Quoting [EMAIL PROTECTED] ([EMAIL PROTECTED]): > PATCH [06/06] > > This patch introduces the .write seq operation for /proc/pid/semundo. > > In order to simplify the locking strategy, the write operation is only allowed > to 'current'. > > > Signed-off-by: Nadia Derbey <[EMAIL PROTECTED]>
Acked-by: Serge Hallyn <[EMAIL PROTECTED]> Have you written a patch to cryo in light of the new (target==current) restriction? thanks, -serge > > --- > fs/proc/base.c | 2 > ipc/sem.c | 250 > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++- > 2 files changed, 250 insertions(+), 2 deletions(-) > > Index: linux-2.6.26-rc5-mm3/fs/proc/base.c > =================================================================== > --- linux-2.6.26-rc5-mm3.orig/fs/proc/base.c 2008-06-24 10:03:33.000000000 > +0200 > +++ linux-2.6.26-rc5-mm3/fs/proc/base.c 2008-06-24 13:21:44.000000000 > +0200 > @@ -2526,7 +2526,7 @@ static const struct pid_entry tgid_base_ > INF("io", S_IRUGO, tgid_io_accounting), > #endif > #ifdef CONFIG_SYSVIPC > - REG("semundo", S_IRUGO, semundo), > + REG("semundo", S_IWUSR|S_IRUGO, semundo), > #endif > }; > > Index: linux-2.6.26-rc5-mm3/ipc/sem.c > =================================================================== > --- linux-2.6.26-rc5-mm3.orig/ipc/sem.c 2008-06-24 12:59:15.000000000 > +0200 > +++ linux-2.6.26-rc5-mm3/ipc/sem.c 2008-06-25 08:56:07.000000000 +0200 > @@ -1554,7 +1554,27 @@ static int semundo_open(struct inode *in > goto out_err; > } > > - ulp = get_proc_ulp(task); > + if (file->f_flags & O_WRONLY || file->f_flags & O_RDWR) { > + /* > + * Writing is only allowed to current > + */ > + if (task != current) { > + put_task_struct(task); > + ret = -EPERM; > + goto out_err; > + } > + /* > + * No need to increment the undo_list's refcnt: only current > + * can be freeing it through exit, and we are current. > + * Only signal through the ulp NULL pointer that it won't be > + * necessary to decrement the refcnt during release. > + * Actually, in this path the undo_list will be gotten during > + * the write operation. > + */ > + ulp = NULL; > + } else > + ulp = get_proc_ulp(task); > + > ns = get_ipc_ns(task->nsproxy->ipc_ns); > put_task_struct(task); > > @@ -1574,6 +1594,233 @@ out_err: > return ret; > } > > +/* Skip all spaces at the beginning of the buffer */ > +static inline int skip_space(const char __user **buf, size_t *len) > +{ > + char c = 0; > + while (*len) { > + if (get_user(c, *buf)) > + return -EFAULT; > + if (c != '\t' && c != ' ') > + break; > + --*len; > + ++*buf; > + } > + return c; > +} > + > +/* Retrieve the first numerical value contained in the string. > + * Note: The value is supposed to be a 32-bit integer. > + */ > +static inline int get_next_value(const char __user **buf, size_t *len, int > *val) > +{ > +#define BUFLEN 11 > + int err, neg = 0, left; > + char s[BUFLEN], *p; > + > + err = skip_space(buf, len); > + if (err < 0) > + return err; > + if (!*len) > + return INT_MAX; > + if (err == '\n') { > + ++*buf; > + --*len; > + return INT_MAX; > + } > + if (err == '-') { > + ++*buf; > + --*len; > + neg = 1; > + } > + > + left = *len; > + if (left > sizeof(s) - 1) > + left = sizeof(s) - 1; > + if (copy_from_user(s, *buf, left)) > + return -EFAULT; > + > + s[left] = 0; > + p = s; > + if (*p < '0' || *p > '9') > + return -EINVAL; > + > + *val = simple_strtoul(p, &p, 0); > + if (neg) > + *val = -(*val); > + > + left = p-s; > + (*len) -= left; > + (*buf) += left; > + > + return 0; > +#undef BUFLEN > +} > + > +/* > + * Reads a line from /proc/self/semundo. > + * Returns the number of undo values read (or errcode upon failure). > + * @id: pointer to the semid (filled in with 1st field in the line) > + * @array: semundo values (filled in iwth remaining fields in the line). > + * @array_len: max # of expected semundo values > + */ > +static inline int semundo_readline(const char __user **buf, size_t *left, > + int *id, short *array, int array_len) > +{ > + int i, val, err; > + > + /* Read semid */ > + err = get_next_value(buf, left, id); > + if (err) > + return err; > + > + /* Read all (semundo-) values of a full line */ > + for (i = 0; ; i++) { > + err = get_next_value(buf, left, &val); > + if (err < 0) > + return err; > + /* reached end of line or end of buffer */ > + if (err == INT_MAX) > + break; > + /* Return an error if we get more values than expected */ > + if (i < array_len) > + array[i] = val; > + else > + return -EINVAL; > + } > + return i; > +} > + > +/* > + * sets or updates the undo values for the undo_list of a given semaphore id. > + * This is exactly the same code sequence as sys_semtimedop if we have undos. > + */ > +static inline int semundo_update(struct ipc_namespace *ns, int semid, > + short *array, int size) > +{ > + struct sem_undo *un; > + struct sem_array *sma; > + int ret = 0; > + > + un = find_alloc_undo(ns, semid); > + if (IS_ERR(un)) { > + ret = PTR_ERR(un); > + goto out; > + } > + > + /* lookup the sem_array */ > + sma = sem_lock(ns, semid); > + if (IS_ERR(sma)) { > + ret = PTR_ERR(sma); > + rcu_read_unlock(); > + goto out; > + } > + > + /* > + * find_alloc_undo opened an rcu read section to protect un. > + * Releasing it here is safe: > + * . sem_lock is held, so we are protected against IPC_RMID > + * . the refcnt won't fall to 0 since exit_sem only operates on > + * current and we are the current. > + */ > + rcu_read_unlock(); > + > + /* > + * semid identifiers are not unique - find_alloc_undo() may have > + * allocated an undo structure, it was invalidated by an RMID and now > + * a new array received the same id. > + * Check and fail. > + * This case can be detected checking un->semid. The existance of > + * "un" itself is guaranteed by rcu. > + */ > + if (un->semid == -1) { > + ret = -EIDRM; > + goto out_unlock; > + } > + > + /* > + * If the number of values given does not match the number of > + * semaphores in the array, consider this as an error. > + */ > + if (size != sma->sem_nsems) { > + ret = -EINVAL; > + goto out_unlock; > + } > + > + /* update the undo values */ > + while (--size >= 0) > + un->semadj[size] = array[size]; > + > + /* maybe some queued-up processes were waiting for this */ > + update_queue(sma); > + > +out_unlock: > + sem_unlock(sma); > +out: > + return ret; > +} > + > +/* > + * write operation for /proc/self/semundo file > + * > + * Only current is allowed to write to its semundo file. > + * > + * The expected string format is: > + * "<semID> <val1> <val2> ... <valN>" > + * > + * It sets (or updates) the sem_undo list for 'current' and the target > + * <semID>, to the given 'undo' values. > + * > + * <semID> must match an existing semaphore array. > + * The number of values following <semID> must match the number of semaphores > + * in the corresponding array. > + * > + * Multiple semID's can be passed simultaneously: newline ('\n') is > considered > + * as a separator in that case. > + * > + * Note: it is not allowed to set the sem_undo list for a given semID using > + * mutliple write calls. > + */ > +static ssize_t semundo_write(struct file *file, const char __user *buf, > + size_t count, loff_t *ppos) > +{ > + struct seq_file *m = file->private_data; > + short *array; > + int err, max_sem, semid = 0; > + size_t left = count; > + struct undo_list_data *data = m->private; > + struct ipc_namespace *ns = data->ipc_ns; > + > + if (data->undo_list) > + /* Should never happen */ > + return -EINVAL; > + > + max_sem = ns->sc_semmsl; > + > + array = kmalloc(sizeof(short)*max_sem, GFP_KERNEL); > + if (array == NULL) > + return -ENOMEM; > + > + while (left) { > + int nval; > + > + nval = semundo_readline(&buf, &left, &semid, array, max_sem); > + if (nval < 0) { > + err = nval; > + goto out; > + } > + > + err = semundo_update(ns, semid, array, nval); > + if (err) > + goto out; > + } > + err = count - left; > + > +out: > + kfree(array); > + return err; > +} > + > static int semundo_release(struct inode *inode, struct file *file) > { > struct seq_file *m = file->private_data; > @@ -1590,6 +1837,7 @@ static int semundo_release(struct inode > const struct file_operations proc_semundo_operations = { > .open = semundo_open, > .read = seq_read, > + .write = semundo_write, > .llseek = seq_lseek, > .release = semundo_release, > }; > > -- _______________________________________________ Containers mailing list [EMAIL PROTECTED] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list Devel@openvz.org https://openvz.org/mailman/listinfo/devel