On Thu, Mar 01, 2018 at 12:43:40PM -0500, Waiman Long wrote: > This patch clamps the semmni value (fourth element of sem_ctls[] > array) to within the [0, IPCMNI] range and prints a warning message > once when an out-of-range value is being written. > > Signed-off-by: Waiman Long <[email protected]> > --- > ipc/ipc_sysctl.c | 13 ++++++++++++- > ipc/sem.c | 28 ++++++++++++++++++++++++++++ > ipc/util.h | 4 ++++ > 3 files changed, 44 insertions(+), 1 deletion(-) > > diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c > index 8eb7268..2c03f57 100644 > --- a/ipc/ipc_sysctl.c > +++ b/ipc/ipc_sysctl.c > @@ -97,12 +97,22 @@ static int proc_ipc_auto_msgmni(struct ctl_table *table, > int write, > return proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos); > } > > +static int proc_ipc_sem_dointvec(struct ctl_table *table, int write, > + void __user *buffer, size_t *lenp, loff_t *ppos) > +{ > + int ret = proc_ipc_dointvec(table, write, buffer, lenp, ppos); > + > + sem_check_semmni(table, current->nsproxy->ipc_ns); > + return ret; > +} > + > #else > #define proc_ipc_doulongvec_minmax NULL > #define proc_ipc_dointvec NULL > #define proc_ipc_dointvec_minmax NULL > #define proc_ipc_dointvec_minmax_orphans NULL > #define proc_ipc_auto_msgmni NULL > +#define proc_ipc_sem_dointvec NULL > #endif > > static int zero; > @@ -186,7 +196,8 @@ static int proc_ipc_auto_msgmni(struct ctl_table *table, > int write, > .data = &init_ipc_ns.sem_ctls, > .maxlen = 4*sizeof(int), > .mode = 0644, > - .proc_handler = proc_ipc_dointvec, > + .proc_handler = proc_ipc_sem_dointvec, > + .flags = CTL_FLAGS_CLAMP_RANGE, > }, > #ifdef CONFIG_CHECKPOINT_RESTORE > { > diff --git a/ipc/sem.c b/ipc/sem.c > index a4af049..739dfca 100644 > --- a/ipc/sem.c > +++ b/ipc/sem.c > @@ -2337,3 +2337,31 @@ static int sysvipc_sem_proc_show(struct seq_file *s, > void *it) > return 0; > } > #endif > + > +#ifdef CONFIG_PROC_SYSCTL > +/* > + * Check to see if semmni is out of range and clamp it if necessary. > + */ > +void sem_check_semmni(struct ctl_table *table, struct ipc_namespace *ns) > +{ > + bool clamped = false; > + > + if (!(table->flags & CTL_FLAGS_CLAMP_RANGE)) > + return; > + > + /* > + * Clamp semmni to the range [0, IPCMNI]. > + */ > + if (ns->sc_semmni < 0) { > + ns->sc_semmni = 0; > + clamped = true; > + } > + if (ns->sc_semmni > IPCMNI) { > + ns->sc_semmni = IPCMNI; > + clamped = true; > + } > + if (clamped) > + pr_warn_once("Kernel parameter \"sem[3]\" was set out of range > [%d, %d], clamped to %d.\n", > + 0, IPCMNI, ns->sc_semmni);
Why are the users issuing a warning, wouldn't the API do the warning on its own, specially since we're adding a warn flag? Luis
