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Move meta file usage to a file backed hashtable #11

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2c6eb66
move meta file usage to a filebacked hashmap
corbinlc Jan 28, 2019
2f029e4
make it more portable and print errors the proot way
corbinlc Jan 28, 2019
35ed6c6
small fix
corbinlc Jan 28, 2019
1c532c3
change init flow to only happen after bindings are resolved
corbinlc Jan 28, 2019
75a97de
use shorten_path, not path when checking directory permissions and ca…
corbinlc Jan 30, 2019
3df19a9
add unlink functionality for meta db
corbinlc Jan 30, 2019
34b5d0b
cleaning up some things based on review, more to come later
corbinlc Feb 1, 2019
3ebacf1
everything i am changing for now related to leveldb
corbinlc Feb 1, 2019
c60a7df
remove directory checks to further improve performance
corbinlc Feb 4, 2019
8ea1532
handle migration correctly and store mode in decimal
corbinlc Feb 4, 2019
998dd31
use lstat instead of stat to not follow symbolic links down when read…
corbinlc Feb 5, 2019
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2 changes: 1 addition & 1 deletion src/GNUmakefile
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ OBJDUMP ?= $(CROSS_COMPILE)objdump

CPPFLAGS += -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -I. -I$(VPATH)
CFLAGS += -Wall -Wextra -O2
LDFLAGS += -ltalloc -Wl,-z,noexecstack
LDFLAGS += -lleveldb -ltalloc -Wl,-z,noexecstack

OBJECTS += \
cli/cli.o \
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7 changes: 1 addition & 6 deletions src/extension/fake_id0/access.c
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Expand Up @@ -14,7 +14,6 @@ int handle_access_enter_end(Tracee *tracee, Reg path_sysarg,
int status, mode, perms, mask;
char path[PATH_MAX];
char rel_path[PATH_MAX];
char meta_path[PATH_MAX];

status = read_sysarg_path(tracee, path, path_sysarg, CURRENT);
if(status < 0)
Expand All @@ -35,10 +34,6 @@ int handle_access_enter_end(Tracee *tracee, Reg path_sysarg,
if(mode & F_OK)
return 0;

status = get_meta_path(path, meta_path);
if(status < 0)
return status;

mask = 0;
if((mode & R_OK) == R_OK)
mask += 4;
Expand All @@ -47,7 +42,7 @@ int handle_access_enter_end(Tracee *tracee, Reg path_sysarg,
if((mode & X_OK) == X_OK)
mask += 1;

perms = get_permissions(meta_path, config, 1);
perms = get_permissions(path, config, 1);
if((perms & mask) != mask)
return -EACCES;

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9 changes: 2 additions & 7 deletions src/extension/fake_id0/chmod.c
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Expand Up @@ -19,7 +19,6 @@ int handle_chmod_enter_end(Tracee *tracee, Reg path_sysarg, Reg mode_sysarg,
gid_t group;
char path[PATH_MAX];
char rel_path[PATH_MAX];
char meta_path[PATH_MAX];

// When path_sysarg is set to IGNORE, the call being handled is fchmod.
if(path_sysarg == IGNORE_SYSARG)
Expand All @@ -34,10 +33,6 @@ int handle_chmod_enter_end(Tracee *tracee, Reg path_sysarg, Reg mode_sysarg,
return 0;
}

status = get_meta_path(path, meta_path);
if(path_exists(meta_path) < 0)
return 0;

status = get_fd_path(tracee, rel_path, dirfd_sysarg, CURRENT);
if(status < 0)
return status;
Expand All @@ -46,11 +41,11 @@ int handle_chmod_enter_end(Tracee *tracee, Reg path_sysarg, Reg mode_sysarg,
if(status < 0)
return status;

read_meta_file(meta_path, &read_mode, &owner, &group, config);
read_meta_file(path, &read_mode, &owner, &group, config);
if(config->euid != owner && config->euid != 0)
return -EPERM;

call_mode = peek_reg(tracee, ORIGINAL, mode_sysarg);
set_sysnum(tracee, PR_getuid);
return write_meta_file(meta_path, call_mode, owner, group, 0, config);
return write_meta_file(path, call_mode, owner, group, 0, config);
}
14 changes: 3 additions & 11 deletions src/extension/fake_id0/chown.c
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Expand Up @@ -39,7 +39,6 @@ int handle_chown_enter_end(Tracee *tracee, Reg path_sysarg, Reg owner_sysarg,
gid_t group, read_group;
char path[PATH_MAX];
char rel_path[PATH_MAX];
char meta_path[PATH_MAX];

if(path_sysarg == IGNORE_SYSARG)
status = get_fd_path(tracee, path, fd_sysarg, CURRENT);
Expand All @@ -53,13 +52,6 @@ int handle_chown_enter_end(Tracee *tracee, Reg path_sysarg, Reg owner_sysarg,
return 0;
}

status = get_meta_path(path, meta_path);
if(status < 0)
return status;

if(path_exists(meta_path) != 0)
return 0;

status = get_fd_path(tracee, rel_path, dirfd_sysarg, CURRENT);
if(status < 0)
return status;
Expand All @@ -68,7 +60,7 @@ int handle_chown_enter_end(Tracee *tracee, Reg path_sysarg, Reg owner_sysarg,
if(status < 0)
return status;

read_meta_file(meta_path, &mode, &read_owner, &read_group, config);
read_meta_file(path, &mode, &read_owner, &read_group, config);
owner = peek_reg(tracee, ORIGINAL, owner_sysarg);
/** When chown is called without an owner specified, eg
* chown :1000 'file', the owner argument to the system call is implicitly
Expand All @@ -79,12 +71,12 @@ int handle_chown_enter_end(Tracee *tracee, Reg path_sysarg, Reg owner_sysarg,
owner = read_owner;
group = peek_reg(tracee, ORIGINAL, group_sysarg);
if(config->euid == 0)
write_meta_file(meta_path, mode, owner, group, 0, config);
write_meta_file(path, mode, owner, group, 0, config);

//TODO Handle chown properly: owner can only change the group of
// a file to another group they belong to.
else if(config->euid == read_owner) {
write_meta_file(meta_path, mode, read_owner, group, 0, config);
write_meta_file(path, mode, read_owner, group, 0, config);
poke_reg(tracee, owner_sysarg, read_owner);
}

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15 changes: 3 additions & 12 deletions src/extension/fake_id0/exec.c
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Expand Up @@ -13,7 +13,6 @@ int handle_exec_enter_end(Tracee *tracee, Reg filename_sysarg, Config *config)
{
int status, perms;
char path[PATH_MAX];
char meta_path[PATH_MAX];
uid_t uid;
gid_t gid;
mode_t mode;
Expand All @@ -24,26 +23,18 @@ int handle_exec_enter_end(Tracee *tracee, Reg filename_sysarg, Config *config)
if(status == 1)
return 0;

status = get_meta_path(path, meta_path);
if(status < 0)
return status;

/* If metafile doesn't exist, get out, but don't error. */
if(path_exists(meta_path) != 0)
return 0;

/* Check perms relative to / since there is no dirfd argument to execve */
status = check_dir_perms(tracee, 'r', meta_path, "/", config);
status = check_dir_perms(tracee, 'r', path, "/", config);
if(status < 0)
return status;

/* Check whether the file has execute permission. */
perms = get_permissions(meta_path, config, 0);
perms = get_permissions(path, config, 0);
if((perms & 1) != 1)
return -EACCES;

/* If the setuid or setgid bits are on, change config accordingly. */
read_meta_file(meta_path, &mode, &uid, &gid, config);
read_meta_file(path, &mode, &uid, &gid, config);
if ((mode & S_ISUID) != 0) {
config->ruid = 0;
config->euid = 0;
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11 changes: 11 additions & 0 deletions src/extension/fake_id0/fake_id0.c
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Expand Up @@ -350,6 +350,8 @@ static FilteredSysnum filtered_sysnums[] = {
FILTERED_SYSNUM_END,
};

bool meta_initialized;

/**
* Restore the @node->mode for the given @node->path.
*
Expand Down Expand Up @@ -1079,6 +1081,8 @@ int fake_id0_callback(Extension *extension, ExtensionEvent event, intptr_t data1
Config *config;
int uid, gid;

meta_initialized = false;

errno = 0;
uid = strtol(uid_string, NULL, 10);
if (errno != 0)
Expand Down Expand Up @@ -1206,6 +1210,13 @@ int fake_id0_callback(Extension *extension, ExtensionEvent event, intptr_t data1
Tracee *tracee = TRACEE(extension);
Config *config = talloc_get_type_abort(extension->config, Config);

#ifdef USERLAND
if (!meta_initialized) {
init_meta_hash(tracee);
meta_initialized = true;
}
#endif

return handle_sysenter_end(tracee, config);
}

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