From: Allen Pais <allen.lkml@gmail.com>
To: linux-pci@vger.kernel.org
Cc: bhelgaas@google.com, ast@kernel.org, gregkh@linuxfoundation.org,
linux-kernel@vger.kernel.org,
Allen Pais <apais@linux.microsoft.com>,
Allen Pais <allen.pais@lkml.com>
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: <20201016055235.440159-1-allen.lkml@gmail.com> (raw)
From: Allen Pais <apais@linux.microsoft.com>
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 <allen.pais@lkml.com>
---
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;
--
2.25.1
next 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 ` [RFC] PCI: allow sysfs file owner to read the config space with CAP_SYS_RAWIO 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
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