[PATCH] initramfs overwrite fix

This patch ensures that initramfs overwrites work correctly, even when dealing
with device nodes of different types.  Furthermore, when replacing a file
which already exists, we must make very certain that we truncate the existing
file.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Michael Neuling <mikey@neuling.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 30 insertions, 6 deletions

diff --git a/init/initramfs.c b/init/initramfs.c
index f81cfa40a719..d28c1094d7e5 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -30,6 +30,7 @@ static void __init free(void *where)
 
 static __initdata struct hash {
         int ino, minor, major;
+        mode_t mode;
         struct hash *next;
         char name[N_ALIGN(PATH_MAX)];
 } *head[32];
@@ -41,7 +42,8 @@ static inline int hash(int major, int minor, int ino)
         return tmp & 31;
 }
 
-static char __init *find_link(int major, int minor, int ino, char *name)
+static char __init *find_link(int major, int minor, int ino,
+                              mode_t mode, char *name)
 {
         struct hash **p, *q;
         for (p = head + hash(major, minor, ino); *p; p = &(*p)->next) {
@@ -51,14 +53,17 @@ static char __init *find_link(int major, int minor, int ino, char *name)
                         continue;
                 if ((*p)->major != major)
                         continue;
+                if (((*p)->mode ^ mode) & S_IFMT)
+                        continue;
                 return (*p)->name;
         }
         q = (struct hash *)malloc(sizeof(struct hash));
         if (!q)
                 panic("can't allocate link hash entry");
-        q->ino = ino;
-        q->minor = minor;
         q->major = major;
+        q->minor = minor;
+        q->ino = ino;
+        q->mode = mode;
         strcpy(q->name, name);
         q->next = NULL;
         *p = q;
@@ -229,13 +234,25 @@ static int __init do_reset(void)
 static int __init maybe_link(void)
 {
         if (nlink >= 2) {
-                char *old = find_link(major, minor, ino, collected);
+                char *old = find_link(major, minor, ino, mode, collected);
                 if (old)
                         return (sys_link(old, collected) < 0) ? -1 : 1;
         }
         return 0;
 }
 
+static void __init clean_path(char *path, mode_t mode)
+{
+        struct stat st;
+
+        if (!sys_newlstat(path, &st) && (st.st_mode^mode) & S_IFMT) {
+                if (S_ISDIR(st.st_mode))
+                        sys_rmdir(path);
+                else
+                        sys_unlink(path);
+        }
+}
+
 static __initdata int wfd;
 
 static int __init do_name(void)
@@ -248,9 +265,15 @@ static int __init do_name(void)
         }
         if (dry_run)
                 return 0;
+        clean_path(collected, mode);
         if (S_ISREG(mode)) {
-                if (maybe_link() >= 0) {
-                        wfd = sys_open(collected, O_WRONLY|O_CREAT, mode);
+                int ml = maybe_link();
+                if (ml >= 0) {
+                        int openflags = O_WRONLY|O_CREAT;
+                        if (ml != 1)
+                                openflags |= O_TRUNC;
+                        wfd = sys_open(collected, openflags, mode);
+
                         if (wfd >= 0) {
                                 sys_fchown(wfd, uid, gid);
                                 sys_fchmod(wfd, mode);
@@ -291,6 +314,7 @@ static int __init do_copy(void)
 static int __init do_symlink(void)
 {
         collected[N_ALIGN(name_len) + body_len] = '\0';
+        clean_path(collected, 0);
         sys_symlink(collected + N_ALIGN(name_len), collected);
         sys_lchown(collected, uid, gid);
         state = SkipIt;