigned int flags)
{
nodemask_t nodes;
int err;
@@ -1357,9 +1357,16 @@ SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
return do_mbind(start, len, mode, mode_flags, &nodes, flags);
}
+SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
+ unsigned long, mode, const unsigned long __user *, nmask,
+ unsigned long, maxnode, unsigned int, flags)
+{
+ return kernel_mbind(start, len, mode, nmask, maxnode, flags);
+}
+
/* Set the process memory policy */
-SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
- unsigned long, maxnode)
+static long kernel_set_mempolicy(int mode, const unsigned long __user *nmask,
+ unsigned long maxnode)
{
int err;
nodemask_t nodes;
@@ -1377,9 +1384,15 @@ SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
return do_set_mempolicy(mode, flags, &nodes);
}
-SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
- const unsigned long __user *, old_nodes,
- const unsigned long __user *, new_nodes)
+SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
+ unsigned long, maxnode)
+{
+ return kernel_set_mempolicy(mode, nmask, maxnode);
+}
+
+static int kernel_migrate_pages(pid_t pid, unsigned long maxnode,
+ const unsigned long __user *old_nodes,
+ const unsigned long __user *new_nodes)
{
struct mm_struct *mm = NULL;
struct task_struct *task;
@@ -1469,11 +1482,20 @@ out_put:
}
+SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
+ const unsigned long __user *, old_nodes,
+ const unsigned long __user *, new_nodes)
+{
+ return kernel_migrate_pages(pid, maxnode, old_nodes, new_nodes);
+}
+
/* Retrieve NUMA policy */
-SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
- unsigned long __user *, nmask, unsigned long, maxnode,
- unsigned long, addr, unsigned long, flags)
+static int kernel_get_mempolicy(int __user *policy,
+ unsigned long __user *nmask,
+ unsigned long maxnode,
+ unsigned long addr,
+ unsigned long flags)
{
int err;
int uninitialized_var(pval);
@@ -1496,6 +1518,13 @@ SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
return err;
}
+SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
+ unsigned long __user *, nmask, unsigned long, maxnode,
+ unsigned long, addr, unsigned long, flags)
+{
+ return kernel_get_mempolicy(policy, nmask, maxnode, addr, flags);
+}
+
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
@@ -1514,7 +1543,7 @@ COMPAT_SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
if (nmask)
nm = compat_alloc_user_space(alloc_size);
- err = sys_get_mempolicy(policy, nm, nr_bits+1, addr, flags);
+ err = kernel_get_mempolicy(policy, nm, nr_bits+1, addr, flags);
if (!err && nmask) {
unsigned long copy_size;
@@ -1546,7 +1575,7 @@ COMPAT_SYSCALL_DEFINE3(set_mempolicy, int, mode, compat_ulong_t __user *, nmask,
return -EFAULT;
}
- return sys_set_mempolicy(mode, nm, nr_bits+1);
+ return kernel_set_mempolicy(mode, nm, nr_bits+1);
}
COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len,
@@ -1568,10 +1597,43 @@ COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len,
return -EFAULT;
}
- return sys_mbind(start, len, mode, nm, nr_bits+1, flags);
+ return kernel_mbind(start, len, mode, nm, nr_bits+1, flags);
}
-#endif
+COMPAT_SYSCALL_DEFINE4(migrate_pages, compat_pid_t, pid,
+ compat_ulong_t, maxnode,
+ const compat_ulong_t __user *, old_nodes,
+ const compat_ulong_t __user *, new_nodes)
+{
+ unsigned long __user *old = NULL;
+ unsigned long __user *new = NULL;
+ nodemask_t tmp_mask;
+ unsigned long nr_bits;
+ unsigned long size;
+
+ nr_bits = min_t(unsigned long, maxnode - 1, MAX_NUMNODES);
+ size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
+ if (old_nodes) {
+ if (compat_get_bitmap(nodes_addr(tmp_mask), old_nodes, nr_bits))
+ return -EFAULT;
+ old = compat_alloc_user_space(new_nodes ? size * 2 : size);
+ if (new_nodes)
+ new = old + size / sizeof(unsigned long);
+ if (copy_to_user(old, nodes_addr(tmp_mask), size))
+ return -EFAULT;
+ }
+ if (new_nodes) {
+ if (compat_get_bitmap(nodes_addr(tmp_mask), new_nodes, nr_bits))
+ return -EFAULT;
+ if (new == NULL)
+ new = compat_alloc_user_space(size);
+ if (copy_to_user(new, nodes_addr(tmp_mask), size))
+ return -EFAULT;
+ }
+ return kernel_migrate_pages(pid, nr_bits + 1, old, new);
+}
+
+#endif /* CONFIG_COMPAT */
struct mempolicy *__get_vma_policy(struct vm_area_struct *vma,
unsigned long addr)