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Security: allow capable check to permit mmap or low vm space
On a kernel with CONFIG_SECURITY but without an LSM which implements security_file_mmap it is impossible for an application to mmap addresses lower than mmap_min_addr. Based on a suggestion from a developer in the openwall community this patch adds a check for CAP_SYS_RAWIO. It is assumed that any process with this capability can harm the system a lot more easily than writing some stuff on the zero page and then trying to get the kernel to trip over itself. It also means that programs like X on i686 which use vm86 emulation can work even with mmap_min_addr set. Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
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@ -426,7 +426,7 @@ static int dummy_file_mmap (struct file *file, unsigned long reqprot,
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unsigned long addr,
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unsigned long addr_only)
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{
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if (addr < mmap_min_addr)
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if ((addr < mmap_min_addr) && !capable(CAP_SYS_RAWIO))
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return -EACCES;
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return 0;
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}
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