archive mirror
 help / color / mirror / Atom feed
From: Allen Pais <>
	Allen Pais <>,
	Allen Pais <>
Subject: [RFC] PCI: allow sysfs file owner to read the config space with CAP_SYS_RAWIO
Date: Fri, 16 Oct 2020 11:22:35 +0530	[thread overview]
Message-ID: <> (raw)

From: Allen Pais <>

 Access to pci config space is explictly checked with CAP_SYS_ADMIN
in order to read configuration space past the frist 64B.

 Since the path is only for reading, could we use CAP_SYS_RAWIO?
This patch contains a simpler fix, I would love to hear from the
Maintainers on the approach.

 The other approach that I considered was to introduce and API
which would check for multiple capabilities, something similar to
perfmon_capable()/bpf_capable(). But I could not find more users
for the API and hence dropped it.

 The problem I am trying to solve is to avoid handing out
CAP_SYS_ADMIN for extended reads of the PCI config space.

Signed-off-by: Allen Pais <>
 drivers/pci/pci-sysfs.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 6d78df981d41..6574c0203475 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -666,7 +666,8 @@ static ssize_t pci_read_config(struct file *filp, struct kobject *kobj,
 	u8 *data = (u8 *) buf;
 	/* Several chips lock up trying to read undefined config space */
-	if (file_ns_capable(filp, &init_user_ns, CAP_SYS_ADMIN))
+	if (file_ns_capable(filp, &init_user_ns, CAP_SYS_ADMIN) ||
+	    file_ns_capable(filp, &init_user_ns, CAP_SYS_RAWIO))
 		size = dev->cfg_size;
 	else if (dev->hdr_type == PCI_HEADER_TYPE_CARDBUS)
 		size = 128;

             reply	other threads:[~2020-10-16  5:52 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-16  5:52 Allen Pais [this message]
2020-10-16  6:20 ` Greg KH
2020-10-19 13:00   ` Allen
2020-10-19 13:16     ` Greg KH
2020-10-19 13:21       ` Allen
2020-10-19 13:47         ` Greg KH
2020-10-19 14:32           ` Allen

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \ \
    --subject='Re: [RFC] PCI: allow sysfs file owner to read the config space with CAP_SYS_RAWIO' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).