On Wed, Dec 21, 2022 at 9:10 AM Roberto Sassu roberto.sassu@huaweicloud.com wrote:
From: Roberto Sassu roberto.sassu@huawei.com
Commit 98de59bfe4b2f ("take calculation of final prot in security_mmap_file() into a helper") moved the code to update prot with the actual protection flags to be granted to the requestor by the kernel to a helper called mmap_prot(). However, the patch didn't update the argument passed to ima_file_mmap(), making it receive the requested prot instead of the final computed prot.
A possible consequence is that files mmapped as executable might not be measured/appraised if PROT_EXEC is not requested but subsequently added in the final prot.
Replace prot with mmap_prot(file, prot) as the second argument of ima_file_mmap() to restore the original behavior.
Cc: stable@vger.kernel.org Fixes: 98de59bfe4b2 ("take calculation of final prot in security_mmap_file() into a helper") Signed-off-by: Roberto Sassu roberto.sassu@huawei.com
security/security.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/security/security.c b/security/security.c index d1571900a8c7..0d2359d588a1 100644 --- a/security/security.c +++ b/security/security.c @@ -1666,7 +1666,7 @@ int security_mmap_file(struct file *file, unsigned long prot, mmap_prot(file, prot), flags); if (ret) return ret;
return ima_file_mmap(file, prot);
return ima_file_mmap(file, mmap_prot(file, prot));}
This seems like a reasonable fix, although as the original commit is ~10 years old at this point I am a little concerned about the impact this might have on IMA. Mimi, what do you think?
Beyond that, my only other comment would be to only call mmap_prot() once and cache the results in a local variable. You could also fix up some of the ugly indentation crimes in security_mmap_file() while you are at it, e.g. something like this:
diff --git a/security/security.c b/security/security.c index d1571900a8c7..2f9cad9ecac8 100644 --- a/security/security.c +++ b/security/security.c @@ -1662,11 +1662,12 @@ int security_mmap_file(struct file *file, unsigned long prot, unsigned long flags) { int ret; - ret = call_int_hook(mmap_file, 0, file, prot, - mmap_prot(file, prot), flags); + unsigned long prot_adj = mmap_prot(file, prot); + + ret = call_int_hook(mmap_file, 0, file, prot, prot_adj, flags); if (ret) return ret; - return ima_file_mmap(file, prot); + return ima_file_mmap(file, prot_adj); }
-- paul-moore.com