Guarded against some hypothetically possible errors

[procprotect.git] / procprotect.c

diff --git a/procprotect.c b/procprotect.c
index 74c48b9..1c3e803 100644 (file)
--- a/procprotect.c
+++ b/procprotect.c
@@ -72,7 +72,7 @@ struct proc_dir_entry *proc_entry;
 
 static int run_acl(unsigned long ino) {
     struct acl_entry *entry;
-    hlist_for_each_entry_rcu(entry, 
+    hlist_for_each_entry_rcu_notrace(entry, 
                             &procprotect_hash[ino & (HASH_SIZE-1)],
                             hlist) {
         if (entry->ino==ino) {
@@ -91,8 +91,16 @@ static int lookup_fast_entry(struct kretprobe_instance *ri, struct pt_regs *regs
     int ret = -1;
     struct procprotect_ctx *ctx;
     struct nameidata *nd = (struct nameidata *) regs->di;
-    struct dentry *parent = nd->path.dentry;
-    struct inode *pinode = parent->d_inode;
+    struct dentry *parent;
+    struct inode *pinode;
+       
+       if (!nd) return ret;
+       parent = nd->path.dentry;
+
+       if (!parent) return ret;
+       pinode = parent->d_inode;
+
+       if (!pinode || !pinode->i_sb || !current || !current->nsproxy) return ret;
 
     if (pinode->i_sb->s_magic == PROC_SUPER_MAGIC
             && current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns) {  
@@ -132,9 +140,13 @@ static int lookup_slow_entry(struct kretprobe_instance *ri, struct pt_regs *regs
     struct procprotect_ctx *ctx;
     struct nameidata *nd = (struct nameidata *) regs->di;
     struct path *p = (struct path *) regs->si;
+    struct dentry *parent;
+       struct inode *pinode;
 
-    struct dentry *parent = nd->path.dentry;
-    struct inode *pinode = parent->d_inode;
+       if (!nd) return;
+       parent = nd->path.dentry;
+    if (!parent) return;
+       pinode= parent->d_inode;
 
     if (pinode->i_sb->s_magic == PROC_SUPER_MAGIC
             && current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns) {  
@@ -219,6 +231,55 @@ static struct kretprobe slow_probe = {
     .data_size = sizeof(struct procprotect_ctx)
 };
 
+int once_only = 0;
+
+static int init_probes(void) {
+       int ret;
+       dolast_probe.kp.addr = 
+               (kprobe_opcode_t *) kallsyms_lookup_name("do_last");
+
+       if (!dolast_probe.kp.addr) {
+               printk("Couldn't find %s to plant kretprobe\n", "do_last");
+               return -1;
+       }
+
+       if ((ret = register_jprobe(&dolast_probe)) <0) {
+               printk("register_jprobe failed, returned %u\n", ret);
+               return -1;
+       }
+       fast_probe.kp.addr = 
+               (kprobe_opcode_t *) kallsyms_lookup_name("lookup_fast");
+
+       if (!fast_probe.kp.addr) {
+               printk("Couldn't find %s to plant kretprobe\n", "lookup_fast");
+               return -1;
+       }
+
+       slow_probe.kp.addr = 
+               (kprobe_opcode_t *) kallsyms_lookup_name("lookup_slow");
+
+       if (!slow_probe.kp.addr) {
+               printk("Couldn't find %s to plant kretprobe\n", "lookup_slow");
+               return -1;
+       }
+
+       if ((ret = register_kretprobe(&fast_probe)) <0) {
+               printk("register_kretprobe failed, returned %d\n", ret);
+               return -1;
+       }
+
+       printk("Planted kretprobe at %p, handler addr %p\n",
+                       fast_probe.kp.addr, fast_probe.handler);
+
+       if ((ret = register_kretprobe(&slow_probe)) <0) {
+               printk("register_kretprobe failed, returned %d\n", ret);
+               return -1;
+       }
+       printk("Planted kretprobe at %p, handler addr %p\n",
+                       slow_probe.kp.addr, slow_probe.handler);
+       return 0;
+}
+
 static void add_entry(char *pathname) {
     struct path path;
     if (kern_path(pathname, 0, &path)) {
@@ -243,6 +304,7 @@ static void add_entry(char *pathname) {
             }
         }
     }
+
 }
 
 
@@ -284,6 +346,12 @@ int procfile_write(struct file *file, const char *buffer, unsigned long count, v
         pathname[count]='\0';
 
     add_entry(pathname);       
+               
+       if (!once_only) {
+               once_only=1;
+               if (init_probes()==-1)
+                       printk(KERN_CRIT "Could not install procprotect probes. Reload module to retry.");
+       }
     printk(KERN_CRIT "Length of buffer=%d",strlen(pathname));
     return count;
 }
@@ -293,6 +361,7 @@ static const struct file_operations procprotect_fops = {
     .write = procfile_write
 };
                           
+
 static int __init procprotect_init(void)
 {
     int ret;
@@ -308,54 +377,8 @@ static int __init procprotect_init(void)
     aclqpath.name = aclpath;
     aclqpath.len = strnlen(aclpath, PATH_MAX);
 
-    dolast_probe.kp.addr = 
-        (kprobe_opcode_t *) kallsyms_lookup_name("do_last");
-
-    if (!dolast_probe.kp.addr) {
-        printk("Couldn't find %s to plant kretprobe\n", "do_last");
-        return -1;
-    }
-
-    if ((ret = register_jprobe(&dolast_probe)) <0) {
-                  printk("register_jprobe failed, returned %u\n", ret);
-                  return -1;
-    }
-    fast_probe.kp.addr = 
-        (kprobe_opcode_t *) kallsyms_lookup_name("lookup_fast");
-
-    if (!fast_probe.kp.addr) {
-        printk("Couldn't find %s to plant kretprobe\n", "lookup_fast");
-        return -1;
-    }
-
-    slow_probe.kp.addr = 
-        (kprobe_opcode_t *) kallsyms_lookup_name("lookup_slow");
-
-    if (!slow_probe.kp.addr) {
-        printk("Couldn't find %s to plant kretprobe\n", "lookup_slow");
-        return -1;
-    }
-
-    
-
-    if ((ret = register_kretprobe(&fast_probe)) <0) {
-        printk("register_kretprobe failed, returned %d\n", ret);
-        return -1;
-    }
-
-    printk("Planted kretprobe at %p, handler addr %p\n",
-            fast_probe.kp.addr, fast_probe.handler);
-
-    if ((ret = register_kretprobe(&slow_probe)) <0) {
-        printk("register_kretprobe failed, returned %d\n", ret);
-        return -1;
-    }
-    printk("Planted kretprobe at %p, handler addr %p\n",
-            slow_probe.kp.addr, slow_probe.handler);
-
     proc_entry = proc_create("procprotect", 0644, NULL, &procprotect_fops);
 
-    add_entry("/proc/sysrq-trigger");
     return ret;
 }