From: Eric Paris Reading /proc/sys/kernel/cap-bound requires CAP_SYS_MODULE. (see proc_dointvec_bset in kernel/sysctl.c) sysctl appears to drive all over proc reading everything it can get it's hands on and is complaining when it is being denied access to read cap-bound. Clearly writing to cap-bound should be a sensitive operation but requiring CAP_SYS_MODULE to read cap-bound seems a bit to strong. I believe the information could with reasonable certainty be obtained by looking at a bunch of the output of /proc/pid/status which has very low security protection, so at best we are just getting a little obfuscation of information. Currently SELinux policy has to 'dontaudit' capability checks for CAP_SYS_MODULE for things like sysctl which just want to read cap-bound. In doing so we also as a byproduct have to hide warnings of potential exploits such as if at some time that sysctl actually tried to load a module. I wondered if anyone would have a problem opening cap-bound up to read from anyone? Cc: Chris Wright Cc: Stephen Smalley Cc: James Morris Signed-off-by: Andrew Morton --- kernel/sysctl.c | 2 +- 1 files changed, 1 insertion(+), 1 deletion(-) diff -puN kernel/sysctl.c~make-reading-proc-sys-kernel-cap-bould-not-require kernel/sysctl.c --- a/kernel/sysctl.c~make-reading-proc-sys-kernel-cap-bould-not-require +++ a/kernel/sysctl.c @@ -1961,7 +1961,7 @@ int proc_dointvec_bset(ctl_table *table, { int op; - if (!capable(CAP_SYS_MODULE)) { + if (write && !capable(CAP_SYS_MODULE)) { return -EPERM; } _