From 455cd5ab305c90ffc422dd2e0fb634730942b257 Mon Sep 17 00:00:00 2001 From: Dan Rosenberg Date: Wed, 12 Jan 2011 16:59:41 -0800 Subject: kptr_restrict for hiding kernel pointers from unprivileged users Add the %pK printk format specifier and the /proc/sys/kernel/kptr_restrict sysctl. The %pK format specifier is designed to hide exposed kernel pointers, specifically via /proc interfaces. Exposing these pointers provides an easy target for kernel write vulnerabilities, since they reveal the locations of writable structures containing easily triggerable function pointers. The behavior of %pK depends on the kptr_restrict sysctl. If kptr_restrict is set to 0, no deviation from the standard %p behavior occurs. If kptr_restrict is set to 1, the default, if the current user (intended to be a reader via seq_printf(), etc.) does not have CAP_SYSLOG (currently in the LSM tree), kernel pointers using %pK are printed as 0's. If kptr_restrict is set to 2, kernel pointers using %pK are printed as 0's regardless of privileges. Replacing with 0's was chosen over the default "(null)", which cannot be parsed by userland %p, which expects "(nil)". [akpm@linux-foundation.org: check for IRQ context when !kptr_restrict, save an indent level, s/WARN/WARN_ONCE/] [akpm@linux-foundation.org: coding-style fixup] [randy.dunlap@oracle.com: fix kernel/sysctl.c warning] Signed-off-by: Dan Rosenberg Signed-off-by: Randy Dunlap Cc: James Morris Cc: Eric Dumazet Cc: Thomas Graf Cc: Eugene Teo Cc: Kees Cook Cc: Ingo Molnar Cc: David S. Miller Cc: Peter Zijlstra Cc: Eric Paris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/sysctl.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'kernel/sysctl.c') diff --git a/kernel/sysctl.c b/kernel/sysctl.c index ae5cbb1e3ced..c6811ee2092b 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -24,6 +24,7 @@ #include #include #include +#include #include #include #include @@ -710,6 +711,15 @@ static struct ctl_table kern_table[] = { .extra1 = &zero, .extra2 = &one, }, + { + .procname = "kptr_restrict", + .data = &kptr_restrict, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero, + .extra2 = &two, + }, #endif { .procname = "ngroups_max", -- cgit v1.2.3 From 556105000334cb440636ef61b862d22b03c24f70 Mon Sep 17 00:00:00 2001 From: Jovi Zhang Date: Wed, 12 Jan 2011 17:00:45 -0800 Subject: sysctl: fix #ifdef guard comment Signed-off-by: Jovi Zhang Acked-by: WANG Cong Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/sysctl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/sysctl.c') diff --git a/kernel/sysctl.c b/kernel/sysctl.c index c6811ee2092b..a05605a4c369 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -2909,7 +2909,7 @@ int proc_do_large_bitmap(struct ctl_table *table, int write, } } -#else /* CONFIG_PROC_FS */ +#else /* CONFIG_PROC_SYSCTL */ int proc_dostring(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) @@ -2961,7 +2961,7 @@ int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int write, } -#endif /* CONFIG_PROC_FS */ +#endif /* CONFIG_PROC_SYSCTL */ /* * No sense putting this after each symbol definition, twice, -- cgit v1.2.3 From e020e742e5dbd8c44d31706995dc13ddc732e274 Mon Sep 17 00:00:00 2001 From: Jovi Zhang Date: Wed, 12 Jan 2011 17:00:45 -0800 Subject: sysctl: remove obsolete comments ctl_unnumbered.txt have been removed in Documentation directory so just also remove this invalid comments [akpm@linux-foundation.org: fix Documentation/sysctl/00-INDEX, per Dave] Signed-off-by: Jovi Zhang Cc: Dave Young Acked-by: WANG Cong Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/sysctl.c | 17 ----------------- 1 file changed, 17 deletions(-) (limited to 'kernel/sysctl.c') diff --git a/kernel/sysctl.c b/kernel/sysctl.c index a05605a4c369..bc86bb32e126 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -246,10 +246,6 @@ static struct ctl_table root_table[] = { .mode = 0555, .child = dev_table, }, -/* - * NOTE: do not add new entries to this table unless you have read - * Documentation/sysctl/ctl_unnumbered.txt - */ { } }; @@ -972,10 +968,6 @@ static struct ctl_table kern_table[] = { .proc_handler = proc_dointvec, }, #endif -/* - * NOTE: do not add new entries to this table unless you have read - * Documentation/sysctl/ctl_unnumbered.txt - */ { } }; @@ -1336,11 +1328,6 @@ static struct ctl_table vm_table[] = { .extra2 = &one, }, #endif - -/* - * NOTE: do not add new entries to this table unless you have read - * Documentation/sysctl/ctl_unnumbered.txt - */ { } }; @@ -1496,10 +1483,6 @@ static struct ctl_table fs_table[] = { .proc_handler = &pipe_proc_fn, .extra1 = &pipe_min_size, }, -/* - * NOTE: do not add new entries to this table unless you have read - * Documentation/sysctl/ctl_unnumbered.txt - */ { } }; -- cgit v1.2.3 From 8c6a98b22b750c9eb52653ba643faa17db8d3881 Mon Sep 17 00:00:00 2001 From: Andy Whitcroft Date: Mon, 24 Jan 2011 09:31:38 -0800 Subject: Input: sysrq - ensure sysrq_enabled and __sysrq_enabled are consistent Currently sysrq_enabled and __sysrq_enabled are initialised separately and inconsistently, leading to sysrq being actually enabled by reported as not enabled in sysfs. The first change to the sysfs configurable synchronises these two: static int __read_mostly sysrq_enabled = 1; static int __sysrq_enabled; Add a common define to carry the default for these preventing them becoming out of sync again. Default this to 1 to mirror previous behaviour. Signed-off-by: Andy Whitcroft Cc: stable@kernel.org Signed-off-by: Dmitry Torokhov --- kernel/sysctl.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel/sysctl.c') diff --git a/kernel/sysctl.c b/kernel/sysctl.c index c33a1edb799f..3afce4dc9ba5 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -169,7 +169,8 @@ static int proc_taint(struct ctl_table *table, int write, #endif #ifdef CONFIG_MAGIC_SYSRQ -static int __sysrq_enabled; /* Note: sysrq code ises it's own private copy */ +/* Note: sysrq code uses it's own private copy */ +static int __sysrq_enabled = SYSRQ_DEFAULT_ENABLE; static int sysrq_sysctl_handler(ctl_table *table, int write, void __user *buffer, size_t *lenp, -- cgit v1.2.3