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selinux: Add helper functions to get and set checkreqprot

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checkreqprot data member in selinux_state struct is accessed directly by
SELinux functions to get and set. This could cause unexpected read or
write access to this data member due to compiler optimizations and/or
compiler's reordering of access to this field.

Add helper functions to get and set checkreqprot data member in
selinux_state struct. These helper functions use READ_ONCE and
WRITE_ONCE macros to ensure atomic read or write of memory for
this data member.

Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Suggested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Suggested-by: Paul Moore <paul@paul-moore.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
This commit is contained in:
Lakshmi Ramasubramanian
2020-09-14 10:31:57 -07:00
committed by Paul Moore
parent e8ba53d002
commit 8861d0af64
3 changed files with 16 additions and 5 deletions
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6
security/selinux/hooks.c
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@@ -3718,7 +3718,7 @@ static int selinux_mmap_file(struct file *file, unsigned long reqprot,
return rc;
}
if (selinux_state.checkreqprot)
if (checkreqprot_get(&selinux_state))
prot = reqprot;
return file_map_prot_check(file, prot,
@@ -3732,7 +3732,7 @@ static int selinux_file_mprotect(struct vm_area_struct *vma,
const struct cred *cred = current_cred();
u32 sid = cred_sid(cred);
if (selinux_state.checkreqprot)
if (checkreqprot_get(&selinux_state))
prot = reqprot;
if (default_noexec &&
@@ -7234,7 +7234,7 @@ static __init int selinux_init(void)
memset(&selinux_state, 0, sizeof(selinux_state));
enforcing_set(&selinux_state, selinux_enforcing_boot);
selinux_state.checkreqprot = selinux_checkreqprot_boot;
checkreqprot_set(&selinux_state, selinux_checkreqprot_boot);
selinux_avc_init(&selinux_state.avc);
mutex_init(&selinux_state.status_lock);
mutex_init(&selinux_state.policy_mutex);