diff options
| author | Alexey Dobriyan <adobriyan@openvz.org> | 2007-01-26 00:57:16 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-01-26 13:51:00 -0800 |
| commit | 1fb844961818ce94e782acf6a96b92dc2303553b (patch) | |
| tree | f58153e0e6a21ee41761786c632f6261c30a3b8b | |
| parent | c20086de9319ac406f1e96ad459763c9f9965b18 (diff) | |
| download | lwn-1fb844961818ce94e782acf6a96b92dc2303553b.tar.gz lwn-1fb844961818ce94e782acf6a96b92dc2303553b.zip | |
[PATCH] core-dumping unreadable binaries via PT_INTERP
Proposed patch to fix #5 in
http://www.isec.pl/vulnerabilities/isec-0017-binfmt_elf.txt
aka
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2004-1073
To reproduce, do
* grab poc at the end of advisory.
* add line "eph.p_memsz = 4096;" after "eph.p_filesz = 4096;"
where first "4096" is something equal to or greater than 4096.
* ./poc /usr/bin/sudo && ls -l
Here I get with 2.6.20-rc5:
-rw------- 1 ad ad 102400 2007-01-15 19:17 core
---s--x--x 2 root root 101820 2007-01-15 19:15 /usr/bin/sudo
Check for MAY_READ like binfmt_misc.c does.
Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/binfmt_elf.c | 9 | ||||
| -rw-r--r-- | fs/binfmt_elf_fdpic.c | 8 |
2 files changed, 17 insertions, 0 deletions
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 90461f49e902..669dbe5b0317 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -682,6 +682,15 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs) retval = PTR_ERR(interpreter); if (IS_ERR(interpreter)) goto out_free_interp; + + /* + * If the binary is not readable then enforce + * mm->dumpable = 0 regardless of the interpreter's + * permissions. + */ + if (file_permission(interpreter, MAY_READ) < 0) + bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP; + retval = kernel_read(interpreter, 0, bprm->buf, BINPRM_BUF_SIZE); if (retval != BINPRM_BUF_SIZE) { diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c index 6e6d4568d548..a4d933a51208 100644 --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -234,6 +234,14 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm, goto error; } + /* + * If the binary is not readable then enforce + * mm->dumpable = 0 regardless of the interpreter's + * permissions. + */ + if (file_permission(interpreter, MAY_READ) < 0) + bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP; + retval = kernel_read(interpreter, 0, bprm->buf, BINPRM_BUF_SIZE); if (retval < 0) |