Merge pull request #35 from appview-team/alpine-latest

Resolve Alpine Latest Bug

Author: seanvaleo

src/appviewelf.c

@@ -159,14 +159,8 @@ getElf(char *path)
     return ebuf;
 }
 
-/*
- * Find the GOT ptr as defined in RELA/DYNSYM (.rela.dyn) for symbol & hook it.
- * .rela.dyn section:
- * The address of relocation entries associated solely with the PLT.
- * The relocation table's entries have a one-to-one correspondence with the PLT.
- */
-int
-doGotcha(struct link_map *lm, got_list_t *hook, Elf64_Rela *rel, Elf64_Sym *sym, char *str, int rsz, bool attach)
+static int
+setGot(struct link_map *lm, got_list_t *hook, Elf64_Sym *sym, char *str, Elf64_Rela *rel, size_t rsz, bool attach)
 {
     int i, match = -1;
     uint64_t prev;
@@ -252,9 +246,46 @@ doGotcha(struct link_map *lm, got_list_t *hook, Elf64_Rela *rel, Elf64_Sym *sym,
     return match;
 }
 
+/*
+ * Find the GOT ptr as defined in RELA/DYNSYM (.rela.dyn) for symbol & hook it.
+ * .rela.dyn section:
+ * The address of relocation entries associated solely with the PLT.
+ * The relocation table's entries have a one-to-one correspondence with the PLT.
+ *
+ * There are 2 relocation tables potentially used in an Elf object;
+ * 1) relocation rel 2) relocation with addends rela
+ * When one or the other is defined, no question. Use what is defined.
+ * When both rel and rela are defined we need to walk both tables. Some of the symbols we want to
+ * match are in rel and others in rela. Therefore, walk both.
+ *
+ * TODO: we should use a struct for param definition instead of so many passed params.
+ */
+int
+doGotcha(struct link_map *lm, got_list_t *hook, Elf64_Sym *sym, char *str, Elf64_Rela *rel, size_t rsz,
+         Elf64_Rela *rela, size_t rasz, bool attach)
+{
+    int matchrel = -1, matchrela = -1;
+
+    if (rel && (rsz > sizeof(Elf64_Rela))) {
+        matchrel = setGot(lm, hook, sym, str, rel, rsz, attach);
+    }
+
+    if (rela && (rasz > sizeof(Elf64_Rela))) {
+        matchrela = setGot(lm, hook, sym, str, rela, rasz, attach);
+    }
+
+    if ((matchrel != -1) || (matchrela != -1)) {
+        return 0;
+    } else {
+        return -1;
+    }
+}
+
 // Locate the needed elf entries from a given link map.
+// TODO: we should use a struct for param definition instead of so many passed params.
 int
-getElfEntries(struct link_map *lm, Elf64_Rela **rel, Elf64_Sym **sym, char **str, int *rsz)
+getElfEntries(struct link_map *lm, Elf64_Sym **sym, char **str,
+              Elf64_Rela **rel, size_t *rsz, Elf64_Rela **rela, size_t *rasz)
 {
     Elf64_Dyn *dyn = NULL;
     char *got = NULL; // TODO; got is not needed, debug, remove
@@ -274,6 +305,14 @@ getElfEntries(struct link_map *lm, Elf64_Rela **rel, Elf64_Sym **sym, char **str
             } else {
                 *str = (char *)(dyn->d_un.d_ptr + lm->l_addr);
             }
+        } else if (dyn->d_tag == DT_PLTGOT) {
+            if (osGetPageProt((uint64_t)dyn->d_un.d_ptr) != -1) {
+                got = (char *)(dyn->d_un.d_ptr);
+            } else {
+                got = (char *)(dyn->d_un.d_ptr + lm->l_addr);
+            }
+            appviewLog(CFG_LOG_DEBUG, "%s:%d DT_PLTGOT: 0x%lx",
+                       __FUNCTION__, __LINE__, (unsigned long int)got);
         } else if (dyn->d_tag == DT_JMPREL) {
             if (osGetPageProt((uint64_t)dyn->d_un.d_ptr) != -1) {
                 *rel = (Elf64_Rela *)((char *)(dyn->d_un.d_ptr));
@@ -282,19 +321,25 @@ getElfEntries(struct link_map *lm, Elf64_Rela **rel, Elf64_Sym **sym, char **str
             }
         } else if (dyn->d_tag == DT_PLTRELSZ) {
             *rsz = dyn->d_un.d_val;
-        } else if (dyn->d_tag == DT_PLTGOT) {
+        } else if (dyn->d_tag == DT_RELA) {
+            // This is a 'new' tag. Use it if present instead of DT_JMPREL
             if (osGetPageProt((uint64_t)dyn->d_un.d_ptr) != -1) {
-                got = (char *)(dyn->d_un.d_ptr);
+                *rela = (Elf64_Rela *)((char *)(dyn->d_un.d_ptr));
             } else {
-                got = (char *)(dyn->d_un.d_ptr + lm->l_addr);
+                *rela = (Elf64_Rela *)((char *)(dyn->d_un.d_ptr + lm->l_addr));
             }
+        } else if (dyn->d_tag == DT_RELASZ) {
+            // This is a 'new' tag. Use it if present instead of DT_PLTRELSZ
+            *rasz = dyn->d_un.d_val;
         }
     }
 
-    appviewLog(CFG_LOG_TRACE, "%s:%d name: %s dyn %p sym %p rel %p str %p rsz %d got %p laddr 0x%lx\n",
-                __FUNCTION__, __LINE__, lm->l_name, dyn, *sym, *rel, *str, *rsz, got, lm->l_addr);
+    appviewLog(CFG_LOG_DEBUG, "%s:%d name: %s dyn %p sym %p str %p rel %p rsz %ld rela %p rasz %ld got %p laddr 0x%lx",
+               __FUNCTION__, __LINE__, lm->l_name, dyn, *sym, *str, *rel, *rsz, *rela, *rasz, got, lm->l_addr);
 
-    if (*sym == NULL || *rel == NULL || (*rsz < sizeof(Elf64_Rela))) {
+    // if we have neither rel or rela then we have no entries
+    if ((*sym == NULL) || (((*rel == NULL) || (*rsz < sizeof(Elf64_Rela))) &&
+                           ((*rela == NULL) || (*rasz < sizeof(Elf64_Rela))))) {
         return -1;
     }
 

src/appviewelf.h

@@ -22,8 +22,10 @@ typedef struct {
 
 void freeElf(char *, size_t);
 elf_buf_t * getElf(char *);
-int doGotcha(struct link_map *, got_list_t *, Elf64_Rela *, Elf64_Sym *, char *, int, bool);
-int getElfEntries(struct link_map *, Elf64_Rela **, Elf64_Sym **, char **, int *rsz);
+int doGotcha(struct link_map *, got_list_t *, Elf64_Sym *, char *,
+             Elf64_Rela *, size_t, Elf64_Rela *, size_t, bool);
+int getElfEntries(struct link_map *, Elf64_Sym **, char **,
+                  Elf64_Rela **, size_t *, Elf64_Rela **, size_t *);
 Elf64_Shdr* getElfSection(char *, const char *);
 void * getSymbol(const char *, char *);
 void * getDynSymbol(const char *, char *);

src/fn.h

@@ -188,6 +188,8 @@ typedef struct {
     int (*SSL_read)(SSL *, void *, int);
     int (*SSL_write)(SSL *, const void *, int);
     int (*SSL_get_fd)(const SSL *);
+    int (*SSL_read_ex)(SSL *, void *, size_t, size_t *);
+    int (*SSL_write_ex)(SSL *, const void *, size_t, size_t *);
     ssize_t (*gnutls_record_recv)(gnutls_session_t, void *, size_t);
     ssize_t (*gnutls_record_send)(gnutls_session_t, const void *, size_t);
     ssize_t (*gnutls_record_recv_early_data)(gnutls_session_t, void *, size_t);