From e226ff0214bb81b4ada3553cfbd4de958c268cce Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Tue, 30 Aug 2022 18:27:13 +0800 Subject: [PATCH] random: don't let 644 read-only sysctls be written to stable inclusion from stable-v5.10.119 commit 66307429b5df542004c43d822f80ea1c61703898 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6BB Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=66307429b5df542004c43d822f80ea1c61703898 -------------------------------- commit 77553cf8f44863b31da242cf24671d76ddb61597 upstream. We leave around these old sysctls for compatibility, and we keep them "writable" for compatibility, but even after writing, we should keep reporting the same value. This is consistent with how userspaces tend to use sysctl_random_write_wakeup_bits, writing to it, and then later reading from it and using the value. Cc: Theodore Ts'o Reviewed-by: Dominik Brodowski Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman Signed-off-by: Zheng Zengkai Acked-by: Xie XiuQi --- drivers/char/random.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 389c58e11af5..ee430c1753a9 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1669,6 +1669,13 @@ static int proc_do_uuid(struct ctl_table *table, int write, void *buffer, return proc_dostring(&fake_table, 0, buffer, lenp, ppos); } +/* The same as proc_dointvec, but writes don't change anything. */ +static int proc_do_rointvec(struct ctl_table *table, int write, void *buffer, + size_t *lenp, loff_t *ppos) +{ + return write ? 0 : proc_dointvec(table, 0, buffer, lenp, ppos); +} + extern struct ctl_table random_table[]; struct ctl_table random_table[] = { { @@ -1690,14 +1697,14 @@ struct ctl_table random_table[] = { .data = &sysctl_random_write_wakeup_bits, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_dointvec, + .proc_handler = proc_do_rointvec, }, { .procname = "urandom_min_reseed_secs", .data = &sysctl_random_min_urandom_seed, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_dointvec, + .proc_handler = proc_do_rointvec, }, { .procname = "boot_id", -- GitLab