ovl: relax permission checking on underlying layers
Make permission checking more consistent: - special files don't need any access check on underling fs - exec permission check doesn't need to be performed on underlying fs Reported-by: "J. Bruce Fields" <bfields@fieldses.org> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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@ -286,13 +286,22 @@ int ovl_permission(struct inode *inode, int mask)
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if (err)
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return err;
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old_cred = ovl_override_creds(inode->i_sb);
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if (!upperinode &&
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!special_file(realinode->i_mode) && mask & MAY_WRITE) {
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/* No need to do any access on underlying for special files */
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if (special_file(realinode->i_mode))
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return 0;
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/* No need to access underlying for execute */
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mask &= ~MAY_EXEC;
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if ((mask & (MAY_READ | MAY_WRITE)) == 0)
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return 0;
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/* Lower files get copied up, so turn write access into read */
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if (!upperinode && mask & MAY_WRITE) {
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mask &= ~(MAY_WRITE | MAY_APPEND);
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/* Make sure mounter can read file for copy up later */
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mask |= MAY_READ;
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}
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old_cred = ovl_override_creds(inode->i_sb);
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err = inode_permission(realinode, mask);
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revert_creds(old_cred);
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