From c040d8cac33ad4e991767be5acc66a8fada2a0a1 Mon Sep 17 00:00:00 2001 From: Josh Boyer Date: Mon, 25 Feb 2013 10:00:31 -0500 Subject: [PATCH] Honor dmesg_restrict for /dev/kmsg (rhbz 903192) --- ...or-dmesg_restrict-sysctl-on-dev-kmsg.patch | 46 +++++++++++++++++++ kernel.spec | 7 +++ 2 files changed, 53 insertions(+) create mode 100644 0001-kmsg-Honor-dmesg_restrict-sysctl-on-dev-kmsg.patch diff --git a/0001-kmsg-Honor-dmesg_restrict-sysctl-on-dev-kmsg.patch b/0001-kmsg-Honor-dmesg_restrict-sysctl-on-dev-kmsg.patch new file mode 100644 index 000000000..acaf5f881 --- /dev/null +++ b/0001-kmsg-Honor-dmesg_restrict-sysctl-on-dev-kmsg.patch @@ -0,0 +1,46 @@ +From feaf4959c30d0640093a607c577940d3e9351076 Mon Sep 17 00:00:00 2001 +From: Josh Boyer +Date: Fri, 22 Feb 2013 11:47:37 -0500 +Subject: [PATCH] kmsg: Honor dmesg_restrict sysctl on /dev/kmsg + +Originally, the addition of the 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 + +Reported-by: Christian Kujau +CC: stable@vger.kernel.org +Signed-off-by: Josh Boyer +--- + kernel/printk.c | 3 +++ + 1 file changed, 3 insertions(+) + +diff --git a/kernel/printk.c b/kernel/printk.c +index f24633a..398ef9a 100644 +--- a/kernel/printk.c ++++ b/kernel/printk.c +@@ -615,6 +615,9 @@ static int devkmsg_open(struct inode *inode, struct file *file) + 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; +-- +1.8.1.2 + diff --git a/kernel.spec b/kernel.spec index 23f5a7e5b..c99d328e5 100644 --- a/kernel.spec +++ b/kernel.spec @@ -739,6 +739,9 @@ Patch21251: sock_diag-Fix-out-of-bounds-access-to-sock_diag_handlers.patch #rhbz 812111 Patch21260: alps-v2.patch +#rhbz 903192 +Patch21261: 0001-kmsg-Honor-dmesg_restrict-sysctl-on-dev-kmsg.patch + Patch22000: weird-root-dentry-name-debug.patch #selinux ptrace child permissions @@ -1435,6 +1438,9 @@ ApplyPatch alps-v2.patch #CVE-2013-1763 rhbz 915052,915057 ApplyPatch sock_diag-Fix-out-of-bounds-access-to-sock_diag_handlers.patch +#rhbz 903192 +ApplyPatch 0001-kmsg-Honor-dmesg_restrict-sysctl-on-dev-kmsg.patch + # END OF PATCH APPLICATIONS %endif @@ -2291,6 +2297,7 @@ fi # || || %changelog * Mon Feb 25 2013 Josh Boyer - 3.9.0-0.rc0.git7.1 +- Honor dmesg_restrict for /dev/kmsg (rhbz 903192) - Linux v3.8-7888-gab78265 * Sun Feb 24 2013 Josh Boyer - 3.9.0-0.rc0.git6.1