summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
Diffstat
-rw-r--r--fs/fs_context.c105
-rw-r--r--fs/fsopen.c67
-rw-r--r--include/linux/fs_context.h22
-rw-r--r--include/linux/module.h6
4 files changed, 179 insertions, 21 deletions
diff --git a/fs/fs_context.c b/fs/fs_context.c
index eb806fae3117..dcf3786f90f9 100644
--- a/fs/fs_context.c
+++ b/fs/fs_context.c
@@ -11,6 +11,7 @@
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/module.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include <linux/fs.h>
@@ -23,6 +24,7 @@
#include <linux/pid_namespace.h>
#include <linux/user_namespace.h>
#include <net/net_namespace.h>
+#include <asm/sections.h>
#include "mount.h"
#include "internal.h"
@@ -365,6 +367,8 @@ struct fs_context *vfs_dup_fs_context(struct fs_context *src_fc)
get_net(fc->net_ns);
get_user_ns(fc->user_ns);
get_cred(fc->cred);
+ if (fc->log)
+ refcount_inc(&fc->log->usage);
/* Can't call put until we've called ->dup */
ret = fc->ops->dup(fc, src_fc);
@@ -382,7 +386,6 @@ err_fc:
}
EXPORT_SYMBOL(vfs_dup_fs_context);
-#ifdef CONFIG_PRINTK
/**
* logfc - Log a message to a filesystem context
* @fc: The filesystem context to log to.
@@ -390,27 +393,100 @@ EXPORT_SYMBOL(vfs_dup_fs_context);
*/
void logfc(struct fs_context *fc, const char *fmt, ...)
{
+ static const char store_failure[] = "OOM: Can't store error string";
+ struct fc_log *log = fc ? fc->log : NULL;
+ const char *p;
va_list va;
+ char *q;
+ u8 freeable;
va_start(va, fmt);
-
- switch (fmt[0]) {
- case 'w':
- vprintk_emit(0, LOGLEVEL_WARNING, NULL, 0, fmt, va);
- break;
- case 'e':
- vprintk_emit(0, LOGLEVEL_ERR, NULL, 0, fmt, va);
- break;
- default:
- vprintk_emit(0, LOGLEVEL_NOTICE, NULL, 0, fmt, va);
- break;
+ if (!strchr(fmt, '%')) {
+ p = fmt;
+ goto unformatted_string;
}
+ if (strcmp(fmt, "%s") == 0) {
+ p = va_arg(va, const char *);
+ goto unformatted_string;
+ }
+
+ q = kvasprintf(GFP_KERNEL, fmt, va);
+copied_string:
+ if (!q)
+ goto store_failure;
+ freeable = 1;
+ goto store_string;
+
+unformatted_string:
+ if ((unsigned long)p >= (unsigned long)__start_rodata &&
+ (unsigned long)p < (unsigned long)__end_rodata)
+ goto const_string;
+ if (log && within_module_core((unsigned long)p, log->owner))
+ goto const_string;
+ q = kstrdup(p, GFP_KERNEL);
+ goto copied_string;
+
+store_failure:
+ p = store_failure;
+const_string:
+ q = (char *)p;
+ freeable = 0;
+store_string:
+ if (!log) {
+ switch (fmt[0]) {
+ case 'w':
+ printk(KERN_WARNING "%s\n", q + 2);
+ break;
+ case 'e':
+ printk(KERN_ERR "%s\n", q + 2);
+ break;
+ default:
+ printk(KERN_NOTICE "%s\n", q + 2);
+ break;
+ }
+ if (freeable)
+ kfree(q);
+ } else {
+ unsigned int logsize = ARRAY_SIZE(log->buffer);
+ u8 index;
+
+ index = log->head & (logsize - 1);
+ BUILD_BUG_ON(sizeof(log->head) != sizeof(u8) ||
+ sizeof(log->tail) != sizeof(u8));
+ if ((u8)(log->head - log->tail) == logsize) {
+ /* The buffer is full, discard the oldest message */
+ if (log->need_free & (1 << index))
+ kfree(log->buffer[index]);
+ log->tail++;
+ }
- pr_cont("\n");
+ log->buffer[index] = q;
+ log->need_free &= ~(1 << index);
+ log->need_free |= freeable << index;
+ log->head++;
+ }
va_end(va);
}
EXPORT_SYMBOL(logfc);
-#endif
+
+/*
+ * Free a logging structure.
+ */
+static void put_fc_log(struct fs_context *fc)
+{
+ struct fc_log *log = fc->log;
+ int i;
+
+ if (log) {
+ if (refcount_dec_and_test(&log->usage)) {
+ fc->log = NULL;
+ for (i = 0; i <= 7; i++)
+ if (log->need_free & (1 << i))
+ kfree(log->buffer[i]);
+ kfree(log);
+ }
+ }
+}
/**
* put_fs_context - Dispose of a superblock configuration context.
@@ -435,6 +511,7 @@ void put_fs_context(struct fs_context *fc)
put_user_ns(fc->user_ns);
put_cred(fc->cred);
kfree(fc->subtype);
+ put_fc_log(fc);
put_filesystem(fc->fs_type);
kfree(fc->source);
kfree(fc);
diff --git a/fs/fsopen.c b/fs/fsopen.c
index d256f1ac9ff1..5fce6347de7a 100644
--- a/fs/fsopen.c
+++ b/fs/fsopen.c
@@ -20,6 +20,52 @@
#include <uapi/linux/mount.h>
#include "mount.h"
+/*
+ * Allow the user to read back any error, warning or informational messages.
+ */
+static ssize_t fscontext_read(struct file *file,
+ char __user *_buf, size_t len, loff_t *pos)
+{
+ struct fs_context *fc = file->private_data;
+ struct fc_log *log = fc->log;
+ unsigned int logsize = ARRAY_SIZE(log->buffer);
+ ssize_t ret;
+ char *p;
+ bool need_free;
+ int index, n;
+
+ ret = mutex_lock_interruptible(&fc->uapi_mutex);
+ if (ret < 0)
+ return ret;
+
+ if (log->head == log->tail) {
+ mutex_unlock(&fc->uapi_mutex);
+ return -ENODATA;
+ }
+
+ index = log->tail & (logsize - 1);
+ p = log->buffer[index];
+ need_free = log->need_free & (1 << index);
+ log->buffer[index] = NULL;
+ log->need_free &= ~(1 << index);
+ log->tail++;
+ mutex_unlock(&fc->uapi_mutex);
+
+ ret = -EMSGSIZE;
+ n = strlen(p);
+ if (n > len)
+ goto err_free;
+ ret = -EFAULT;
+ if (copy_to_user(_buf, p, n) != 0)
+ goto err_free;
+ ret = n;
+
+err_free:
+ if (need_free)
+ kfree(p);
+ return ret;
+}
+
static int fscontext_release(struct inode *inode, struct file *file)
{
struct fs_context *fc = file->private_data;
@@ -32,6 +78,7 @@ static int fscontext_release(struct inode *inode, struct file *file)
}
const struct file_operations fscontext_fops = {
+ .read = fscontext_read,
.release = fscontext_release,
.llseek = no_llseek,
};
@@ -50,6 +97,16 @@ static int fscontext_create_fd(struct fs_context *fc, unsigned int o_flags)
return fd;
}
+static int fscontext_alloc_log(struct fs_context *fc)
+{
+ fc->log = kzalloc(sizeof(*fc->log), GFP_KERNEL);
+ if (!fc->log)
+ return -ENOMEM;
+ refcount_set(&fc->log->usage, 1);
+ fc->log->owner = fc->fs_type->owner;
+ return 0;
+}
+
/*
* Open a filesystem by name so that it can be configured for mounting.
*
@@ -62,6 +119,7 @@ SYSCALL_DEFINE2(fsopen, const char __user *, _fs_name, unsigned int, flags)
struct file_system_type *fs_type;
struct fs_context *fc;
const char *fs_name;
+ int ret;
if (!ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN))
return -EPERM;
@@ -84,5 +142,14 @@ SYSCALL_DEFINE2(fsopen, const char __user *, _fs_name, unsigned int, flags)
return PTR_ERR(fc);
fc->phase = FS_CONTEXT_CREATE_PARAMS;
+
+ ret = fscontext_alloc_log(fc);
+ if (ret < 0)
+ goto err_fc;
+
return fscontext_create_fd(fc, flags & FSOPEN_CLOEXEC ? O_CLOEXEC : 0);
+
+err_fc:
+ put_fs_context(fc);
+ return ret;
}
diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h
index 7ab8b44fab3e..1f966670c8dc 100644
--- a/include/linux/fs_context.h
+++ b/include/linux/fs_context.h
@@ -13,6 +13,7 @@
#define _LINUX_FS_CONTEXT_H
#include <linux/kernel.h>
+#include <linux/refcount.h>
#include <linux/errno.h>
#include <linux/security.h>
#include <linux/mutex.h>
@@ -95,6 +96,7 @@ struct fs_context {
struct user_namespace *user_ns; /* The user namespace for this mount */
struct net *net_ns; /* The network namespace for this mount */
const struct cred *cred; /* The mounter's credentials */
+ struct fc_log *log; /* Logging buffer */
const char *source; /* The source name (eg. dev path) */
const char *subtype; /* The subtype to set on the superblock */
void *security; /* Linux S&M options */
@@ -151,15 +153,21 @@ extern int vfs_get_super(struct fs_context *fc,
extern const struct file_operations fscontext_fops;
-#ifdef CONFIG_PRINTK
+/*
+ * Mount error, warning and informational message logging. This structure is
+ * shareable between a mount and a subordinate mount.
+ */
+struct fc_log {
+ refcount_t usage;
+ u8 head; /* Insertion index in buffer[] */
+ u8 tail; /* Removal index in buffer[] */
+ u8 need_free; /* Mask of kfree'able items in buffer[] */
+ struct module *owner; /* Owner module for strings that don't then need freeing */
+ char *buffer[8];
+};
+
extern __attribute__((format(printf, 2, 3)))
void logfc(struct fs_context *fc, const char *fmt, ...);
-#else
-static inline __attribute__((format(printf, 2, 3)))
-void logfc(struct fs_context *fc, const char *fmt, ...)
-{
-}
-#endif
/**
* infof - Store supplementary informational message
diff --git a/include/linux/module.h b/include/linux/module.h
index 5bf5dcd91009..7dc4dc79b634 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -709,6 +709,12 @@ static inline bool is_module_text_address(unsigned long addr)
return false;
}
+static inline bool within_module_core(unsigned long addr,
+ const struct module *mod)
+{
+ return false;
+}
+
/* Get/put a kernel symbol (calls should be symmetric) */
#define symbol_get(x) ({ extern typeof(x) x __attribute__((weak)); &(x); })
#define symbol_put(x) do { } while (0)
generated by cgit (git 2.34.1) at 2024-06-02 22:39:08 +0000