linux-kernel - [PATCH] efi/esrt: Allow ESRT access without CAP_SYS

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Message-ID: <20230512194302.1662230-1-nicholasbishop@google.com>
Date:   Fri, 12 May 2023 19:43:02 +0000
From:   Nicholas Bishop <nicholasbishop@...gle.com>
To:     Ard Biesheuvel <ardb@...nel.org>, linux-efi@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Peter Jones <pjones@...hat.com>,
        Nicholas Bishop <nicholasbishop@...gle.com>
Subject: [PATCH] efi/esrt: Allow ESRT access without CAP_SYS_ADMIN

Access to the files in /sys/firmware/efi/esrt has been restricted to
CAP_SYS_ADMIN since support for ESRT was added, but this seems overly
restrictive given that the files are read-only and just provide
information about UEFI firmware updates.

Remove the CAP_SYS_ADMIN restriction so that a non-root process can read
the files, provided a suitably-privileged process changes the file
ownership first. The files are still read-only and still owned by root by
default.

Signed-off-by: Nicholas Bishop <nicholasbishop@...gle.com>
---
 drivers/firmware/efi/esrt.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/firmware/efi/esrt.c b/drivers/firmware/efi/esrt.c
index d5915272141f..aab96ab64a1a 100644
--- a/drivers/firmware/efi/esrt.c
+++ b/drivers/firmware/efi/esrt.c
@@ -95,10 +95,6 @@ static ssize_t esre_attr_show(struct kobject *kobj,
 	struct esre_entry *entry = to_entry(kobj);
 	struct esre_attribute *attr = to_attr(_attr);
 
-	/* Don't tell normal users what firmware versions we've got... */
-	if (!capable(CAP_SYS_ADMIN))
-		return -EACCES;
-
 	return attr->show(entry, buf);
 }
 
-- 
2.40.1.606.ga4b1b128d6-goog