SYSCTL_WRITES_WARN was added in f4aacea2f5d1a ("sysctl: allow for strict
write position handling"), and released in v3.16 in August of 2014. Since
then I can find only 1 instance of non-zero offset writing[1], and it
was fixed immediately in CRIU[2]. As such, it appears safe to flip this
to the strict state now.[1] https://www.google.com/search?q="when%20file%20position%20was%20not%200"; [2] http://lists.openvz.org/pipermail/criu/2015-April/019819.html Signed-off-by: Kees Cook <[email protected]> --- Documentation/sysctl/kernel.txt | 15 +++++++-------- kernel/sysctl.c | 2 +- 2 files changed, 8 insertions(+), 9 deletions(-) diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt index af70d1541d3a..be61d53e997f 100644 --- a/Documentation/sysctl/kernel.txt +++ b/Documentation/sysctl/kernel.txt @@ -810,14 +810,13 @@ via the /proc/sys interface: Each write syscall must fully contain the sysctl value to be written, and multiple writes on the same sysctl file descriptor will rewrite the sysctl value, regardless of file position. - 0 - (default) Same behavior as above, but warn about processes that - perform writes to a sysctl file descriptor when the file position - is not 0. - 1 - Respect file position when writing sysctl strings. Multiple writes - will append to the sysctl value buffer. Anything past the max length - of the sysctl value buffer will be ignored. Writes to numeric sysctl - entries must always be at file position 0 and the value must be - fully contained in the buffer sent in the write syscall. + 0 - Same behavior as above, but warn about processes that perform writes + to a sysctl file descriptor when the file position is not 0. + 1 - (default) Respect file position when writing sysctl strings. Multiple + writes will append to the sysctl value buffer. Anything past the max + length of the sysctl value buffer will be ignored. Writes to numeric + sysctl entries must always be at file position 0 and the value must + be fully contained in the buffer sent in the write syscall. ============================================================== diff --git a/kernel/sysctl.c b/kernel/sysctl.c index dc6858d6639e..081873afba6b 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -173,7 +173,7 @@ extern int no_unaligned_warning; #define SYSCTL_WRITES_WARN 0 #define SYSCTL_WRITES_STRICT 1 -static int sysctl_writes_strict = SYSCTL_WRITES_WARN; +static int sysctl_writes_strict = SYSCTL_WRITES_STRICT; static int proc_do_cad_pid(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos); -- 1.9.1 -- Kees Cook Chrome OS & Brillo Security -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
