poke. Nothing got applied. I'll drop
kmsg-honor-dmesg_restrict-sysctl-on-dev-kmsg.patch, see if that has any
effect ;)
From: Josh Boyer <jwboyer@xxxxxxxxxx>
Subject: kmsg: honor dmesg_restrict sysctl on /dev/kmsg
Originally, the addition of dmesg_restrict covered both the syslog
method of accessing dmesg, as well as /dev/kmsg itself. This was done
indirectly by security_syslog calling cap_syslog before doing any LSM
checks.
However, commit 12b3052c3ee ("capabilities/syslog: open code cap_syslog
logic to fix build failure") moved the code around and pushed the checks
into the caller itself. That seems to have inadvertently dropped the
checks for dmesg_restrict on /dev/kmsg. Most people haven't noticed
because util-linux dmesg(1) defaults to using the syslog method for access
in older versions. With util-linux 2.22 and a kernel newer than 3.5,
dmesg(1) defaults to reading directly from /dev/kmsg.
Fix this by making an explicit check in the devkmsg_open function.
This fixes https://bugzilla.redhat.com/show_bug.cgi?id=903192
Signed-off-by: Josh Boyer <jwboyer@xxxxxxxxxx>
Reported-by: Christian Kujau <lists@xxxxxxxxxxxxxxx>
Cc: Eric Paris <eparis@xxxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/printk.c | 3 +++
1 file changed, 3 insertions(+)
diff -puN kernel/printk.c~kmsg-honor-dmesg_restrict-sysctl-on-dev-kmsg kernel/printk.c
--- a/kernel/printk.c~kmsg-honor-dmesg_restrict-sysctl-on-dev-kmsg
+++ a/kernel/printk.c
@@ -620,6 +620,9 @@ static int devkmsg_open(struct inode *in
struct devkmsg_user *user;
int err;
+ if (dmesg_restrict && !capable(CAP_SYSLOG))
+ return -EACCES;
+
/* write-only does not need any file context */
if ((file->f_flags & O_ACCMODE) == O_WRONLY)
return 0;
_
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