| Message ID | 20200512223946.888020-1-aquini@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] kernel: sysctl: ignore out-of-range taint bits introduced via kernel.tainted | expand |
On Tue, May 12, 2020 at 06:39:46PM -0400, Rafael Aquini wrote: > Users with SYS_ADMIN capability can add arbitrary taint flags > to the running kernel by writing to /proc/sys/kernel/tainted > or issuing the command 'sysctl -w kernel.tainted=...'. > These interface, however, are open for any integer value > and this might an invalid set of flags being committed to > the tainted_mask bitset. > > This patch introduces a simple way for proc_taint() to ignore > any eventual invalid bit coming from the user input before > committing those bits to the kernel tainted_mask. > > Signed-off-by: Rafael Aquini <aquini@redhat.com> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Luis
On Wed, May 13, 2020 at 12:39:53AM +0000, Luis Chamberlain wrote: > On Tue, May 12, 2020 at 06:39:46PM -0400, Rafael Aquini wrote: > > Users with SYS_ADMIN capability can add arbitrary taint flags > > to the running kernel by writing to /proc/sys/kernel/tainted > > or issuing the command 'sysctl -w kernel.tainted=...'. I just notice 2 minor 'screw ups' on my part in the commit log: > > These interface, however, are open for any integer value This one probably needs to be reprhased as: "The interface, however, is ... " > > and this might an invalid set of flags being committed to and I'm missing a verb here, as it should read: "and this might cause an invalid ... " I hope these are easy fixes, in the pre-merge step. (Sorry!) > > the tainted_mask bitset. > > > > This patch introduces a simple way for proc_taint() to ignore > > any eventual invalid bit coming from the user input before > > committing those bits to the kernel tainted_mask. > > > > Signed-off-by: Rafael Aquini <aquini@redhat.com> > > Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> > Thanks! -- Rafael
diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 8a176d8727a3..fcd46fc41206 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -2628,10 +2628,9 @@ static int proc_taint(struct ctl_table *table, int write, * to everyone's atomic.h for this */ int i; - for (i = 0; i < BITS_PER_LONG && tmptaint >> i; i++) { - if ((tmptaint >> i) & 1) + for (i = 0; i < TAINT_FLAGS_COUNT; i++) + if ((1UL << i) & tmptaint) add_taint(i, LOCKDEP_STILL_OK); - } } return err;
Users with SYS_ADMIN capability can add arbitrary taint flags to the running kernel by writing to /proc/sys/kernel/tainted or issuing the command 'sysctl -w kernel.tainted=...'. These interface, however, are open for any integer value and this might an invalid set of flags being committed to the tainted_mask bitset. This patch introduces a simple way for proc_taint() to ignore any eventual invalid bit coming from the user input before committing those bits to the kernel tainted_mask. Signed-off-by: Rafael Aquini <aquini@redhat.com> --- Changelog: v2: simplify the bit iterator within proc_taint(), and silently drop out-of-range bits (akpm) kernel/sysctl.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)