From d013db029491b49e1459d5a55ecd9ec1be1447ca Mon Sep 17 00:00:00 2001 From: Tyler Hicks Date: Fri, 4 May 2018 01:08:12 +0000 Subject: [PATCH] seccomp: Separate read and write code for actions_logged sysctl Break the read and write paths of the kernel.seccomp.actions_logged sysctl into separate functions to maintain readability. An upcoming change will need to audit writes, but not reads, of this sysctl which would introduce too many conditional code paths on whether or not the 'write' parameter evaluates to true. Signed-off-by: Tyler Hicks Acked-by: Kees Cook Signed-off-by: Paul Moore --- kernel/seccomp.c | 64 ++++++++++++++++++++++++++++++------------------ 1 file changed, 40 insertions(+), 24 deletions(-) diff --git a/kernel/seccomp.c b/kernel/seccomp.c index dc77548167ef..f4afe6790e4c 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -1199,48 +1199,64 @@ static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names) return true; } -static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write, - void __user *buffer, size_t *lenp, - loff_t *ppos) +static int read_actions_logged(struct ctl_table *ro_table, void __user *buffer, + size_t *lenp, loff_t *ppos) { char names[sizeof(seccomp_actions_avail)]; struct ctl_table table; - int ret; - - if (write && !capable(CAP_SYS_ADMIN)) - return -EPERM; memset(names, 0, sizeof(names)); - if (!write) { - if (!seccomp_names_from_actions_logged(names, sizeof(names), - seccomp_actions_logged)) - return -EINVAL; - } + if (!seccomp_names_from_actions_logged(names, sizeof(names), + seccomp_actions_logged)) + return -EINVAL; table = *ro_table; table.data = names; table.maxlen = sizeof(names); - ret = proc_dostring(&table, write, buffer, lenp, ppos); + return proc_dostring(&table, 0, buffer, lenp, ppos); +} + +static int write_actions_logged(struct ctl_table *ro_table, void __user *buffer, + size_t *lenp, loff_t *ppos) +{ + char names[sizeof(seccomp_actions_avail)]; + struct ctl_table table; + u32 actions_logged; + int ret; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + memset(names, 0, sizeof(names)); + + table = *ro_table; + table.data = names; + table.maxlen = sizeof(names); + ret = proc_dostring(&table, 1, buffer, lenp, ppos); if (ret) return ret; - if (write) { - u32 actions_logged; + if (!seccomp_actions_logged_from_names(&actions_logged, table.data)) + return -EINVAL; - if (!seccomp_actions_logged_from_names(&actions_logged, - table.data)) - return -EINVAL; - - if (actions_logged & SECCOMP_LOG_ALLOW) - return -EINVAL; - - seccomp_actions_logged = actions_logged; - } + if (actions_logged & SECCOMP_LOG_ALLOW) + return -EINVAL; + seccomp_actions_logged = actions_logged; return 0; } +static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos) +{ + if (write) + return write_actions_logged(ro_table, buffer, lenp, ppos); + else + return read_actions_logged(ro_table, buffer, lenp, ppos); +} + static struct ctl_path seccomp_sysctl_path[] = { { .procname = "kernel", }, { .procname = "seccomp", },