SELinux: call cap_file_mmap in selinux_file_mmap (8cf948e7) · Commits · 戴 / test

Currently SELinux does not check CAP_SYS_RAWIO in the file_mmap hook. This means there is no DAC check on the ability to mmap low addresses in the memory space. This function adds the DAC check for CAP_SYS_RAWIO while maintaining the selinux check on mmap_zero. This means that processes which need to mmap low memory will need CAP_SYS_RAWIO and mmap_zero but will NOT need the SELinux sys_rawio capability. Signed-off-by:

Eric Paris <eparis@redhat.com> Signed-off-by:

James Morris <jmorris@namei.org>

security/selinux/hooks.c

+13 −1

Original line number	Diff line number	Diff line
		@@ -3030,9 +3030,21 @@ static int selinux_file_mmap(struct file *file, unsigned long reqprot,
		int rc = 0;
		u32 sid = current_sid();

		if (addr < mmap_min_addr)
		/*
		* notice that we are intentionally putting the SELinux check before
		* the secondary cap_file_mmap check. This is such a likely attempt
		* at bad behaviour/exploit that we always want to get the AVC, even
		* if DAC would have also denied the operation.
		*/
		if (addr < mmap_min_addr) {
		rc = avc_has_perm(sid, sid, SECCLASS_MEMPROTECT,
		MEMPROTECT__MMAP_ZERO, NULL);
		if (rc)
		return rc;
		}

		/* do DAC check on address space usage */
		rc = cap_file_mmap(file, reqprot, prot, flags, addr, addr_only);
		if (rc \|\| addr_only)
		return rc;

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