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-rw-r--r--libsandbox/wrapper-funcs/__wrapper_exec.c39
1 files changed, 28 insertions, 11 deletions
diff --git a/libsandbox/wrapper-funcs/__wrapper_exec.c b/libsandbox/wrapper-funcs/__wrapper_exec.c
index d372366..226c0c0 100644
--- a/libsandbox/wrapper-funcs/__wrapper_exec.c
+++ b/libsandbox/wrapper-funcs/__wrapper_exec.c
@@ -83,8 +83,8 @@ static bool sb_check_exec(const char *filename, char *const argv[])
({ \
Elf##n##_Ehdr *ehdr = (void *)elf; \
Elf##n##_Phdr *phdr = (void *)(elf + ehdr->e_phoff); \
- Elf##n##_Addr vaddr, filesz, vsym = 0, vstr = 0, vhash = 0; \
- Elf##n##_Off offset, symoff = 0, stroff = 0, hashoff = 0; \
+ Elf##n##_Addr vaddr, filesz, vsym = 0, vstr = 0, vhash = 0, vliblist = 0; \
+ Elf##n##_Off offset, symoff = 0, stroff = 0, hashoff = 0, liblistoff = 0; \
Elf##n##_Dyn *dyn; \
Elf##n##_Sym *sym, *symend; \
uint##n##_t ent_size = 0, str_size = 0; \
@@ -102,11 +102,12 @@ static bool sb_check_exec(const char *filename, char *const argv[])
dyn = (void *)(elf + phdr[i].p_offset); \
while (dyn->d_tag != DT_NULL) { \
switch (dyn->d_tag) { \
- case DT_SYMTAB: vsym = dyn->d_un.d_val; break; \
- case DT_SYMENT: ent_size = dyn->d_un.d_val; break; \
- case DT_STRTAB: vstr = dyn->d_un.d_val; break; \
- case DT_STRSZ: str_size = dyn->d_un.d_val; break; \
- case DT_HASH: vhash = dyn->d_un.d_val; break; \
+ case DT_SYMTAB: vsym = dyn->d_un.d_val; break; \
+ case DT_SYMENT: ent_size = dyn->d_un.d_val; break; \
+ case DT_STRTAB: vstr = dyn->d_un.d_val; break; \
+ case DT_STRSZ: str_size = dyn->d_un.d_val; break; \
+ case DT_HASH: vhash = dyn->d_un.d_val; break; \
+ case DT_GNU_LIBLIST: vliblist = dyn->d_un.d_val; break; \
} \
++dyn; \
} \
@@ -126,6 +127,8 @@ static bool sb_check_exec(const char *filename, char *const argv[])
stroff = offset + (vstr - vaddr); \
if (vhash >= vaddr && vhash < vaddr + filesz) \
hashoff = offset + (vhash - vaddr); \
+ if (vliblist >= vaddr && vliblist < vaddr + filesz) \
+ liblistoff = offset + (vliblist - vaddr); \
} \
\
/* Finally walk the symbol table. This should generally be fast as \
@@ -133,19 +136,33 @@ static bool sb_check_exec(const char *filename, char *const argv[])
* out there do not export any symbols at all. \
*/ \
if (symoff && stroff) { \
- /* Hash entries are always 32-bits. */ \
- uint32_t *hashes = (void *)(elf + hashoff); \
/* Nowhere is the # of symbols recorded, or the size of the symbol \
* table. Instead, we do what glibc does: use the sysv hash table \
* if it exists, else assume that the string table always directly \
* follows the symbol table. This seems like a poor assumption to \
- * make, but glibc has gotten by this long. \
+ * make, but glibc has gotten by this long. See determine_info in \
+ * glibc's elf/dl-addr.c. \
+ * \
+ * Turns out prelink will violate that assumption. Fortunately it \
+ * will insert its liblist at the same location all the time -- it \
+ * replaces the string table with its liblist table. \
+ * \
+ * Long term, we should behave the same as glibc and walk the gnu \
+ * hash table first before falling back to the raw symbol table. \
* \
* We don't sanity check the ranges here as you aren't executing \
* corrupt programs in the sandbox. \
*/ \
sym = (void *)(elf + symoff); \
- symend = vhash ? (sym + hashes[1]) : (void *)(elf + stroff); \
+ if (vhash) { \
+ /* Hash entries are always 32-bits. */ \
+ uint32_t *hashes = (void *)(elf + hashoff); \
+ symend = sym + hashes[1]; \
+ } else if (vliblist) \
+ symend = (void *)(elf + liblistoff); \
+ else \
+ symend = (void *)(elf + stroff); \
+ \
while (sym < symend) { \
char *symname = (void *)(elf + stroff + sym->st_name); \
if (ELF##n##_ST_VISIBILITY(sym->st_other) == STV_DEFAULT && \