From 806bb07571b698d90169c3b73cb65cd09c900284 Mon Sep 17 00:00:00 2001
From: Jakub Filak <jfilak@redhat.com>
Date: Fri, 17 Apr 2015 14:40:20 +0200
Subject: [ABRT PATCH] ccpp: do not use value of /proc/PID/cwd for chdir
Avoid symlink resolutions.
This issue was discovered by Florian Weimer of Red Hat Product Security.
Signed-off-by: Jakub Filak <jfilak@redhat.com>
---
src/hooks/abrt-hook-ccpp.c | 85 +++++++++++++++++++++++-----------------------
1 file changed, 42 insertions(+), 43 deletions(-)
diff --git a/src/hooks/abrt-hook-ccpp.c b/src/hooks/abrt-hook-ccpp.c
index 82ff555..d600bb7 100644
--- a/src/hooks/abrt-hook-ccpp.c
+++ b/src/hooks/abrt-hook-ccpp.c
@@ -144,6 +144,7 @@ static off_t copyfd_sparse(int src_fd, int dst_fd1, int dst_fd2, off_t size2)
/* Global data */
static char *user_pwd;
+static DIR *proc_cwd;
static char *proc_pid_status;
static struct dump_dir *dd;
static int user_core_fd = -1;
@@ -163,13 +164,6 @@ static int user_core_fd = -1;
*/
static const char percent_specifiers[] = "%scpugteh";
static char *core_basename = (char*) "core";
-/*
- * Used for error messages only.
- * It is either the same as core_basename if it is absolute,
- * or $PWD/core_basename.
- */
-static char *full_core_basename;
-
static char* get_executable(pid_t pid, int *fd_p)
{
@@ -198,6 +192,18 @@ static char* get_executable(pid_t pid, int *fd_p)
return executable;
}
+static DIR *open_cwd(pid_t pid)
+{
+ char buf[sizeof("/proc/%lu/cwd") + sizeof(long)*3];
+ sprintf(buf, "/proc/%lu/cwd", (long)pid);
+
+ DIR *cwd = opendir(buf);
+ if (cwd == NULL)
+ perror_msg("Can't open process's CWD for CompatCore");
+
+ return cwd;
+}
+
static char* get_cwd(pid_t pid)
{
char buf[sizeof("/proc/%lu/cwd") + sizeof(long)*3];
@@ -268,13 +274,9 @@ static int dump_suid_policy()
static int open_user_core(uid_t uid, uid_t fsuid, pid_t pid, char **percent_values)
{
- errno = 0;
- if (user_pwd == NULL
- || chdir(user_pwd) != 0
- ) {
- perror_msg("Can't cd to '%s'", user_pwd);
+ proc_cwd = open_cwd(pid);
+ if (proc_cwd == NULL)
return -1;
- }
struct passwd* pw = getpwuid(uid);
gid_t gid = pw ? pw->pw_gid : uid;
@@ -337,15 +339,10 @@ static int open_user_core(uid_t uid, uid_t fsuid, pid_t pid, char **percent_valu
}
}
- full_core_basename = core_basename;
- if (core_basename[0] != '/')
+ if (g_need_nonrelative && core_basename[0] != '/')
{
- if (g_need_nonrelative)
- {
- error_msg("Current suid_dumpable policy prevents from saving core dumps according to relative core_pattern");
- return -1;
- }
- core_basename = concat_path_file(user_pwd, core_basename);
+ error_msg("Current suid_dumpable policy prevents from saving core dumps according to relative core_pattern");
+ return -1;
}
/* Open (create) compat core file.
@@ -381,7 +378,7 @@ static int open_user_core(uid_t uid, uid_t fsuid, pid_t pid, char **percent_valu
struct stat sb;
errno = 0;
/* Do not O_TRUNC: if later checks fail, we do not want to have file already modified here */
- int user_core_fd = open(core_basename, O_WRONLY | O_CREAT | O_NOFOLLOW | g_user_core_flags, 0600); /* kernel makes 0600 too */
+ int user_core_fd = openat(dirfd(proc_cwd), core_basename, O_WRONLY | O_CREAT | O_NOFOLLOW | g_user_core_flags, 0600); /* kernel makes 0600 too */
xsetegid(0);
xseteuid(0);
if (user_core_fd < 0
@@ -391,15 +388,15 @@ static int open_user_core(uid_t uid, uid_t fsuid, pid_t pid, char **percent_valu
|| sb.st_uid != fsuid
) {
if (user_core_fd < 0)
- perror_msg("Can't open '%s'", full_core_basename);
+ perror_msg("Can't open '%s' at '%s'", core_basename, user_pwd);
else
- perror_msg("'%s' is not a regular file with link count 1 owned by UID(%d)", full_core_basename, fsuid);
+ perror_msg("'%s' at '%s' is not a regular file with link count 1 owned by UID(%d)", core_basename, user_pwd, fsuid);
return -1;
}
if (ftruncate(user_core_fd, 0) != 0) {
/* perror first, otherwise unlink may trash errno */
- perror_msg("Can't truncate '%s' to size 0", full_core_basename);
- unlink(core_basename);
+ perror_msg("Can't truncate '%s' at '%s' to size 0", core_basename, user_pwd);
+ unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);
return -1;
}
@@ -466,10 +463,8 @@ static int create_or_die(const char *filename)
if (dd)
dd_delete(dd);
if (user_core_fd >= 0)
- {
- xchdir(user_pwd);
- unlink(core_basename);
- }
+ unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);
+
errno = sv_errno;
perror_msg_and_die("Can't open '%s'", filename);
}
@@ -573,7 +568,7 @@ int main(int argc, char** argv)
(long)pid, executable);
}
- user_pwd = get_cwd(pid); /* may be NULL on error */
+ user_pwd = get_cwd(pid);
log_notice("user_pwd:'%s'", user_pwd);
sprintf(path, "/proc/%lu/status", (long)pid);
@@ -672,6 +667,8 @@ int main(int argc, char** argv)
error_msg_and_die("Error saving '%s'", path);
}
log("Saved core dump of pid %lu (%s) to %s (%llu bytes)", (long)pid, executable, path, (long long)core_size);
+ if (proc_cwd != NULL)
+ closedir(proc_cwd);
return 0;
}
@@ -791,10 +788,7 @@ int main(int argc, char** argv)
unlink(path);
dd_delete(dd);
if (user_core_fd >= 0)
- {
- xchdir(user_pwd);
- unlink(core_basename);
- }
+ unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);
/* copyfd_sparse logs the error including errno string,
* but it does not log file name */
error_msg_and_die("Error writing '%s'", path);
@@ -807,8 +801,7 @@ int main(int argc, char** argv)
)
) {
/* nuke it (silently) */
- xchdir(user_pwd);
- unlink(core_basename);
+ unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);
}
/* Because of #1211835 and #1126850 */
@@ -879,6 +872,8 @@ int main(int argc, char** argv)
}
free(rootdir);
+ if (proc_cwd != NULL)
+ closedir(proc_cwd);
return 0;
}
@@ -890,19 +885,23 @@ int main(int argc, char** argv)
if (fsync(user_core_fd) != 0 || close(user_core_fd) != 0 || core_size < 0)
{
/* perror first, otherwise unlink may trash errno */
- perror_msg("Error writing '%s'", full_core_basename);
- xchdir(user_pwd);
- unlink(core_basename);
+ perror_msg("Error writing '%s' at '%s'", core_basename, user_pwd);
+ unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);
+ if (proc_cwd != NULL)
+ closedir(proc_cwd);
return 1;
}
if (ulimit_c == 0 || core_size > ulimit_c)
{
- xchdir(user_pwd);
- unlink(core_basename);
+ unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);
+ if (proc_cwd != NULL)
+ closedir(proc_cwd);
return 1;
}
- log("Saved core dump of pid %lu to %s (%llu bytes)", (long)pid, full_core_basename, (long long)core_size);
+ log("Saved core dump of pid %lu to %s at %s (%llu bytes)", (long)pid, core_basename, user_pwd, (long long)core_size);
}
+ if (proc_cwd != NULL)
+ closedir(proc_cwd);
return 0;
}
--
1.8.3.1